UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF PREVENTION,

PESTICIDES AND 

TOXIC SUBSTANCES

MEMORANDUM								

	

DATE:	February 21, 2007

SUBJECT: 	Drinking Water Assessment for the Use of Pyraclostrobin (P.C.
Code: 099100) on Underlinted Cotton Seed, Cotton Gin By-Products, and
Berries Group 13 (DP Barcode D326246)

FROM:	Amer Al-Mudallal, Chemist

Nancy Andrews, Branch Chief

Environmental Risk Branch1

Environmental Fate and Effects Division (7507P)

TO:		Tony Kish, Risk Manager (RM-22)

John Bazuin, RM Team Reviewer

Registration Division (7505P)

Barry E. O’Keefe, Risk Assessor/Biologist

Registration Action Branch 3

Health Effects Division (7509P)

	

The Environmental Fate and Effects Division (EFED) reviewed the proposed
use rates associated with the Section-3 request for the use of the
active ingredient pyraclostrobin on underlinted cotton seed, cotton gin
by-products, and berries group 13 (DP Barcode D326246).  EFED concluded
that the proposed use rates are much lower than the use rate on turf,
the crop that was selected for the drinking water assessment. 
Therefore, the estimated concentrations of pyraclostrobin in drinking
water associated with the previous section 3 request for the use of
pyraclostrobin In-furrow on Potatoes (DP Barcode D303496, October 6,
2004) remain valid.

Here is a summary of the previous water assessment:

Tier 2 drinking water assessment was performed using PRZM 3.12/ EXAMS
2.7.97 modeling with index reservoir (IR) scenarios and percent cropped
area (PCA) adjustment factors.   The assessment was based on the highest
registered use rate of pyraclostrobin on turf.  A Florida turf scenario
was used with 6 ground applications of 0.5 lbs ai/acre, 14 day
intervals.  The modeled scenario reflects a region with high rainfall
and high vulnerability to runoff.  A default PCA factor of 0.87 was
used. The Tier II modeling predicts that the concentrations of
pyraclostrobin in surface water are not likely to exceed 10.2 µg/L for
the peak concentration, 0.8 µg/L for the annual average concentration,
and 0.5 µg/L for the 30 year average concentrations.

The groundwater concentrations were estimated using a Tier I SCI-GROW
model (version 2.2, Nov. 1, 2001).  The assessment was based on the
highest registered use rate of pyraclostrobin on turf.  The SCI-GROW
model predicts the acute and chronic concentrations of pyraclostrobin in
shallow ground water to be 0.02 ppb. 

If you have any further questions regarding this assessment, please
contact Amer Al-Mudallal at (703) 605-0566.

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