Document ID: EPA-HQ-OPP-2007-0414-0021
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-07-02T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES 

AND TOXIC SUBSTANCES

  SEQ CHAPTER \h \r 1 MEMORANDUM			

September 25, 2007								

SUBJECT:	  SEQ CHAPTER \h \r 1 Phase 6 Response to Substantive Public
Comments on Antimicrobials Division’s Occupational and Residential
Assessments for the Reregistration Eligibility Decision (RED) Document
for Octhilinone (OIT); Case 2475; PC Code 099901.

									

FROM:	Cassi L. Walls, Ph.D., Chemist

		Risk Assessment and Science Support Branch (RASSB)

		Antimicrobials Division

THROUGH:	Norm Cook, Branch Chief

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division

TO:		  SEQ CHAPTER \h \r 1 K. Avivah Jacob, Chemical Review Manager

		Regulatory Management Branch II

		Antimicrobials Division

		

	  SEQ CHAPTER \h \r 1 The attached document is in response to the Phase
5 public comments regarding the Reregistration Eligibility Decision
(RED) Document for Octhilinone (OIT).  This document specifically
addresses only those substantive comments relating to the occupational
exposure and risk assessments.  AD’s Occupational and Residential
Exposure Assessment has been revised to reflect typographical and
numerical errors captured during the comment period.  

	

 Octhilinone (OIT)

AD Response to Phase 5 Public Comments

Comments from the OIT Task Force

Comment:  The Agency has inappropriately conducted dermal exposure and
risk assessments in its assessment of OIT and should correct those
documents to show that no dermal exposure assessment is needed.

Response:   AD toxicologists selected a short-term dermal endpoint based
on irritation effects and an intermediate-term dermal endpoint based on
systemic effects.  Because dermal effects were observed in the studies
reviewed by the toxicologists, it was deemed necessary to assess dermal
exposures and risks for OIT.  A quantitative short-term dermal
assessment was not conducted for the occupational handlers where
exposures can be mitigated by the use protective clothing and gloves. 
However, following standard AD procedure (see other AD REDs), dermal
assessments were conducted where mitigation options are not viable such
as painting and residential exposure scenarios.

Comment:  Since the method [pertaining to the airless sprayer unit
exposure value] proposed is a radical departure from the use of PHED
data and policy that EPA has developed around it, a clear explanation
for the policy change needs to be made.

Response:  The airless sprayer PHED data was used in the assessment. 
The PHED airless sprayer unit exposure data were normalized in terms of
an air concentration (mg/m3/%ai) rather than a dose (mg/lb ai).  It was
necessary to express the PHED data in terms of an air concentration to
perform an inhalation route-specific risk assessment.

Comment:  Table 4.2.2, Footnote A.  This equation seems to have no basis
in policy or science.  It appears to be some adaptation of the Human
Equivalent Concentration (HEC) methodology, but there is no citation for
its basis or use.

Response:   This equation is no longer being used.  The inhalation
toxicological endpoints are now expressed in terms of HECs.  The HECs
were estimated using Regional Deposited Dose Ratios (RDDR) for
nonhygroscopic particles and the inhalation NOAEL.  All of the
inhalation MOEs have now been updated in the ORE assessment using the
HEC methodology.

Comment:  It is entirely unclear why one would assume that a painter
dips both hands in paint and leaves it on the hands.  Such an assumption
is not consistent with any painting technique involving a brush or
roller.  However, even if one were to assume that the painter was very
sloppy and had a film of the paint on both hands, it is the nature of
the paint to quickly dry.  Once dry the OIT becomes much less
bioavaliable as indicated by in vitro tests of paint applied to skin. 
The data indicate that bioavailability drops by 20-fold from paint
versus active ingredient in solvent.  This information has been supplied
to EPA, and it should be used in the risk assessment.

It is important to note that EPA’s OPP has developed a standard
operating procedure of the painting and wood preservative treatment
handler scenario.  Further, if a systemic toxicity endpoint is of
concern, EPA has previously addressed the scenario using the SOP in an
appropriate manner (see Propiconazole).

Response:   The paint “two-hand immersion” method explanation is
misleading as currently written and has been clarified in the ORE
assessment.  Although the short-term dermal paint assessment method was
based on ChemSteer’s two-hand immersion model, it was not really
assumed that the painter’s hands were covered in paint rather, it was
assumed that the paint film thickness on the skin, regardless of the
surface area covered, was 10.3 mg/cm2.  This type of method was
necessary to use to properly estimate MOEs since the dermal irritation
endpoint was in terms of surface area (mg/cm2) not dose (mg/kg/day).  If
the endpoint was based on systemic effects, not dermal irritation, AD
would have used a similar approach as used in the propiconazole
assessment.  Furthermore, the intermediate-term dermal assessment (where
the endpoint was based on systemic effects) for painters was not
conducted because it was assumed that OIT treated paint would not be
used by professional painters on a continuous basis.

