  SEQ CHAPTER \h \r 1 ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 82

[EPA-HQ-OAR-2002-0064; FRL-xxxx-x]	

RIN 2060-AK26

Protection of Stratospheric Ozone:  Listing of Substitutes for
Ozone-Depleting

Substances–n-Propyl Bromide

AGENCY:  Environmental Protection Agency.

ACTION:  Notice of Proposed Rulemaking

SUMMARY:  Pursuant to the U.S. Environmental Protection Agency’s (EPA
or “we”) Significant New Alternatives Policy (SNAP) program, this
action proposes to list n-propyl bromide (nPB) as an acceptable
substitute for methyl chloroform and chlorofluorocarbon (CFC)-113 in the
solvent cleaning sector and to list nPB as acceptable, subject to use
conditions, as a substitute for methyl chloroform, CFC-113, and
hydrochlorofluorocarbon (HCFC)-141b in the coatings end use.  We also
recommend that users be exposed to no more than 17 parts per million of
nPB on an eight-hour, time-weighted average.  This action also proposes
to list nPB as an unacceptable substitute for methyl chloroform,
CFC-113, and HCFC-141b when used in adhesives or in aerosol solvents
because nPB in these end uses poses unacceptable risks to human health,
when compared with other substitutes that are available.  This proposal
supersedes EPA’s proposal of June 3, 2003 on the acceptability of nPB
as a substitute for ozone-depleting substances. 

EPA is also taking comment on an alternate proposal in which nPB would
be acceptable, subject to use conditions, as a substitute for
ozone-depleting substances.  Under that alternate proposal, users would
be allowed to use nPB only if they meet a workplace exposure limit of 17
ppm on an eight-hour time-weighted average, monitor workers’ exposure
to nPB with personal breathing zone samples on an eight-hour
time-weighted average, both initially and periodically, and keep records
of the worker exposure data on site at the facility.  

DATES:  Comments must be received in writing by [Insert date 60 days
after Federal Register publication date].  Under the Paperwork Reduction
Act, comments on the information collection provisions must be received
by OMB on or before [insert date [thirty] days after date of publication
in the Federal Register].  Any person interested in requesting a public
hearing, must submit such request on or before [insert 30 days from date
of publication in the Federal Register].  If a public hearing is
requested, a separate notice will be published announcing the date and
time of the public hearing and the comment period will be extended until
30 days after the public hearing to allow rebuttal and supplementary
information regarding any material presented at the public hearing. 
Inquires regarding a public hearing should be directed to the contact
person listed below. 

ADDRESSES:  Submit your comments, identified by Docket ID No.
EPA-HQ-OAR-2002-0064, by one of the following methods:

  HYPERLINK "http://www.regulations.gov"  http://www.regulations.gov . 
Follow the on-line instructions for submitting comments.

E-mail: A-And-R-Docket@epa.gov

Mail:  Air and Radiation Docket, Environmental Protection Agency,
Mailcode 6102T, 1200 Pennsylvania Ave., NW, Washington, DC, 20460,
Attention Docket ID No. EPA-HQ-OAR-2002-0064.  In addition, please mail
a copy of your comments on the information collection provisions to the
Office of Information and Regulatory Affairs, Office of Management and
Budget (OMB), Attn: Desk Officer for EPA, 725 17th St. NW., Washington,
DC 20503.

Hand Delivery:  EPA Docket Center, (EPA/DC) EPA West, Room B102, 1301
Constitution Ave., NW, Washington, D.C., Attention Docket ID No.
EPA-HQ-OAR-2002-0064.  Such deliveries are only accepted during the
Docket’s normal hours of operation, and special arrangements should be
made for deliveries of boxed information.

     Instructions:  Direct your comments to Docket ID No.
EPA-HQ-OAR-2002-0064.  EPA's policy is that all comments received will
be included in the public docket without change and may be made
available online at   HYPERLINK "http://www.regulations.gov" 
www.regulations.gov , including any personal information provided,
unless the comment includes information claimed to be Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute.  Do not submit information that you consider to
be CBI or otherwise protected through www.regulations.gov or e-mail. 
The www.regulations.gov websites is an “anonymous access” system,
which means EPA will not know your identity or contact information
unless you provide it in the body of your comment.  If you send an
e-mail comment directly to EPA without going through
www.regulations.gov, your e-mail address will be automatically captured
and included as part of the comment that is placed in the public docket
and made available on the Internet.  If you submit an electronic
comment, EPA recommends that you include your name and other contact
information in the body of your comment and with any disk or CD-ROM you
submit.  If EPA cannot read your comment due to technical difficulties
and cannot contact you for clarification, EPA may not be able to
consider your comment.  Electronic files should avoid the use of special
characters, any form of encryption, and be free of any defects or
viruses.  For additional instructions on submitting comments, go to
Section I.B. of the SUPPLEMENTARY INFORMATION section of this document.

	Docket: All documents in the docket are listed in the   HYPERLINK
"http://www.regulations.gov"  www.regulations.gov  index.  Although
listed in the index, some information is not publicly available, i.e.,
CBI or other information whose disclosure is restricted by statute. 
Certain other material, such as copyrighted material, is not placed on
the Internet and will be publicly available only in hard copy form. 
Publicly available docket materials are available either electronically
in   HYPERLINK "http://www.regulations.gov"  www.regulations.gov  or in
hard copy at the Air and Radiation Docket, EPA/DC, EPA West, Room B102,
1301 Constitution Ave., NW, Washington, DC.  The Public Reading Room is
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays.  The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air and Radiation Docket is
(202) 566-1742.

FOR FURTHER INFORMATION CONTACT:  Margaret Sheppard, Stratospheric
Protection Division, Office of Atmospheric Programs, Mail Code 6205J,
Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460; telephone number (202) 343-9163; fax number (202)
343-2338, e-mail address:  sheppard.margaret@epa.gov.  Notices and
rulemakings under the SNAP program are available on EPA’s
Stratospheric Ozone World Wide Web site at www.epa.gov/ozone/snap/regs. 

SUPPLEMENTARY INFORMATION: 

	Table of Contents

 TOC \f 

I. 	General Information

A. Does this action apply to me?

B. What should I consider as I prepare my comments for EPA?

C.  What acronyms and abbreviations are used in the preamble?

II.  	How does the Significant New Alternatives Policy (SNAP) program
work?

	A. What are the statutory requirements and authority for the SNAP
program?

	B. How do the regulations for the SNAP program work?

	C. Where can I get additional information about the SNAP program?

III.	Is EPA listing n–propyl bromide as an acceptable substitute for
ozone-depleting substances?

A.  What is EPA proposing today?

B.  What is n-propyl bromide?

C.  What industrial end uses are included in our proposed decision?

D.  What does an unacceptability determination on adhesives and aerosols
mean?

E. What is the scope of the proposed determination for coatings?

F.   How would the use conditions in the alternate proposal work?  

IV.	What criteria did EPA consider in preparing this proposal?

	A.	Availability

	B. 	Impacts on the atmosphere and local air quality 

	C.	Ecosystem and other environmental impacts

	D.	Flammability and fire safety

	E.	Impact on human health

V.	How did EPA derive the proposed workplace exposure limit and
community exposure guideline used to assess impacts on human health?

	A.	Workplace exposure limit

	B.	Community exposure guideline

VI.	What listing is EPA proposing for each sector or end use, and why?

	A.	Solvent Cleaning

B.	Aerosol Solvents

C.	Adhesives

D.	Coatings

VII	How did EPA choose the use conditions in the alternate proposal, and
why?

	A.	Use conditions and their rationale

	B.	Advantages and disadvantages of the alternate proposal

VIII.	What other options did EPA consider?

	A.	Regulatory options based on the ACGIH's Threshold Limit Value

	B.	Regulatory options requiring ventilation equipment

IX.	What are the anticipated costs of this regulation to the regulated
community?

X. 	Comparison of EPA’s June 2003 proposal and this proposal

How can I use nPB as safely as possible? 

Statutory and Executive Order Reviews

Executive Order 12866:  Regulatory Planning and Review 

Paperwork Reduction Act

Regulatory Flexibility Act (RFA)

Unfunded Mandates Reform Act

Executive Order 13132: Federalism

Executive Order 13175:  Consultation and Coordination with Indian Tribal
Governments

Executive Order 13045:  Protection of Children from Environmental Health
and Safety Risks 

Executive Order 13211:  Actions that Significantly Affect Energy Supply,
Distribution, or Use

National Technology Transfer and Advancement Act

References

 I. 	General Information tc "I. 	General Information"   TC "I. 	General
Information" \f A \l "1"  

	A.	Does this action apply to me?  tc "	A. Does this action apply to me?
" \l 2 

	This proposed rule would regulate the use of n-propyl bromide as a
solvent used in industrial equipment for metals cleaning, electronics
cleaning, or precision cleaning, as an aerosol solvent, and as a carrier
solvent in adhesives and coatings.  Businesses in these end uses that
currently might be using nPB, or might want to use it in the future,
include:

Businesses that clean metal parts, such as automotive manufacturers,
machine shops, machinery manufacturers, and electroplaters.

Businesses that manufacture electronics or computer equipment.

Businesses that require a high level of cleanliness in removing oil,
grease, or wax, such as for aerospace applications or for manufacture of
optical equipment.

Foam fabricators that glue pieces of polyurethane foam together or foam
cushion manufacturers that glue fabric around a cushion.

Furniture manufacturers that use adhesive to attach wood parts to
floors, tables and counter tops.

A company that manufactures ammunition for the U.S. Department of
Defense.

	Regulated entities may include:

Table 1–Potentially Regulated Entities, by North American Industrial
Classification System (NAICS) Code or Subsector

Category	NAICS code or subsector	Description of regulated entities

Industry	331	Primary Metal Manufacturing

Industry	332	Fabricated Metal Product Manufacturing

Industry/Military	332992 	Small Arms Ammunition Manufacturing

Industry	333	Machinery Manufacturing

Industry	334	Computer and Electronic Product Manufacturing

Industry	335	Equipment Appliance, and Component Manufacturing

Industry	336	Transportation Equipment Manufacturing

Industry	337	Furniture and Related Product Manufacturing

Industry	339	Miscellaneous Manufacturing

Industry	326150	Urethane and Other Foam Product (except Polystyrene)
Manufacturing



	This table is not intended to be exhaustive, but rather a guide
regarding entities likely to be regulated by this action.  If you have
any questions about whether this action applies to a particular entity,
consult the person listed in the preceding section, “FOR FURTHER
INFORMATION CONTACT.”

	B. 	What should I consider as I prepare my comments for EPA?  tc "	B. 
What should I consider as I prepare my comments for EPA? " \l 2 

		1.	Submitting Confidential Business Information (CBI).  Do not submit
this information to EPA through www.regulations.gov or e-mail.  Clearly
mark the part or all of the information that you claim to be CBI.  For
CBI information in a disk or CD ROM that you mail to EPA, mark the
outside of the disk or CD ROM as CBI and then identify electronically
within the disk or CD ROM the specific information that is claimed as
CBI.  In addition to one complete version of the comment that includes
information claimed as CBI, a copy of the comment that does not contain
the information claimed as CBI must be submitted for inclusion in the
public docket.  Information so marked will not be disclosed except in
accordance with procedures set forth in 40 CFR part 2.  

		2.	Tips for Preparing Your Comments.  When submitting comments,
remember to:

Identify the rulemaking by docket number and other identifying
information (subject heading, Federal Register date and page number).

Follow directions - The agency may ask you to respond to specific
questions or organize comments by referencing a Code of Federal
Regulations (CFR) part or section number.

Explain why you agree or disagree; suggest alternatives and substitute
language for your requested changes.

Describe any assumptions and provide any technical information and/or
data that you used.

If you estimate potential costs or burdens, explain how you arrived at
your estimate in sufficient detail to allow for it to be reproduced.

Provide specific examples to illustrate your concerns, and suggest
alternatives.

Explain your views as clearly as possible, avoiding the use of profanity
or personal threats.

Make sure to submit your comments by the comment period deadline
identified.

    	C.	What acronyms and abbreviations are used in the preamble?  tc
"C.  What acronyms and abbreviations are used in the preamble? " \l 2 

	Below is a list of acronyms and abbreviations used in this document. 

8-hr—eight hour

ACGIH–American Conference of Governmental Industrial Hygienists

AEL–acceptable exposure limit

ASTM–American Society for Testing and Materials

BMD–benchmark dose

BMDL–benchmark dose lowerbound, the lower 95%-confidence level bound
on the dose/exposure associated with the benchmark response

BSOC–Brominated Solvents Consortium

CAA–Clean Air Act

CAS Reg. No–Chemical Abstracts Service Registry Identification Number

CBI–Confidential Business Information

CEG–community exposure guideline

CERHR–Center for the Evaluation of Risks to Human Reproduction

CFC-113–the ozone-depleting chemical
1,1,2-trifluoro-1,2,2-trichloroethane, C2Cl3F3, CAS Reg. No. 76-13-1

CFC–chlorofluorocarbon

cfm–cubic feet per minute

CFR–Code of Federal Regulations

CNS–central nervous system

DNA—deoxyribonucleic acid

EDSTAC--The Endocrine Disruptor Screening and Testing Advisory Committee

EPA–the United States Environmental Protection Agency

FR–Federal Register

GWP—global warming potential

HCFC-123–the ozone-depleting chemical
1,2-dichloro-1,1,2-trifluoroethane, CAS Reg. No. 306-83-2

HCFC-141b–the ozone-depleting chemical 1,1-dichloro-1-fluoroethane,
CAS Reg. No. 1717-00-6

HCFC-225ca/cb–the commercial mixture of the two ozone-depleting
chemicals 3,3-dichloro- 1,1,1,2,2-pentafluoropropane, CAS Reg. No.
422-56-0 and 1,3-dichloro-1,1,2,2,3-pentafluoropropane, CAS Reg. No.
507-55-1

HCFC–hydrochlorofluorocarbon

HEC–human equivalent concentration

HFC-245fa–the chemical 1,1,3,3,3-pentafluoropropane, CAS Reg. No.
460-73-1

HFC-365mfc–the chemical 1,1,1,3,3-pentafluorobutane, CAS Reg. No.
405-58-6

HFC-4310mee –the chemical 1,1,1,2,3,4,4,5,5,5-decafluoropentane, CAS
Reg. No. 138495-42-8 HFC–hydrofluorocarbon

HFE–hydrofluoroether

HHE–health hazard evaluation

ICF–ICF Consulting

ICR–Information Collection Request

iPB–isopropyl bromide, C3H7Br, CAS Reg. No. 75-26-3, an isomer of
n-propyl bromide; also called 2-bromopropane or 2-BP

Koc–organic carbon partition coefficient, for determining the tendency
of a chemical to bind to organic carbon in soil

LC50 –the concentration at which 50% of test animals die

LOAEL–Lowest Observed Adverse Effect Level

Log Kow–logarithm of the octanol-water partition coefficient, for
determining the tendency of a chemical to accumulate in lipids or fats
instead of remaining dissolved in water

mg/l–milligrams per liter

MSDS–Material Safety Data Sheet

NAICS–North American Industrial Classification System

NESHAP–National Emission Standard for Hazardous Air Pollutants

NIOSH–National Institute for Occupational Safety and Health

NOAEL–No Observed Adverse Effect Level

NOEL–No Observed Effect Level

nPB–n-propyl bromide, C3H7Br, CAS Reg. No. 106-94-5; also called
1-bromopropane or 1-BP

NPRM–Notice of Proposed Rulemaking

NTP–National Toxicology Program

NTTAA–National Technology Transfer and Advancement Act

ODP–ozone depletion potential

ODS–ozone-depleting substance

OEHHA–Office of Environmental Health Hazard Assessment of the
California Environmental Protection Agency

OMB–U.S. Office of Management and Budget

OSHA–the United States Occupational Safety and Health Administration

PCBTF–parachlorobenzotrifluoride, CAS Reg. No. 98-56-6 

PEL–Permissible Exposure Limit

ppm–parts per million

RCRA–Resource Conservation and Recovery Act

RFA–Regulatory Flexibility Act

RfC–reference concentration

SNAP–Significant New Alternatives Policy 

TCA–the ozone-depleting chemical 1,1,1-trichloroethane, CAS Reg. No.
71-55-6; also called methyl chloroform, MCF, or 1,1,1

–Threshold Limit Value™

TSCA–Toxic Substances Control Act

TWA–time-weighted average

UF–uncertainty factor

UMRA–Unfunded Mandates Reform Act

U.S.C.–United States Code

VMSs–volatile methyl siloxanes

VOC–volatile organic compound

WEL–workplace exposure limit

II.  	How does the Significant New Alternatives Policy (SNAP) program
work? tc "II.  	How does the Significant New Alternatives Policy (SNAP)
program work?" 

	A.  What are the statutory requirements and authority for the SNAP
program?

	Section 612 of the Clean Air Act (CAA) authorizes EPA to develop a
program for evaluating alternatives to ozone-depleting substances,
referred to as the Significant New Alternatives Policy (SNAP) program. 
The major provisions of section 612 are: 

Rulemaking–Section 612(c) requires EPA to promulgate rules making it
unlawful to replace any class I (chlorofluorocarbon, halon, carbon
tetrachloride, methyl chloroform, and hydrobromofluorocarbon) or class
II (hydrochlorofluorocarbon) substance with any substitute that the
Administrator determines may present adverse effects to human health or
the environment where the Administrator has identified an alternative
that (1) reduces the overall risk to human health and the environment,
and (2) is currently or potentially available.

Listing of Unacceptable/Acceptable Substitutes--Section 612(c) also
requires EPA to publish a list of the substitutes unacceptable for
specific uses.  We must publish a corresponding list of acceptable
alternatives for specific uses.

Petition Process--Section 612(d) grants the right to any person to
petition EPA to add a substitute to or delete a substitute from the
lists published in accordance with section 612(c).  EPA has 90 days to
grant or deny a petition.  Where the Agency grants the petition, we must
publish the revised lists within an additional six months.

90-day Notification--Section 612(e) requires EPA to require any person
who produces a chemical substitute for a class I substance to notify the
Agency not less than 90 days before new or existing chemicals are
introduced into interstate commerce for significant new uses as
substitutes for a class I substance.  The producer must also provide the
Agency with the producer's health and safety studies on such
substitutes.

Outreach--Section 612(b)(1) states that the Administrator shall seek to
maximize the use of federal research facilities and resources to assist
users of class I and II substances in identifying and developing
alternatives to the use of such substances in key commercial
applications.

Clearinghouse--Section 612(b)(4) requires the Agency to set up a public
clearinghouse of alternative chemicals, product substitutes, and
alternative manufacturing processes that are available for products and
manufacturing processes which use class I and II substances.

	B.  How do the regulations for the SNAP program work?

	On March 18, 1994, EPA published the original rulemaking (59 FR 13044)
that described the process for administering the SNAP program and issued
the first acceptability lists for substitutes in the major industrial
use sectors.  These sectors include:  refrigeration and air
conditioning; foam blowing; solvents cleaning; fire suppression and
explosion protection; sterilants; aerosols; adhesives, coatings and
inks; and tobacco expansion.  These sectors comprise the principal
industrial sectors that historically consumed large volumes of
ozone-depleting substances.

	Anyone who plans to market or produce a substitute for an
ozone-depleting substance (ODS) in one of the eight major industrial use
sectors must provide the Agency with health and safety studies on the
substitute at least 90 days before introducing it into interstate
commerce for significant new use as an alternative.  This requirement
applies to the person planning to introduce the substitute into
interstate commerce, typically chemical manufacturers, but may also
include importers, formulators or end-users when they are responsible
for introducing a substitute into commerce.

	The Agency has identified four possible decision categories for
substitutes:  acceptable; acceptable subject to use conditions;
acceptable subject to narrowed use limits; and unacceptable.  Use
conditions and narrowed use limits are both considered “use
restrictions” and are explained below.  Substitutes that are deemed
acceptable with no use restrictions (no use conditions or narrowed use
limits) can be used for all applications within the relevant sector
end-use.  Substitutes that are acceptable subject to use restrictions
may be used only in accordance with those restrictions.  It is illegal
to replace an ODS with a substitute listed as unacceptable.

	After reviewing a substitute, the Agency may make a determination that
a substitute is acceptable only if certain conditions of use are met to
minimize risks to human health and the environment.  We describe such
substitutes as "acceptable subject to use conditions."  If you use these
substitutes without meeting the associated use conditions, you use these
substitutes in an unacceptable manner and you could be subject to
enforcement for violation of section 612 of the Clean Air Act.

	For some substitutes, the Agency may permit a narrowed range of use
within a sector.   For example, we may limit the use of a substitute to
certain end-uses or specific applications within an industry sector or
may require a user to demonstrate that no other acceptable end uses are
available for their specific application.  We describe these substitutes
as “acceptable subject to narrowed use limits.”  If you use a
substitute that is acceptable subject to narrowed use limits, but use it
in applications and end-uses which are not consistent with the narrowed
use limit, you are using these substitutes in an unacceptable manner and
you could be subject to enforcement for violation of section 612 of the
Clean Air Act.

	The Agency publishes its SNAP program decisions in the Federal
Register.  For those substitutes that are deemed acceptable subject to
use restrictions (use conditions and/or narrowed use limits), or for
substitutes deemed unacceptable, we first publish these decisions as
proposals to allow the public opportunity to comment, and we publish
final decisions as final rulemakings. 

In contrast, we publish substitutes that are deemed acceptable with no
restrictions in “notices of acceptability,” rather than as proposed
and final rules.  As described in the rule implementing the SNAP program
(59 FR 13044), we do not believe that rulemaking procedures are
necessary to list alternatives that are acceptable without restrictions
because such listings neither impose any sanction nor prevent anyone
from using a substitute.

	Many SNAP listings include “comments” or “further information.”
 These statements provide additional information on substitutes that we
determine are either unacceptable, acceptable subject to narrowed use
limits, or acceptable subject to use conditions.  Since this additional
information is not part of the regulatory decision, these statements are
not binding for  use of the substitute under the SNAP program.  However,
regulatory requirements listed in this column are binding under other
programs.  The further information does not necessarily include all
other legal obligations pertaining to the use of the substitute. 
However, we encourage users of substitutes to apply all statements in
the “Further Information” column in their use of these substitutes. 
In many instances, the information simply refers to sound operating
practices that have already been identified in existing industry and/or
building-code standards.  Thus, many of the comments, if adopted, would
not require the affected industry to make significant changes in
existing operating practices.	

C.  Where can I get additional information about the SNAP program?

	For copies of the comprehensive SNAP lists of substitutes or additional
information on

SNAP, look at EPA’s Ozone Depletion World Wide Web site at
http://www.epa.gov/ozone/snap/lists/index.html.  For more information on
the Agency's process

for administering the SNAP program or criteria for evaluation of
substitutes, refer to the SNAP final rulemaking published in the Federal
Register on March 18, 1994 (59 FR 13044), codified at Code of Federal
Regulations at 40 CFR part 82, subpart G.  You can find a complete
chronology of SNAP decisions and the appropriate Federal Register
citations at http://www.epa.gov/ozone/snap/chron.html.

III.	Is EPA listing n–propyl bromide as an acceptable substitute for
ozone-depleting substances? tc "III.	Is EPA listing n–propyl bromide
as an acceptable substitute for ozone-depleting substances?" 

	A.	What is EPA proposing today?  tc "	A.  What is EPA proposing today?
" \l 2 

	In this action, EPA proposes to list n-propyl bromide (nPB) as (1)
acceptable for use as a substitute for CFC-113 and methyl chloroform in
solvent cleaning in the metals, precision and electronics cleaning end
uses; (2) unacceptable for use as a substitute for CFC-113, methyl
chloroform and HCFC-141b in the adhesive and aerosol solvent end uses;
and (3) acceptable subject to use conditions (limited to coatings at
facilities that have provided EPA with information as of [INSERT DATE OF
PUBLICATION] demonstrating their ability to meet the recommended
workplace exposure limit) as a substitute for methyl chloroform,
CFC-113, and HCFC-141b in the coatings end use.  This Notice of Proposed
Rulemaking (NPRM) supersedes the NPRM published on June 3, 2003 (68 FR
33284). 

We also are taking comment on an alternate proposal.  Under the
alternate proposal, nPB would be acceptable, subject to use conditions,
in the metals, electronics, and precision cleaning, aerosol solvent,
adhesives, and coatings end uses.  The use of nPB in these end uses
would be subject to conditions that users must (1) meet a workplace
exposure limit of 17 ppm on an eight-hour time-weighted average (8-hr
TWA), (2) monitor workers’ exposure to nPB using a personal breathing
zone sampler on an eight-hour time-weighted average initially and
periodically (every 6 months or longer, depending on the concentration
during initial monitoring), and (3) keep records of the worker exposure
data on site at the facility for at least three years from the date of
the measurement.

	B.	What is n-propyl bromide?  tc "	B.   What is n-propyl bromide? " \l
2 

	n-propyl bromide (nPB), also called 1-bromopropane, is a non-flammable
organic solvent with a strong odor.  Its chemical formula is C3H7Br. 
Its identification number in Chemical Abstracts Service’s registry
(CAS Reg. No.) is 106-94-5.  nPB is used to remove wax, oil, and grease
from electronics, metal, and other materials.  It also is used as a
carrier solvent in adhesives.  Some brand names of products using nPB
are:  Abzol®, EnSolv®, and Solvon® cleaners; Pow-R-Wash® NR Contact
Cleaner, Superkleen Flux Remover 2311 and LPS NoFlash NU Electro Contact
Cleaner aerosols; and Whisper Spray and Fire Retardant Soft Seam 6460
adhesives.

	C. 	What industrial end uses are included in our proposed decision?  tc
"	C. 	What industrial end uses are included in our proposed decision? "
\l 2 	

Solvent Cleaning  TC "Solvent Cleaning" \f A \l "3"  

	General metals, precision, and electronics cleaning includes cleaning
with industrial cleaning equipment such as vapor degreasers, in-line
cleaning systems, or automated equipment used for cleaning below the
boiling point.  We understand that nPB is use primarily for cleaning in
vapor degreasers.  Manual cleaning, such as pail-and-brush, hand wipe,
recirculating over-spray (“sink-on-a-drum”) parts washers, immersion
cleaning into dip tanks with manual parts handling, and use of squirt
bottles, is not currently regulated under the SNAP program.  However,
EPA is reviewing whether these applications should be covered under the
SNAP program, and for now, we do not recommend the use of nPB in these
applications because of the difficulty of controlling emissions to a
safe level.  EPA also does not regulate the use of solvents as carriers
for flame retardants, dry cleaning, or paint stripping.  

2.	Aerosol Solvents  TC "Aerosol Solvents" \f A \l "3"  

	We understand that nPB is being used as an aerosol solvent in:

     •    Lubricants, coatings, or cleaning fluids for electrical or
electronic equipment;

     •    Lubricants, coatings, or cleaning fluids for aircraft
maintenance; or

     •    Spinnerrette lubricants and cleaning sprays used in the
production of synthetic fibers.

Recently, users of HCFC-141b, in particular, have been considering the
use of nPB as an ODS substitute in these industrial applications.  

Adhesives  TC "Adhesives" \f A \l "3"  

	Types of adhesives covered under the SNAP program are those that
formerly used methyl chloroform, specifically, adhesives for laminates,
flexible foam, hardwood floors, tire patches, and metal to rubber
adhesives.  Of these applications, nPB-based adhesives have been used
most widely in spray adhesives used in manufacture of foam cushions, and
to a lesser degree in laminate adhesives.  

