UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

		     WASHINGTON, D.C. 20460

							                                            	  OFFICE OF

				PREVENTION, PESTICIDES

	AND TOXIC SUBSTANCES

	

April 4, 2008

MEMORANDUM

SUBJECT:	Revised Risk Assessments to Support the Reregistration
Eligibility Decision (RED) Document for the Wood Preservative Uses of
Chromated Arsenicals (Case 0132) 

FROM:	Lance Wormell, Chemical Review Manager

		Regulatory Management Branch 2

Antimicrobials Division (7510P)

TO:		Public Docket EPA-HQ-OPP-2003-0250

	This document presents the Environmental Protection Agency’s (EPA or
“the Agency”) Case Overview and revised risk assessments for
reregistration Case 0132: Wood Preservative Uses of Chromated
Arsenicals.

Attachments

Attachment 1:

Human Health Risk Assessment and Ecological Effects Assessment for the
Reregistration Eligibility Decision (RED) Document of Inorganic
Arsenicals and/or Chromium-based Wood Preservatives. March 31, 2008.

Attachment 2: 

Occupational Exposure Chapter for Inorganic Arsenicals and
Chromium-based Wood Preservatives in Support of the Reregistration
Eligibility Decision (RED) Document for the Chromated Arsenicals (RED
Case 0132). March 18, 2008.

Attachment 3:

Hazard Identification and Toxicology Endpoint Selection for Inorganic
Arsenic and Inorganic Chromium.  March 12, 2008.

Attachment 4:

Incident Report Associated with Inorganic Arsenical Wood Preservatives. 
February 2, 2004.

Attachment 5:

Ecological Hazard and Environmental Risk Assessment RED Chapter for
Inorganic Arsenical Wood Preservatives (CCA).  March 10, 2008.

Attachment 6:

Environmental Fate and Transport Assessment of CCA-C for Reregistration
Eligibility Decision (RED) Process.  February 19, 2008.

Attachment 7:

Product Chemistry Science Chapter of CCA-C for Reregistration
Eligibility Decision (RED) Process.  February 27, 2008.

I.	CASE OVERVIEW

Case 0132, chromated arsenicals, includes heavy duty chemical wood
preservatives containing some combination of chromium, arsenic, and/or
copper.  These compounds are chromated copper arsenate (CCA), ammoniacal
copper zinc arsenate (ACZA), ammoniacal copper arsenate (ACA), and acid
copper chromate (ACC).  The registered active ingredients assessed in
case 0132 are arsenic acid, arsenic pentoxide, chromic acid, and sodium
dichromate (see Table 1).  The wood preservative chemicals in this case
are colloquially referred to as “CCA” (chromated copper arsenate)
although they also include other chromated arsenical wood preservative
uses. Since the 1940s, wood has been pressure treated with chromated
arsenicals in treatment cylinders, also called retorts, to protect wood
from rotting due to insect and microbial agent attack.

Table 1.  Active Ingredients to be Assessed in the CCA RED

Case Number	CAS Number	PC Code	Empirical Formula	Name Used in RED
Documents	Common Name

0132	7778-39-4	006801	H3AsO4	  Arsenic Acid	Orthoarsenic Acid 

(o-Arsenic Acid)

0132	1303-28-2	006802	As2O5	Arsenic Pentoxide	Arsenic Acid

Anhydride

0132	7738-94-5	021101	CrO3	Chromic Acid	Chromic Acid Flake;

Chromium Trioxide

0132	10588-01-9	068304	Na2Cr2O72H2O	Sodium Dichromate	Chromic Acid,
Disodium Salt

  

Cupric oxide (PC Code 042401), the form of copper used in the treatment
solutions for the wood preservatives containing arsenic and/or chromium,
is also outside the scope of this assessment.  Non-antimicrobial uses of
cupric oxide were addressed in a July 2006 RED (EPA 738-R-06-020). 
Antimicrobial uses of cupric oxide will be addressed in a separate RED
document at a future date.  Similarly, zinc oxide (PC Code 088502) –
the form of zinc used as an active ingredient in the formulations of
ACZA – is also outside the scope of this assessment because it has
been addressed in the August 2002 RED for zinc salts (EPA-738-F-92-007).
 

Currently there are 20 products registered for pressure treatment of
wood intended for above ground and ground contact, as well as in fresh
water and marine environments. Wood treated with these preservatives are
specified for commercial, institutional, and limited residential/farm
construction uses in indoor and outdoor sites.  All 20 products are
Restricted Use Pesticides.

Table 2 presents a summary of the active Manufacturing Use Products
(MUP) and End-Use Products (EUP) considered for reregistration. 

Table 2. Active Registrations Considered in Case 0132

Company	EPA Reg. No.	Product Name	MUP	EUP

Osmose, Inc.	3008-66	Arsenic Acid	(1



3008-72	Osmose Arsenic Acid 75%

(1

	3008-17	Osmose K-33-C (72%) Wood Preservative

(2

	3008-34	Osmose K-33 (60%) Wood Preservative

(2

	3008-76	Osmose Technical Grade Cupric Oxide	(



3008-78	Osmose Chromic Acid	(

	Chemical Specialties, Inc.	10465-32	CSI Arsenic Acid 75%

(1

	10465-28	CCA Type-C Wood Preservative 60%

(2

	10465-41	Chromic Acid	(



10465-42	CSI Technical Cupric Oxide	(

	Arch Wood Protection, Inc.	62190-7	Arsenic Acid 75%	(1



62190-27	Chemonite Part A

(3

	62190-8	Wolman Concentrate 72%

(2

	62190-14	Wolmanac Concentrate 60%

(2

	62190-28	Chemonite Part B

(

	62190-29	Chemonite Part C

(

	62190-13	Copper Oxide	(



62190-21	Arch Chromic Acid	(

	Elementis Chromium, LP	75449-1	Sodium Bichromate Liquid	(



75449-2	Chromic Acid Flake	(

	1 As arsenic acid

2 As arsenic pentoxide (arsenic acid anhydride)3 As arsenic acid but
only as part of three part system to result in ACZA

No tolerance currently exists for the wood preservative uses of chomated
arsenicals.  

