### 1 OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

PC Code: 128965

DP Barcode: 398044 , 396054

D ate: February 7 , 2012

MEMORANDUM

SUBJECT: Drinking Water Assessment for the Etofenprox Label Amendment

TO: Andrew Ertman, Risk Manager Reviewer

Barbara Madden

, Risk Manager

Minor Use Team

Registration Division ( 750 5 P )

Kristin Rury, Biologist

Paula Deschamp, Branch Chief



### Risk Assessment Branch III

Health Effects Division (7509P)

FROM: Chuck Peck , Environmental Engineer

Environmental Risk Branch IV

Environmental Fate and Effects Division (7507 P )

REVIEWED

BY: 

### Jim Carleton, Ph.D., Senior Scientist

Environmental Risk Branch IV

Environmental Fate and Effects Division (7507P )

APPROVED

BY: Marietta Echeverria , Branch Chief

Environmental Risk Branch IV

Environmental Fate and Effects Division (7507 P )

This memo is in response to a request for drinking water estimates based on an IR4 request to

remov e the cropland and pastureland application restrictions from the Zenivex TM E4 Ready to

Use (RTU) ( EPA Reg. No. 2724

- 807 ) and Zenivex TM E20 ( EPA Reg. No. 2724

- 7 91) labels , both

of which contain the active ingredient etofenprox

. Zenivex TM E4 RTU and Zenivex TM E20 are

insecticide s used in ultra low volumes to control mosquitoes , non

- biting midges, and biting and

non

- biting flies. The label s ha ve been amended to allow appli cation over agricultural areas prior

to or following harvest for the control of adult m osquitoes within or adjacent to these areas.

In January 2010, EFED conducted a drinking water assessment which include d a quantitative

assessment of the proposed use on mound

- building ants and a closer evaluation of all currently

labeled outdoor uses (DP Barcode 370749, 371459 ). In the 2010 assessment, the highest surface

### 2 water source drinking water concentrations occurred for a modeled co

- occurrence of use on rice

and vector control. Estimated groundwater concentrations were several orders of magni tude less

than those in surface water. The results from the previous assessment are provided in Table 1.

As the amendment to the proposed label does not increase the maximum application rates , EFED

recommends using the estimated drinking water concentrat ions from the January 2010

assessment. It should be noted that EFED has reviewed a new aqueous photolysis study

submitted for etofenprox (MRID 48353301) and, while the half

- life has been reduced, the

estimated drinking water concentrations were not impacted

.

Table 1. Total Residue EDWCs of Etofenprox in Surface Water and Ground Water for Current Uses Based

on the Maximum Use Patterns, Rice and Outdoor Foggers.

Source Use (modeled rate) 1

- in

- 10

- year Peak Exposure

(μg/L) 1

- in

- 10

- year

Annua l Mean

Exposure (μg/L) 30

- year Mean

Exposure (μg/L)

Surface water Rice & vector control

(0.45 lbs a.i./A/year) B 1.4 1.2 <1.2

Surface water Rice (0.27 lbs a.i./A/year) 1.0 1.0 <1.0

Ground water Outdoor fogger (0.52 lbs a.i./A/year) 3.0 x 10

- 3 3.0 x 10

- 3 <3.0 x 10

- 3

A Proposed uses include a proposed use for mound

- building ant control and a proposed label amendment

for the current outdoor structural use.

B These EDWCs represent an upper bound on co

- occurrence between use on rice and vector control use.