Coatings  TC "Coatings" \f A \l "3"  

	The SNAP program regulates the use of carrier solvents in durable
coatings, including paints, varnishes, and aerospace coatings (59 FR
13118).  The SNAP program currently does not regulate carrier solvents
in lubricant coatings, such as silicone coatings used on medical
equipment (59 FR 13119).  Methyl chloroform has been used as a carrier
solvent in coatings, and to a much lesser degree, HCFC-141b also has
been a carrier solvent.  This rule responds to a submission from a
facility that is substituting methyl chloroform with nPB in an
ammunition coating (sealant).

5.	Proposed Text for Listing Decisions  TC "5.		Proposed Listings" \f A
\l "3"  

	In the proposed regulatory text at the end of this document, you will
find our proposed listing decisions for those end uses that would be
unacceptable or acceptable subject to narrowed use limits.  The proposed
conditions listed in the “Use Conditions“ column would be
enforceable while information contained in the “Further Information”
column of those tables provides additional recommendations on the safe
use of nPB.  Although EPA expects nPB users to conform to all
information included in a final listing, the “further information”
is not part of the regulatory decision, and therefore is not mandatory. 
Also, there may be other legal obligations pertaining to the
manufacture, use, handling, and disposal of nPB that are not included in
the information listed in the tables.  Our listings of substitutes that
are acceptable without restriction are not provided in the Code of
Federal Regulations because they are not regulatory requirements.  EPA
is proposing to find nPB acceptable without restrictions in some end
uses, rather than issuing the listing in a notice, in order to give the
public the opportunity to comment on issues that are relevant to all end
uses.  You may find lists of substitutes that are acceptable without
restrictions on EPA’s SNAP web site at
http://www.epa.gov/ozone/snap/lists/index.html.  Our proposed decisions
and the alternate proposals for each end use are summarized below in
tables 2 through 8. PROPOSED LISTINGS

Table 2.  SOLVENT CLEANING

PROPOSED ACCEPTABLE SUBSTITUTES

End Use	Substitute	Decision	Further Information

Metals cleaning, electronics cleaning, and precision cleaning	n-propyl
bromide (nPB) as a substitute for CFC-113 and methyl chloroform
Acceptable 	EPA recommends the use of personal protective equipment,
including chemical goggles, flexible laminate protective gloves and
chemical-resistant clothing.  

EPA expects that all users of nPB will adhere to a voluntary acceptable
exposure limit of 17 parts per million (ppm) on an 8-hour time-weighted
average and would comply with any final Permissible Exposure Limit that
the Occupational Safety and Health Administration issues in the future. 
 

nPB, also known as 1-bromopropane, is Number 106-94-5 in the Chemical
Abstracts Service (CAS) Registry.



Note: In accordance with the limitations provided in Section 310(a) of
the Clean Air Act (42 U.S.C. 7610(a)), nothing in this table shall
affect the Occupational Safety and Health Administrations’ authority
to promulgate and enforce standards and other requirements under the
Occupational Safety and Health Act of 1970 (29 U.S.C. 651 et seq.)

  



Table 3.  AEROSOLS

PROPOSED UNACCEPTABLE SUBSTITUTES

End Use	Substitute	Decision	Further Information

Aerosol solvents	n-propyl bromide (nPB) as a substitute for CFC-113,
HCFC-141b, and methyl chloroform	Unacceptable	EPA finds unacceptable
risks to human health in this end use compared to other available
alternatives.  nPB, also known as 1-bromopropane, is Number 106-94-5 in
the CAS Registry.



Table 4.  ADHESIVES, COATINGS, AND INKS

PROPOSED UNACCEPTABLE SUBSTITUTES

End Use	Substitute	Decision	Further Information

Adhesives	n-propyl bromide (nPB) as a substitute for CFC-113, HCFC-141b,
and methyl chloroform	Unacceptable	EPA finds unacceptable risks to human
health in this end use compared to other available alternatives.  nPB,
also known as 1-bromopropane, is Number 106-94-5 in the CAS Registry.



Table 5.  ADHESIVES, COATINGS, AND INKS

SUBSTITUTES THAT ARE PROPOSED ACCEPTABLE SUBJECT TO USE CONDITIONS

End Use	Substitute	Decision	Use Conditions	Further Information

Coatings	n-propyl bromide (nPB) as a substitute for methyl chloroform,
CFC-113, and HCFC-141b	Acceptable subject to use conditions	Use is
limited to coatings at facilities that have provided EPA information
demonstrating their ability to meet the recommended workplace exposure
limit as of [INSERT DATE OF PUBLICATION].

	EPA recommends the use of personal protective equipment, including
chemical goggles, flexible laminate protective gloves and
chemical-resistant clothing.  

EPA expects that all users of nPB will adhere to a voluntary acceptable
exposure limit of 17 ppm on an 8-hour time-weighted average and would
comply with any final Permissible Exposure Limit that the Occupational
Safety and Health Administration issues in the future.  

nPB, also known as 1-bromopropane, is Number 106-94-5 in the CAS
Registry.

Note 1: In accordance with the limitations provided in Section 310(a) of
the Clean Air Act (42 U.S.C. 7610(a)), nothing in this table shall
affect the Occupational Safety and Health Administrations’ authority
to promulgate and enforce standards and other requirements under the
Occupational Safety and Health Act of 1970 (29 U.S.C. 651 et seq.)

Note 2:  As of [INSERT DATE OF PUBLICATION], the Lake City Army
Ammunition Plant is the only facility that has provided information to
EPA demonstrating the facility's ability to meet the recommended
workplace exposure limit when using nPB in coatings.

ALTERNATE PROPOSAL

Table 6.  SOLVENT CLEANING

Alternate Proposal:  SUBSTITUTES THAT ARE PROPOSED ACCEPTABLE SUBJECT TO
USE CONDITIONS

End Use	Substitute	Decision	Use Conditions	Further Information

Metals cleaning, electronics cleaning, and precision cleaning	n-propyl
bromide (nPB) as a substitute for CFC-113, HCFC-141b, and methyl
chloroform	Acceptable subject to use conditions	The owner or operator of
a facility must ensure that users of nPB achieve a workplace exposure
limit (WEL) of 17 ppm on an 8-hour time-weighted average.

The owner or operator of a facility must ensure that workers using nPB
are monitored for their exposure to nPB using personal breathing zone
samples on an eight-hour, time-weighted average (8-hr TWA) no later than
90 days after the effective date of this rule.

If the most recent data from exposure monitoring shows all personal
breathing exposures to be at or below 8.5 ppm, no periodic exposure
monitoring is required.  If the most recent data from exposure
monitoring shows all exposures to be at or below 17 ppm, but some above
8.5 ppm, the owner or operator must take personal breathing zone samples
for nPB users at least once during the next six months.  

The owner or operator may discontinue the periodic 8-hour TWA monitoring
for nPB users at the facility where at least two consecutive sets of
measurements taken at least seven days apart are below 8.5 ppm.

The owner or operator must determine the exposure of each nPB user by
either taking personal breathing zone air samples of each user's
exposure or samples that are representative of each user's exposure. 
The samples are representative where the owner or operator has taken one
or more personal breathing zone air samples for at least one nPB user in
each job classification in a work area during every work shift, and the
nPB user sampled is expected to have the highest exposure to nPB.  

The owner or operator also must perform exposure monitoring when a
change in workplace conditions indicates that employee exposure may have
increased or whenever new applications of nPB are introduced.  Perform
exposure monitoring before making planned changes, and perform
monitoring no later than 7 days after an emergency change in conditions.

All personal breathing zone samples must be analyzed either by NIOSH
method 1003 or 1025 or by another method that is accurate to + 25% at a
95 percent confidence level.

The owner or operator must keep records of nPB worker exposure data at
the facility for at least three years from the date the measurements
were taken.   	EPA recommends the use of personal protective equipment,
including chemical goggles, flexible laminate protective gloves and
chemical-resistant clothing.  The American Conference of Governmental
Industrial Hygienists recommends a threshold limit value of 10 ppm. 

nPB, also known as 1-bromopropane, is Number 106-94-5 in the CAS
Registry.

Note that the Occupational Safety and Health Administration (OSHA) may
establish a final Permissible Exposure Limit (PEL) standard in the
workplace at 29 CFR part 1910 under 42 U.S.C. 7610(a).

OSHA’s standard on access to employee exposure and medical records
requires retaining exposure records for at least 30 years (29 CFR
1910.1020(d)(ii)).  



Note: In accordance with the limitations provided in Section 310(a) of
the Clean Air Act (42 U.S.C. 7610(a)), nothing in this table shall
affect the Occupational Safety and Health Administrations’ authority
to promulgate and enforce standards and other requirements under the
Occupational Safety and Health Act of 1970 (29 U.S.C. 651 et seq.)

Table 7.  AEROSOLS

Alternate Proposal:  SUBSTITUTES THAT ARE PROPOSED ACCEPTABLE SUBJECT TO
USE CONDITIONS

End Use	Substitute	Decision	Use Conditions	Further Information

Aerosol solvents	n-propyl bromide (nPB) as a substitute for CFC-113,
HCFC-141b, and methyl chloroform	Acceptable subject to use conditions
The owner or operator of a facility must ensure that users of nPB
achieve a workplace exposure limit (WEL) of 17 ppm on an 8-hour
time-weighted average.

The owner or operator of a facility must ensure that workers using nPB
are monitored for their exposure to nPB using personal breathing zone
samples on an eight-hour, time-weighted average (8-hr TWA) no later than
90 days after the effective date of this rule.

If the most recent data from exposure monitoring shows all personal
breathing exposures to be at or below 8.5 ppm, no periodic exposure
monitoring is required.  If the most recent data from exposure
monitoring shows all exposures to be at or below 17 ppm, but some above
8.5 ppm, the owner or operator must take personal breathing zone samples
for nPB users at least once during the next six months.  

The owner or operator may discontinue the periodic 8-hour TWA monitoring
for nPB users at the facility where at least two consecutive sets of
measurements taken at least seven days apart are below 8.5 ppm.

The owner or operator must determine the exposure of each nPB user by
either taking personal breathing zone air samples of each user's
exposure or samples that are representative of each user's exposure. 
The samples are representative where the owner or operator has taken one
or more personal breathing zone air samples for at least one nPB user in
each job classification in a work area during every work shift, and the
nPB user sampled is expected to have the highest exposure to nPB.  

The owner or operator also must perform exposure monitoring when a
change in workplace conditions indicates that employee exposure may have
increased or whenever new applications of nPB are introduced.  Perform
exposure monitoring before making planned changes, and perform
monitoring no later than 7 days after an emergency change in conditions.

All personal breathing zone samples must be analyzed either by NIOSH
method 1003 or 1025 or by another method that is accurate to + 25% at a
95 percent confidence level.

The owner or operator must keep records of nPB worker exposure data at
the facility for at least three years from the date the measurements
were taken.   	EPA recommends the use of personal protective equipment,
including chemical goggles, flexible laminate protective gloves and
chemical-resistant clothing.  The American Conference of Governmental
Industrial Hygienists recommends a threshold limit value of 10 ppm. 

nPB, also known as 1-bromopropane, is Number 106-94-5 in the CAS
Registry.

Note that the Occupational Safety and Health Administration (OSHA) may
establish a final Permissible Exposure Limit (PEL) standard in the
workplace at 29 CFR part 1910 under 42 U.S.C. 7610(a).

OSHA’s standard on access to employee exposure and medical records
requires retaining exposure records for at least 30 years (29 CFR
1910.1020(d)(ii)).  



Note: In accordance with the limitations provided in Section 310(a) of
the Clean Air Act (42 U.S.C. 7610(a)), nothing in this table shall
affect the Occupational Safety and Health Administrations’ authority
to promulgate and enforce standards and other requirements under the
Occupational Safety and Health Act of 1970 (29 U.S.C. 651 et seq.)

Table 8.  ADHESIVES, COATINGS, AND INKS

Alternate Proposal:  SUBSTITUTES THAT ARE PROPOSED 

ACCEPTABLE SUBJECT TO USE CONDITIONS

End Use	Substitute	Decision	Use Conditions	Further Information

Adhesives and coatings 	n-propyl bromide (nPB) as a substitute for
CFC-113, HCFC-141b, and methyl chloroform	Acceptable subject to use
conditions	The owner or operator of a facility must ensure that users of
nPB achieve a workplace exposure limit (WEL) of 17 ppm on an 8-hour
time-weighted average.  

The owner or operator of a facility must ensure that workers using nPB
are monitored for their exposure to nPB using personal breathing zone
samples on an eight-hour, time-weighted average (8-hr TWA) no later than
90 days after the effective date of this rule.

If the most recent data from exposure monitoring shows all personal
breathing exposures to be at or below 8.5 ppm, no periodic exposure
monitoring is required.  If the most recent data from exposure
monitoring shows all exposures to be at or below 17 ppm, but some above
8.5 ppm, the owner or operator must take personal breathing zone samples
for nPB users at least once during the next six months.  

The owner or operator may discontinue the periodic 8-hour TWA monitoring
for nPB users at the facility where at least two consecutive sets of
measurements taken at least seven days apart are below 8.5 ppm.

The owner or operator must determine the exposure of each nPB user by
either taking personal breathing zone air samples of each user's
exposure or samples that are representative of each user's exposure. 
The samples are representative where the owner or operator has taken one
or more personal breathing zone air samples for at least one nPB user in
each job classification in a work area during every work shift, and the
nPB user sampled is expected to have the highest exposure to nPB.  

The owner or operator also must perform exposure monitoring when a
change in workplace conditions indicates that employee exposure may have
increased or whenever new applications of nPB are introduced.   Perform
exposure monitoring before making planned changes, and perform
monitoring no later than 7 days after an emergency change in conditions.


All personal breathing zone samples must be analyzed either by NIOSH
method 1003 or 1025 or by another method that is accurate to + 25% at a
95 percent confidence level.

The owner or operator must keep records of nPB worker exposure data at
the facility for at least three years from the date the measurements
were taken.  	EPA recommends the use of personal protective equipment,
including chemical goggles, flexible laminate protective gloves and
chemical-resistant clothing.  The American Conference of Governmental
Industrial Hygienists recommends a threshold limit value of 10 ppm. 
nPB, also known as 1-bromopropane, is Number 106-94-5 in the CAS
Registry.

Note that the Occupational Safety and Health Administration (OSHA) may
establish a final Permissible Exposure Limit (PEL) standard in the
workplace at 29 CFR part 1910 under 42 U.S.C. 7610(a).

OSHA’s standard on access to employee exposure and medical records
requires retaining exposure records for at least 30 years (29 CFR
1910.1020(d)(ii)).

Note: In accordance with the limitations provided in Section 310(a) of
the Clean Air Act (42 U.S.C. 7610(a)), nothing in this table shall
affect the Occupational Safety and Health Administrations’ authority
to promulgate and enforce standards and other requirements under the
Occupational Safety and Health Act of 1970 (29 U.S.C. 651 et seq.)

D.  What does an unacceptability determination on adhesives and aerosols
mean?  tc "	D. How would the proposed unacceptability determination on
adhesives work? " \l 2 

	In this action, EPA is proposing to find nPB unacceptable as a
substitute for methyl chloroform, CFC-113, and HCFC-141b for use as a
carrier solvent in adhesives and as an aerosol solvent.  If this
proposal were to become final, it would be illegal to use nPB or blends
of nPB and other solvents in adhesives or in aerosol solvent
formulations as a substitute for ozone-depleting substances.  

	E. What is the scope of the proposed determination for coatings?  tc "
E. How would the proposed regulatory restriction on coatings work? " \l
2 

	We propose to list nPB as an acceptable substitute, subject to use
conditions, for methyl chloroform, CFC-113, and HCFC-141b in coatings
for facilities that have provided EPA information demonstrating their
ability to meet the recommended workplace exposure limit as of [INSERT
DATE OF PUBLICATION].  EPA has received a petition to allow use for the
ammunition coating application at Lake City Army Ammunition Plant.  This
is the only coatings application or facility for which EPA has exposure
and usage data demonstrating an ability to meet the recommended
workplace exposure limit when using nPB in coatings.  If other
facilities are interested in using nPB as a substitute for methyl
chloroform, CFC-113, or HCFC-141b in their coatings application, or if a
person wishes to market nPB for such use, then the interested party
would need to make a submission under the SNAP program.

How would the use conditions in the alternate proposal work?  TC "How
would the use conditions in the alternative proposal work?" \f A \l "2" 
  

At each facility where nPB is used, the following requirements would
apply under the alternate proposal:

Workplace Exposure Limit

The owner or operator would be required to ensure that workers using nPB
achieve a workplace exposure limit (WEL) of 17 ppm on an 8-hour
time-weighted average.  The exposure limit could be met through
engineering controls (e.g., ventilation equipment or additional cooling
coils on a vapor degreaser), work practices, or reduced use of nPB.  

Initial Worker Exposure Monitoring

For each facility where nPB is used, the owner or operator of the
facility would be required to ensure that personal breathing zone air
samples of each nPB user’s exposure would be collected on an
eight-hour, time-weighted average initially within 90 days after a final
rule becomes effective.  Monitoring measurements may be taken with an
organic chemical monitoring badge on the collar or a tube filled with
charcoal on the collar.  

Periodic Exposure Monitoring

The owner or operator of the facility would be required to ensure that
personal breathing zone air samples of user exposure are collected
periodically on an eight-hour, time-weighted average depending on the
results of the most recent set of exposure data.  A monitoring program
could be instituted by the company or by the nPB supplier for that
facility.  Periodic sampling requirements would be based on the most
recent monitoring results, as follows:

Table 9.  Exposure Levels and Periodic Exposure Monitoring 

under the Alternate Proposal

If exposure measurements for nPB are at this level:	then the owner or
operator:

all measurements at or below 8.5 ppm	is not required to perform periodic
exposure monitoring.

all measurements at or below 17.0 ppm, with some measurements above 8.5
ppm	must take personal breathing zone samples again at least once in the
next six months. 

at least one measurement above 17.0 ppm	must stop using nPB in the
application exceeding the exposure limit until exposure data show the
WEL can be met. 

unknown, in cases of new workplace conditions increasing exposure or new
applications of nPB	must take personal breathing zone samples as a test
before using nPB in new industrial applications or conditions, or within
7 days of an emergency caused by a leak, rupture or breakdown, and use
this value to determine the next time monitoring is required.  

 For periodic monitoring, the owner or operator would be allowed either
to monitor each nPB user’s exposure, or to monitor exposure of a
representative nPB user in each job classification in a work area during
every work shift, where the monitored nPB user is expected to have the
highest exposure.  

The owner or operator would be allowed to discontinue the periodic
8-hour TWA monitoring for nPB users at the facility where at least two
consecutive sets of measurements taken at least seven days apart are
below 8.5 ppm.

Monitoring for new conditions or applications

Whenever there is a change in workplace conditions that may increase
exposure or whenever a new application of nPB is introduced, the owner
or operator would be required to take personal breathing zone samples
accounting for all nPB users as a test before using nPB in manufacturing
or repair.   These could be either samples for each nPB user or samples
representing each job classification in a work area during a work shift,
so long as the samples are based on the user with the likely highest
exposure.  Examples of changes in workplace conditions that may increase
exposure include changes in production, process control equipment, or
work practices, or a leak, rupture, or other breakdown.  Examples of
introduction of a new application of nPB include aerosol contact
cleaning in a location with regional ventilation or natural ventilation,
where previous measurements were carried out on workers in a location
with local ventilation, or cleaning with an open-top vapor degreaser
when previous measurements were performed on workers using enclosed,
conveyorized cleaning equipment.  If the change occurs because of an
unpredictable emergency, then the owner or operator would need to ensure
exposure monitoring takes place within 7 days of the change.

Sampling methods and accuracy

Exposure samples would be required to be analyzed either by NIOSH 
method 1003 for halogenated hydrocarbons or method 1025 for
1-bromopropane and 2-bromopropane or by another method that is accurate
to + 25% at the 95 percent confidence level.

Recordkeeping requirements

The owner or operator of the facility would be required to keep records
of the monitored exposure data at the facility for at least three years
from the date the measurements were taken for purposes of this rule. 
These records would be required to be made available in the event of a
facility inspection or a request for the data by EPA.   Note that the
employer would still need to meet OSHA’s standard on access to
employee exposure and medical records, which requires retaining any
exposure records for at least 30 years (29 CFR 1910.1020(d)(ii)).  

IV.	What criteria did EPA consider in preparing this proposal? tc "IV.
What did EPA consider in preparing today’s proposal?" 

	In the original rule implementing the SNAP program (March 18, 1994; 59
FR 13044, at 40 CFR 82.180(a)(7)), the Agency identified the criteria we
use in determining whether a substitute is acceptable or unacceptable as
a replacement for class I or II compounds:

(i) Atmospheric effects and related health and environmental impacts;
[e.g., ozone depletion potential]

(ii) General population risks from ambient exposure to compounds with
direct toxicity and to increased ground-level ozone;

(iii) Ecosystem risks [e.g., bioaccumulation, impacts on surface and
groundwater];

(iv) Occupational risks;

(v) Consumer risks;

(vi) Flammability; and

(vii) Cost and availability of the substitute.

	In this review, EPA considered all the criteria above except for
consumer risks.  n-propyl bromide is used in industrial applications
such as electronics cleaning or spray adhesives used in foam
fabrication.  In those consumer products made using nPB, such as a piece
of furniture or a computer, the nPB would have evaporated long before a
consumer would purchase the item.  Therefore, we believe there is no
consumer exposure risk to evaluate in the end uses we evaluated for this
rule.

	The Agency evaluated the criteria set forth at 40 CFR 82.180(a)(7) in
determining whether nPB is an acceptable substitutes for methyl
chloroform, CFC-113, and HCFC-141b in metals, electronics and precision
cleaning, aerosol solvents, adhesives and coatings.  The Agency has
determined that the Clean Air Act does not authorize EPA to regulate for
global climate change purposes (Fabricant, 2003).  The Agency has not
yet concluded how this determination would affect its consideration of
the global warming potential (GWP) of substitutes under the SNAP
program.  Regardless, the global warming potential of nPB is not a
determinative factor in EPA's proposed determination.  The GWP for nPB
is comparable to or below that of previously approved substitutes in
these end uses (ICF, 2006a).  

	Section 612(c) of the Clean Air Act directs EPA to publish a list of
replacement substances (“substitutes”) for class I and class II
ozone depleting substances based on whether the Administrator determines
they are safe (when compared with other currently or potentially
available substitutes) for specific uses or are to be prohibited for
specific uses.  EPA must compare the risks to human health and the
environment of a substitute to the risks associated with other
substitutes that are currently or potentially available.  In addition,
EPA also considers whether the substitute for class I and class II ODSs
“reduces the overall risk to human health and the environment”
compared to the ODSs being replaced.  Our evaluation is based on the end
use; for example, we compared nPB as a metal cleaning solvent against
other available or potentially available metal cleaning alternatives,
and we compared nPB as a carrier solvent in adhesives to other available
or potentially available adhesive alternatives.  

	Although EPA does not judge the effectiveness of an alternative for
purposes of determining whether it is acceptable, we consider
effectiveness when determining whether alternatives that pose less risk
are available in a particular application within an end use.  There are
a wide variety of acceptable alternatives listed for solvent cleaning,
but not all are appropriate for a specific application because of
differences in soils, materials compatibility, degree of cleanliness
required, local environmental requirements, and other factors.  For
example, aqueous cleaners are effective cleaners in many situations and
are the substitute of choice for many in the metal cleaning end use. 
However, in some specific precision cleaning applications that require a
high degree of cleanliness and that have narrow spaces that may trap
water used in rinsing, aqueous cleaners may not be appropriate and thus
are not available in that specific application.  

	 EPA evaluated each of the criteria separately and then considered
overall risk to human health and the environment in comparison to other
available or potentially available alternatives.  We concluded that
overall, environmental risks were not sufficient to find nPB
unacceptable in any of the evaluated end uses.  However, the overall
risks to human health, and particularly the risks to worker health, are
sufficiently high in the adhesive and aerosol solvent end uses to
warrant our proposal to find nPB unacceptable.

A.	Availability   tc "Availability  " \l 3 

	Other alternatives are available in each end use considered in this
proposal.  Examples of other available alternatives for metals,
electronics, and precision cleaning that have already been found
acceptable or acceptable subject to use conditions under the SNAP
program include:  aqueous cleaners, semi-aqueous cleaners, alcohols,
ketones, esters, ethers, terpenes, HCFC-225ca/cb, hydrofluoroethers
(HFEs), hydrofluorocarbon (HFC)-4310mee, HFC-365mfc,
heptafluorocyclopentane, hydrocarbons, volatile methyl siloxanes (VMSs),
trans-1,2-dichloroethylene, methylene chloride, trichloroethylene (TCE),
perchloroethylene, parachlorobenzotrifluoride (PCBTF), and alternative
technologies like supercritical fluids, plasma cleaning, and
ultraviolet/ozone cleaning.  Some alternatives are unlikely to be used
in particular end uses applications because of constraints such as
cleaning performance, materials compatibility, cost, workplace exposure
requirements, or flammability.  For example, no-clean technology is used
in electronics cleaning and not in precision cleaning because of the
need for a high degree of cleanliness in precision cleaning.  Of the
available substitutes, aqueous cleaners or solvents for vapor degreasing
such as TCE, blends of alcohols or trans-1,2-dichloroethylene and HFCs
or HFEs, and HCFC-225ca/cb are most likely to be used in the same
applications as nPB.  nPB is already commercially available in solvent
cleaning, and is used mostly for vapor degreasing in the electronics and
precision cleaning end uses. (IBSA, 2002) 

	Many of the same substitutes may be used and are commercially available
in aerosol solvents:  water-based formulations, alcohols, ketones,
esters, ethers, terpenes, HCFC-141b, HCFC-225ca/cb, HFEs, HFC-4310mee,
HFC-365mfc, HFC-245fa, hydrocarbons, trans-1,2-dichloroethylene,
chlorinated solvents, and PCBTF.  Of these, hydrocarbons, alcohols,
blends of trans-1,2-dichloroethylene and HFEs or HFCs, and HCFC-225ca/cb
are most likely to be used in the same applications as nPB.  nPB is
already commercially available in aerosols.  Its use is primarily for
electrical contact cleaning, with some use for benchtop cleaning
applications (Williams, 2005).

	Many alternatives are also available for use in adhesives, coatings,
and inks:  water-based formulations, high solid formulations, alcohols,
ketones, esters, ethers, terpenes, HFEs, hydrocarbons,
trans-1,2-dichloroethylene, chlorinated solvents, PCBTF, and a number of
alternative technologies (e.g., powder, hot melt, thermoplastic plasma
spray, radiation-cured, moisture-cured, chemical-cured, and reactive
liquid).  Of these, the alternative adhesives most likely to be used in
the same applications as nPB are water-based formulations, adhesives
with methylene chloride, and flammable adhesives with acetone (IRTA,
2000).  nPB is already used in adhesives, and particularly in foam
fabrication and in constructing seating for aircraft (IRTA, 2000;
Seilheimer, 2001).

	To our knowledge, nPB is potentially available as a carrier solvent in
coatings, but has not yet been commercialized, except for use by one
facility, the Lake City Army Ammunition Plant.  The Lake City Army
Ammunition Plant evaluated twenty-nine carrier solvent alternatives to
methyl chloroform and determined that nPB is the only satisfactory
alternative for their application given the current process at that
facility (Harper, 2005).  

