Document ID: EPA-HQ-OPP-2006-0732-0006
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-01-02T05:00Z

UNITED STAES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF

 PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

MEMORANDUM

DATE:  	30/AUGUST/2007  

SUBJECT:	Note to File: Trifloxystrobin: Change in EDWC from 92 ppb to
140 ppb for the Acute Dietary Assessment Results in Negligible Change.

PC Code:		129112   	

Decision Number:  	369020

DP Number:		343362

REVIEWER:	Debra Rate, Ph.D., Biologist 

Alternative Risk Integration and Assessment (ARIA) Team

Risk Integration Minor Use and Emergency Response Branch 			
(RIMUERB)/Registration Division (7505P)

THROUGH:	John Redden, Team Leader

		ARIA Team

RIMUERB/Registration Division (7505P)

Following the assessment of trifloxystrobin grasses grown for seed, it
was determined that the estimated drinking water concentrations (EDWCs)
for the chemical trifloxystrobin should have been based on the highest
combined residues of the parent (trifloxystrobin) and the acid
metabolite (CGA-3211130).  

Previously, the acute dietary assessment was based on the water number,
92 ppb, reported as the combined residues of trifloxystrobin obtained by
FIRST model for use on turf.  The chronic analysis utilized the parent
plus metabolite (140 ppb), as determined by the Interim Rice Paddy
Model.  As will be demonstrated below, both numbers are very
conservative and the change in % aPAD utilized is negligible.  The
Environmental Fate and Effects Division (EFED) determined that the
highest EDWC for both acute and chronic analysis should use 140 ppb
based on the model for the use on rice.  Because this model does not
account for degradation of the chemical or dilution with uncontaminated
water outside of the rice paddy, the calculated EDWCs (140 ppb) are
expected to exceed concentrations likely to be found in drinking water
derived from surface water sources (DP Num: 296318; S. Abel, et. al.;
30/MAR/2004).

Trifloxystrobin acute and chronic dietary exposure assessments were
conducted using the Dietary Exposure Evaluation Model software with the
Food Commodity Intake Database (DEEM-FCID™, Version 2.03), which
incorporates consumption data from USDA’s Continuing Surveys of Food
Intakes by Individuals (CSFII), 1994-1996 and 1998 (DP Num: 332107, B.
Hanson, 30/NOV/2006).  The residues expected in water are incorporated
in this analysis.

Previously, the acute dietary exposure for food and water (92 ppb)
utilized <1% of the aPAD for females 13-49 years old at the 95th
percentile with the dietary exposure of 0.017357 mg/kg/day.  Using the
higher water number provided by EFED from the rice paddy model of 140
ppb for the acute dietary analysis the calculated dietary exposure
becomes 0.018733 mg/kg/day which also translates to <1% of the aPAD.  

Population Subgroup	EDWC (ppb)	Dietary Exposure (mg/kg/day)	Acute
Dietary

(95th Percentile)

% aPAD*

Females 13-49 years old	92 	0.017357     	<1

Females 13-49 years old	140	0.018733	<1

Although the risk has not been significantly changed, all future dietary
assessments will utilize the EDWC of 140 ppb for both chronic and acute
dietary assessments, unless EFED communicates that they have determined
that new water models and uses require a change in the magnitude of the
EDWC.

Trifloxystrobin	Note to File	DP Number: 343362	

PC Code: 129112		

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