UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, D.C. 20460

							                                               OFFICE OF

				PREVENTION, PESTICIDES

	AND TOXIC SUBSTANCES

MEMORANDUM

Date:		April 8, 2008

Subject:	Issues to Consider in Commenting on the Revised Risk
Assessments for the Wood Preservative Uses of Pentachlorophenol (Case
2505)

From:		Sherrie Kinard, Chemical Review Manager

Risk Assessment and Science Support Branch

Antimicrobials Division (7510P)

To:	Pentachlorophenol Docket (EPA-HQ-OPP-2004-0402)

	The Environmental Protection Agency’s (EPA or “the Agency”)
Office of Pesticide Programs (OPP) has completed its revised risk
assessments in support of the reregistration eligibility decision (RED)
for the wood preservative uses of pentachlorophenol (sometimes
colloquially referred to as the “Penta RED”).  This document was
prepared to help identify for potential respondents the kind of
information that the Agency believes would be useful in making its
reregistration decision.  The revised risk assessments and other support
documents are available for public comment in public docket #
EPA-HQ-OPP-2004-0402 at   HYPERLINK "http://www.regulations.gov/" 
http://www.regulations.gov/ .

SECTION I: BACKGROUND

EPA is releasing for public comment its revised risk assessments to
support the reregistration eligibility decisions for the three heavy
duty chemical wood preservatives: chromated arsenicals,
pentachlorophenol, and creosote.  Case 2505, pentachlorophenol, includes
heavy duty chemical wood preservatives containing pentachlorophenol and
the micro-contaminants, hexachlorobenzene (HCB), and dioxin/furan (CDDs
and CDFs).  These micro-contaminants are found in the technical grade of
pentachlorophenol.  Since 1936, wood has been pressure treated with
pentachlorophenol in treatment cylinders, also called retorts, to
protect wood from rotting due to insect and microbial agent attack.

Publishing revised risk assessments and risk mitigation/exposure
reduction options for public comment is part of EPA’s Six-Phase public
participation process.  The Agency uses this process to involve the
public in developing pesticide reregistration decisions.  After the
60-day public comment period closes, EPA will evaluate the responses
received, update its revised risk assessments as appropriate, and issue
its final risk assessments and reregistration eligibility decision.  The
RED document is currently scheduled to be released in September 2008 and
will present the Agency’s determination on which wood preservative
uses of pentachlorophenol meet the “no unreasonable adverse effects”
standard of the Federal Insecticide, Fungicide, and Rodenticide Act
(FIFRA).  

Pentachlorophenol (PCP, Penta) is a general biocide which has
historically been used extensively (as is its salt, sodium
pentachlorophenate or NaPCP) as a fungicide, bactericide, herbicide,
molluscide, algicide and insecticide by agriculture and other industries
including textiles, paints, oil drilling and forestry.  Although its
primary use in the U.S. is as a wood preservative, PCP has been used in
rice and sugar production, in water treatment, as a pre-harvest
defoliant in cotton, and as a general pre-emergence herbicide.  It has
also been utilized in numerous products including adhesives,
construction materials, leather and paper.  Pentachlorophenol is
classified as a Restricted Use Product (RUP) when used as a wood
preservative.  Currently, the only registered uses of pentachlorophenol
are as a wood preservative; therefore, this RED only assesses the uses
of pentachlorophenol as a wood preservative.

SECTION II: CHANGES TO THE RISK ASSESSMENTS

	EPA has reviewed current information since the previous risk
assessments were released including submissions received during the
Phase 3 public comment period that ended on May 30, 2005.  Based on this
current information, no significant changes from the previous
assessments have been made; however, ORD/NCEA is currently in the
process of updating the carcinogenicity assessment. 

	Pentachlorophenol was classified as a B2 (probable human carcinogen)
carcinogen at a joint February 1990 meeting of the FIFRA Science
Advisory Panel and Science Advisory Board. The SAP/SAB concluded that
the liver tumors, pheochromocytomas, and hemangiosarcomas were
treatment-related and supported the B2 classification. These tumors were
observed in female mice from a study conducted by the National
Toxicology Program in 1989 (NTP Technical Report 349, March 1989) using
pure pentachlorophenol or a technical grade formulation, Dowicide EC-7. 
 In November of 1990, the Health Effects Division's Carcinogenicity
Assessment Review Committee met and concurred with the B2 classification
and also recommended quantification of risk using the combined incidence
of hemangiosarcomas, liver tumors, and pheochromocytomas in female mice
from the two data sets generated with the two PCP formulations used in
the NTP study (Health Effects Division document # 013274, HED archive
record series).   Using a 3/4 scaling factor, an oral cancer risk
estimate (q1*) of 7.0 x 10-2 was  calculated on this basis.  The slope
factor was calculated as the geometric mean of the individual slope
factors derived from two data sets: female mouse data for technical
grade and Dowicide EC-7 pentachlorophenol.  

EPA is currently completing a new IRIS assessment that will include a
cancer unit risk value for pentachlorophenol. Based on the ongoing
re-evaluation to estimate carcinogenic potential of pentachlorophenol,
OPP will use the current risk estimate for pentachlorophenol until any
new risk estimates are fully peer reviewed.   

SECTION III: QUESTIONS

This section provides questions to elicit and guide comments on EPA’s
revised risk assessments.  Note that these questions are offered for
comment and are not meant to imply that EPA intends to complete or
require any of the measures herein.  When submitting comments, please
identify the question(s) you are addressing and include discussions,
explanations, and references where possible.

1. Occupational Risks

Cancer and non-cancer risks posed to treatment plant workers and
post-application handlers (i.e., workers touching or inhaling
pentachlorophenol during or after treatment) exceed the Agency’s level
of concern.  To reduce similar risks for other chemicals, EPA has
historically required implementation of risk reduction measures.  These
measures are chemical- and risk-specific, and might include limiting the
ways in which or products to which the chemical may be applied,
additional personal protective equipment (PPE), and/or restricted
entry/re-entry intervals.  Risk reduction measures might also include
pressure treatment plant “engineering controls” such as hydraulic
doors, hydraulic bridge rails, and/or a ventilation system.  

What practical and effective measures might EPA implement to reduce
worker exposure during treatment (i.e., pressure treatment workers) and
after treatment?

If the measures identified in 1.a. were to be implemented, what are the
potential economic and/or other impacts to small-, medium-, and
large-sized treatment plants?

If the measures identified in 1.a. were to be implemented, approximately
how much time would it take to implement each measure at a small-,
medium-, and large-sized treatment plant?

2. Benefits and Alternatives

EPA has reviewed submissions received during the Phase 3 public comment
period that ended on May 30, 2005.  EPA is in the process of finalizing
its own benefits, alternatives, and economic analyses for the three
heavy duty chemical wood preservatives.  These documents will also be
posted in docket # EPA-HQ-OPP-2004-0402.

For pentachlorophenol, what unique uses and benefits exist that are not
already captured in the existing documents?

What alternatives, either chemical or non-chemical, exist for heavy duty
wood preservative uses of pentachlorophenol that are not already
captured in the existing documents?

What information is available on best management practices for using
pentachlorophenol to pressure treat wood (recommended application
methods/times, storage/disposal instructions, etc.)?  

What air monitoring data are available in and around plants that
currently use pentachlorophenol as a wood preservative?

Page   PAGE  1  of   NUMPAGES  4 

 US EPA. Pentachlorophenol- Preliminary Risk Assessment for the
Reregistration Eligibility Decision (RED) Document.  February 14, 2008.