	Based on this information, we conclude that other alternatives are
available in metals, electronics, and precision cleaning, aerosol
solvents and adhesives.  Other alternatives are potentially available or
available in coatings, but other alternatives may not be potentially
available for the specific application addressed in today’s proposal,
ammunition coatings.

	B. 	Impacts on the atmosphere and local air quality   TC "2.
Atmospheric effects" \f A \l "3"   

	As discussed in the June, 2003 proposal, nPB emissions from the
continental United States are estimated to have an ozone depletion
potential (ODP) of approximately 0.013-0.018, (Wuebbles, 2002), lower
than that of the ozone depletion potential of the substances that nPB
would replace -- CFC-113 (ODP=1.0), and methyl chloroform and HCFC-141b
(ODPs = 0.12) (WMO, 2002).  Some other acceptable alternatives for these
ODSs also have low ODPs.  For example, HCFC-225ca/cb has an ODP of
0.02-0.03 (WMO, 2002) and is acceptable in metals cleaning and aerosol
solvents, and acceptable subject to use conditions in precision cleaning
and electronics cleaning.  HCFC-123 has an ODP of 0.02 (WMO, 2002), and
is an acceptable substitute in precision cleaning.  There are other
acceptable cleaners that essentially have no ODP--aqueous cleaners,
HFEs, HFC-4310mee, HFC-365mfc, HFC-245fa, hydrocarbons, VMSs, methylene
chloride, TCE, perchloroethylene, and PCBTF.  Based on this information,
we do not believe the use of nPB within the U.S., and within the
end-uses reviewed in this rulemaking, poses a significantly greater risk
to the ozone layer than other available substitutes.  

	Comments on the June 2003 NPRM expressed concern that other countries,
particularly those in equatorial regions, might assume that nPB does not
pose a danger to the stratospheric ozone layer if the U.S. EPA’s SNAP
program finds nPB acceptable (Linnell, 2003; Steminiski, 2003).  We
recognize the concern that if significant nPB usage were to occur in
equatorial regions, there could be an impact on the ozone layer. 
However, EPA is regulating use in the U.S. and cannot dictate actions
taken by other countries.  We believe the more appropriate forum to
address this concern is through the Parties to the Montreal Protocol.  

	Use of nPB is controlled as a volatile organic compound (VOC) under
state and local regulations to comply with National Ambient Air Quality
Standards for ground-level ozone, which is a respiratory irritant. 
Users located in ozone non-attainment areas may need to consider using a
substitute for cleaning that is not a VOC or if they choose to use a
substitute that is a VOC, they may need to control emissions.  Companies
have petitioned EPA, requesting that we exempt nPB from regulation as a
VOC.  However, unless and until EPA issues a final rulemaking exempting
a compound from the definition of VOC, that compound is still regulated
as a VOC.  Other acceptable ODS-substitute solvents that are VOCs for
state air quality planning purposes include most oxygenated solvents
such as alcohols, ketones, esters, and ethers; hydrocarbons and
terpenes; trichloroethylene; trans-1,2-dichloroethylene;
monochlorotoluenes; and benzotrifluoride.  Some VOC-exempt solvents that
are acceptable ODS substitutes include HFC-245fa for aerosol solvents;
HCFC-225ca/cb, HFC-365mfc and HFC-4310mee for metals electronics, and
precision cleaning and aerosol solvents; and methylene chloride,
perchloroethylene, HFE-7100, HFE-7200, PCBTF, acetone, and methyl
acetate for metals, electronics, and precision cleaning, aerosol
solvents, adhesives, and coatings. 

	C.	Ecosystem and other environmental impacts  TC "3.	Ecosystem and
other environmental impacts" \f A \l "3"  

	EPA considered the possible impacts of nPB if it were to pollute soil
or water as a waste and compared these impacts to screening criteria
developed by the Endocrine Disruptor Screening and Testing Advisory
Committee (EDSTAC, 1998) (see Table 11).  Available data on the organic
carbon partition coefficient (Koc), the breakdown processes in water and
hydrolysis half-life, and the volatilization half-life indicate that nPB
is less persistent in the environment than many solvents and would be of
low to moderate concern for movement in soil.  Based on the LC50, the
acute concentration at which 50% of tested animals die, nPB’s toxicity
to aquatic life is moderate, being less than that for some acceptable
cleaners (for example, trichloroethylene, hexane, d-limonene, and
possibly some aqueous cleaners) and greater than that for some others
(methylene chloride, acetone, isopropyl alcohol, and some other aqueous
cleaners).  Based on EPA’s criteria for listing under the Toxics
Release Inventory, nPB would not be sufficiently toxic to aquatic life
to warrant listing, since the LC50 is greater than 10 mg/l (US EPA,
1992).  Based on its relatively low bioconcentration factor and log Kow
value, nPB is not prone to bioaccumulation.  Table 10 summarizes
information on environmental impacts of nPB; trans-1,2-dichloroethylene,
a commonly-used solvent in blends for aerosol solvents, precision
cleaning, and electronics cleaning; acetone, a commonly-used carrier
solvent in adhesives; trichloroethylene, a solvent used for metals,
electronics, and precision cleaning; and methyl chloroform, an ODS that
nPB would replace.Table 10.  Ecosystem and Other Environmental
Properties of nPB and Other Solvents

Property	Description of environmental property	Value for nPB	Value for
trans-1,2-dichloro-ethylene	Value for acetone	Value for
trichloroethylene	Value for methyl chloroform

Koc, organic-carbon partition coefficient	Degree to which a substance
tends to stick to soil or move in soil.  Lower values (< 300)* indicate
great soil mobility; values of 300 to 500 indicate moderate mobility in
soil.	330 (Source: ICF, 2004a)	32 to 49 (Source:  ATSDR, 1996)	5.4
(Source:  ATSDR, 1994)	106 to 460 (Source:  ATSDR, 1997)	152 (Source: US
EPA, 1994b)

Break down in water	Mechanism and speed with which a compound breaks
down in the environment.  (Hydrolysis half-life values > 25 weeks* are
of concern.)	Hydrolysis is significant.  Hydrolysis half-life of 26 days
(Source: ICF, 2004a)	Photolytic decomposition, dechlorination and
biodegradation are significant; hydrolysis not significant (Source: 
ATSDR, 1996)	Biodegrada-tion is most significant form of breakdown
(Source:  ATSDR, 1994)	Volatilization and biodegradation most
significant, with hydrolysis relatively insignificant.  Hydrolysis
half-life of 10.7 to 30 months (Source:  ATSDR, 1997)	Volatilization
most significant;  biodegradation and hydrolysis also occur (Source: 
ATSDR, 2004)

Volatilization half-life from surface waters	Tendency to volatilize and
pass from water into the air.	3.4 hours-4.4 days (Source: ICF, 2004a)	3
to 6.2 hours (Source:  ATSDR, 1996)	7.8 to 18 hours (Source:  ATSDR,
1994)	3.4 hours to 18 days (Source:  ATSDR, 1997)	hours to weeks
(Source: US EPA, 1994b)

LC50 (96 hours) for fathead minnows	Concentration at which 50% of
animals die from toxicity after exposure for 4 days.	67 mg/L (Source: 
Geiger, 1988)	108 mg/L (Source: US EPA, 1980)	7280 to 8120 mg/L (Source:
 Fisher Scientific, 2001)	40.7 to 66.8 mg/L (Source:  NPS, 1997)	52.8 to
105 mg/L (Source: US EPA, 1994b)

log Kow 	Logarithm of the octanol/water partition coefficient, a measure
of tendency to accumulate in fat.  Log Kow values >3* indicate high
tendency to accumulate.	2.10 (Source: ICF, 2004a)	-0.48 (Source: 
LaGrega et al., 2001, p. 1119)	-0.24 (Source:  LaGrega et al., 2001, p.
1117)	2.38 (Source:  LaGrega et al., 2001, p. 1127)	2.50 (Source:
LaGrega et al., 2001, p. 1127)

Bioconcen-tration factor 	High factors (>1000)* indicate strong tendency
for fish to absorb the chemical from water into body tissues.	23
(Source:  HSDB, 2004)	5 to 23 (Source:  ATSDR, 1996)	<1 (Source:  ATSDR,
1994)	10 to 100 (Source:  ATSDR, 1997)	<9 (Source: US EPA, 1994b)

* Criteria from EDSTAC, 1998.	

	nPB is not currently regulated as a hazardous air pollutant and is not
listed as a hazardous waste under the Resource Conservation and Recovery
Act (RCRA).  nPB is not required to be reported as part of the Toxic
Release Inventory under Title III of the Superfund Amendments and
Reauthorization Act.  Despite this, large amounts of nPB could be
harmful if disposed of in water.  We recommend that users dispose of nPB
as they would dispose of any spent halogenated solvent (F001 waste under
RCRA).  Users should not dump nPB into water, and should dispose of it
by incineration.  We conclude that nPB does not clearly pose a greater
risk to the environment than other available alternatives, and that the
use of nPB within the U.S. should not be prohibited under the SNAP
program on the basis of its environmental impacts.	

	D.	Flammability and fire safety  tc "		4.	Flammability and fire safety
" \l 3 

	Using standard test methods for determining flash point, such as the
American Society for Testing and Materials (ASTM) D 92 open cup, ASTM
D56 Tag closed cup, and ASTM D93 Pensky-Martens closed cup methods, nPB
displayed no flash point (BSOC, 2000; Miller, 2003; Morford, 2003a and
2000b; Shubkin, 2003; Weiss Cohen, 2003).  Thus under standard test
conditions, nPB is not flammable, and it should not be flammable under
normal use conditions.  With its low potential for flammability, nPB is
comparable to chlorinated solvents, HCFCs, HFEs, HFC-245fa, HFC-4310mee,
and aqueous cleaners, and is less flammable than many acceptable
substitutes, such as ketones, alcohols, terpenes, and hydrocarbons.  nPB
exhibits lower and upper flammability limits of approximately 3% to 8%
(BSOC, 2000).  A number of other solvents that are typically considered
to be non-flammable also have flammability limits (for example,
methylene chloride, HCFC-141b, and methyl chloroform).  If the
concentration of vapor of such a solvent falls between the upper and
lower flammability limits, it could catch fire in presence of a flame. 
Such a situation is unusual, but users should take appropriate
precautions in cases where the concentration of vapor could fall between
the flammability limits.  

	E.	Impact on human health  tc "		5.	Impact on human health " \l 3  

	In evaluating potential human health impacts of nPB, EPA considered
impacts on both exposed workers and on the general population.  Using
the same approach commented on and then finalized in the original SNAP
rulemaking, EPA evaluated the available toxicity data using EPA
guidelines to develop health-based criteria to characterize human health
risks (US EPA, 1994a. RfC Guidelines; US EPA, 1991.  Guidelines for
Developmental Toxicity Risk Assessment; US EPA, 1995b.  Benchmark Dose
guidelines; US EPA, 1996.  Guidelines for Reproductive Toxicity Risk
Assessment).  

	To assess human health risks, EPA followed the four basic steps of risk
assessment outlined by the National Academy of Sciences:  hazard
identification, dose-response relationship, exposure assessment, and
risk characterization (NAS, 1983).  First, EPA examined available
studies on nPB’s effects.  Second, EPA developed a workplace exposure
limit (WEL) (also known as an acceptable exposure limit [AEL]) for
evaluating worker exposure and a community exposure guideline (CEG) for
evaluating exposure to the general population based upon inhalation
exposure.  Third, EPA compared the WEL and CEG to available exposure
data and projections of exposure levels to assess exposure.  Finally,
EPA decided whether there was sufficient evidence indicating that nPB
could be used as safely as other alternatives available in a particular
end use.

		1.	Occupational health risks

f Industrial Hygienists (ACGIH) Threshold Limit Values™ (TLVs). 
However, EPA found that the ability to meet the recommended nPB
workplace exposure limit (WEL) of 17 ppm (8-hour time weighted average
[TWA]) varies, depending on equipment used and the end use.  In some
uses, users clearly can meet the WEL (metals, electronics and precision
cleaning), while in other end uses, users may not be able to meet the
WEL following current industry practices (adhesives and aerosols).   We
discuss the ability to meet the nPB WEL in each end use below in section
VI.

	Rat studies indicate that dermal exposure to nPB results in neither
appreciable absorption through the skin (RTI, 2005) nor systemic
toxicity (Elf Atochem, 1995).  Unlike methyl chloride and dichlorvos,
which are absorbed through the skin and could contribute to systemic
toxicity (ACGIH, 1991), EPA is not proposing to include a skin notation
for nPB in the information provided to users associated with this
rulemaking because of the relatively low level of absorption.  The ACGIH
provides no skin notation in its TLV documentation for several solvents,
including nPB, methylene chloride, and perchloroethylene, and there is
no evidence that absorption through the skin is greater for nPB than for
the other halogenated compounds.  Given the possibility that some nPB
can be absorbed through the skin in humans, and that the solvent can
irritate the skin, EPA encourages users to wear protective clothing and
flexible laminate gloves when using nPB and encourages vendors to
include such precautions in their Material Safety Data Sheets (MSDSs). 

	EPA also considered the potential health effects of contamination of
nPB formulations with isopropyl bromide (iPB).  In the June 2003
proposed rule, we proposed as a use condition that nPB formulations
contain no more than 0.05% iPB by weight.  Industry has met this
contamination limit for several years without regulation.  Furthermore,
EPA believes that if users are meeting the recommended workplace
exposure limit for nPB of 17 ppm, a worker’s exposure to iPB will be
sufficiently low to avoid adverse effects.  Therefore, this proposed
rule does not include a use condition limiting iPB content in nPB
formulations.

		2.	General population risks  

EPA used a community exposure guideline of 1 ppm to assess potential
risks to the general population living near a facility using nPB (see
section V.B below) and determined that community exposures were likely
to be higher for nPB used in adhesives than for nPB used in aerosol
solvents or in metals cleaning, electronics cleaning, or precision
cleaning.  EPA modeled inhalation exposure to nPB to people living near
a plant using nPB-based adhesives in several scenarios using the
Agency’s SCREEN3 model and found that the exposure to individuals in
the general population was below the community exposure guideline.  The
analysis indicates that nPB is no greater a hazard to the general
population than other acceptable solvents under the SNAP program.  For
further discussion, see the risk screen for nPB (ICF, 2006a). 

V.	How did EPA derive the proposed workplace exposure limit and
community exposure guideline used to assess impacts on human health?  TC
"How did EPA derive the proposed workplace exposure limit and community
exposure guideline used to assess impacts on human health?" \f A \l "2" 


This proposal evaluates human health risks using a workplace exposure
limit (WEL) to assess occupational exposure to nPB and a community
exposure guideline (CEG) to assess the general public’s exposure to
nPB.  EPA proposes to use a WEL of 17 ppm averaged over 8 hours and a
CEG of 1 ppm averaged over 24 hours.  The derivation of these values is
described below in sections V.A and V.B, respectively.  To assess human
health risks in each end use, EPA then compared the WEL to measured and
projected occupational exposures, and the CEG to projections of exposure
to the general public.

A.	Workplace exposure limit  TC "1.	Workplace Exposure Limit" \f A \l
"3"  

 OSHA has not developed a permissible exposure limit (PEL) for nPB that
EPA could use to evaluate toxicity risks from workplace exposure.  The
American Conference of Governmental Industrial Hygienists (ACGIH), an
independent organization with expertise in industrial hygiene and
toxicology, has developed a final workplace exposure limit of 10 ppm
(ACGIH, 2005); however, as discussed below, EPA has concerns about the
documentation and basis of ACGIH’s derivation.  Further, there is a
wide range of exposure limits recommended by nPB vendors (from 5 ppm to
100 ppm).  After considering all of the various exposure limits
recommended by industry and governmental organizations, and individual
companies and consultants, and a thorough review of all available data,
EPA has developed a recommended WEL of 17 ppm averaged over eight hours
to assess human health risks and to evaluate the acceptability of nPB in
potential use sectors.  

In the June 2003 NPRM, EPA proposed that an exposure limit of 25 ppm
would be protective of a range of effects observed in animal and human
studies, including reproductive and developmental toxicity,
neurotoxicity, and hepatotoxicity.  Reduction of sperm motility in rats,
noted across multiple studies at relatively low exposures, was
determined to be the most sensitive effect, and we derived the
recommended exposure limit in the June 2003 NPRM from a dose response
relationship in male rat offspring (“F1 generation”) whose parents
were exposed to nPB from prior to mating through birth and weaning of
the litters (WIL Research Laboratories, 2001).  For this proposed rule,
we reviewed both new information and the previously available
information on health effects in developing an exposure limit.

1.	Newly Available Data on Health Effects

Since publication of the June 2003 NPRM, EPA has examined additional
occupational (Table 11) and animal (Table 12) studies that have become
available:  

Table 11. Recent Studies on nPB Occupational Exposure

Case Study	Sample Size/Population	Exposure Data	Observations	Remarks

Beck and Caravati, 2003	6 foam cushion factory workers (gluers)	Exposure
during 30-40 hr/wk for a 3-month period. Exposure measured in one day
was a mean of 130 ppm (range, 91-176 ppm). 	Lower leg weakness
accompanied by pain and difficulty with standing and walking, numbness
of legs and feet, hyperreflexia and hypertonicity of lower extremities,
dizziness and shortness of breath, and peripheral neurotoxicity. 
Measured serum bromide levels were elevated, range 44-170 mg/dL.	Small
sample size studied.  Possible interference or synergistic effects from
other adhesive ingredients (1,2-epoxybutane and styrene-butadiene). 

Majersik et al., 2004; Majersik et al., 2005 * 	6 foam cushion factory
workers (gluers)	5-8 hr/day for at least 2 years with mean air
concentration of 130 ppm on last day of study.  Measurements taken over
9 hours (equivalent to 92-127 ppm with mean of 108 ppm for an 8-hour
TWA).	Subacute onset of lower extremity pain, difficulty walking, and
high serum bromide levels in blood.  Neurotoxic symptoms persisted for
at least 2 years after exposure ended.	Follow-up to Beck and Caravati
(2003). Chronic nPB exposure associated with incapacitating neurotoxic
syndrome.  Initial report from Utah OSHA indicated erroneously that
workers were not spraying while measurements were taken.  In fact,
adhesives were being sprayed and ventilation equipment was not being
used, making measurements likely to be representative of conditions
during the past several months at the plant.  

Ichihara et al., 2004a	37 chemical plant workers (24 males and 13
females)	12 hour shifts over 2-day period, mean concentration of 82 ppm
(range, 0-170 ppm) 	Mucosal irritation (nose, throat), headache,
dizziness, constipation, intoxication, and feeling light-headed or
heavy-headed.  Four female workers complained of disruption or cessation
of menstruation.  No severe chronic symptoms of neurological damage at
less than 170 ppm.  Several workers had hemoglobin and hematocrit values
outside of the normal range and were diagnosed with mild anemia; most of
these cases also showed signs of iron deficiency.	Inadequate exposure
characterization and exposure to other potential toxicants, small sample
size, and no appropriate control group.  Healthy worker effect possible,
where more sensitive workers left the factory between 1996 and 1999. 

Ichihara et al., 2004b	27 female chemical plant workers (23 age matched
with 23 females from a beer factory control group)	1-day exposure
period, range of exposure, 0.34-49 ppm	Responses indicated anxiety,
fatigue, confusion, tension, and depression.  Changes in menstrual
status but not statistically significant.  Effects on peripheral and
central nervous system —diminished vibration sensation of the foot;
significantly longer distal latency in the tibial nerve; decreased
values in sensory nerve conduction velocity in the sural nerve; and
lower scores on memory and perceptual tests.  No comparable effects seen
in control group. 	No long-term exposure measurements, small sample
size; lack of controls for age, height, and body-weight.  Low B vitamin
levels in normal range in some workers but researchers concluded this
did not cause observed neurological effects.  Additionally, the study
did not indicate any significant differences in the prevalence of
menstrual cycle abnormalities.

Nemhauser, 2005 *	Foam cushion factory workers (gluers) in North
Carolina 	In 1999 study, 16 workers exposed to mean air concentration of
116 ppm, and 12 sprayers exposed to mean concentration of 108 ppm with
range of 58 to 254 ppm.  In 2001 study, 13 workers exposed to nPB mean
air concentration of 46 ppm and 12 sprayers were exposed to mean
concentration of 101 ppm, with range of 38 to 281 ppm.	Higher exposure
to nPB and dose-dependent relationship among those who reported anxiety,
headache, and ataxia.  No reproductive abnormalities reported in medical
survey for men or women.  Semen analysis found no differences between
exposed and unexposed workers.	Small sample sizes studied with moderate
worker participation.  Healthy worker effect likely occurred: those that
had most significant health effects had already removed themselves from
workplace by the time of the study.  No arsenic found at the plant. 
Neurotoxic effects caused by nPB.  See related Health Hazard Evaluation
(HHE): NIOSH, 2003a.

NIOSH, 2003a	16 workers in 1999 evaluation; 13 workers in 2001 follow-up
evaluation. 	1999 Initial Site Visit: geometric mean nPB concentration
(from personal samples), 81.2 (range, 18-254 ppm); 2001 follow-up: 
geometric mean, 81.2 ppm (range, 7-281 ppm)	Most workers exposed to >25
ppm nPB levels.  Exposure concentrations lower in 2001 than 1999, but
difference not statistically significant.  Headache, anxiety, feeling
drunk associated with nPB exposure.  Hematological endpoints unaffected
in exposed group.  No correlation of nPB exposure with sperm or semen
indices or with neurological abnormalities.  	Arsenic was not attributed
to occupational exposure.  The National Institute for Occupational
Safety and Health (NIOSH) stated that neurological symptoms may have
been related to excess exposure to nPB, but that no other effects could
conclusively be related to nPB exposure.

Raymond and Ford, 2005*	4 foam cushion factory workers (gluers) in North
Carolina	Exposure study conducted 9 months after index patient became
ill indicated workers exposed to mean nPB air concentration of 116 ppm. 
4 workers exposed for 2-3 weeks before initial symptoms detected. 
Dizziness, numbness, ocular symptoms, lower extremity weakness and
unsteady gait, weakness, hypesthesia, and ataxic gait in all four
workers.  Symptoms decreased over time but after six years, at least one
worker re-exposed twice at other furniture plants; one or more still
suffer from ataxia.	Small sample size, possible confounding effect from
arsenic. 

Toraason et al., 2006	 41 and 22 foam cushion factory workers (gluers)
at 2 facilities	1-3 days up to 8 hrs per day, with concentrations of
 0.2 – 271 ppm at facility A, 4 - 27 ppm at facility B.	No
statistically significant differences in DNA damage with worker’s nPB
exposure.  In vitro results showed nPB increased DNA damage.	Authors
find limited evidence that nPB poses a “small risk” for DNA damage. 

	*Presentation at North American Congress of Clinical Toxicology on
September 14, 2005.	

Table 12. Recent Animal Studies of nPB Effects

Citation	Population/

in rat liver cells ≥ 250 ppm (males) and ≥ 500 ppm (females), with
increased severity at higher doses.  No adverse central nervous system
(CNS) effects or histopathology reported.	Unpublished study. 
Conclusions drawn from a review of raw data from the National Toxicology
Program (NTP) web site.  In general, the severity of effects (in
non-reproductive organs) is slightly higher at lower concentrations in
male rats than in females. 

RTI, 2005	Female and male B6C3F1mice and Fisher 344N  rats, four to six
animals in each test trial	Exposure via several injection routes
(intraperitoneal, intravenous, cannuliz-ation), inhalation, and dermal.
Injection conducted via bolus dosing at 5, 20, or 100 mg/kg body weight.
 Inhalation concentrations of 70, 240, 800, and 2700 ppm administered in
a single acute exposure.  A dose of 96 mg/kg was applied to a shaved
area on the backs of six male rats with a non-occlusive charcoal filter
covering (that is, one that does not prevent evaporation).  	nPB cleared
by mice after 48 hours as follows:  45% as volatiles in the breath, 28%
as CO2 in the breath, 26% in urine, <3% in feces, and 2% retained in the
body.  Distribution was similar in male rats, although amounts in urine
and volatiles in breath were higher in mice.  At higher doses, the
amount of nPB excreted in urine and as CO2 decreased, with a much
greater change in rats compared to mice.

After pretreatment with a cytochrome P450 inhibitor, a decrease in nPB
cleared as CO2 (80%) and urine (40%); pretreatment with a glutathione
inhibitor reduced  nPB cleared as CO2 by 10% and urine by 4%.

The Vmax, a measure of the maximum initial rate of an enzyme-catalysed
reaction, is 0.227 for male rats, 0.143 for female rats, 0.329 for male
mice and 0.234 for female mice.  Half-lives were comparable between
males and females at ≤ 800 ppm.

For rats exposed to nPB through skin, 37% of the dose was excreted in
volatiles, 1.2 % in urine, 1.7%  as CO2, and 35.7% was on the
applicators or in the skin washes.  Only 0.32% remained in tissues. 
Airborne concentrations of nPB in the chamber were 4 to 10 ppm after
dosing.	RTI concluded that:  

nPB administered via intraperitoneal injection or inhalation is
eliminated mostly through the breath, with urine as a secondary path.

Metabolism of nPB appears to be primarily through cytochrome P450
enzymes (CYP2E1), particularly in mice; glutathione conjugation still
plays an important role in rats.

At high concentrations, female rats may have a decreased capacity to
metabolize nPB compared to male rats.

nPB decreases glutathione levels in the liver after a one-time exposure
to nPB at concentrations as low as 70 ppm.

nPB is not appreciably absorbed (~3-27%) in rats following dermal
application.

EPA agrees with these points, except we found that gender differences
were only apparent in rats at very high concentrations (2700 ppm and
greater).  We also note that:

Inhalation tests were only one-time exposures at very high
concentrations (240 to 2700 ppm), and thus, are not comparable to
long-term dosing at the lower levels expected in the workplace.

Results of dermal testing are not conclusive because of potential for
inhalation exposure.

Sohn et al., 2002	40 male and 40 female Sprague-Dawley rats	6 hr/day, 5
day/wk for 13 weeks, test groups (10/sex/dose) were exposed to 0, 200,
500 or 1250 ppm	No effects on mortality, activity, weight gain, food
consumption, urinalysis, or histological effects in the brains and
spinal cords. 	The differences between the various studies may be due to
variability in exposure methodology and achieved concentrations of nPB. 


Stump, 2005* 	125 female/125 male rats in first generation and 100
female/100 male rats in offspring generation	Both test groups of 25 male
rats/ 25 female rats exposed to 0, 100, 200, 250, 500 and 750 ppm nPB
for 10 weeks	Decreased litter size at 250 and 500 ppm in both
generations. Decreased fertility at 100 and 250 ppm in offspring
generation. 

ignificant decrease in antral follicles at ≥ 200 ppm, and a decrease
in the number of female rats exhibiting regular estrous cycles in
400-ppm females during 7-9 weeks of exposure and at 2-3 weeks at the
800-ppm dose.	Data suggest that nPB is affecting the maturation of
ovarian follicles.  A no observed adverse effect level (NOAEL) of 200
ppm is identified with a LOAEL of 400 ppm for the changes in estrus
cycles.    