Chemical Information

Type of Pesticide:	Fungicide, Insecticide, Miticide and Molluscicide

      

Use Sites:		Arsenic and chromium compounds used as wood preservatives
are Restricted Use Pesticides specified for commercial pressure
treatment applications only (i.e., impregnated into forest products
using a vacuum pressure system).  Treated products include terrestrial
uses (e.g., utility poles, cross ties, timbers, posts, lumber, and
groundline-contact building components) and aquatic uses (e.g.,
piles/posts/timbers).  Detailed information on currently approved use
sites is presented in Appendix B of the Occupational Exposure Chapter
for Inorganic Arsenicals and Chromium-based Wood Preservatives in
Support of the Reregistration Eligibility Decision (RED) Document for
the Chromated Arsenicals dated March 18, 2008.

Target Pests:	Invertebrates: (Insects, Miscellaneous Invertebrates, and
Related Organisms.)

		 			- Wood Boring Insects

		- Termites

		- Ants

		- Marine Borers (Limnoria & Teredo)

Plant Pathogenic Organisms: (Bacteria, Fungi, and Other Fouling
Organisms.)

		- Ascomycetes

		- Wood Rot/Decay

		- Wood Rot/Decay Fungi

		- Wood Rot/Decay Fungi (Spores)

		- Dry Rot

		- Brown Rot

		- White Rot

Types of Treatment:  Pressure Treatment; Vacuum Pressure Treatment.

Equipment:  	Pressure Treating Cylinder/Vessel/Retort.

Timing: 		Prior to end use of wood.

Use Rates: 	Detailed use rate information is presented in Appendix B of
the Occupational Exposure Chapter for Inorganic Arsenicals and
Chromium-based Wood Preservatives in Support of the Reregistration
Eligibility Decision (RED) Document for the Chromated Arsenicals dated
March 18, 2008.

B. Estimated Usage of Pesticide

C. Estimated Usage of Pesticide tc \l1 "C. Estimated Usage of Pesticide 

This section summarizes the best estimates available for the wood
preservatives containing arsenic and/or chromium. These estimates are
derived from a variety of published and proprietary sources available to
the Agency. 

Technical sources of Arsenic used as wood preservatives are derived from
Arsenic trioxide imported principally from China to produce Arsenic acid
for formulation of CCA and related arsenicals.  About 90% of all arsenic
consumed is for the production of wood preservatives (U.S. Geological
Survey, Mineral Commodity Summaries, 1997).  Statistics indicate that
wood preservatives make up 72% of the Chromic acid market (Chemical
Market Reporter, 2000).

According to EPA sources, the most common of the waterborne
preservatives is CCA (as Type C containing 47.5% chromium, 18.5% copper,
and 34% arsenic) which by the mid-1990's represented 90% of the U.S.
waterborne preservatives market.  Market statistics for 2002 indicated
that there were between 300 and 350 wood treatment plants in the US that
used CCA.  The U.S. consumed approximately 110 million pounds of CCA in
2002 (EPA proprietary data and Vlosky 2006).  In 2002 the total volume
of CCA-treated wood products was estimated at approximately 350 million
cubic feet. 

C.	Regulatory History

  

Formulated wood preservative products containing arsenic and/or chromium
compounds have been registered since the 1940's when pesticides were
under the regulatory purview of the United States Department of
Agriculture (USDA) and subsequently have been regulated by EPA under
FIFRA since the 1970s.  The wood preservative pesticides containing
arsenic and/or chromium compounds are registered as technical
source/manufacturing-use products or formulated industrial end-use
product concentrates or mixtures intended for aqueous dilution to form
CCA, ACZA, ACA and ACC treatment solutions.  

Case 0132 was previously identified as “Chromated Arsenicals” in
OPP’s Spring 1998 “Status of Pesticides in Registration,
Reregistration, and Special Review (Rainbow Report)” and included four
additional active ingredients which have since been cancelled and
therefore are not eligible for reregistration and are not further
addressed in this document: sodium arsenate (PC Code 013505) cancelled
2004, potassium dichromate (PC Code 068302) cancelled 2000, sodium
pyroarsenate (PC Code 013401), cancelled 1991, sodium chromate (PC Code
068303)  cancelled 1987, and ammonium arsenate (PC Code 013601)
cancelled 1987.  

One additional arsenic compound, arsenic trioxide (PC Code 007001), is
currently registered as an insecticide for use in ant bait products. 
This compound is does not have any wood preservative use and therefore
is not within the scope of this assessment. The Agency will complete a
separate reregistration eligibility decision for this chemical.

The Agency required registrants to submit studies in response to
Registration Standards issued in 1986 and 1988 (PB87-114088, and
PB89-102842) for chromated arsenical compounds. Data from submitted
studies along with more recent industry-sponsored studies were used to
characterize the risks associated with the uses described in this
document.  Additional data required to be eligible reregistration,
including any previously required and unfulfilled data, will be
presented in the RED document. 

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