Document ID: EPA-HQ-OPP-2003-0250-0052
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-04-16T04:00Z

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 Chromated Arsenicals (Case
0132)

From:		Lance Wormell, Chemical Review Manager

Registration Management Branch 2

Antimicrobials Division

To:		CCA Docket (EPA-HQ-OPP-2003-0250)

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 chromated arsenicals (sometimes colloquially
referred to as the “CCA 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-2003-0250 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 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).  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. 

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 chromated arsenicals meet the “no unreasonable adverse
effects” standard of the Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA).  

Note that risks posed by copper are not assessed in the CCA RED.  Human
health risks posed by copper compounds were addressed in the July 2006
“Coppers” RED (available in docket # EPA-HQ-OPP-2005-0558) and
ecological risks will be addressed in a separate RED scheduled for
September 2009.  Because virtually all residential uses of CCA were
voluntarily cancelled effective December 31, 2003, this RED also does
not assess residential uses of chromated arsenicals.  EPA’s risk
assessment for previously registered residential uses is available in
docket # EPA-HQ-OPP-2003-0250.

SECTION II: CHANGES TO THE RISK ASSESSMENTS

EPA has reviewed new information since the previous risk assessments
were released including submissions received during the Phase 3 public
comment period that ended on May 17, 2004.  Based on this new
information, in addition to making numerous clarifications and minor
changes throughout the documents, EPA has incorporated the following
significant revisions:

Occupational risk estimates are presented for individual chemicals by
test site and job function.  Previously, risk estimates were presented
for CCA only and were summarized across test site and job function. 

Updated occupational risk estimates are presented based on more robust
hexavalent chromium exposure data (Forest Products Research Laboratory,
2005).

Screening level risk estimates are presented for wood fabricators
exposed to inhaled treated wood dust during construction.  Previously,
risk estimates were presented for wood treatment plant workers only.

The target margin of exposure (MOE) for hexavalent chromium inhalation
is 30.  The previous target MOE of 100 was lowered because the
additional uncertainty factor associated with using an epidemiological
study is no longer needed.

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., wood fabricators exposed to inhaled
treated wood dust during construction) 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 (i.e., wood fabricators exposed to inhaled treated wood
dust during construction)?

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?

What air monitoring data are available in and around plants that
currently use chromated arsenicals as wood preservatives?

2. Benefits and Alternatives

EPA has reviewed submissions received during the Phase 3 public comment
period that ended on May 17, 2004 as well as the American Chemistry
Council’s March 19, 2008 document entitled “Analysis of Benefits of
CCA-Treated Wood” (available in docket # EPA-HQ-OPP-2003-0250).  EPA
is also 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-2003-0250.

For each chromated arsenical product (e.g., CCA, AZCA), 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 chromated arsenicals that are not already
captured in the existing documents?

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

Page   PAGE  3  of   NUMPAGES  3 

 US EPA. 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.