*Presentation at North American Congress of Clinical Toxicology on
September 14, 2005

Data collected from actual occupational settings indicate that severe,
possibly irreversible, neurological effects may occur at sustained
concentrations of approximately 100 ppm or greater, with variability in
effects observed in different studies, although in most cases exposures
may have been much higher.  For example, in Ichihara et al. (2002a),
doctors performed a health assessment first, and then the exposure
assessment was performed later (Miller, 2005); therefore, the exposure
concentrations measured may not accurately represent the concentrations
that may have induced the observed adverse effects.  Because of design
and methodological limitations, such as small numbers of subjects and
limited exposure information, none of these recent studies individually
provide a sufficient quantitative basis to derive a WEL.  

In general, the recent animal studies collectively show a range of
effects associated with nPB exposure that are qualitatively consistent
with previously published findings.  (Exceptions to this are the
negative results regarding CNS toxicity in the NTP (2003) study and the
Sohn (2002) study on rats.)  In particular, Yamada et al. (2003)
reported estrous cycle irregularities that  Sekiguchi (2002) also noted
after a short-duration exposure, and these effects also were reported in
a multi-generation study (WIL, 2001) in which an increase in estrous
cycle length was observed in animals exposed to nPB at levels of 250-750
ppm.  The expert panel for the Center for the Evaluation of Risks to
Human Reproduction (CERHR, 2002a) concluded, based on the WIL (2001)
findings, that the lowest observed adverse effect level (LOAEL) for
female reproductive effects is 250 ppm and the no observed adverse
effect level (NOAEL) is 100 ppm.  However, neither the authors of the
WIL (2001) study nor the expert panel of the CERHR statistically
evaluated the estrous cycle data.  At the time of the June 2003
proposal, EPA stated that while the increase in estrous cycle length in
the WIL study may be a result of nPB exposure, “the effect cannot be
conclusively attributed to exposure without statistical analysis” and
because of the lack of statistically-analyzed data, “this endpoint
should not be used for developing the AEL.” (68 FR 33296) 

After further reviewing the Yamada et al. (2003) study, published just
prior to the 2003 NPRM, EPA re-evaluated the literature (Ichihara et
al., 1999, 2002, 2004a,b; Sekiguchi, 2002, Yamada et al., 2003; WIL,
2001) to assess potential reproductive toxicity in females (ICF, 2006a,
Att. A). We focused on the WIL study because of the following strengths
described in the June 2003 NPRM: (1) it was conducted in accord with
Good Laboratory Practice procedures and standard test guidelines over
multiple generations; (2) it underwent an independent audit; (3) it
contained a sufficiently large sample size; and (4) the raw data were
provided for detailed statistical analyses.

In WIL (2001), an increase in estrous cycle length was observed in each
exposure group relative to controls prior to mating, and statistically
significant decreases in the number of estrous cycles were observed at
>250 ppm in females of the “F0” (parental) generation, and at 500
ppm in the offspring.  In this study, both of these changes were early
biomarkers of reproductive success as the nature and magnitude of
reproductive toxicity increased with increasing dose.  For example, at
500 ppm, females were not having their estrous cycle and more than half
were unable to deliver offspring after mating; all females exposed to
750 ppm failed to reproduce.  

As discussed by ICF (2004b), three external expert reviewers agreed that
the finding of a statistically significant decrease in the number of
estrous cycles and increase in estrous cycle length was a
toxicologically significant finding, particularly when considered
together with other reproductive endpoints (ICF, 2004b).  The reviewers
further noted that: (1) there are significant similarities between the
female reproductive systems of humans and rodents; (2) effects on the
ovarian cycle are associated with reduced fertility in both humans and
rats; and (3) changes in estrous cycles in rats have potential human
relevance.  EPA Guidelines for Reproductive Risk Assessment (US EPA,
1996) state that “significant evidence that the estrous cycle (or
menstrual cycle in primates) has been disrupted should be considered an
adverse event.  Included should be evidence of abnormal cycle length or
pattern, ovulation failure, or abnormal menstruation.”

Given the clear relationship between decreasing number of estrous cycles
with increasing dose in WIL (2001), consistent with Yamada et al. (2003)
and with other effects on the female reproductive system, ICF (2005a)
conducted benchmark dose analyses on the number of estrous cycles during
the 3-week period prior to mating, following 7 weeks of nPB exposure.  
The statistical model that provided the best fit to the dose-response
data yielded a lower-bound benchmark dose level (BMDL) of 162 ppm (ICF,
2006a, Att. A).  

This BMDL results in a lower WEL than that calculated using the points
of departure based on other endpoints, such as liver effects, or effects
on the nervous system.  We note that there are a variety of reproductive
health effects with BMDLs in the range from 160 to 210 ppm, including:

Number of estrous cycles during a 3-week period (F0 generation) at 162
ppm (ICF, 2006a)

Sperm motility (F1 offspring generation) at 169 ppm (ICF, 2002a)

Decreased live litter size at 170 ppm (F2 offspring generation) and 190
ppm (F1 offspring generation) (TERA, 2004; Stelljes and Wood, 2004)

No estrous cycle incidence (F1 offspring generation) at 180 ppm (TERA,
2004)

Change in prostate weight (F0 parental generation) at 190 ppm (TERA,
2004)

Estrous cycle length (F0 parental generation) at 210 ppm (TERA, 2004)

These effects are seen in males, females, and offspring, and in
different generations of the two- generation study (WIL, 2000).  They
also are consistent with results seen in one-generation reproductive
studies, such as Ichihara et al., 2000 and Yamada, 2003.  Of these
effects, the one occurring at the lowest level, and thus protecting
against all adverse health effects, is the number of estrous cycles
during a 3-week period.  Consistent with Agency guidance (US EPA,
1994a), EPA is using 162 ppm as a “point of departure” to derive the
WEL.  

2.	Derivation of WEL

	To calculate the WEL for nPB, EPA uses standard risk assessment methods
delineated in Agency guidance (US EPA, 1994a) in evaluating data,
choosing a benchmark dose level or a NOAEL, and making the adjustments
and uncertainty factors prescribed to account for differences in the
duration of exposure and in sensitivity between and within species.

		Adjustment for Occupational Exposure Pattern  

To account for differences between the exposure pattern used in the WIL
study (6 hours per day for 7 days per week) when compared to a typical
workweek of 8 hours per day and 5 days a week, a “human equivalent
concentration” (HEC) is first calculated by adjusting the benchmark
dose level:

(162 ppm x 6 hours/8 hours) x 7 days/5days = 170 ppm

		Uncertainty Factors

According to EPA risk assessment guidance for reference concentrations
(RfC) (EPA 1994a), uncertainty factors of up to 10 may be applied to the
HEC for each of the following conditions:

Data from animal studies are used to estimate effects on humans;

Data on healthy people or animals are adjusted to account for variations
in sensitivity among members of the human population (inter-individual
variability);

Data from subchronic studies are used to provide estimates for chronic
exposure;

Studies that only provide a LOAEL rather than a NOAEL or benchmark dose;
or 

An incomplete database of toxicity information exists for the chemical.

EPA believes that two uncertainty factors are appropriate for this
database to account for (1) physiological differences between humans and
rats; and (2) variability within the working population.  The rationale
for the use of these two uncertainty factors is described below.

EPA RfC guidelines state that an uncertainty factor of 10 may be used
for potential differences between study animals and humans.  This factor
of 10 consists in turn of two uncertainty factors of 3 – the first to
account for differences in pharmacodynamics and the second to account
for differences in pharmacokinetics between the study animal and humans.
(The value of three is the square root of 10 rounded to one digit, with
10 representing an order of magnitude (EPA,1994a).  In practice, EPA
uses the square root of 10 when there are two or four uncertainty
factors of 3, yielding a total uncertainty factor of 10 or 100, and we
use a value of 3 when multiplying by other uncertainty factors).  By EPA
RfC guidelines (EPA, 1994a), no adjustment for differences in
pharmacokinetics is necessary in this instance because the blood/air
partition coefficient for nPB in the human (7.1) is less than in the rat
(11.7), indicating that the delivered dose of nPB into the bloodstream
in rats is slightly higher than in humans.  Consistent with Appendix J
of EPA’s RfC guidelines for an inhaled compound that exerts its
effects through the bloodstream, EPA applies an uncertainty factor of 1
for pharmacokinetics. 

However, EPA recognizes that the lack of an uncertainty adjustment for
pharmacokinetic differences between animals and humans rests on a
default approach applied to category 3 gases described in Appendix J of
its guidelines for deriving an inhalation RfC.  This default approach
assumes that nPB’s toxicokinetics follow a model in which: (1) the
toxicity is directly related to the inhaled parent compound in the
arterial blood, and (2) the critical metabolic pathways scale across
species, with respect to body weight, in the same way as the ventilation
rate.  Given the hypothesized metabolic pathways for nPB (ICF, 2002a;
CERHR, 2002a), it is plausible that toxicity in rats may be related to a
reactive metabolite in the target tissue rather than the blood level of
the parent compound.  EPA is not aware of any quantitative data on nPB
metabolism in humans, or evidence implicating the biologically active
agent or mode of action.  Some commenters on the June 2003 NPRM stated
that EPA should use an uncertainty factor of 2 or 3 for
pharmacokinetics, or an overall uncertainty factor of 10 for rat to
human extrapolation because of a lack of information on the metabolism
and mode of action of nPB (Werner, 2003; Risotto, 2003).  Recent studies
provide additional data regarding metabolism of nPB in rats and mice
(RTI, 2005), but data on human metabolism are still lacking.  

Despite the difference in metabolic pathways for nPB in mice and rats
(RTI, 2005), no significant species-specific differences in toxicity
exist between rats and mice at inhaled concentrations <500 ppm for 13
weeks (NTP, 2003; ICF, 2006c).  EPA requests additional data and comment
from the public on the pharmacokinetics, metabolism, and mode of action
of nPB that will help determine whether an interspecies uncertainty
factor greater than the default value of 1 is warranted to account for
pharmacokinetics.  If data become available indicating that nPB does not
conform to the constraints assumed by the default pharmacokinetic model
in the RfC guidelines, we would revise our risk assessment for nPB as
necessary, and apply an uncertainty factor for pharmacokinetics
consistent with the RfC guidelines in extrapolating from animal to
humans.  Depending on the resulting difference in the recommended WEL,
we would also revise our acceptability determinations accordingly. 
Given the available data on the blood/air partition coefficient and EPA
RfC guidance in the absence of other information, EPA is applying the
same rationale used for other compounds reviewed under EPA’s SNAP
program with a comparable amount of data where an uncertainty factor of
1 for pharmacokinetics was applied.  To account for uncertainty in
pharmacodynamics of nPB, EPA is applying the default uncertainty factor
(UF) of 3.  This follows the procedures in EPA’s RfC guidelines for
situations where there are no data to compare pharmacodynamics in rats
versus humans (EPA, 1994a).  Recently published data on humans and
rodents do not decrease the uncertainty regarding the pharmacodynamics
of nPB; therefore, modification of the UF of 3 for differences between
species is not justified.  

EPA is also applying an uncertainty factor of 3 to protect for sensitive
subpopulations and variability in the working population.  There are
preexisting reproductive conditions as well as significant variability
in fertility among otherwise healthy women.  For example, in a study of
782 couples, Dunson et al. (2002) found that fertility was twice as high
for women ages 19 to 26 years compared to women ages 35 to 39 years, and
that factors other than age (e.g., smoking, sexually transmitted
diseases, occupational exposure) accounted for a three-fold difference
in fertility rates.  Since similar sources of variability would be
expected among individuals in the workplace, variability in reproductive
capacity of workers of more than 2-fold and less than 10-fold based on
the finding of Dunson et al. (2002) might be expected.  EPA’s RfC
guidelines recommend an uncertainty factor of 10 to account for
intraspecies variability within the general population.  However, in
developing a WEL, EPA’s focus is on worker exposure, which excludes
some particularly vulnerable populations, such as children, most
adolescents, and the elderly.  Under EPA guidelines, 3 is a default
value for an uncertainty factor where there is indication that a value
less than an order of magnitude (10) but greater than one is
appropriate, and where the available data are not sufficiently
quantified to select a specific value.

The uncertainty factors of 3 for animal-human extrapolation and 3 for
variability within the human working population (each representing half
an order of magnitude) yield a composite uncertainty factor of 10.  When
the human equivalent concentration of 170 ppm derived above is divided
by a total uncertainty factor of 10, the proposed WEL of 17 ppm results.
 This is higher than the value (i.e., 10 ppm) that would have been
obtained had EPA used the NOAEL of 100 ppm for either male or female
reproductive effects in the WIL (2001) study as the point of departure. 
This also is higher than the TLV of 10 ppm developed by the ACGIH.  EPA
believes that the benchmark dose approach more accurately characterizes
the observed effects and provides a more robust utilization of the data.
 Further, if EPA had used one of the other reproductive endpoints, such
as sperm motility or live litter size, we would have calculated a WEL in
the range of 18 to 22 ppm.

3.	Other Recent Analyses of nPB Toxicity  

Since the 2003 NPRM, a number of reviews of nPB toxicity have been
issued, several of which include recommendations for occupational
exposure limits.  CERHR, 2003a and 2004a are similar to CERHR, 2002a,
the expert panel report for nPB for the Center for the Evaluation of
Risks to Human Reproduction (CERHR).  CERHR, 2003b and 2004b are similar
to CERHR, 2002b, the CERHR expert panel’s report for iPB.  Rozman and
Doull, 2005 derived a WEL of 25 ppm for nPB based on neurotoxicity,
using more recent information than Rozman and Doull, 2002.  

EPA reviewed Rodricks (2002) in developing its June 2003 NPRM, although
the study was not explicitly mentioned in that preamble.  Rodricks
(2002) suggests a WEL of 60 to 88 ppm for nPB, based on male
reproductive effects.  The Stelljes and Wood (2004) analysis is similar
in its results to SLR International (2001), a study by the same authors.
 EPA previously reviewed both these studies in developing the June 2003
NPRM.   Both studies concluded with a recommended WEL of 156 ppm, based
on male reproductive effects.  Stelljes (2005) reviews RTI’s 2005
study on metabolism of nPB in mice and rats and other literature and
speculates that humans should be less sensitive to nPB than either mice
or rats based on differences in metabolite production.  Stelljes (2005)
recommends that no uncertainty factor is required to extrapolate from
animals to humans and that an uncertainty factor of no more than 2 is
appropriate to account for differences within the working population. 
All of these documents assigned uncertainty factors in a manner that is
not sufficiently supported by the available data and that is
inconsistent with EPA’s guidance.  For example, Stelljes (2005)
discusses metabolic data in rats and mice from RTI, 2005 and concludes
that on this basis, the uncertainty factor for extrapolation from
animals to humans should be 1.  However, the metabolic data relate to
pharmacokinetics--the activity of chemicals in the body--and do not
address EPA’s proposed uncertainty factor of 3 related to
pharmacodynamics (the biochemical and physiological effects of chemicals
in the body and the mechanism of their actions).  Using the WEL from one
of these documents would result in a higher, less protective WEL than we
would determine following the approach EPA has used for other chemicals
under the SNAP program and would ignore significant sources of
uncertainty in health effects.  In addition, based on our most recent
examination of the health effects of nPB, these documents do not select
the most sensitive endpoint to protect against female reproductive
effects, effects on live litter size, and other adverse health effects. 
Thus, we are concerned that the WELs based on these documents are not
sufficiently protective and would result in an inappropriate
acceptability decision.  Detailed reviews of these documents are
available in the public docket.

TERA, 2004 reviews other WEL derivations for nPB, performs a benchmark
dose analysis, and recommends a WEL of 20 ppm based on live litter size.
 This document is consistent with EPA guidance for benchmark dose
modeling and for assigning uncertainty factors.  A review of this
document is available in the public docket.

The California Environmental Protection Agency’s Office of
Environmental Exposure and Hazard Assessment (OEHHA) listed both nPB and
iPB as reproductive toxins on the basis of developmental, male
reproductive, and female reproductive toxicity under the State’s Safe
Drinking Water and Toxic Enforcement Act of 1986, also known as
Proposition 65 (OEHHA, 2006).  Under this law, California is required to
list chemicals known to be carcinogenic or to be reproductive toxins and
to update that list at least annually.  

	The American Conference of Government Industrial Hygienists (ACGIH)
issued a recommended Threshold Limit Value™ (TLV) of 10 ppm
(time-weighted average) for nPB (ACGIH, 2005).  ACGIH summarized
numerous studies showing different effects of nPB and identified no
observed effect levels (NOELs) of 200 ppm for hepatoxicity (ClinTrials,
1997b) and less than 100 ppm for developmental toxicity, as evidenced by
decreased fetal weight (Huntingdon Life Sciences, 2001).  

In prior SNAP reviews, EPA has used ACGIH TLVs where available in
assessing a chemical’s risks and determining its acceptability.  ACGIH
is recognized as an independent, scientifically knowledgeable
organization with expertise in issues of toxicity and industrial
hygiene.  However, in this case, EPA believes that ACGIH’s TLV for nPB
has significant limitations as a reliable basis for a workplace exposure
limit, especially given the availability of other, more comprehensive
analyses described in this proposal.  First, according to the authors of
the Huntingdon Life Sciences study, the decrease in fetal weight was an
artifact of sampling procedure that biased the data (test animals were
only sacrificed at the end of the day rather than at random).  The CERHR
expert panel excluded “aberrantly low” fetal weights from one litter
in this study and calculated a BMDL greater than 300 ppm for this
endpoint after removing those outlier data (CERHR, 2002a, 2003a, and
2004a).  TERA calculated a similar BMDL when  analyzing the same data
set (TERA, 2004).  Further, the reference list in the documentation on
the TLV indicates that ACGIH did not review and evaluate all the studies
available prior to the development of the recommended exposure limit. 
For example, key supporting articles that reported disruption of estrous
cycles (Yamada et al., 2003 and Sekiguchi et al., 2002) were not
discussed in the TLV documentation.  Further, ACGIH did not provide any
reasoning for the selection of the chosen endpoint over others (e.g.,
reproductive toxicity and/or neurotoxicity).  The lack of discussion of
applied uncertainty factors also prevents a determination of how ACGIH
arrived at a TLV of 10 ppm.  In summary, EPA is not basing its proposed
acceptability determination for nPB on the ACGIH TLV because: (1) other
scientists evaluating the database for nPB did not find the reduced pup
weight to be the most sensitive endpoint; (2) benchmark dose (BMD)
analysis of the reduced pup weight data (CERHR, 2002a; TERA, 2004)
results in a higher BMDL (roughly 300 ppm) than those for sperm effects
and estrous cycle changes; and (3) ACGIH may not have reviewed the
complete body of literature as several studies discussing neurotoxicity
and changes in estrous cycle length were omitted from the list of
references.  A review of this document is available in the public
docket.

	B.	Community exposure guideline tc "		2.	CEG " \l 3 

	In this proposal, EPA is using a community exposure guideline (CEG) of
1 ppm to evaluate potential health risks among populations living near
facilities using nPB.  This community exposure guideline is an estimate
of a continuous inhalation exposure (averaged over 24 hours per day, 7
days per week) to the general public (including sensitive subgroups)
that is likely to be without an appreciable risk of adverse health
effects during a lifetime.

	EPA calculated the community exposure guideline using increased estrous
cycle length as the point of departure, the BMDL of 162 ppm for a
reduced number of estrous cycles during a three-week period, and an HEC
of 40 ppm as follows:

162 ppm x (6 hours exposure in study/24 hours avg time) x (7 days/7
days) = 40 ppm

EPA used an uncertainty factor of 3 for extrapolation from animals to
humans, as discussed above in section VI.A, and an uncertainty factor of
10 for variability within the general population, consistent with
EPA’s RfC guidelines.  Dividing the HEC of 40 ppm by 30 yields a
community exposure guideline of approximately 1 ppm, the same as the
value calculated using liver effects or sperm motility as an endpoint.  

	EPA evaluated general population exposure using EPA’s SCREEN3 (US
EPA, 1995a) air dispersion model to assess the likely maximum
concentration of nPB from single sources.  EPA used data collected from
actual facilities (Swanson, 2002) to characterize two scenarios:  (1) a
typical large, high-use adhesive application facility where the closest
resident is 100 meters away; and (2) a smaller facility with average-use
adhesive application in an urban area, where the nearest resident is
only 3 meters away.  The results indicated that modeled exposures in
either scenario did not exceed the CEG of 1 ppm.  The highest exposure
modeled was 0.24 ppm at a distance of 3 meters away from the source in
the urban scenario, while most other exposures were at least an order of
magnitude lower (ICF, 2003; ICF, 2006a).  Because the community exposure
guideline was not exceeded for any of the exposure scenarios in this
conservative screening approach, EPA has concluded that nPB exposure to
populations living close to facilities using nPB is not a major concern.

VI.	What listing is EPA proposing for each sector or end use, and why? 
tc "C.	What  proposals is EPA making for each sector or end use based on
these criteria? " \l 2 

	In this rule, EPA is proposing to find nPB unacceptable in adhesive and
aerosol solvent end uses, acceptable subject to use conditions in the
coatings end use, and acceptable in the metals, electronics and
precision cleaning end uses.  The proposed listings are intended to
allow the use of nPB where it can be used safely (i.e., with exposure at
or below 17 ppm on an eight-hour [8-hr] TWA), and to prohibit its use
where nPB cannot be used safely.  We also are taking comment on the
alternate approach of finding nPB acceptable subject to use conditions
in the adhesive and aerosol solvent end uses.  We summarize these
proposed decisions for each end use and sector and the alternate
proposal in Table 13.



Table 13.  Proposed Decisions by End Use and Sector

For nPB in this sector and end use:	Our proposal is to list nPB as:	And
our alternate proposal is:

Solvent Cleaning

Metals Cleaning	Acceptable (without restriction)	Acceptable, subject to
use conditions2

Electronics Cleaning	Acceptable (without restriction)	Acceptable,
subject to use conditions2

Precision Cleaning	Acceptable (without restriction)	Acceptable, subject
to use conditions2

Aerosols

Aerosol solvents	Unacceptable	Acceptable, subject to use conditions2

Adhesives, Coatings, and Inks

Coatings	Acceptable, subject to use conditions1	Acceptable, subject to
use conditions2 

Adhesives	Unacceptable	Acceptable, subject to use conditions2

 1  Use of nPB in this end use is limited to coatings at facilities that
have provided EPA information demonstrating their ability to meet the
recommended workplace exposure limit as of [INSERT DATE OF PUBLICATION]
(i.e., the Lake City Army Ammunition Plant).

2  Use conditions would include proposed requirements that users must 
(1) meet a workplace exposure limit of 17 ppm on an eight-hour
time-weighted average, (2) monitor workers’ exposure to nPB using a
personal breathing zone sampler on an eight-hour time-weighted average
initially and periodically (every 6 months or longer, depending on the
concentration during initial monitoring), and (3) keep records of the
worker exposure data on site at the facility for at least three years
from the date of the measurement.

A.	Solvent Cleaning 

	There are a number of alternatives that reduce the risks from ozone
depletion or from smog production7 slightly more than nPB when used in
industrial solvent cleaning equipment.  However, we found no single
alternative that could work in all applications that clearly would
reduce overall risks to human health and the environment in metals
cleaning, electronics cleaning, and precision cleaning.  Balancing the
different criteria discussed above in section IV., nPB does not pose a
significantly greater risk than other substitutes or than the ODS it is
replacing in these end uses if users meet the recommended exposure
limit.  As discussed below, we believe that users can and will meet the
recommended exposure limit in these end uses.  Thus, we propose to list
nPB as acceptable in metals cleaning, electronics cleaning, and
precision cleaning.

	EPA believes that the great majority of users of nPB in metals
cleaning, electronics cleaning, and precision cleaning have been able to
attain exposure levels of less than 17 ppm with their existing
equipment.  Recently measured exposure levels for nPB are much lower
than historic exposure data from the 1970s and 1980s for metals cleaning
and electronics cleaning (ICF, 2006a); this reflects both improvements
in industrial hygiene practices and improvements in cleaning equipment
since 1994 spurred by the National Emission Standard for Hazardous Air
Pollutants for Halogenated Solvent Cleaning (59 FR 61801). 
Concentrations of nPB emitted from industrial solvent cleaning equipment
were found to be below 25 ppm in roughly 88% of 500 samples on an 8-hr
time-weighted average, below 17 ppm in 80% of these samples, and below
10 ppm in roughly 70% of these samples (US EPA, 2003).  The WEL of 17
ppm was attained the vast majority of the time, even when users were
trying to meet their suppliers’ higher exposure limits of 25 ppm
instead of 17 ppm, and even in the absence of any regulatory
requirements.  

	One nPB supplier provided evidence that on the few occasions when nPB
concentrations from vapor degreasers were higher than the company’s
recommended WEL of 25 ppm, users were able to reduce exposure easily and
inexpensively by changing work practices, such as reducing drafts near
the cleaning equipment (Kassem, 2003).  The ability to meet the
workplace exposure limit depends on:  (1) the features of the cleaning
equipment used, such as the presence of secondary cooling coils; and (2)
the work practices, such as avoiding drafts near cleaning equipment and
lifting cleaned pieces out slowly from the cleaning equipment. 
Workplace controls could include, but are not limited to, the use of the
following:  covers on cold-cleaning and vapor degreasing equipment when
not in use; devices to limit air movement over the degreaser; and/or a
lip-vent exhaust system to capture vapors and vent them out of the room.
 Training workers in industrial hygiene practices and in the proper use
of cold cleaning and vapor degreasing equipment, as well as warning
workers of the symptoms that may occur from over-exposure to nPB, will
also help reduce exposure.  Therefore, we expect that users of nPB in
the solvent cleaning sector following typical industry practices and
using typical equipment for vapor degreasing will continue to meet the
WEL and to use nPB safely without regulatory requirements.  This is the
approach the SNAP program has taken with many other solvents where users
are readily able to meet available workplace exposure limit and there is
no enforceable OSHA PEL (e.g., HFC-365mfc, HFC-245fa,
heptafluorocyclopentane, ketones, alcohols, esters, hydrocarbons, etc.).
 Based on the available exposure data and current industry practices,
EPA believes that workers using nPB in industrial solvent cleaning
equipment for metals cleaning, electronics cleaning, and precision
cleaning are unlikely to be exposed to amounts of nPB above EPA’s
proposed workplace exposure level of 17 ppm.  

	B.	Aerosol Solvents  tc "2.	Aerosol Solvents " \l 3 

	In this rule, EPA proposes to find nPB unacceptable in the aerosol
solvent end use.  As for solvent cleaning, we found that some
alternatives could reduce particular environmental risks more than nPB,
such as generation of ground level “smog” or ozone depletion
potential.  There are a number of aerosol solvent alternatives that do
not pose any potential for ozone depletion or for ground-level smog
formation.  However, in balancing the different concerns and criteria
for evaluation, we find the greatest concern in this end use is with
nPB’s human health effects.  We propose to find nPB unacceptable in
aerosol solvents because it increases overall impacts on human health
and the environment significantly more than other available
alternatives. 