AD has reviewed the “bioavailablity” data and has incorporated the
results into the ORE assessment.

Comment:  To address the potential OIT residential post-application
exposures resulting from consumer contacted with treated (i.e.,
impregnated) materials, AD should follow EPA’s Standard Operating
Procedures for Residential Exposure Assessments.  Chapter 11.2 of that
document described a predictive method for estimating the migration of
residues from impregnated materials. Specifically, the Polymer Migration
Estimation Model (AMEM) is a computer program to describe the migration
of additives out of polymeric materials. … The current calculations
presented in the ORE chapter of the OIT RED are based on the assumption
that 100% of the OIT in the impregnated or treated material is available
for transfer, and that the following “default assumption” percent
transfers may occur: carpet 5%, vinyl flooring 10%, clothing 5%, and
toys 0.5%. … Thus, it is reasonable to use the AMEM model to address
EPA’s uncertainty, i.e., estimate the fraction of OIT that may migrate
from the matrix and be available for transfer.  It is recommended that
AD revise the carpet, vinyl flooring, clothing, mattress and toy
scenarios accordingly…. It is important to reiterate that the OIT is
used in carpet backing and not in the pile of the carpet, so there is no
direct contact.

Response:   The AMEM model results (i.e., 0.86% of OIT is available on
the surface of the polymer for exposure) provided by the OIT Task force
will be used in the vinyl flooring scenarios assessed in the ORE
chapter.  However, the AMEM results can only be used in the vinyl
flooring assessments because AMEM only assesses migration through
polymer matrices not textiles such as clothing, mattress ticking/covers,
and carpet pile.  Since, the toy scenario already assumes that only 0.5%
OIT is available on the surface of the polymer and 50% of the available
residue is transferred via mouthing, the AMEM modeling is not necessary
for the toy scenario. Currently, there are several labels that list
indoor and outdoor carpeting as well as, backing as potential use sites.
 If the use is limited to carpet backing then a quantitative exposure
assessment would not be necessary to conduct and the current labels
would need to be updated to accurately reflect this use pattern.

Comment:  Similar to the liquid pour CMA data, the available [liquid
pump] CMA data are of lower quality and there are significantly fewer
replicates than the Agency typically deems adequate. …  It is unclear
why the PHED data (Scenarios 3 and 6) were not used.

Response:   It is AD’s standard policy to use the CMA data since they
were developed specifically for antimicrobial chemicals.  AD
acknowledges the limitations with the CMA data and is therefore
requiring the generation of confirmatory exposure data specific to
antimicrobial chemicals.

Comment:  The unit exposure values do not reflect the typical use of a
second layer of clothing. … The high pressure spray operator wears,
per label requirement, a full-face respirator fitted with an organic
cartridge, protective eyewear, gloves and boots that are impervious to
the solution, a long-sleeve shirt, long pants, and coveralls.

Response:   The unit exposure values have been revised to incorporate
labeled PPE requirements.

Comment:  In addition to the “Herculean” strength necessary to lift
and pour 2,000 gallons per day of active ingredient, this quantity of
material would not be poured.

Response:   This value represents the amount of material (i.e., paint,
coatings, stain, etc.) that is treated via open pour techniques.  It is
not the amount of active ingredient lifted and poured on a daily basis.

Comment:  The Agency has assumed that the professional airless spray
[paint] operators wear no respiratory protection.  This is not true of
either union or non-union workers.  Wearing a respirator is not
something that’s typically optional, rather it is a common industrial
hygiene practice.  Even in the case of small operations, where wearing a
respirator is not mandatory, virtually every airless sprayer utilizes
one.

Response:   Because OIT is a materials preservative (i.e., in-can
preservative), there are no pesticidal claims on preserved paint. 
Therefore, there are no enforceable EPA registered labels for preserved
paint thus, we must assume baseline exposures (i.e., no use of gloves
and respirator) when conducting risk assessments for these types of
products.

Comment:  The next step in deriving an MOE is estimating a relevant
airless sprayer operator breathing zone concentration of OIT (mg/m3)
during a workday for comparison to the HEC derived above.  For this
purpose, a study conducted by the National Paints and Coatings
Association (Reinhardt and Fendick 2000) was selected. … Thus, this
inspirable OIT air concentration associated with inspirable particles,
is estimated to range from 0.037 mg OIT/m3 to 0.053 mg OIT/m3.

Response:   The Reinhardt and Fendick study was reviewed and deemed
appropriate to use in the ORE assessment.  These data were used to
augment the existing database of PHED airless sprayer unit exposure
values rather than replace them.

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