UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

OFFICE OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

PC Code: 055801

DP Barcodes: DP 354916

MEMORANDUM					DATE: July 24, 2008

							

	

SUBJECT:	Response to Public Comments on the Environmental Fate and
Effects Division (EFED) Ecological Risk Assessment for the Naphthalene
RED

FROM:	Mark Corbin, Senior Environmental Scientist

		Environmental Risk Branch 3

		Environmental Fate and Effects Division (7507P)

THRU:	Karen Whitby, Acting Branch Chief

Environmental Risk Branch 3

		Environmental Fate and Effects Division (7507P)

TO:		Molly Clayton

		Reregistration Branch 3

		Special Review and Reregistration Division (7508P)

This memorandum transmits the Environmental Fate and Effects
Division’s (EFED) response to public comments on the Ecological Risk
Assessment dated June 28, 2007.  Public comments relevant to the EFED
risk assessment consist of one submission from Willert Home Products
(Willert) dated July 11, 2008 and a second submission from Honeywell
International, Inc (Honeywell).  Each submission focuses on a single
aspect of EFED’s fate and transport assessment and will be responded
to separately.  Based on the comments, EFED does not believe that a
revision to either the ecological risk assessment or drinking water
assessment is necessary.  Reasons for this conclusion will be summarized
for each comment and response below.

Willert Comment

The comment from Willert focuses on the EFED assumption of treated area
for a typical home application.  EFED assumed treatment areas of a
single band 12 inches wide for selected areas while Willert indicates
that the product will be treated in bands no wider than 3 inches.  The
rational for this assumption is not provided and there is no specific
limitation on the label as to how many bands of any size can be applied.
 In EFED’s case we assume 12 inches to be conservative and to account
for the uncertainty in the label directions.  Willert can reduce this
uncertainty by limiting applications to a specific width.  If these
limitations are applied, the EEC in EFED’s assessment would be reduced
by a relevant factor (for instance, an EEC of 12 ppb based on a 12-inch
width would be reduced by a factor of 4 to 3 ppb based on a 3-inch wide
band).  Until such time as the label reflects this limitation EFED
believes the assumption of a 12-inch treatment band should remain.  

Willert also takes issue with EFED’s assumption of the size of the
treated area.  In this case, EFED assumed a single 12-inch band around a
typical 1,000-square-foot house and a 20-ft by 100-ft garden.  Using an
assumed ¼ acre lot size as the basis for calculating a percent treated
area, EFED determined that roughly 4.1% of the residential lot could be
treated.  These estimates were based on US Census data for typical lot
sizes.  On the other hand, Willert provides no data to support the
contention that a 1% treated area is more reasonable other than to say
that a “3 inch treatment band, which is still probably larger than
typical use.”  Based on these comments EFED does not believe the 4.1%
is unreasonable, given the lack of data on usage and the previously
cited assumptions from Landis.  Therefore, EFED’s assessment has not
been modified.

Honeywell Comment

The comment from Honeywell focuses on EFED’s selection of the
adsorption coefficient used in aquatic exposure modeling for both
ecological and drinking water exposure assessments.  EFED relied on a
registrant-submitted overview of open literature data (MRID 45346801)
which provided supplemental data on the adsorption/desorption and
aerobic soil metabolism properties of naphthalene.

For sorption a total of 13 open literature studies were submitted and
summarized and indicated that Koc values ranged from 131 to 1470 L/kg
for a variety of soils from North America, Europe and China (the minimum
value was incorrectly reported as 200 in the assessment).  Using
EFED’s guidance for the selection of environmental fate properties to
be used as model inputs, EFED selected the lowest value from this range.
 In accordance with EFED guidance the value selected represents the
lowest non-sand Koc where a greater than 3-fold variation is seen in the
available data (the 3-fold variation is only relevant for Sci-Grow
groundwater modeling).  More detail on the guidance for input selection
may be found at the following website:

  HYPERLINK
"http://www.epa.gov/oppefed1/models/water/input_guidance2_28_02.htm" 
http://www.epa.gov/oppefed1/models/water/input_guidance2_28_02.htm 

In contrast, Honeywell cites numerous sources of data for adsorption
values and believes that a value of 800 L/kg would be appropriate. 
However, even if all the additional data had been available and
considered at the time of the assessment, EFED’s guidance will still
necessitate selection of the lowest non-sand value, in this case the 131
L/kg value.  Therefore, the assessment has not been changed.

However, in order to provide context to the importance of this value in
the existing assessment, one use pattern has been remodeled using the
higher Koc value.  The results indicate that the surface water EEC for
the outdoor use for snake control would be reduced from 1.4 ppb (peak
EEC) to roughly 1.0 ppb (a reduction of approximately 30%).  Given that
the original risk assessment did not identify any risk to aquatic
organisms this change will not influence the risk conclusions of the
original assessment and no changes have been made.

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