	Available information on the use of nPB in aerosols shows that aerosol
users may not be able to maintain exposures to nPB at or below the
recommended WEL without ventilation or with only regional ventilation
such as a fan for an entire room.  Personal breathing zone samples
collected in a recent study showed 8-hour time-weighted average (TWA)
exposures of 5.5, 13, and 32 ppm for workers using 310 g of nPB from a
spray can (Linnell, 2003).   The two higher exposure levels occurred in
the absence of any local or regional ventilation; the use of both local
and regional ventilation equipment with ventilation levels around 1900
ft3/min was associated with the lowest exposure level.  Similar
measurements were made in another study:  8-hr TWA exposures of 11.3,
15.1, 17.0, and 30.2 ppm with regional ventilation of 300 cubic feet per
minute from a fan for the entire room (Confidential submission, 1998). 
In these same two studies, exposure measurements taken from the
breathing zone of workers over 15-minutes, if divided by 32 to estimate
an equivalent 8-hr TWA, would have varied from less than 1 ppm to 34.4
ppm (Linnell, 2003; Confidential submission, 1998).

	These monitoring data are consistent with or slightly higher than data
from EPA modeling that estimates exposures for workers using different
amounts of aerosol (500 and 1000 g over a full day), different rates of
ventilation (450 to 1350 cfm), and different aerosol solvent
formulations (pure nPB and mixtures of nPB and other solvents
commercially available) (ICF, 2006a).  In a space with an air exchange
rate of 450 ft3/minute or less, EPA’s modeling predicts 8-hour average
exposure of approximately 16 to 17 ppm if a user sprays 450 g of pure
nPB (approximately 1 lb), and corresponding higher exposure values at
higher spray rates (e.g., 33 ppm if the amount of nPB sprayed is 900 g)
(ICF, 2006a).  Therefore, if users varied the amount of nPB used only
slightly above a pound per day on average or had ventilation levels
below 450 cfm (face velocity of 50 fpm), they would be exposed in excess
of the WEL.  EPA is aware of no data on ventilation levels that would
demonstrate that most users of aerosol solvents, or of nPB in
particular, would use aerosols in locations with ventilation levels of
450 cfm or greater.  The available worker exposure studies examined
ventilation levels of 0, 48, 300, 472, 640, and 1900 cfm, implying that
manufacturers for this sector believe that ventilation flow rates could
be lower than 450 cfm.  Based on the available monitoring and modeling
data, we expect exposure to nPB to exceed the proposed workplace
exposure limit of 17 ppm in confined spaces and in the many applications
for nPB-based aerosols where ventilation equipment is not or cannot be
installed, such as on energized electrical equipment (Linnell, 2003;
Werner, 2003; CSMA, 1999).  Aerosol manufacturers have stated that the
majority of the market for nPB used in aerosols is for electrical
contact cleaning (Williams, 2005).  We are reviewing nPB as a
replacement for HCFC-141b and in-place cleaning such as for electrical
contact cleaning comprised the majority of the aerosol market for
HCFC-141b (US EPA, 2004).  Further, because aerosol cans are portable
and their use cannot reasonably be monitored continuously, EPA cannot
ensure that nPB-based aerosols are barred from use in confined spaces
where exposure levels would be likely to exceed the WEL and create
excessive health risks.  Thus, EPA believes that it would be difficult
or even impossible to meet a recommended workplace exposure limit of 17
ppm in the majority of situations where nPB would be used as a
substitute for HCFC-141b as an aerosol solvent.

	EPA has found numerous other aerosol solvents acceptable.  These
aerosol solvents can be used safely in a manner consistent with their
respective workplace exposure limits.  This is highlighted in a study
comparing concentrations of eight different chemicals that are
acceptable under the SNAP program in aerosol formulations:  HFE-7100,
HFE-7200, trans-1,2-dichloroethylene, HCFC-225ca and -225cb, acetone,
pentane, and HFC-134a.  In this study, with ventilation of only 48 cfm,
8-hr TWA exposure from the different chemicals varied from 35.5 ppm to
194.0 ppm, and all chemicals met their respective recommended exposure
levels (ICF, 2006a).  nPB exposure in similar ranges would be from two
to eleven times the WEL for nPB.  Thus, nPB would impose significantly
more risk to human health and the environment than other alternatives
available for this end use.  

 

	C.	Adhesives

	EPA proposes to find nPB unacceptable in the adhesive end use.  As for
solvent cleaning and aerosols, we found that some alternative adhesive
formulations could reduce particular environmental risks more than nPB,
such as generation of ground level “smog” or ozone depletion
potential.  However, we find the greatest concern in this end use is
with nPB’s human health effects.  We propose to find nPB unacceptable
in adhesives because it increases overall impacts on human health and
the environment significantly more than other available alternatives.

   tc "		3.	Adhesives " \l 3 	Available information on exposure levels
during use of nPB-based adhesives indicates that it would be difficult
to meet a recommended exposure limit of 17 ppm.  Therefore, we believe
nPB poses a significantly greater risk than other available substitutes
in this end use.  For exposure to nPB when used in adhesives, NIOSH
investigators initially reported that mean exposures to nPB ranged from
60 to 381 ppm (8-hour time weighted averages) at three different
foam-fabrication facilities using nPB-based adhesives (NIOSH, 2000a,
2000b, 2001, 2002a, 2002b, 2003a).  In one facility, average (mean) nPB
exposures were reduced from 169 ppm to 19 ppm, following installation of
ventilation equipment recommended by NIOSH (NIOSH, 2000b).  Although use
of spray booths at this facility had a dramatic effect of reducing the
average exposure level to 19.4 ppm, individual exposures were still
excessive.  Eleven of fourteen sprayers (79%) and sixteen of all thirty
workers (53%) monitored continued to have exposures exceeding the
proposed WEL of 17 ppm.  

	At another facility using nPB-based adhesives, the average exposure was
reduced from 58 pm to 19 ppm after the company installed ventilation
recommended by NIOSH (NIOSH, 2001).  Data on exposure for sprayers found
fewer individuals receiving high exposures than at the facility
monitored in NIOSH (2000b), but 44% (15 of 34) of exposure samples were
higher than the proposed recommended WEL of 17 ppm, even after improving
ventilation. 

	Modeled data of workplace exposure based on average amounts of spray
adhesive and average ventilation would result in exposure levels of
roughly 60 ppm, more than three times the WEL (ICF, 2006a).  In at least
four cases, workers using nPB-based adhesives have been exposed to
excessive amounts of nPB, to the point where they needed to be
hospitalized for adverse neurological effects (Ichihara et al., 2002 and
Miller, 2005; Raymond and Ford, 2005; Beck and Caravati, 2003, and
Majersik et al., 2004, 2005; Calhoun County, 2005).  

	Considering the exposure data for nPB-based adhesives, we believe it is
unlikely that, even with ventilation, exposure levels for adhesives
users would be below the proposed recommended WEL on a consistent basis.
 Overall, 48% of all workers in these two facilities using nPB-based
adhesives were exposed to concentrations of nPB greater than the
proposed recommended WEL of 17 ppm (31 of 64 workers), even after
installing state-of-the-art ventilation with assistance from NIOSH. 
Sprayers had significantly higher individual exposures than workers who
did not work directly with the nPB-based adhesive.

	Given the information above, we are concerned that nPB-based adhesives
cannot be reliably used in a manner that protects human health.  We
request comment and data on whether it is feasible to use nPB-based
adhesives with worker exposure levels consistently below the proposed
recommended WEL of 17 ppm on an 8-hr TWA. 

	The available information indicates that all acceptable carrier
solvents in adhesives other than nPB have projected or actual exposure
less than the appropriate workplace exposure limit set by OSHA, the
ACGIH, the American Industrial Hygiene Association, or EPA.  Examples of
other carrier solvents currently used in adhesives and acceptable under
the SNAP Program include hydrocarbon solvents, acetone, methylene
chloride, and water.  EPA finds that there are other available
alternatives that present less risk to human health and the environment
compared to nPB in the adhesives end use.  

	During the public comment period on the June 2003 NPRM, one commenter
representing the adhesives industry stated that there are some small but
critical applications that require nonflammability and high solvency
(Collatz, 2003).  The commenter did not specify what those applications
are, and whether there was information showing that other types of
adhesives, such as those using water, flammable solvents, or methylene
chloride, are technically infeasible in these applications.  We request
comment and data on whether there are any unique applications of nPB in
the adhesives end use for which there are no other technically feasible
alternatives, and thus, for which nPB should be allowed.  If so, we
would consider finding nPB acceptable subject to narrowed use limits,
with requirements for each end user to perform a demonstration that
there are no other technically feasible alternatives for their
particular site, to install local exhaust ventilation equipment designed
to reduce exposure levels to the proposed recommended WEL, and to
perform worker exposure monitoring.  Alternatively, if there were
sufficient information provided during the public comment period showing
that there are applications in which only nPB can be used, we would
consider finding nPB acceptable in adhesives, subject to use conditions
requiring installation of local exhaust ventilation and worker exposure
monitoring, and subject to a narrowed use limit for those specific
applications where other alternatives are not technically feasible,
without requiring a site-specific demonstration that nPB is the only
feasible alternative.  This would allow for safer use of nPB in any
applications where nPB is the only alternative, if any such applications
exist.

	D.	Coatings  tc "		4.	Coatings " \l 3 

	We are proposing to find nPB acceptable, subject to use conditions, for
facilities that have provided EPA information demonstrating their
ability to meet the recommended workplace exposure limit as of [INSERT
DATE OF PUBLICATION].  The SNAP submission with information on coatings
was made for a single facility and EPA is unaware of anyone else 
interested in using nPB in this end use.  Workplace exposure levels to
nPB from ammunition sealant at Lake City Army Ammunition Plant ranged
from less than 1 ppm up to 21 ppm on an eight-hour time-weighted
average.  Thirty-four of 35 samples had concentrations below 10 ppm, and
the mean concentration for the plant was less than 4 ppm (Lake City Army
Ammunition Plant, 2004).  The vast majority of measurements show worker
exposure well below EPA’s proposed recommended workplace exposure
limit of 17 ppm.  Thus, we believe that nPB can be used as safely as
other acceptable solvents used at their workplace exposure limits under
the conditions at this facility.  

	Other acceptable substitutes for ozone-depleting substances in
coatings, in general, include oxygenated solvents, hydrocarbon solvents,
terpenes, hydrofluoroethers 7100 and 7200, benzotrifluorides (include
parachlorobenzotrifluoride), monochlorotoluenes,
trans-1,2-dichloroethylene, chlorinated solvents, water-based
formulations, and high-solids formulations.  In the particular
application for ammunition coatings, the submitter evaluated a large
number of alternatives and found that n-propyl bromide was the only one
of 29 solvents tested that could meet performance specifications at this
facility (Harper, 2005).  Thus, it is not clear that there are other
available substitutes available for this specific application, and
exposure data show that in this specific application, nPB can be used in
a way that does not significantly increase risks to human health
compared to other acceptable substitutes in the coatings end use.

VII.   How did EPA choose the use conditions in the alternate proposal,
and why?

	We also take comment on an alternate proposal.  In order to provide
flexibility for companies to choose nPB, but only where it would not
pose a significantly greater risk than use of other available
alternatives, we could require users to meet use conditions specifying a
worker exposure limit, monitoring, and recordkeeping.  Users would be
required to (1) meet a workplace exposure limit of 17 ppm on an
eight-hour time-weighted average, (2) monitor workers’ exposure to nPB
using a personal breathing zone sampler on an eight-hour time-weighted
average initially and periodically (every 6 months or longer, depending
on the concentration during initial monitoring), and (3) keep records of
the worker exposure data on site at the facility for at least three
years from the date of the measurement.  The use condition requiring
users to meet the WEL would protect human health by ensuring that
exposure is not above a level that is safe.  Monitoring of worker
exposure levels would give users a tool to identify and correct faulty
work practices or improve or replace equipment that provides
insufficient ventilation that, if undetected and uncorrected, would
result in exposure to nPB above the WEL of 17 ppm.  Keeping records of
the monitoring data would give EPA the ability to enforce the monitoring
and exposure limit requirements.  

In developing this proposal, EPA considered whether nPB presented a more
significant risk than other available ODS alternatives.  We believe that
use of nPB does not present significantly more risk so long as exposure
levels are maintained below the proposed WEL.  Establishing use
conditions could help ensure that users meet the WEL.  Therefore, EPA is
taking comment on use conditions that would require users to meet the
workplace exposure limit and monitor worker exposure.  

A.   Use Conditions and Their Rationale

	The major provisions of the use conditions and the related issues that
EPA considered in developing the alternate proposal are as follows:

Workplace exposure limit.   A requirement to meet the workplace exposure
limit would be an interim measure to ensure that nPB will be used safely
until OSHA issues a final permissible exposure limit (PEL) under the
Occupational Safety and Health Act.  In the event that OSHA issues a
final PEL, it would supersede EPA’s WEL.  EPA is specifically
deferring to OSHA, and has no intention to assume responsibility to
displace OSHA’s authority under Public Law 91-596.  EPA’s WEL would
not pre-empt the authority of OSHA to take regulatory or enforcement
action with respect to exposure to this substance.  This is made clear
by the Clean Air Act under which EPA would promulgate this regulation
(Subchapter VI – Stratospheric Ozone Protection), which provides at 42
U.S.C. 7610 in pertinent part: “…this chapter [Chapter 85 – Air
Pollution Prevention] shall not be construed as superseding or limiting
the authorities, under any other provision of law, of the Administrator
or any other Federal officer, department, or agency.”  By issuing a
WEL for nPB, EPA’s intention would be to fill existing regulatory gaps
during the interim period of substitution away from ozone-depleting
compounds and provide the needed margin of protection for human health
and the environment until OSHA develops other regulatory controls or
standards under appropriate authorities.

Worker exposure monitoring.  We modeled the worker exposure monitoring
requirements on OSHA’s requirements for monitoring for methylene
chloride. 29 CFR 1910.1052(d).  We expect that the regulated community
would be familiar with this approach and there might be fewer changes
for regulated businesses if OSHA later were to establish a workplace
standard for nPB.  Because the WEL is an 8-hr TWA value that is derived
from studies that measured exposure via inhalation, the proposed use
conditions require the owner or operator to monitor 8-hr TWA values that
measure workers’ exposure in the breathing zone (e.g., samples from a
worker’s collar).  We are not proposing to monitor short-term
exposures because acute, short-term exposures of nPB are not of
significant health concern, so long as long-term exposures are below the
8-hour TWA limit (ERG, 2004).

	Option for monitoring representative set of workers.  Personal breath
zone samples could be taken either from each worker using nPB or from a
representative set of exposed workers expected to have the highest
exposure.  Allowing exposure monitoring from representative workers
using nPB, rather than requiring separate monitoring for each individual
using nPB, would reduce overall compliance burden, while still detecting
any exposure levels in excess of the WEL and avoiding underestimates of
exposure.  

	Initial monitoring.  Users already using nPB would need to undergo
exposure monitoring no later than 90 days after the date the final rule
becomes effective.  A user that has never used nPB before would need to
perform initial monitoring before beginning to use nPB in the
facility’s industrial applications.  

	Periodic monitoring.	Monitoring would have to be performed periodically
on a schedule based on the results of the most recent set of exposure
monitoring data.  Monitoring from workers’ personal breathing zone
would be required during the next six months if an initial measurement
finds exposure levels between the action level and the 8-hour TWA
exposure limit.  No periodic monitoring would be required if initial
measurements are below the action level.  We would use a value of 8.5
ppm, half the proposed WEL of 17 ppm, as the action level.  OSHA
standards also set an action level of half the PEL. 

	Monitoring would no longer be required where the most recent exposure
monitoring data found all worker exposures at or below 8.5 ppm.  OSHA
rules also reduce monitoring requirements for exposures below the action
level because if measured values are that low, it is unlikely that any
measurement will exceed the PEL unless a major change to the process
occurs.

	Monitoring for changes in workplace conditions or nPB use.  New
monitoring would be required if an event occurs that would make the most
recent set of monitoring data no longer representative.  Examples of
these changes are discussed above in section III.F.  Normally, EPA would
expect that the owner or operator would plan new applications of nPB or
changes to control equipment or work practices and would perform a test
for worker exposure levels before using nPB on a regular basis in that
application.  In the case of an emergency, such as a breakdown of
ventilation equipment or a leak, we would expect exposure monitoring to
be performed as soon as possible, and no later than 7 days after the
change in workplace conditions.   This period is intended to give an
owner or operator time to locate and purchase exposure monitoring
equipment in an emergency where the equipment may not already be
available at the facility.  

Monitoring method and accuracy.  We take comment on the use of NIOSH
methods 1003 and 1025 (NIOSH, 2003b and c) for analyzing nPB exposure
under the alternate proposal.  Several of the studies that supplied EPA
with exposure data used this method and they are standardized methods
prepared by NIOSH, a recognized authority on industrial hygiene.  In
addition, we would allow other methods that are accurate to + 25% at the
95 percent confidence level.  Based on the accuracy of available
methods, most OSHA standards require exposure monitoring accurate to 25%
at the 95 percent confidence level, as in the methylene chloride
standard (29 CFR 1910.1052(d)(1)(iii)(A)) and other OSHA standards.

Recordkeeping requirements.  We would require that users keep records of
the worker exposure data for up to three years from the date the
measurement is taken. This would provide information allowing EPA to
determine if facilities are complying with the WEL and if people exposed
to nPB are sufficiently protected.  However, we note that OSHA’s
standard on access to employee exposure and medical records requires
retaining exposure records for at least 30 years (29 CFR
1910.1020(d)(ii)), and these requirements would still be in effect.  

Responsibility for meeting requirements.  Under the alternate proposal,
the owner or operator of a facility using nPB would be responsible for
meeting the rule’s use conditions. 

B.	Advantages and disadvantages of the alternate proposal

Setting use conditions that require users to meet a WEL and to monitor
and keep records to demonstrate achieving the WEL would protect the
health of nPB users while giving industry more flexibility and more
options for ODS substitutes, compared to finding nPB unacceptable.  This
could be especially useful for users of HCFC-141b as an aerosol solvent
who are seeking an effective ODS substitute.  If there were any
situations in which other available alternatives did not provide as good
performance, nPB would still be available as an option, provided the use
conditions could be met.  The monitoring requirements would encourage
good industrial hygiene and safe use of nPB.

Considering the list of use conditions above, we believe that setting
use conditions requiring a WEL, worker exposure monitoring, and
recordkeeping would be complex and potentially confusing.  Requiring
users to meet the WEL, although providing greater potential flexibility,
also would provide less certainty about how to comply.  A user could
spend considerable time and expense trying to meet the WEL, only to find
that it is not achievable. 

In the past, EPA only required a WEL for solvents that were new for
which there was limited workplace experience and a concern that the
exposure limit might be exceeded, such as when HFC-4310mee,
HCFC-225ca/cb, monochlorotoluenes, and benzotrifluorides were first
introduced.  Since then, we have concluded that users would easily be
able to meet exposure limits for most substitutes for which such a limit
existed, and thus, EPA found no need to impose a workplace exposure
limit as a use condition.  For a compound such as nPB, for which
workplace exposure data exist, there is greater certainty as to whether
the WEL would be exceeded.  Given the limited circumstances under which
we expect aerosol and adhesive users could meet the workplace exposure
limit and given the availability of other, less toxic alternatives in
both of these end uses, EPA would prefer to find nPB unacceptable in
aerosols and adhesives.   Further, considering that so many users of nPB
for metals, electronics, and precision cleaning and the users of nPB at
the Lake City Army Ammunition Plant meet the proposed WEL without
regulatory requirements (US EPA 2003; Lake City Army Ammunition Plant,
2004), it appears unnecessary to require an exposure limit in those end
uses.

What other options did EPA consider?

EPA considered several different options in preparing this proposed
rule, but we prefer the approach proposed in this rule.  We also take
comment on the options discussed below.

A.	Regulatory options based on the ACGIH’s Threshold Limit Value

	We considered using ACGIH’s TLV of 10 ppm as a workplace exposure
limit to recommend and to use in assessing human health risks to
workers.  For certain other compounds that EPA found acceptable, we used
a TLV when available (e.g., acetone, cyclohexane, isopropyl alcohol). 
However, as discussed above in section V.A, EPA has concerns about the
documentation and basis of ACGIH’s TLV derivation for nPB.  We note
that if we were to choose the TLV as the appropriate workplace exposure
limit for assessing human health risks of nPB, we would have proposed
the same decisions for each end use for the following reasons.    

	We believe that workers using nPB in solvent cleaning usually will not
be exposed in excess of the ACGIH’s TLV of 10 ppm because roughly 70%
of samples from the workplace already meet this level, even when users
were aiming to meet a higher exposure limit of 25 ppm (US EPA, 2003). 
Further, information from an nPB solvent supplier with a product
stewardship program demonstrates that users could take steps that
effectively reduce emissions further (Kassem, 2003).  

	For aerosol solvents, as mentioned above in Section VI.B, it would be
difficult for users in this end use to meet a higher recommended WEL of
17 ppm.  Considering available exposure data from personal samples in
two studies, only one of seven samples on an eight-hour time-weighted
average showed an exposure level of 10 ppm or lower (ICF, 2006a). 
Modeled exposures exceeded 10 ppm, even with some ventilation, if more
than a pound of nPB were used in a day.  

	In the adhesives end use, 80% of the exposure data are above 10 ppm,
even after installing state-of-the-art ventilation.  Only one sprayer
was exposed to 10 ppm or less in reports from NIOSH (NIOSH, 1999, 2000a,
2002a, 2002b, 2003, etc).  Modeled data of workplace exposure based on
average amounts of spray adhesive and average ventilation would result
in exposure levels of roughly 60 ppm, approximately six times more than
a level of 10 ppm (ICF, 2006a).  

	Tests at the Lake City Army Ammunition Plant showed an ability to meet
a WEL of 10 ppm, with the vast majority of measurements below that
value.  Thirty-four of 35 samples had concentrations below 10 ppm, and
the mean concentration for the plant was less than 4 ppm (Lake City Army
Ammunition Plant, 2004).  

Regulatory options requiring ventilation equipment

	We considered use conditions for the adhesive and aerosol solvent end
uses that would reduce the human health risks of using nPB by reducing
exposure levels with requirements for installation and use of
ventilation equipment.

Aerosols

	For the aerosol solvent end use, EPA considered proposing a requirement
for installation of ventilation equipment.  Such a use condition would
need to specify and define which kinds of ventilation equipment would be
necessary.  For example, because one study on exposure levels found that
exposure fell below 17 ppm reliably only where both local exhaust
ventilation and regional ventilation equipment were used, a possible
requirement would be for installation of both local exhaust ventilation
and regional ventilation.  Local exhaust ventilation is ventilation that
removes vapors from a specific work location using ducts and fans. 
Regional ventilation is ventilation that moves air around in a large
working area, such as one or more fans used for an entire room.  A
problem with requiring the type of ventilation equipment that all
facilities must use is that it still might not provide enough
ventilation in some situations and in other situations may be
unnecessary to meet the WEL.

	Another approach for aerosols we considered was to require a specific
level of ventilation.  Possible criteria for the level of ventilation
would be the air flow rate, in cubic feet per minute (cfm) or cubic
meters per second, or the face velocity at the location where a user
would work, in feet per minute (fpm) or meters per second face velocity.
 Based on both modeling and exposure data from one study (ICF, 2006a;
Linnel, 2003), an appropriate air flow rate for nPB-based aerosols would
be greater than 1900 cfm and an appropriate face velocity would be 170
fpm.  Alternatively, we considered requiring that facilities meet the
guidelines for face velocity in spray booths from the ACGIH Ventilation
Manual, in the range of 100 to 150 fpm, depending on the specific type
of booth.

	These options would appear to provide greater flexibility for industry
compared to finding nPB unacceptable in aerosol solvents.  However, our
understanding is that in most aerosol applications, it might not be
feasible to install adequate ventilation, and thus, to reduce human
health risks.  In the case of benchtop cleaning or degreasing, such as
during rework of individual parts that are not yet sufficiently clean,
it is possible to transport the part to a hood or spray booth to provide
sufficient ventilation.  However, for applications that require in-place
cleaning such as cleaning energized electrical contacts and switches,
maintenance in underground mines, or cleaning hot elevator motors, it is
not feasible to install ventilation equipment in place or to remove the
parts for cleaning in ventilation equipment (CSMA, 1999; Linnell, 2003).
 Information available to EPA shows that benchtop cleaning is perhaps
25% or less of the market for the ODS being replaced in aerosols (ICF,
2004) and that electrical contact cleaning makes up the vast majority of
the market for nPB-based aerosols (Williams, 2005); thus, we expect that
necessary ventilation cannot be installed in most aerosol applications
for nPB.  It would be difficult to explain and potentially confusing for
users that an aerosol product may be used for cleaning in one location
in a facility, but not in another, particularly when the ODS being
substituted for could be used in all locations without excessive worker
exposure.   Further, it would be difficult for EPA to enforce use
conditions on ventilation equipment, because aerosols are portable and
can easily be used outside of the ventilation equipment.  Other
acceptable substitutes, such as blends of HFEs or HFCs and
trans-dichloroethylene, are available in these end uses.

Adhesives

EPA also considered use conditions for ventilation equipment or for
specific ventilation levels for use of nPB-based adhesives.  However, to
date, we have found no study that demonstrates a ventilation option that
could achieve a WEL of 17 ppm when using spray adhesives.  Even with
state-of-the-art ventilation equipment installed with the expert
assistance of NIOSH, adhesives users were not able to lower exposure
limits sufficient to protect the vast majority of their workers. 
Modeling of different levels of adhesive usage and ventilation, based on
conditions at different facilities indicates that air flow rates would
need to be more than 100,000 cfm.  Even this high air flow rate might
not be sufficient, since an air flow rate of 28,500 cfm resulted in
exposure levels of 3.5 to 35 times the WEL, depending on the amount of
adhesive used (ICF, 2006a, Att. D).  Less toxic substitutes such as
water-based adhesives and acetone-based adhesives are available in this
end use.  

IX. 	What are the anticipated costs of this regulation to the regulated
community? tc "What are the anticipated costs of this regulation to the
regulated community?" 

	As part of our rulemaking process, EPA estimated potential economic
impacts of this proposed regulation.  In our analysis, we assumed that
capital costs are annualized over 15 years or less using a discount rate
for determining net present value of 7.0%.  The acceptability
determination for solvents cleaning imposes no requirements and thus
creates no additional cost to users.  In addition, because the use
condition for coatings still permits nPB’s use in the only known
coatings application using nPB, we find no additional cost to the user
community from this regulatory provision.  We found that if this
proposed rule were to become final, the cost to the user community of
the unacceptability determinations, which are regulatory prohibitions on
the use of nPB in adhesives and aerosols, would be in the range of $2.3
to $6.7 million per year for adhesive users and $ 36.3 to 39.7 million
per year for aerosol users.  

	EPA also considered potential costs end users could incur if they
implemented the recommended acceptable exposure limit and are not
already achieving it.  EPA found that those users using nPB-based
solvents in a vapor degreaser would save money by reducing solvent
losses, and that the savings would recover the costs of emissions
controls (e.g., secondary cooling coils, automated lifts or hoists)
within a year of installation.  Based on evidence from solvent
suppliers, EPA believes that some of those users would have chosen to
use nPB in order to avoid meeting requirements of the national emission
standard for halogenated solvents cleaning and that they would only
become aware of the potential savings due to reduced solvent usage as a
result of this proposal (Ultronix, 2001; Kassem, 2003; Tattersall,
2004).  Based on available exposure data for each sector, we assumed
that 80% of nPB users in the non-aerosol solvent cleaning sector already
achieve exposure levels of 17 ppm or less (US EPA, 2003).  Of those nPB
solvent users with exposure levels above 17 ppm, we examined the cost
associated with reducing emissions on average by 60%. 

Full implementation of the recommended workplace exposure guideline
across all nPB users in solvent cleaning would save up to $2 million
dollars per year.  The value will depend on the number of users that
attempt to meet the recommended exposure guideline, the number already
achieving the WEL with existing equipment, the initial exposure level of
cleaning solvent users, the price of nPB, and the amount of emission
control equipment installed.  

When the potential costs of compliance with the regulatory requirements
and the recommended workplace exposure limit are considered together,
EPA estimated the total cost in all sectors would range from $ 37.0 to
44.4 million annually.   

	We also estimated the cost to the user community of the use conditions
in the alternate proposal for aerosols, adhesives, coatings, and solvent
cleaning.  The requirements for users to meet a workplace exposure limit
and to perform exposure monitoring would be in the range of $ 41.5 to
72.2 million per year.  The upper end of the range of estimated impacts
likely assumes laboratory grade ventilation for aerosols, which we
expect to be significantly more expensive than standard industrial fume
hoods or spray booths (approximately $10,000 compared to $1,000 for each
hood).  For coatings, use of nPB is limited to a single facility that
already performs workplace exposure monitoring.  For aerosols and
adhesives, we assumed the installation of fume hoods or spray booths,
the use of personal protective equipment, and monitoring for 1.9 to 2.0
times per year.  For solvent cleaning, we assumed no change in equipment
for 80% of users, the upgrading of vapor degreasing equipment for the
remaining 20%, and monitoring an average of 1.3 times per year.  Using
these assumptions, we calculated the cost of the use conditions in the
alternate proposal at $18.0 to 24.0 million for adhesive users, $24.3 to
43.5 million for aerosol users, and $ -0.8 to $ 4.7 million for solvent
cleaning users.  The estimated cost of the use conditions does not
consider that some users could choose to switch to other alternatives at
a lower cost. 

	Estimated costs of the proposed regulation and alternate proposal are
summarized in Table 14.  For more detailed information, see section
XIII.C. below and EPA’s analysis in the docket (US EPA, 2006).

Table 14.  Estimated Costs of Regulatory Options EPA is Providing for
Comment

Sector or End Use	Requirements under Alternate Proposal	Annual Cost of
Alternate Proposal	Requirements under Proposed Rule	Annual Cost of
Proposed Rule

Solvent Cleaning (Metals, Electronics, and Precision Cleaning)	Achieve
WEL of 17 ppm; exposure monitoring, one or two times per year;
recordkeeping 	$-0.8 to 4.7 million	None explicit; recommended WEL of 17
ppm with expectation that users will meet WEL	Cost savings of up to $
2.0 million from reduced solvent consumption when meeting WEL

Aerosol Solvents	Achieve WEL of 17 ppm; exposure monitoring one or two
times per year; Recordkeeping	$24.3 to 43.5 million	Cease use of nPB and
switch to a different ODS substitute.	$ 36.3 to 39.7 million

Coatings	Achieve WEL of 17 ppm; exposure monitoring, one or  two times
per year; recordkeeping. 	None; only known facility using nPB-based
coatings already achieves the WEL and performs exposure monitoring	None
explicit; recommended WEL of 17 ppm with expectation that users will
meet WEL. Decision only applies to use nPB in coatings at at facilities
that have provided EPA information demonstrating their ability to meet
the recommended workplace exposure limit as of [INSERT DATE OF
PUBLICATION].	None; only known facility using nPB-based coatings already
achieves the WEL

Adhesives	Achieve WEL of 17 ppm; exposure monitoring, one or two times
per year; recordkeeping	$ 18.0 to 24.0 million	Cease use of nPB and
switch to a different ODS substitute.	$ 2.3 to 6.7 million

Total

$ 41.5 to 72.2 million

$37.0 to 44.4 million

 			

X.	Comparison of EPA’s June 2003 proposal and this proposal tc "VII.
Comparison of EPA’s June 2003 proposal and today’s proposal"  

	Table 15 compares the acceptability determination and evidence cited in
the June 2003 proposal and this proposal. 

Table   SEQ Table \* ARABIC  1 5: n-Propyl Bromide Acceptability
Decision

Proposed Decision	2003 Proposed Rule	Current Proposed Rule—Preferred
Proposal

Industrial End Uses #1-3:

Metals Cleaning, Electronics Cleaning, and Precision Cleaning (Solvent
Cleaning)	Acceptable, Subject to a Use Condition (Limiting use to nPB
formulations containing no more than 0.05% by weight isopropyl bromide);
WEL of 25 ppm1 on 8-hr TWA recommended	Acceptable; WEL of 17 ppm2 on
8-hr TWA recommended

Industrial End Use #4:

Aerosol Solvents	Acceptable, Subject to a Use Condition (Limiting use to
nPB formulations containing no more than 0.05% by weight isopropyl
bromide; WEL of 25 ppm1 on 8-hr TWA recommended	Unacceptable

Industrial End Use #5:

Adhesives	Acceptable, Subject to a Use Condition  (Limiting use to nPB
formulations containing no more than 0.05% by weight isopropyl bromide;
WEL of 25 ppm1 on 8-hr TWA recommended	Unacceptable

Industrial End Use #6: Coatings	Not addressed	Acceptable, Subject to
Narrowed Use Limits (Decision limited to  coatings at facilities that
have provided EPA information demonstrating their ability to meet the
recommended workplace exposure limit as of [INSERT DATE OF PUBLICATION);
WEL of 17 ppm2 on 8-hr TWA recommended

1 Proposed Workplace Exposure Limit of 25 ppm based upon nPB’s effect
on sperm motility from ICF’s evaluation of the WIL 2001 Study “An
Inhalation Two-Generation Reproductive Toxicity Study of 1-Bromopropane
in Rats.” 	

ICF, 2001. ‘‘Brief Discussion of the BMD Approach: Overview of its
Purpose, Methods, Advantages, and Disadvantages.’’ Prepared for U.S.
EPA.

ICF, 2002a. ‘‘Risk Screen for Use of N Propyl Bromide.’’
Prepared for U.S. EPA, May, 2002.

ICF, 2002b. Comments on the NTP- Center for the Evaluation of Risks to
Human Reproduction, Final Report on 1- Bromopropane.  Cover Letter Dated
5/9/02.

Also, evaluation of documents by CERHR (2002a, b), Doull and Rozman
(2001), Rodricks (2002), Rozman and Doull (2002), SLR International
(2001), and others.

2 Proposed Workplace Exposure Limit of 17 ppm based upon nPB’s effect
on the number of estrous cycles and estrous cycle length from ICF’s
re-evaluation of the WIL 2001 Study “An Inhalation Two-Generation
Reproductive Toxicity Study of 1-Bromopropane in Rats.” 	

ICF, 2006a, “Risk Screen for Use of N Propyl Bromide”, Prepared for
U.S. EPA, April, 2006.

ICF, 2004c, “Expert Panel Response on nPB AEL”, Prepared for U.S.
EPA, December, 2004

ICF, 2004d, “nPB Human Relevance”, Prepared for U.S. EPA, September,
2004

Also, evaluation of documents by Stelljes and Wood (2004); TERA (2004);
ACGIH (2005); Rozman and Doull (2005); Stelljes (2005); and others.

XI. 	 How can I use nPB as safely as possible? tc "VIII. 	 How can I use
nPB as safely as possible?" 

Below are actions that will help nPB users meet the workplace exposure
limit proposed in this rule:

All end uses

All users of nPB should wear appropriate personal protective equipment,
including chemical goggles, flexible laminate protective gloves (e.g.,
Viton, Silvershield) and chemical-resistant clothing.  Special care
should be taken to avoid contact with the skin since nPB, like many
halogenated solvents, can be absorbed through the skin. 

Limit worker exposure to solvents to minimize any potential adverse
health effects.  Workers should avoid staying for long periods of time
in areas near where they have been using the solvent.  Where possible,
shorten the period during each day when a worker is exposed.

Use less solvent, or use a different solvent, either alone or in a
mixture with nPB.

Follow all recommended safety precautions specified in the
manufacturer’s MSDS.

Workers should receive safety training and education that includes
potential health effects of exposure to nPB, covering information
included on the appropriate MSDSs, as required by OSHA's Hazard
Communication Standard (29 CFR 1910.1200).

Request a confidential consultation from your State government on all
aspects of occupational safety and health.  You can contact the
appropriate state agency that participates in OSHA’s consultation
program.  These contacts are on OSHA’s web site at     HYPERLINK
"http://www.osha.gov/oshdir/consult.html." 
http://www.osha.gov/oshdir/consult.html.   For further information on
OSHA’s confidential consultancy program, visit OSHA’s web page at  
HYPERLINK "http://www.osha.gov/html/consultation.html" 
http://www.osha.gov/html/consultation.html .

Use the employee exposure monitoring programs and product stewardship
programs where offered by manufacturers and formulators of nPB-based
products.

If the manufacturer or formulator of your nPB-based product does not
have an exposure monitoring program, we recommend that you start your
own exposure monitoring program, and/or request a confidential
consultation from your State government.

 	A medical monitoring program should be established for the early
detection and prevention of acute and chronic effects of exposure to
nPB.  The workers' physician(s) should be given information about the
adverse health effects of exposure to nPB and the workers' potential for
exposure.

Solvent cleaning

For non-aerosol solvent cleaning, follow guidelines in the NESHAP for
halogenated solvents cleaning if you are using nPB.  The equipment and
procedural changes described in the halogenated solvents NESHAP can
reduce emissions, reduce solvent losses and lower the cost of cleaning
with organic solvents.  For more information on the halogenated solvents
NESHAP, visit http://www.epa.gov/ttn/atw/eparules.html and     HYPERLINK
"http://www.epa.gov/ttn/atw/degrea/halopg.html." 
http://www.epa.gov/ttn/atw/degrea/halopg.html. 

Spray applications

For spray applications (e.g., aerosols), use sufficient ventilation to
meet the recommended 17 ppm WEL. 

For ventilation, we recommend that you follow the design guidelines for
ventilation in ACGIH’s Industrial Ventilation: A Manual of Recommended
Practice (ACGIH, 2002).  In particular, the guidelines in Chapter 10.75
are appropriate for spray booths, and the guidelines in Chapter 10.35
are appropriate for laboratory hoods.  

The ACGIH Ventilation Manual recommends a minimum flow rate of 150 cubic
feet per minute (cfm) for each sq-ft of opening for a small booth with
at least 4 sq-ft of open face area.  This equates to an average face
velocity of 150 ft/min.  For a large booth, the recommended face
velocity is 100 ft/min for walk-in booths and 100 to 150 ft/min for a
large spray booth where the operator works outside.  In general, the
opening should be kept as small as possible to accommodate the
work-pieces, generally 12 inches wider and taller than the largest piece
of work.  If all spraying is not directed towards the back of the booth
or the booth is too shallow for the size of the pieces being sprayed or
is disruptive air currents are present at the face of the booth, a
greater flow of air will be needed.

We note that these steps are useful for reducing exposure to any
industrial solvent, and not just nPB.

XII.	Statutory and Executive Order Reviews tc "Statutory and Executive
Order Reviews" 

	A. 	Executive Order 12866:  Regulatory Planning and Review 

	Under Executive Order (EO) 12866   SEQ CHAPTER \h \r 1 (58 FR 51735,
October 4, 1993), this action is a "significant regulatory action.” 
It raises novel legal or policy issues arising out of legal mandates,
the President's priorities, or the principles set forth in the Executive
Order.   SEQ CHAPTER \h \r 1  Accordingly, EPA submitted this action to
the Office of Management and Budget (OMB) for review under EO 12866 and
any changes made in response to OMB recommendations have been documented
in the docket for this action.

	  SEQ CHAPTER \h \r 1 In addition, EPA prepared an analysis of the
potential costs and benefits associated with this action.  This analysis
is contained in the document “Analysis of Economic Impacts of nPB
Rulemaking.”  A copy of the analysis is available in the docket for
this action (Ref. EPA-HQ-OAR-2002-0064) and the analysis is briefly
summarized here.  EPA estimates the total costs of the proposed rule to
between $37 and 44.4 million per year, with the health benefits being as
high as $111 million per year.

Paperwork Reduction Act	

The information collection requirements in this proposed rule have been
submitted for approval to the Office of Management and Budget (OMB)
under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.  An
Information Collection Request (ICR) document has been prepared by EPA
(ICR No. 2224.01) and a copy may be obtained from Susan Auby by mail at
Collection Strategies Division; U.S. Environmental Protection Agency
(2822T); 1200 Pennsylvania Ave., NW,  Washington, DC 20460, by email at
auby.susan@epamail.epa.gov, or by calling (202) 566-1672.  A copy may
also be downloaded off the internet at   HYPERLINK
"http://www.regulations.gov"  www.regulations.gov . in Docket
EPA-HQ-OAR-2002-0064.  

If the provisions of this proposed rule become final, there would be no
new information collection burden.  This proposed rule is an Agency
determination.  It contains no new requirements for reporting or
recordkeeping.  OMB has previously approved the information collection
requirements contained in the existing regulations in subpart G of 40
CFR part 82 under the provisions of the Paperwork Reduction Act, 44
U.S.C. 3501 et seq. and has assigned OMB control number 2060-0226 (EPA
ICR No. 1596.05).  This ICR included five types of respondent reporting
and record-keeping activities pursuant to SNAP regulations:  submission
of a SNAP petition, filing a SNAP//Toxic Substance Control Act (TSCA)
Addendum, notification for test marketing activity, record-keeping for
substitutes acceptable subject to use restrictions, and record-keeping
for small volume uses.

However, if EPA were to finalize the alternate proposal, users of nPB
would have an information collection burden from exposure monitoring and
recordkeeping.  Under the alternate proposal, users of nPB would be
required to monitor worker exposure initially and periodically (usually
every 6 months) and keep records of these exposure data at the facility
for at least three years from the date the samples were taken.  This
data is necessary to ensure that users of nPB are meeting the regulatory
use conditions.  If the data indicates that the use condition is not
being met, it could be used by EPA or citizens in an enforcement action
against the facility.  These data would be considered available to the
public and would not be considered confidential.  

The estimated burden of recordkeeping for the entire regulated community
under the alternate proposal is as much as $12.8 million and 24,050
hours per year.  The estimated recordkeeping burden for a typical user
is $96 and 0.18 hours per worker per monitoring event.  We estimate
approximately 1.6 monitoring events per year per worker, assuming that
roughly 60% of exposed workers must be monitored every six months and
40% must be monitored once annually.  We estimate that up to 75,000
workers would be monitored for exposure to nPB.  Costs include the
annual cost of purchasing passive organic exposure monitoring badges,
the annual cost of services for analyzing the resulting exposure, and
the annual cost of reviewing and filing the data up to 2 times per year.
  

	Burden means the total time, effort, or financial resources expended by
persons to generate, maintain, retain, or disclose or provide
information to or for a Federal agency.  This includes the time needed
to review instructions; develop, acquire, install, and utilize
technology and systems for the purposes of collecting, validating, and
verifying information, processing and maintaining information, and
disclosing and providing information; adjust the existing ways to comply
with any previously applicable instructions and requirements; train
personnel to be able to respond to a collection of information; search
data sources; complete and review the collection of information; and
transmit or otherwise disclose the information. 

	An Agency may not conduct or sponsor, and a person is not required to
respond to, a collection of information unless it displays a currently
valid OMB control number.  The OMB control numbers for EPA's regulations
are listed in 40 CFR Part 9 and 48 CFR Chapter 15. 

We request comments on the Agency's need for this information, the
accuracy of the provided burden estimates, and any suggested methods for
minimizing respondent burden, including through the use of automated
collection techniques.  Send comments on the ICR to the Director,
Collection Strategies Division; U.S. Environmental Protection Agency
(2822T); 1200 Pennsylvania Ave., NW, Washington, DC 20460; and to the
Office of Information and Regulatory Affairs, Office of Management and
Budget, 725 17th St., N.W., Washington, DC 20503, marked "Attention:
Desk Officer for EPA."  Include the ICR number in any correspondence. 
Since OMB is required to make a decision concerning the ICR between 30
and 60 days after [Insert date of publication in the FEDERAL REGISTER],
a comment to OMB is best assured of having its full effect if OMB
receives it by [Insert date 30 days after publication in the FEDERAL
REGISTER].  The final rule will respond to any OMB or public comments on
the information collection requirements contained in this proposal.

C.  	Regulatory Flexibility Act (RFA)

	The Regulatory Flexibility Act (RFA) generally requires an agency to
prepare a regulatory flexibility analysis of any rule subject to notice
and comment rulemaking requirements under the Administrative Procedure
Act or any other statute unless the agency certifies that the rule will
not have a significant economic impact on a substantial number of small
entities.  Small entities include small businesses, small organizations,
and small governmental jurisdictions.  The RFA provides default
definitions for each type of small entity.  Small entities are defined
as: (1) a small business as defined by the Small Business
Administration’s (SBA) regulations at 13 CFR 121.201; (2) a small
governmental jurisdiction that is a government of a city, county, town,
school district or special district with a population of less than
50,000; and (3) a small organization that is any not-for-profit
enterprise which is independently owned and operated and is not dominant
in its field.  However, the RFA also authorizes an agency to use
alternate definitions for each category of small entity, “which are
appropriate to the activities of the agency” after proposing the
alternate definition(s) in the Federal Register and taking comment.  5
USC 601(3) - (5).  In addition, to establish an alternate small business
definition, agencies must consult with SBA’s Chief Counsel for
Advocacy.

	For purposes of assessing the impacts of the proposed rule on small
entities, EPA is proposing to define “small business” as a small
business with less than 500 employees, rather than use the individual
SBA size standards for the numerous NAICS subsectors and codes.  We
believe that no small governments or small organizations are affected by
this rule.  EPA chose to use the alternate definition to simplify the
economic analysis.  This approach slightly reduced the number of small
businesses subject toincluded in our analysis but slightly increased the
percentages of small business significantly impacted in the analysis. 
Furthermore, this size standard was set by the Small Business
Administration for all NAICS codes for businesses using nPB-based
adhesives, one of the end uses that would be affected by this rule.  We
solicited comments on the choice of this alternate definition for this
analysis on the June 2003 NPRM, and received no public comments.  We
again request comment on this alternate definition of “small
business.”

	EPA consulted with the Small Business Administration Office of Advocacy
on the alternate small business definition of 500 employees for the June
2003 proposal.  The Office of Advocacy concurred with EPA’s approach. 
The number and types of small businesses that would be regulated have
not changed significantly in this NPRM from the June 2003 proposal, and
EPA is proposing the same definition.

	After considering the economic impacts of this proposed rule on small
entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities.  EPA
estimates that up to 4850 small industrial end users currently use nPB
in the end uses addressed by this rule and thus could be subject to the
regulatory impacts of this rule.  This number includes approximately
1470 users of nPB industrial cleaning solvents (e.g., cleaning with
vapor degreasers), 3100 users of nPB-based aerosol solvents, and 280
users of nPB-based adhesives.  Considering together the regulatory
impacts on adhesive and aerosol users that must switch to other
alternatives and the costs to solvent users to implement the recommended
17 ppm exposure limit, we found that up to 258 (8%) small businesses
would experience impacts of 1% or greater of annual sales and no small
businesses would experience impacts of 3% or greater of annual sales. 
Based on the relatively small number and percentage of small businesses
that would experience significant impacts, EPA concludes that this rule
would not have a significant economic impact on a substantial number of
small entities.

	In the case of coatings uses, our understanding is that only a single
facility, the Lake City Army Ammunition Plant, is currently using
coatings with nPB as the carrier solvent, and this facility could
continue to use nPB following its current practices.  Therefore, we
consider there to be no economic impact of this rule on coatings users
and have not done further analysis for this end use.  

	Types of businesses that would be subject to this proposed rule
include:

Manufacturers of primary metals, where there may be a need to clean off
oil and grease (NAICS subsectors 331).

Manufacturers of fabricated metal parts, including plating, ball and
roller bearings, machined parts, and other metal parts that require oil
and grease to be cleaned off; and manufacturers of ammunition using
coatings or sealants (NAICS subsectors 332, 333, and 339).

Manufacturers of computers and electronic equipment that clean with nPB
cleaning solvents (NAICS subsector 334).

Manufacturers of appliances, electrical equipment, and components that
require oil, grease, and solder flux to be cleaned off (NAICS subsection
335).

Manufacturers of transportation equipment, such as aerospace equipment
that requires cleaning either in a tank or with aerosols, or aircraft
seating, which is assembled using adhesives containing nPB as a carrier
solvent; and ship or boat builders applying  adhesives with nPB (NAICS
subsector 336). 

Manufacturers of furniture, including various kinds of furniture with
cushions and countertops assembled using adhesives containing nPB as a
carrier solvent (NAICS subsector 337). 

Foam fabricators, who assemble foam cushions or sponges using adhesives
containing nPB as a carrier solvent (NAICS code 326150).  

EPA estimates that up to 4850 small industrial end users currently use
nPB in the end uses addressed by this rule and thus could be subject to
the regulatory impacts of this rule.  This number includes approximately
1470 users of nPB industrial cleaning solvents (e.g., cleaning with
vapor degreasers), 3100 users of nPB-based aerosol solvents, and 280
users of nPB-based adhesives.  

	In order to consider the resources that affected small businesses have
available to operate and to respond to the proposed regulatory
requirements, EPA compared the cost of meeting the proposed regulatory
requirements to small businesses’ annual sales.  In our analysis for
this proposed rule, we used the average value of shipments for the
products manufactured by the end user as a proxy for sales or revenues,
since these data are readily available from the U.S. Department of
Commerce.  The following tables display the average value of shipments
for different sizes of business and different NAICS subsectors or codes
in the affected industrial sectors.  EPA then used data from these
sources to determine the potential economic impacts of this proposed
rule on small businesses of this proposed rule.

Table 16.  Average Value of Shipments in NAICS Subsectors Performing
Solvent Cleaning,

by Number of Employees at Business

Number of Employees at Business	Average Value of Shipments per Business
($) by NAICS Subsector Code

	331, Primary Metal Mfg	332, Fabricated Metal Products	333, Machinery
334, Computer and Electronic Products	335, Electrical Equipment,
Appliance, and Component Mfg	336, Transport-ation Equipment	337,
Furniture and Related Products	339,Misc. Mfg

1 to 4 employees	368,580	222,973	301,232	345,007	315,772	412,460	180,805
181,876

5 to 9 employees	1,369,866	835,793	1,049,335	1,317,238	1,243,065
1,414,384	712,557	773,320

10 to 19 employees	2,828,531	1,654,147	1,988,048	2,566,913	2,483,327
2,573,352	1,704,272	1,543,581

20 to 49 employees	7,258,463	4,119,582	4,768,137	5,672,245	5,389,945
5,738,739	3,297,360	3,910,203

50 to 99 employees	17,350,990	10,300,841	11,882,524	12,951,836
12,650,236	12,735,583	8,460,846	9,836,121

100 to 249 employees	38,539,490	27,472,772	29,166,421	31,258,875
31,290,638	34,256,544	20,153,844	24,981,108

250 to 499 employees	95,889,945	61,152,558	81,774,945	84,270,454
77,279,974	86,911,454	48,821,903	68,880,502

Avg Value Ship Small Businesses in Sub-sector	11,935,698	3,812,656
5,359,829	8,261,788	9,539,205	11,029,561	2,536,805	2,923,741

Avg Value Ship ALL Businesses in Subsector	28,783,017	4,168,836
6,620,907	20,810,094	13,417,905	45,029,773	2,875,473	3,857,370

Avg Value Shipments Subset Small Businesses using nPB	22,311,696	     
6,814,736 	9,337,066	11,246,045	12,066,562	13,422,547	5,178,300
5,461,637

1 Aerosol solvents are used in NAICS subsectors 334, 335 and 336. 
Non-aerosol solvents are used in all seven NAICS subsectors.

2 “d” designates “Data withheld to avoid disclosing data of
individual companies; data are included in higher level totals.”  The
average value of shipments for businesses estimates those values marked
with “d,” and thus may be overestimated or underestimated.  	

Table 17. Average Value of Shipments in NAICS Categories

Using nPB as a Carrier Solvent in Adhesives, by Number of Employees at
Business

Number of Employees at Business	Average Value of Shipments per Small
Business ($) by NAICS Sub Sector



	337121,

Upholstered household furniture

	337110,

Wood kitchen cabinet and counter tops	326150,

Urethane and other foam products (except polystyrene)	336360,

Motor vehicle seating and interior trim	337124,

Metal household furniture

1 to 4 employees	234,345	156,833	496,318	425,863	187,950

5 to 9 employees	963,021	622,744	1,305,183	1,728,132	903,393

10 to 19 employees	1,771,416	1,141,119	3,152,283	3,082,486	1,431,480

20 to 49 employees	3,653,623	2,619,197	6,615,331	5,508,370	3,538,684

50 to 99 employees	8,089,968	7,386,365	13,281,000	14,088,500	7,547,536

100 to 249 employees	17,502,175	17,151,091	31,524,872	44,310,286
19,821,719

250 to 499 employees	40,250,813	55,982,674	64,119,800	123,803,610	D(1)

Avg Small Businesses  in Sub sector	3,588,297	1,150,768	10,472,992
12,542,725	3,141,720

Avg ALL Businesses in Sub sector	5,490,101	1,475,602	11,110,822
44,808,573	5,239,747

Avg Subset Small Businesses using nPB	 11,519,540 	5,999,622 	18,950,068
	12,019,847 	20,401,301 

 (1)“d” designates “Data withheld to avoid disclosing data of
individual companies; data are included in higher level totals.”  The
average value of shipments for businesses estimates those values marked
with “d,” and thus may be overestimated or underestimated.  

	This proposed rule requires that nPB would be unacceptable for use in
adhesives and aerosols.  The available alternatives identified include
adhesive formulations based on water, methylene chloride, or flammable
solvents such as acetone and aerosol formulations of flammable solvents,
combustible solvents, blends of trans-dichloroethylene and HFEs or HFCs,
and HCFC-225ca/cb.  We considered various aspects of the cost of
switching to other alternatives, including the cost of meeting OSHA
requirements and the cost of the alternative adhesive.

	We estimate that up to 9 small businesses using nPB-based adhesives, or
roughly 3% of the 280 or so small businesses that use nPB-based
adhesives, would experience a cost increase (i.e., an impact) of greater
than 1.0% of annual sales, and no small businesses would experience an
impact of greater than 3% of annual sales if this proposed rule became
final.  For small businesses using nPB-based aerosols, we estimate that
approximately 249 would experience a cost increase of greater than 1.0%
of annual sales.  This equates to roughly 8% of the 3100 or so small
businesses currently using nPB-based aerosol solvents.  No small
businesses using aerosols would experience an impact of greater than 3%
of annual sales.  Approximately five percent of all 4850 or so small
businesses choosing to use nPB would experience an impact of greater
than 1.0% of annual sales and no small businesses would experience an
impact of greater than 3.0% of annual sales.  Because of the small total
number and small percentage of affected businesses that would experience
an impact of greater than either 1.0% or 3.0% of annual sales, EPA does
not consider this rule to have a significant impact on a substantial
number of small businesses.

	The Agency analyzed the cost impacts of implementing the exposure limit
for solvent cleaning uses in order to provide additional information
about potential effects on small businesses.  Businesses using nPB-based
cleaning solvents for metals cleaning, electronics cleaning, or
precision cleaning would experience significant cost benefits by
reducing spending on solvent.  

	Considering together the regulatory impacts on adhesive and aerosol
users that must switch to other alternatives and the costs to solvent
users to implement the recommended 17 ppm exposure limit, we found that
up to 258 (8%) small businesses would experience impacts of 1% or
greater of annual sales and no small businesses would experience impacts
of 3% or greater of annual sales.  Based on the relatively small number
and percentage of small businesses that would experience significant
impacts, EPA concludes that this rule would not have a significant
economic impact on a substantial number of small entities.

	We also analyzed the potential small business impacts of the alternate
proposal.  Under the alternate proposal, users would have to: (1) meet a
workplace exposure limit of 17 ppm on an eight-hour time-weighted
average, (2) monitor workers’ exposure to nPB using a personal
breathing zone sampler on an eight-hour time-weighted average initially
and periodically (every 6 months or longer, depending on the
concentration during initial monitoring), and (3) keep records of the
worker exposure data on site at the facility for at least three years
from the date of the measurement.  We assume that the cost of following
the alternate proposal is the cost of installing ventilation for
aerosols and adhesives or emission controls for solvent cleaning, the
cost of using personal protective equipment, and the cost of monitoring
worker exposure.  Approximately 67 to 387 aerosol solvent users (2 to 13
percent), 25 to 54 adhesive users (9 to 19 percent), no solvent cleaning
users, and 2.6 to 12.6 percent of all 4850 or so small businesses would
experience impacts of greater than 1% of annual sales if they chose to
meet nPB the proposed requirements with the applicable use conditions
rather than switching to another ODS substitute.  Four to nine users of
nPB-based adhesives, or less than 1% of all small businesses, would
experience impacts of 3% or greater of annual sales under the alternate
proposal.  Based on this analysis, the alternate proposal would not
create a significant adverse impact on a significant number of small
entities.

	Although this proposed rule would not have a significant economic
impact on a substantial number of small entities if it became final, EPA
nonetheless has tried to reduce the impact of this rule on small
entities.  Before selecting the regulatory option in this proposed rule,
we considered a number of regulatory options, such as:

•	Placing a narrowed use limit on the use of nPB in adhesives and
aerosols that would allow its use only in those cases where alternatives
are technically infeasible due to performance or safety issues.  This
would have required testing, recordkeeping, and some installation of
capital equipment.

Requiring that when nPB is used in adhesives or aerosols, it must be
used with local ventilation equipment and personal protective equipment.
  This would have required further installation of capital equipment,
without necessarily protecting workers as thoroughly as a required
workplace exposure limit or requiring a switch to another alternative. 

Requiring that users clean metal, electronics, or other parts with nPB
in low-emission air-tight vapor degreasing equipment.

•	Requiring that users clean metal, electronics, or other parts with
nPB in vapor degreasing equipment that meets the requirements of the
national emission standards for halogenated solvent cleaning.

Prohibiting the use of nPB in all end uses.

Retaining the previously proposed requirement for a limit on iPB content
in nPB formulations.  

The costs of a number of these options are included in EPA’s analysis
(EPA, 2006).

	In developing our regulatory options, we considered information we
learned from contacting small businesses using or selling nPB.  EPA
staff visited the site of a small business using nPB for cleaning
electronics.  We contacted several fabricators of foam cushions that
have used adhesives containing nPB.  We participated in meetings with a
number of adhesive manufacturers and users of adhesives in furniture
construction.  We developed a fact sheet and updated our program web
site to inform small businesses about the proposed rule and to request
their comments. 

	We continue to be interested in the potential impacts of the proposed
rule on small entities and welcome comments on issues related to such
impacts.   

	D.	Unfunded Mandates Reform Act

	Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public Law
104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and tribal
governments and the private sector.  Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed  and final rules with "Federal mandates" that may
result in expenditures to State, local, and tribal governments, in the
aggregate, or to the private sector, of $100 million or more in any one
year. Before promulgating an EPA rule for which a written statement is
needed, section 205 of the UMRA generally requires EPA to identify and
consider a reasonable number of regulatory alternatives and adopt the
least costly, most cost-effective or least burdensome alternative that
achieves the objectives of the rule.  The provisions of section 205 do
not apply when they are inconsistent with applicable law.  Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted.  Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan.  The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.  EPA has determined that this rule does not contain a
Federal mandate that may result in expenditures of $100 million or more
for State, local, and tribal governments, in the aggregate, or the
private sector in any one year.  This proposed rule does not affect
State, local, or tribal governments.  The enforceable requirements of
the rule for the private sector affect a number of end users in
manufacturing.  The estimated cost of the proposed requirements for the
private sector is approximately $37.0 to 44.4 million per year, and the
alternate proposal would cost the private sector approximately $ 49.6 to
76.2 million per year.  Therefore, the impact of this rule on the
private sector is less than $100 million per year.  Thus, this rule is
not subject to the requirements of sections 202 and 205 of the UMRA. 
EPA has determined that this rule contains no regulatory requirements
that might significantly or uniquely affect small governments.  This
regulation applies directly to facilities that use these substances and
not to governmental entities.

	E.	Executive Order 13132: Federalism

	Executive Order 13132, entitled “Federalism” (64 FR 43255, August
10, 1999), requires EPA to develop an accountable process to ensure
“meaningful and timely input by State and local officials in the
development of regulatory policies that have federalism implications.”
 “Policies that have federalism implications” is defined in the
Executive Order to include regulations that have “substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government.”  

	This proposed rule does not have federalism implications.  It will not
have substantial direct effects on the States, on the relationship
between the national government and the States, or on the distribution
of power and responsibilities among the various levels of government, as
specified in Executive Order 13132.  This regulation applies directly to
facilities that use these substances and not to governmental entities. 
Thus, Executive Order 13132 does not apply to this rule.

	F.	Executive Order 13175:  Consultation and Coordination with Indian
Tribal

Governments 

	Executive Order 13175, entitled “Consultation and Coordination with
Indian Tribal Governments” (65 FR 67249, November 6, 2000), requires
EPA to develop an accountable process to ensure “meaningful and timely
input by tribal officials in the development of regulatory policies that
have tribal implications.”  “Policies that have tribal
implications” is defined in the Executive Order to include regulations
that have “substantial direct effects on one or more Indian tribes, on
the relationship between the Federal government and the Indian tribes,
or on the distribution of power and responsibilities between the Federal
government and Indian tribes.”  

	This proposed rule does not have tribal implications.  It will not have
substantial direct effects on tribal governments, on the relationship
between the Federal government and Indian tribes, or on the distribution
of power and responsibilities between the Federal government and Indian
tribes, as specified in Executive Order 13175.

	This proposed rule would not significantly or uniquely affect the
communities of Indian tribal governments, because this regulation
applies directly to facilities that use these substances and not to
governmental entities.  Thus, Executive Order 13175 does not apply to
this proposed rule.

Executive Order 13045:  Protection of Children from Environmental Health
and Safety Risks 

	Executive Order 13045:  “Protection of Children from Environmental
Health Risks and Safety Risks” (62 FR 19885, April 23, 1997) applies
to any rule that: (1) is determined to be "economically significant" as
defined under Executive Order 12866, and (2) concerns an environmental
health or safety risk that EPA has reason to believe may have a
disproportionate effect on children.  If the regulatory action meets
both criteria, the Agency must evaluate the environmental health or
safety effects of the planned rule on children, and explain why the
planned regulation is preferable to other potentially effective and
reasonably feasible alternatives considered by the Agency.

	This proposed rule is not subject to the Executive Order because it is
not economically significant as defined in Executive Order 12866, and
because the Agency does not have reason to believe the environmental
health or safety risks addressed by this action present a
disproportionate risk to children.  The exposure limits and
acceptability listings in this proposed rule apply to the workplace. 
These are areas where we expect adults are more likely to be present
than children, and thus, the agents do not put children at risk
disproportionately. 

	Further, this proposed rule provides both regulatory restrictions and
recommended exposure guidelines based upon toxicological studies in
order to reduce risk of exposure to a reproductive toxin, nPB.  This
proposed rule is not subject to Executive Order 13045 because it is not
economically significant as defined in Executive Order 12866 and because
the Agency does not have reason to believe the environmental health or
safety risks addressed by this action present a disproportionate risk to
children.  The public is invited to submit or identify peer-reviewed
studies and data, of which the agency may not be aware, that assessed
results of early life exposure to nPB.

	H. 	Executive Order 13211:  Actions that Significantly Affect Energy
Supply, Distribution, or Use

	This rule is not a “significant energy action” as defined in
Executive Order 13211, “Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use” (66 FR 28355
(May 22, 2001)) because it is not likely to have a significant adverse
effect on the supply, distribution, or use of energy.  This action would
impact manufacturing of various metal, electronic, medical, and optical
products cleaned with solvents containing nPB and products made with
adhesives containing nPB.  Further, we have concluded that this rule is
not likely to have any adverse energy effects.

	I.	National Technology Transfer and Advancement Act

	As noted in the proposed rule, Section 12(d) of the National Technology
Transfer and Advancement Act of 1995 ("NTTAA"), Pub L. No. 104-113, §
12(d) (15 U.S.C. 272 note) directs EPA to use voluntary consensus
standards in its regulatory activities unless to do so would be
inconsistent with applicable law or otherwise impractical.  Voluntary
consensus standards are technical standards (e.g., materials
specifications, test methods, sampling procedures, and business
practices) that are developed or adopted by voluntary consensus
standards bodies. The NTTAA directs EPA to provide Congress, through
OMB, explanations when the Agency decides not to use available and
applicable voluntary consensus standards. 

	This action does not involved technical standards. Therefore, EPA did
not consider the use of any voluntary consensus standards.  We note that
the American Conference of Governmental Industrial Hygienists (ACGIH),
although it sets voluntary standards, is not a voluntary consensus
standards body.  Therefore, use of a proposed or final workplace
exposure limit from the ACGIH is not subject to the NTTAA.

XIII.	References tc "X.	References"  

	The documents below are referenced in the preamble.  All documents are
located in the Air Docket at the address listed in section I.B.1 at the
beginning of this document.  Unless specified otherwise, all documents
are available electronically through the Federal Docket Management
System, Docket # EPA-HQ-OAR-2002-0064.  Some specific items are
available only in hard copy in dockets A-2001-07 or A-92-42 (legacy
docket numbers for SNAP nPB rule and for SNAP program and submissions). 
Numbers listed after the reference indicate the docket and item numbers.

What criteria did EPA consider in preparing this proposal?

Fabricant, 2003.  Memo to Acting Administrator, Marianne L. Horinko. 
2003.  EPA’s Authority to Impose Mandatory Controls to Address Global
Climate Change under the Clean Air Act, from Robert E. Fabricant. 

ICF, 2006a.  ICF Consulting.  Risk Screen on Substitutes for
Ozone-Depleting Substances for Adhesive, Aerosol Solvent, and Solvent
Cleaning Applications.  Proposed Substitute:  n-Propyl Bromide.  April
18, 2006.  

Availability

Harper, 2005.  Telephone call from M. Sheppard, EPA to Dr. S. Harper,
ATK. Re: Availability of other methyl chloroform substitutes for the
Lake City Army Ammunition Plant.  October 11, 2005.

IBSA, 2002.    SEQ CHAPTER \h \r 1 Record of September 5, 2002 Meeting
with the International Brominated Solvents Association Inc.  (A-2001-07,
II-D-60)

IRTA, 2000.    SEQ CHAPTER \h \r 1 Alternative Adhesive Technologies in
the Foam Furniture and Bedding Industries: A Cleaner Technologies
Substitution Assessment, Cost and Performance Evaluation.  Michael
Morris and Katy Wolf, Institute for Research and Technical Assistance. 
Prepared for the U.S. EPA Office of Pollution Prevention Technology,
June 2000. (A-2001-07, II-D-70)

Seilheimer, 2001.    SEQ CHAPTER \h \r 1 Telephone Log of April 4, 2001
call between Margaret Sheppard, EPA, and Bob Seilheimer, Imperial
Adhesives.  (A-2001-07, II-B-5)

Williams, 2005.  Notes on conversation of Ed Williams, Technical
Manager, LPS Laboratories, and Margaret Sheppard, EPA.   November 3,
2005

Ozone-Depletion Potential and Other Environmental Impacts

Atmospheric and Environmental Research, Inc, 1995:  Estimates of the
Atmospheric Lifetime, Global Warming Potential and Ozone Depletion
Potential of n-Propyl Bromide.  Independent study prepared for Albemarle
Corporation.  (A-2001-07, II-D-17)

ATSDR, 1994. Toxicological Profile For Acetone.   Agency for Toxic
Substances and Disease Registry.  May, 1994.  Available at   HYPERLINK
"http://www.atsdr.cdc.gov/toxprofiles/tp21-c5.pdf" 
http://www.atsdr.cdc.gov/toxprofiles/tp21-c5.pdf 

ATSDR, 1996. Toxicological Profile For 1,2-Dichloroethene.   Agency for
Toxic Substances and Disease Registry.  August, 1996.  Available at  
HYPERLINK "http://www.atsdr.cdc.gov/toxprofiles/tp87-c5.pdf" 
http://www.atsdr.cdc.gov/toxprofiles/tp87-c5.pdf 

ATSDR, 1997. Toxicological Profile For Trichloroethylene.   Agency for
Toxic Substances and Disease Registry.  September, 1997.  Available at
http://www.atsdr.cdc.gov/toxprofiles/tp19-c5.pdf

ATSDR, 2004.  Draft Toxicological Profile For 1,1,1-Trichloroethane. 
Agency for Toxic Substances and Disease Registry.  September, 2004. 
Updated draft for comment. Available at   HYPERLINK
"http://www.atsdr.cdc.gov/toxprofiles/tp70-c6.pdf" 
http://www.atsdr.cdc.gov/toxprofiles/tp70-c6.pdf 

	EDSTAC, 1998.  Final Report of the Endocrine Disruptor Screening and
Testing Advisory Committee.  August, 1998.  

Fisher Scientific, 2001.  Material Safety Data Sheet for acetone. 
Updated March 19, 2001.  Available at   HYPERLINK
"http://www.mhatt.aps.anl.gov/dohn/msds/acetone.html" 
http://www.mhatt.aps.anl.gov/dohn/msds/acetone.html 

Geiger et al., 1998.  Geiger, D.L., Call, D.J., and Brooke, L.T.  1988. 
Acute Toxicities of Organic Chemicals to Fathead Minnows (Pimephales
promelas), Vol. 4.  In: Center for Lake Superior Environmental Stud.,
Univ.of Wisconsin-Superior, Superior, WI I:355.  (Summarized in ICF,
2004a)

HSDB, 2004.  Hazardous Substances Databank File for 1-Bromopropane. 
Accessed 1/2004 from the World Wide Web at
http://toxnet.nlm.nih.gov/cgi-bin/sis/search/f?./temp/~dLwM9e:1
(Summarized in ICF, 2004a)

ICF, 2004a.  ICF Consulting.  Memo to E. Birgfeld, EPA, re: nPB Aquatic
Toxicity.  January 19, 2004.

LaGrega, M., Buckingham, P., Evans, J., and Environmental Resources
Management, 2001.  Hazardous Waste Management.  Second Edition. 
McGraw-Hill, New York, NY.  2001. 

Linnell, 2003.  Comments from the Electronics Industry Alliance. 
(EPA-HQ-OAR-2002-0064 items -0043, -0044, and -0045)

NPS, 1997.  Irwin, R.J., M. VanMouwerik, L. Stevens, M.S. Seese, and W.
Basham.  1997. Environmental Contaminants Encyclopedia.  National Park
Service,Water Resources Division, Fort Collins, Colorado.

Steminiski, 2003.  July 27, 2003 Comment from J. Steminiski, Ph. D.
(EPA-HQ-OAR-2002-0064-0035 and -0043)

U.S. Economic Census, 2002a.  General Summary:  2002.  Subject Series. 
Report No. EC02-31SG-1, October, 2005.  U.S. Census Bureau.

U.S. Economic Census, 2002b.  U.S. Economic Census for Island Areas,
2002.  Report for Northern Marianas Islands, Rpt. No.  IA02-00A-NMI,
May, 2004.  U.S. Census Bureau.

U.S. Economic Census, 2002c.  U.S. Economic Census for Island Areas,
2002.  Report for Guam, Rpt. No. IA02-00A-GUAM, March, 2005.  U.S.
Census Bureau.

U.S. Economic Census, 2002d.  U.S. Economic Census for Island Areas,
2002.  Report for Virgin Islands, Rpt. No. IA02-00A-VI , April, 2005. 
U.S. Census Bureau.

U.S. Economic Census, 2002e.  U.S. Economic Census for Island Areas,
2002.  Report for American Samoa, Rpt. No. IA02-00A-AS, April, 2005.
U.S. Census Bureau.

U.S. Economic Census, 2002f.  U.S. Economic Census for Island Areas,
2002.  Report for Puerto Rico: Manufacturing, Rpt. No. IA02-00I-PRM,
October, 2005. U.S. Census Bureau. 

US EPA, 1980.  Ambient Water Quality Criteria for Dichloroethylenes. EPA
440/5-80-041  October, 1980.  Available at   HYPERLINK
"http://www.epa.gov/waterscience/pc/ambientwqc/dichloroethylenes80.pdf" 
http://www.epa.gov/waterscience/pc/ambientwqc/dichloroethylenes80.pdf 

US EPA, 1992.  Hazard Assessment Guidelines for Listing Chemicals on the
Toxic Release Inventory, Revised Draft.  Washington, DC:  Office of
Pollution, Prevention and Toxics. As referenced in ICF, 2004f.

US EPA, 1994b.  Chemical Summary for Methyl Chloroform, prepared by
Office of Pollution Prevention and Toxics, August, 1994. 

WMO, 2002:  Scientific Assessment of Ozone Depletion: 2002, Global Ozone
Research and Monitoring Project – Report No. 47, Geneva, 2003 Full
report available online at    HYPERLINK
"http://esrl.noaa.gov/csd/assessments/" 
http://esrl.noaa.gov/csd/assessments/    (A-2001-07, II-A-20) 

Wuebbles, Donald J.  2002.  “The Effect of Short Atmospheric Lifetimes
on Stratospheric Ozone.”  Written for Enviro Tech International, Inc. 
Department of Atmospheric Sciences, University of Illinois-Urbana.
(A-2001-07, II-D-29)

Flammability and Fire Safety

	BSOC, 2000.  February 1, 2000 Tabulation of Flammability Studies on
n-Propyl Bromide from the Brominated Solvents Committee, and other
information on flammability of n-propyl bromide.  (A-2001-07, II-D-45)

Miller, 2003.  Albemarle Corporation comments- Flash Point Data for
n-Propyl Bromide.  (EPA-HQ-OAR-2002-0064-0040)

Morford, 2003a.  Enviro Tech International Comment re Section IV D
Flammability with Exhibits (7/25/03) (EPA-HQ-OAR-2002-0064-0030 and
EPA-HQ-OAR-2002-0064-0031)

Morford, 2003b.  Enviro Tech Int. Flammability of nPB & Comparison With
Methylene Chloride- Additional Comments on Flammability (7/29/03)
(EPA-HQ-OAR-2002-0064-0036)

Shubkin, 2003.  R. Shubkin, Poly Systems, EPA received 7/23/03 Re:
Comment on Flammability of n-Propyl Bromide as Discussed in Proposed
Rule Published in Federal Register (EPA-HQ-OAR-2002-0064-0025)

Weiss Cohen, 2003.  T. Weiss Cohen, Dead Sea Bromine Group,7/31/2003
Comment to Federal Register Proposed Rules of June 3, 2003, on
Protection of Stratospheric Ozone: Listing of Substitutes for
Ozone-Depleting Substances - n-Propyl Bromide
(EPA-HQ-OAR-2002-0064-0053)

Human Health; Derivation of Workplace Exposure Limit and Community
Exposure Guideline

ACGIH, 1991.  Skin Notation Documentation for Methyl Chloride. Available
online at www.acgih.org.

ACGIH, 2005.  Documentation for Threshold Limit Value for
1-Bromopropane.  2005.  Available online at www.acgih.org.

Beck and Caravati, 2003.   Neurotoxicity associated with 1-bromopropane
exposure.Utah Poison Control Center, University of Utah, Salt Lake City,
UT. J Toxicology Clinical Toxicology  41(5):729. (Abstract from
conference). 2003.  

		CERHR, 2002a.  NTP- Center for the Evaluation of Risks to Human
Reproduction Expert Panel Report on the Reproductive and Developmental
Toxicity of 1-Bromopropane [nPB].  March 2002.  (A-2001-07, II-A-11) 

CERHR, 2002b.  NTP- Center for the Evaluation of Risks to Human
Reproduction Expert Panel Report on the Reproductive and Developmental
Toxicity of 2-Bromopropane [iPB].  March 2002.  (A-2001-07, II-A-12)

CERHR, 2003a.  NTP- CERHR Monograph on the Potential Human Reproductive
and Developmental Effects of 1-Bromopropane.  October 2003.  

CERHR, 2003b.  NTP- CERHR Monograph on the Potential Human Reproductive
and Developmental Effects of 2-Bromopropane.  October 2003.  

CERHR, 2004a. NTP-CERHR Expert Panel report on the reproductive and
developmental toxicity of 1-bromopropane.  Center for the Evaluation of
Risks to Human Reproduction. Repro Toxicol. Vol.18, pp.157-188.  2004. 

CERHR, 2004b.  NTP-CERHR Expert Panel report on the reproductive and
developmental toxicity of 2-bromopropane. Boekelheide, et al. Repro
Toxicol. Vol.18, pp.189-217.  2004. 

ClinTrials, 1997a.  A 28-Day Inhalation Study of a VaporFormulation of
ALBTA1 in the Albino Rat.  Report No. 91189.  Prepared by ClinTrials
BioResearch Laboratories, Ltd., Senneville, Quebec, Canada.  May 15,
1997.  Sponsored by Albemarle Corporation, Baton Rouge, LA. (A-91-42,
X-A-4)

ClinTrials, 1997b.  ALBTA1: A 13-Week Inhalation Study of a Vapor
Formulation of ALBTA1 in the Albino Rat.  Report No. 91190.   Prepared
by ClinTrials BioResearch Laboratories, Ltd., Senneville, Quebec,
Canada.  February 28, 1997.  Sponsored by Albemarle Corporation, Baton
Rouge, LA. (A-91-42, X-A-5)

Dunson et al, 2002.  Dunson, D., Colombo, and B., Baird, D. Changes with
age in the level and duration of fertility in the menstrual cycle. 
Human Reproduction, Vol. 17, No. 5, pp. 1399-1403, 2002.

Elf Atochem, 1995.  Micronucleus Test by Intraperitoneal Route in Mice. 
n-Propyl Bromide.  Study No. 12122 MAS.  Study Director, Brigitte
Molinier.  Study performed by Centre International de Toxoicologie,
Misery, France, September 6, 1995.  (A-91-42, X-A-9)

Fueta et al., 2002.  Y. Fueta, K. Fukunaga, T. Ishidao, H. Hori. 
Hyperexcitability and changes in activities of Ca2+/calmodulin-dependent
kinase II and mitogen-activated protein kinase in the hippocampus of
rats exposed to 1-bromopropane.  2002.  Life Sciences 72 (2002) 521-529.
	

Fueta et al., 2004. Y. Fueta, T. Fukuda, T. Ishidao, H. Hori. 
Electrophysiology and immunohistochemistry in the hippocampal CA1 and
the Dentate Gyrus of Rats Chronically exposed to 1-Bromopropane, a
Substitute for Specific Chlorofluorocarbons.  Neuroscience 124 (2004)
593-603.

	Honma et al., 2003.  Honma, T, Suda M, Miyagawa M. “Inhalation of
1-bromopropane causes excitation in the central nervous system of male
F344 rats.” Neurotoxicology. 2003 Aug; 24 (4-5):563-75.

Huntingdon Life Sciences, 2001. A Developmental Toxicity Study in Rat 
Via Whole Body Inhalation Exposure. (A-2001-07, II-D-27)

ICF, 2002a.  Risk Screen for Use of N-Propyl Bromide.  ICF Consulting. 
Prepared for U.S. EPA, May, 2002. (EPA-HQ-OAR-2002-0064-0006 through
-0012)

ICF, 2003.  ICF Consulting.  General Population Exposure Assessment for
N-Propyl Bromide.  June 03, 2003.  (EPA-HQ-OAR-2002-0064-0011)

ICF, 2004b.  ICF Consulting.  External Expert Review Panel on N-Propyl
Bromide.  December 13, 2004.

ICF, 2006a.  ICF Consulting.  Risk Screen on Substitutes for
Ozone-Depleting Substances for Adhesive, Aerosol Solvent, and Solvent
Cleaning Applications.  Proposed Substitute:  n-Propyl Bromide.  April
18, 2006.  Attachments:  A, Determination of an AEL; B, Derivation of an
RfC; C, Evaluation of the Global Warming Potential; D, Occupational
Exposure Analysis for Adhesive Applications; E, Occupational Exposure
Analysis for Aerosol Solvent Applications; F, General Population
Exposure Assessment for n-Propyl Bromide 

ICF, 2006b.  ICF Consulting.  Revised Memorandum regarding RTI
Metabolism Study on nPB.  April, 2006.

ICF, 2006c.  ICF Consulting.  Evaluation of Memorandum from Dr. M.
Stelljes.  April, 2006.

Ichihara et al., 1998.  Ichihara M., Takeuchi Y., Shibata E., Kitoh J.,
et al. Neurotoxicity of 1-Bromopropane.  1998.  Translated by Albemarle
Corporation. (A-91-42, X-A-33)  

Ichihara G., Jong X., Onizuka J., et al,. 1999.  Histopathological
changes of nervous system and reproductive organ and blood biochemical
findings in rats exposed to 1_bromopropane.  (Abstract only)  Abstracts
of the 72nd Annual Meeting of Japan Society for Occupational Health. 
May 1999. Tokyo.  (A-2001-07, II-A-15)

Ichihara G., Kitoh J., Yu, X., et al., 2000. 1-Bromopropane, an
alternative to ozone layer depleting solvents, is dose-dependently
neurotoxic to rats in long-term inhalation   exposure.  Toxicol Sciences
55:116-123.  (A-2001-07, II-A-8)

Ichihara G. et al., 2002.  Neurological Disorders in Three Workers
Exposed to 1-Bromopropane.  J Occu. Health 44:1-7.  (A-2001-07, II-D-64)

Ichihara et al., 2004a.  G. Ichihara, W. Li, X. Ding, S. Peng, X. Yu, E.
Shibata, T. Yamada, H. Wang, S. Itohara, S. Kanno, K. Sakai, H. Ito, K.
Kanefusa, and Y. Takeuchi.  A Survey on Exposure Level, Health Status,
and Biomarkers in Workers Exposed to 1-Bromopropane.   Am Jrnl of Ind
Med 45:63–75 (2004) 

Ichihara et al., 2004b. Gaku Ichihara, Weihua Li, Eiji Shibata, Xuncheng
Ding, Hailan Wang, Yideng Liang, Simeng Peng, Seiichiro Itohara,
Michihiro Kamijima, Qiyuan Fan, Yunhui Zhang, Enhong Zhong, Xiaoyun Wu,
William M. Valentine, and Yasuhiro Takeuchi.  Neurological Abnormalities
in Workers of 1-Bromopropane Factory.  Env’l Health Perspectives, 30
June 2004.  

Ishidao et al., 2002.  Ishidao T, Kunugita N, Fueta Y, Arashidani K,
Hori H. Effects of inhaled 1-bromopropane vapor on rat metabolism.
Toxicol Lett. 2002 Aug 5;134(1-3):237-43

	Majersik et al., 2004.  Chronic Exposure to 1-Bromopropane Associated
with Spastic Paraparesis and Distal Neuropathy: A Report of Six Foam
Cushion Gluers.  Poster paper from 129th Annual Meeting of the American
Neurological Association, Toronto.  October, 2004

Majersik et al, 2005.  “Spastic Paraparesis and Distal Neuropathy
Associated with Chronic Exposure to 1BP,” Presentation by Drs. J.
Majersik, M. Caravati, and J. Steffens at the North American Congress of
Clinical Toxicologists.  September 14, 2005.

Miller, 2005.  “1-Bromopropane:  A Private Neurological Practice
Experience in 2000,” Presentation by Dr. J. M. Miller, at the North
American Congress of Clinical Toxicologists.  September 14, 2005

NAS, 1983.  The National Academies of Science, Risk Assessment in the
Federal Government: Managing the Process, 1983.  Available online at  
HYPERLINK "http://newton.nap.edu/catalog/366.html" 
http://newton.nap.edu/catalog/366.html  (Executive summary in docket as
EPA-HQ-OAR-2002-0064-xxxx)

Nemhauser, 2005.  “Bromopropane:  A Health Hazard Evaluation
Revisited”  Presentation by Dr. J. Nemhauser, U.S Public Health
Service, Centers for Disease Control & Presentation at the North
American Congress of Clinical Toxicologists.  September 14, 2005.

NIOSH, 2003a.  NIOSH Health Hazard Evaluation Report #99-0260-2906  Marx
Industries, Inc. Sawmills, NC Available online at   HYPERLINK
"http://www.cdc.gov/niosh/hhe/reports/pdfs/1999-0260-2906.pdf" 
http://www.cdc.gov/niosh/hhe/reports/pdfs/1999-0260-2906.pdf . 

NTP, 2003.  Results of 13-week Inhalation Testing by the National
Toxicology Program.  Available at   HYPERLINK
"http://ntp-apps.niehs.nih.gov/ntp_tox/" 
http://ntp-apps.niehs.nih.gov/ntp_tox/ 

	index.cfm?fuseaction=ntpsearch.searchresults&searchterm=106-94-5

OEHHA, 2006.  State Of California Environmental Protection Agency,
Office Of Environmental Health Hazard Assessment.  Chemicals Known To
The State To Cause Cancer Or Reproductive Toxicity. June 9, 2006 

Raymond and Ford, 2005.  “Clinical Case Presentations from a Foam
Furniture Fabrication Plant in North Carolina,” Presentation by Drs.
Larry Raymond and Marsha Ford at the North American Congress of Clinical
Toxicologists.  September 14, 2005

Risotto, 2003.  Comments of the Halogenated Solvents Industry Alliance
on nPB proposed rule.  June, 2003.  (EPA-HQ-OAR-2002-0064-0050)

Rodricks, 2002.  October 21, 2002 remarks from Dr. J. Rodricks, Environ,
to R. Morford, Enviro Tech International concerning derivation of an OEL
for n-propyl bromide with cover letter to EPA from Enviro Tech
International (A-2001-07, II-D-65)

Rozman and Doull, 2002.  “Derivation of an Occupational Exposure Limit
for n-Propyl Bromide Using an Improved Methodology” App Occu. Env.
Hyg. 17: 711-716 (A-2001-07, II-D-63)

Rozman and Doull, 2005.  Presentation by Drs. Rozman and Doull at the
North American Congress of Clinical Toxicologists.  September 14, 2005. 


RTI, 2005.  Report on uptake and metabolism of 1-bromopropane in rats
and mice.  Research Triangle Institute report for the National
Toxicology Program.  June, 2005.

Sekiguchi S, Suda M, Zhai YL, Honma T., “Effects of 1-bromopropane,
2-bromopropane, and 1,2-dichloropropane on the estrous cycle and
ovulation in F344 rats.” Toxicol Lett 2002 Jan 5;126(1):41-9
(A-2001-07, II-D-39)

SLR International, 2001. “Inhalation Occupational Exposure Limit for
n-Propyl Bromide.” Prepared for Enviro Tech International, Inc. 2001. 
(A-2001-07, II-D-15)

Sohn et al., 2002.  Sohn YK, Suh JS, Kim JW, Seo HH, Kim JY, Kim HY, Lee
JY, Lee SB, Han JH, Lee YM, Lee JY. “A histopathologic study of the
nervous system after inhalation exposure of 1-bromopropane in rat.”
Toxicol Lett. 2002 May 28;131(3):195-201.

Stelljes and Wood, 2004.  Stelljes, M., Wood, R.  Development of an
occupational exposure limit for n-propylbromide using benchmark dose
methods.  Regulatory Toxicology and Pharmacology 40 (2004) 136–150

Stelljes, ME, 2005.  Mechanistic Hypothesis for n-Propylbromide and
Ramifications for Occupational Exposure Limit in the United States. 
Technical Memorandum to EnviroTech International.  7 September, 2005.

Stump, 2005.  “The Reproductive Toxicity of nPB in Rats,”
Presentation by Dr Donald Stump at the North American Congress of
Clinical Toxicologists.  September 14, 2005.

Swanson, M.B., J.R. Geibig, and K.E. Kelly.  2002.  Alternative
Adhesives Technologies: Foam Furniture and Bedding Industries, Final
Draft.  Volume 2: Risk Screening and Comparison.  Chapter 4: Exposure
Assessment.  Produced by the University of Tennessee Center for Clean
Products and Clean Technologies under a grant from EPA’s Design for
the Environment Branch, Office of Pollution and Prevention and Toxics. 
June 2002.  Available online at   HYPERLINK
"http://eerc.ra.utk.edu/ccpct/aap1.html" 
http://eerc.ra.utk.edu/ccpct/aap1.html .  

TERA, 2004.  Toxicological Excellence for Risk Assessment.  Scientific
Review of 1-Bromopropane Occupational Exposure Limit Derivations –
Preliminary Thoughts and Areas for Further Analysis.  2004.

Toraason, M., Lynch, D.W., DeBorda, D.G., Singh, N., Krieg, E., Butler,
M.A.,Toennis, C.A., Nemhauser, J.B., 2006. DNA damage in leukocytes of
workers occupationallyexposed to 1-bromopropane.  Mutation Research 603
(2006) 1–14

US EPA, 1991. Guidelines for Developmental Toxicity Risk Assessment. 
U.S. Environmental Protection  Agency.  (A-2001-07, II-A-51)

US EPA, 1994a.  U.S. Environmental Protection Agency (US EPA).  1994. 
Methods for derivation of inhalation reference concentrations and
application of inhalation dosimetry.  EPA/600/8-90/066F.  Office of
Health and Environmental Assessment, Washington, DC.  1994. (A-2001-07,
II-A-16)

US EPA, 1995a.  SCREEN3 air dispersion model. (A-2001-07, II-A-53) 

US EPA, 1995b.  The Use of the Benchmark Dose Approach in Health Risk
Assessment. EPA/630-R-94-007.  Risk Assessment Forum, Washington, DC.
(A-2001-07, II-A-17)

US EPA, 1996.  Guidelines for Reproductive Toxicity Risk Assessment.
U.S. Environmental Protection Agency, Risk Assessment Forum, Washington,
DC, 630/R-96/009, 1996.   

US EPA, 2003.    SEQ CHAPTER \h \r 1 Summary of Data on Workplace
Exposure to n-Propyl Bromide, May 21, 2003.  EPA’s summary of exposure
data from nPB suppliers and NIOSH.   (EPA-HQ-OAR-2002-0064-0015 and
EPA-HQ-OAR-2002-0064-0016).

Wang et al., 2003.   H. Wang, G. Ichihara, H. Ito, K. Kato, J. Kitoh, T.
Yamada, X. Yu, S. Tsuboi, Y. Moriyama, and Y. Takeuchi. 2003. 
“Dose-Dependant Biochemical Changes in RateCentral Nervous System
after 12-Week Exposure to 1-Bromopropane”  NeuroToxicology 24: 199-206

Werner, 2003.  Comments from 3M on nPB proposed rule. 
(EPA-HQ-OAR-2002-0064-58).

WIL, 2001.  WIL Research Laboratories. “An inhalation two-generation
reproductive toxicity study of 1-bromopropane in rats.” Sponsored by
the Brominated Solvent Consortium.  May 24, 2001. (II-D-10)

	Yamada T. et al., 2003.  Exposure to 1-Bromopropane Causes Ovarian
Dysfunction in Rats. Toxicol Sci 71:96-103 (A-2001-07, II-A-32)

Decisions for Each Sector or End Use	

Amity International, 2001.    SEQ CHAPTER \h \r 1 Amity Product
Information Bulletin Sheet Ref. No. 00-003: Vapor Degreasing Good
Practice.  5 June 2001.  (A-2001-07, II-A-18)

Beck and Caravati, 2003.    Full citation above for “Human Health”
section.	

Calhoun County, 2005.  Summary of Court Case against Franklin
Technologies and Mid-South Adhesive Company in Calhoun County, MS.

Collatz, 2003.  Comment entitled "Addition of n-Propyl-Bromide to the
Significant New Alternatives Policy (SNAP) List" submitted by Mark
Collatz, Director of Government Relations, The Adhesive and Sealant
Council, Inc.   04-Aug-2003. (EPA-HQ-OAR-2002-0064-0066)

Confidential submission, 1998.  Airborne Exposure Assessment of
1-Bromopropane, 1998.  (A-2001-07, II-D-89)

CSMA, 1999.  Comments from the Chemical Specialties Manufacturers
Association on Reconsideration of the 610 Nonessential Products Ban,
Docket A-98-31, IV-D-02. August 3, 1999.

Harper, 2005.    Full citation above for “Availability” section.

ICF, 2006a.  Full citation above for “Human Health” section.

Ichihara G. et al., 2002.   Full citation above for “Human Health”
section.

Kassem, 2003.  January 10, 2003 Letter from O. M. Kassem, Albemarle
Corporation to K. Bromberg, Small Business Administration Re: n propyl
bromine SNAP.  (A-2001-07, II-D-78)

Lake City Army Ammunition Plant, 2004.  March 9, 2004 Industrial Hygiene
Air Sampling Report for Normal Propyl Bromide Based Mouth Waterproofing
in Manufacture of 5.56 mm Ammunition.  S.A. Hawk.  

Linnell, 2003.  Comments from the Electronics Industry Alliance. 
(IV-D-25/EPA-HQ-OAR-2002-0064 items -0043, -0044, and -0045)

Majersik et al., 2004.  Full citation above for “Human Health”
section.

Majersik et al, 2005.   Full citation above for “Human Health”
section.

Miller, 2005.   Full citation above for “Human Health” section.

NIOSH, 1999.  U.S. Dept. of Health and Human Services, Letter to Custom
Products Inc., December 1, 1999.  Re: results of Dec. 1998 survey of
workplace exposure to nPB at Custom Products. (HHE Report 98-0153)
(A-2001-07, II-D-6)

NIOSH, 2000a.  U.S. Dept. of Health and Human Services, Letter to Marx
Industries, Inc., February 1, 2000.  Re: results of nPB exposure
assessment survey conducted Nov. 16-17, 1999. (A-2001-07, II-D-7) 

NIOSH, 2000b.  U.S. Dept. of Health and Human Services, Letter to Custom
Products Inc., December 21, 2000.  Re: results of nPB exposure
assessment survey conducted Nov. 16, 2000.  (HHE Report 98-0153)
(A-2001-07, II-D-8)

NIOSH, 2001.  U.S. Dept. of Health and Human Services, Letter to STN
Cushion Company, March 7, 2001.   Re: Results of nPB exposure assessment
survey conducted November 14, 2000. (A-2001-07, II-D-9)

NIOSH, 2002a.  NIOSH Health Hazard Evaluation Report: HETA #
98-0153-2883; Custom Products, Inc.; Mooresville, NC.  National
Institute for Occupational Safety and Health.  November 2002.  Available
online at   HYPERLINK
"http://www.cdc.gov/niosh/hhe/reports/pdfs/1998-0153-2883.pdf" 
http://www.cdc.gov/niosh/hhe/reports/pdfs/1998-0153-2883.pdf . 

NIOSH, 2002b.  NIOSH Health Hazard Evaluation Report: HETA
#2000-0410-2891; STN Cushion Company; Thomasville, NC.  National
Institute for Occupational Safety and Health.  August 2002.  Available
online at   HYPERLINK
"http://www.cdc.gov/niosh/hhe/reports/pdfs/2000-0410-2891.pdf" 
http://www.cdc.gov/niosh/hhe/reports/pdfs/2000-0410-2891.pdf .
(A-2001-07, II-A-31)

NIOSH, 2003a.  NIOSH Health Hazard Evaluation Report #99-0260-2906  Marx
Industries, Inc. Sawmills, NC  Available online at   HYPERLINK
"http://www.cdc.gov/niosh/hhe/reports/pdfs/1999-0260-2906.pdf" 
http://www.cdc.gov/niosh/hhe/reports/pdfs/1999-0260-2906.pdf .

Raymond and Ford, 2005.   Full citation above for “Human Health”
section.

US EPA, 2003.  Summary of Data on Workplace Exposure to n-Propyl
Bromide, May 21, 2003.  EPA’s summary of exposure data from nPB
suppliers and NIOSH. (EPA-HQ-OAR-2002-0064-0015 and -0016)

US EPA, 2004.  US EPA Solvent Market Report:  The U.S. Solvent Cleaning
Industry and the Transition to Non Ozone Depleting Substances.  Prepared
for U.S. Environmental Protection Agency, Significant New Alternatives
Policy (SNAP) Program by ICF Consulting.  September 2004.  

Werner, 2003.  Full citation above for “Human Health” section.  

Williams, 2005.   Full citation above for “Availability” section.

How did EPA choose the use conditions in the alternate proposal?

Ensolv, 2006.  Material Safety Data Sheet for Ensolv Solvents.  Enviro
Tech International.  February, 2006.

ERG, 2004.  Analysis of Health and Environmental Impacts of ODS
Substitutes—Evaluating the need to set a short-term exposure or
ceiling limit for n-propyl bromide.  ERG.  June 8, 2004.

NIOSH, 2003b.  Method 1025 for 1- and 2-Bromopropane.  NIOSH Manual of
Analytical Methods, 4th Edition, March 15, 2003.

NIOSH, 2003c.  Method 1003 for Halogenated Hydrocarbons.  NIOSH Manual
of Analytical Methods, 4th Edition, March 15, 2003.

What other options did EPA consider?

CSMA, 1999.   Full citation above for “Decisions for Each Sector and
End Use” section.

ICF, 2006a.   Full citation above for “Human Health” section.

Lake City Army Ammunition Plant, 2004.   Full citation above for
“Decisions for Each Sector and End Use” section

Linnell, 2003.   Full citation above for “Ozone Depletion Potential
and Other Environmental Impacts” section.

Kassem, 2003.   Full citation above for “Decisions for Each Sector and
End Use” section.

NIOSH, 1999.    SEQ CHAPTER \h \r 1 Letter from Dept. of Health and
Human Services to Marx Industries, Inc., February 1, 2000.  Re: results
of nPB exposure assessment survey conducted Nov. 16-17, 1999. 
(A-2001-07, II-D-6)

NIOSH, 2000a.  U.S. Dept. of Health and Human Services, Letter to Marx
Industries, Inc., February 1, 2000.  Re: results of nPB exposure
assessment survey conducted Nov. 16-17, 1999. (A-2001-07, II-D-7)

NIOSH, 2002a.  NIOSH Health Hazard Evaluation Report: HETA #
98-0153-2883; Custom Products, Inc.; Mooresville, NC.  National
Institute for Occupational Safety and Health.  November 2002.  Available
online at   HYPERLINK
"http://www.cdc.gov/niosh/hhe/reports/pdfs/1998-0153-2883.pdf" 
http://www.cdc.gov/niosh/hhe/reports/pdfs/1998-0153-2883.pdf . 

NIOSH.  2002b.  NIOSH Health Hazard Evaluation Report: HETA
#2000-0410-2891; STN Cushion Company; Thomasville, NC.  National
Institute for Occupational Safety and Health.  August 2002.  Available
online at   HYPERLINK
"http://www.cdc.gov/niosh/hhe/reports/pdfs/2000-0410-2891.pdf" 
http://www.cdc.gov/niosh/hhe/reports/pdfs/2000-0410-2891.pdf .
(A-2001-07, II-A-31)

NIOSH, 2003a.  NIOSH Health Hazard Evaluation Report #99-0260-2906  Marx
Industries, Inc. Sawmills, NC  Available online at   HYPERLINK
"http://www.cdc.gov/niosh/hhe/reports/pdfs/1999-0260-2906.pdf" 
http://www.cdc.gov/niosh/hhe/reports/pdfs/1999-0260-2906.pdf .

US EPA, 2003.  Full citation above for “Decisions for Each Sector or
End Use” section.

Williams, 2005.  Full citation above for “Availability” section.

What are the anticipated costs of this regulation to the regulated
community?

Kassem, 2003.  Full citation above for “Decisions for Each Sector and
End Use” section.

Tattersall, 2004.  Conversation between M. Sheppard, EPA, and Tom
Tattersall, MicroCare Corp.

Ultronix, 2001.  Response to questionnaire from EPA by C. Wolf,
Ultronix, 2001. (A-2001-07, II-D-76)

US EPA, 2003.   Full citation above for “Human Health” section.

US EPA, 2006.  Analysis of Economic Impacts of nPB Rulemaking.  2006.

Comparison of EPA’s June 2003 Proposal and This Proposal

ACGIH, 2005.  Full citation above for “Human Health” section.

CERHR, 2002a.  Full citation above for “Human Health” section.

CERHR, 2002b.   Full citation above for “Human Health” section.

Doull and Rozman, 2001.  Derivation of an Occupational Exposure Limit
for n-Propyl Bromide, prepared by John Doull, Ph.D., M.D., and Karl K.
Rozman, Ph.D., D.A.B.T. submitted by Envirotech International, Inc.
(A-2001-07, II-D-14)	

ICF, 2001. Brief Discussion of the BMD Approach: Overview of its
Purpose, Methods, Advantages, and Disadvantages. Prepared for U.S. EPA.
(A-2001-07, II-A-52)

Full citation above for “Human Health” section.

ICF, 2002b. Comments on the NTP- Center for the Evaluation of Risks to
Human Reproduction, Final Report on 1-Bromopropane.  Cover Letter Dated
5/9/02.  (EPA-HQ-OAR-2002-0064-0013)

ICF, 2004g. Expert Panel Response on nPB AEL, Prepared for U.S. EPA,
December, 2004

ICF, 2004h. nPB Human Relevance, Prepared for U.S. EPA, September, 2004

ICF, 2006a.  Full citation above for “Human Health” section.

Rodricks, 2002.   Full citation above for “Human Health” section.

Rozman and Doull, 2002.   Full citation above for “Human Health”
section.

Rozman and Doull, 2005.  Full citation above for “Human Health”
section.

SLR International, 2001.  Full citation above for “Human Health”
section.

Stelljes and Wood, 2004.   Full citation above for “Human Health”
section.

Stelljes, ME.  2005.   Full citation above for “Human Health”
section.

TERA, 2004.   Full citation above for “Human Health” section.

How can I use nPB as safely as possible?

ACGIH, 2002.  Industrial Ventilation: A Manual of Recommended Practice
23rd Edition.  American Conference of Governmental Industrial
Hygienists, Cincinnati, Ohio  Available online at www.acgih.org.

List of Subjects in 40 CFR Part 82

Environmental protection, Administrative practice and procedure, Air
pollution control, Reporting and recordkeeping requirements.

	

Protection of Stratospheric Ozone:  Listing of Substitutes for
Ozone-Depleting

Substances–n-Propyl Bromide

Notice of Proposed Rulemaking

 of   PAGEREF End_of_document \h  142  pages

Dated:  _____________________________________________

___________________________________________________

Stephen L. Johnson, Administrator

For the reasons set out in the preamble, 40 CFR part 82 is proposed to
be amended as follows:

PART 82 - PROTECTION OF STRATOSPHERIC OZONE

1.	The authority citation for Part 82 continues to read as follows:

Authority:  42 U.S.C. 7414, 7601, 7671 - 7671q.

2.	Subpart G is amended by adding Appendix Q to read as follows:

Subpart G - Significant New Alternatives Policy Program

*****

Appendix Q to Subpart G - Substitutes Subject to Use Restrictions and
Unacceptable Substitutes

Listed in the [publication date of final rule] final rule.

AEROSOLS

UNACCEPTABLE SUBSTITUTES 

End Use	Substitute	Decision	Further Information

Aerosol solvents	n-propyl bromide (nPB) as a substitute for CFC-113,
HCFC-141b, and methyl chloroform	Unacceptable 	EPA finds unacceptable
risks to human health in this end use compared to other available
alternatives.  nPB, also known as 1-bromopropane, is Number 106-94-5 in
the CAS Registry.



ADHESIVES, COATINGS, AND INKS

SUBSTITUTES THAT ARE ACCEPTABLE SUBJECT TO USE CONDITIONS

End Use	Substitute	Decision	Use Conditions	Further Information

Coatings	n-propyl bromide (nPB) as a substitute for methyl chloroform,
CFC-113, and HCFC-141b	Acceptable subject to use conditions	Use is
limited to coatings at facilities that have provided EPA information
demonstrating their ability to meet the recommended workplace exposure
limit as of [INSERT DATE OF PUBLICATION].	EPA expects that all users of
nPB will adhere to a voluntary acceptable exposure limit of 17 ppm on an
8-hour time-weighted average and would comply with any final Permissible
Exposure Limit that the Occupational Safety and Health Administration
issues in the future under 42 U.S.C. 7610(a).  

nPB, also known as 1-brompropane, is Number 106-94-5 in the CAS
Registry.

Note 1 : In accordance with the limitations provided in Section 310(a)
of the Clean Air Act (42 U.S.C. 7610(a)), nothing in this table shall
affect the Occupational Safety and Health Administrations’ authority
to promulgate and enforce standards and other requirements under the
Occupational Safety and Health Act of 1970 (29 U.S.C. 651 et seq.)

Note 2:  As of [INSERT DATE OF PUBLICATION], the Lake City Army
Ammunition Plant is the only facility that has provided information to
EPA demonstrating the facility's ability to meet the recommended
workplace exposure limit when using nPB in coatings.

ADHESIVES, COATINGS, AND INKS

UNACCEPTABLE SUBSTITUTES

End Use	Substitute	Decision	Further Information

Adhesives	n-propyl bromide (nPB) as a substitute for CFC-113, HCFC-141b,
and methyl chloroform	Unacceptable	EPA finds unacceptable risks to human
health in this end use compared to other available alternatives.  nPB,
also known as 1-bromopropane, is Number 106-94-5 in the CAS Registry.



BILLING CODE 6560-50-P

  CFC-113 is also referred to as Freon-113, or
1,1,2-trifluoro-1,2,2-trichloroethane.  Its CAS Reg. No. is 76-13-1.

 Methyl chloroform is also referred to as 1,1,1-trichloroethane, TCA,
MCF, or 1,1,1.  Its CAS Reg. No. is 71-55-6.

 HCFC-141b is also referred to as 1,1-dichloro-1-fluoroethane.  Its CAS
Reg. No. is 1717-00-6.

 See 29 CFR 1910.1052(d)(4)(i).  

 Also called trichlorethene or TCE, C2Cl3H, CAS Reg. No. 79-01-6.

 Also called PERC, tetrachloroethylene, or tetrachloroethene, C2Cl4, CAS
Reg. No. 127-18-4.

 nPB emissions in the tropics would have an ODP of 0.071 to 0.100; the
portions of the U.S. outside the continental U.S., such as Alaska,
Hawaii, Guam, and the U.S. Virgin Islands, contain less than 1 percent
of the U.S.’s businesses in industries that could use nPB.  Thus,
their potential impact on the ozone layer must be significantly less
than that of the already low impact from nPB emissions in the
continental U.S.  (U.S. Economic Census, 2002a through f)

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on between two compounds with different WELs does not necessarily mean
that using a compound with a lower WEL is more risky.  Risks from
exposure will also vary due to emission controls in place, work
practices, ventilation, rate of spraying, and vapor pressure of the
solvent.

 iPB is also referred to as 2-bromopropane, 2-propyl bromide, or 2-BP. 
Its CAS registry number is 75-26-3.

 The estrous cycle fulfills the same role in reproduction as the
menstrual cycle in women.  

 In addition, significant changes in the distribution of ovarian cell
types were seen in the high dose groups (750 ppm) but were not counted
in lower dose groups.

 Benchmark dose analysis uses mathematical models to fit dose-response
data and identifies the “benchmark dose” associated with a
“benchmark response” determined to be significant – see EPA’s
Risk Assessment Forum Guidelines for Benchmark Dose Modeling (EPA,
2000a) and 68 FR 33292-33293 in the June NPRM on how EPA uses benchmark
dose modeling in setting an exposure limit.    

 In this analysis, the benchmark response was a 10% reduction in the
mean number of estrous cycles, consistent with EPA guidance (EPA,
2000a).  The BMDL for the same endpoint using a response of one standard
deviation would be slightly higher, at 208 ppm.  

 Pharmacodynamics refers to the biochemical and physiological effects of
chemicals in the body and the mechanism of their actions.

 Pharmacokinetics refers to the activity or fate of chemicals in the
body, including the processes of absorption, distribution, localization
in tissues, biotransformation, and excretion.

 The blood/air partition coefficient is the ratio of a chemical’s
concentration between blood and air when at equilibrium.

	7 Smog, also known as ground-level ozone, is produced from emissions of
volatile organic compounds that react under certain conditions of
temperature and light. 

 Unlike samples measured directly in the breathing zone, area samples
measured in the study are not considered representative of actual
exposure and are not discussed here.  Short-term measurements taken over
15 minutes from personal samplers, although in some cases extremely
high, are not discussed in detail here because available toxicity
information does not indicate need for a short-term exposure limit in
addition to the 8-hr TWA limit (ACGIH, 2005; ERG, 2004; see section
IV.A.5).  Additional information on these other samples is in the
occupational exposure assessment for aerosols in the risk screen for nPB
(ICF, 2006a).

 This corresponds roughly to a regional or room fan at low levels or
natural air currents in an open area.  Confined areas would have even
lower air exchange rates with higher exposure levels.

  We consider use of 1000 g/day to be the high end of typical use, based
on the setup of one of the exposure studies (Confidential Submission,
1998).  The typical aerosol solvent user in the electronics industry
uses a can per day (Williams, 2005).  This is comparable to or slightly
less than the spray rate assumed in the modeling.    

 In its methylene chloride standard, OSHA defined representative
sampling as follows:  “The employer has taken one or more personal
breathing zone air samples for at least one employee in each job
classification in a work area during every work shift, and the employee
sampled is expected to have the highest…exposure.”   (29 CFR
1910.1052(d)(1)(ii)(A)).   

 The action level is the exposure level that is  half the 8-hour TWA
exposure limit.  In this case, the action level would be 8.5 ppm.

	

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