1

U. S. ENVIRONMENTAL PROTECTION AGENCY

Washington, D.C. 20460

OFFICE OF

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

 PC Code: 099050

 DP BARCODE: 364248

MEMORANDUM June 10, 2009

SUBJECT: Tier I Drinking Water Assessment for Acetamiprid Proposed Uses on Red Clover 

(Grown for Seed Only), Grape and Tomato (Greenhouse). 

TO: Laura Nollen, Risk Manager Reviewer

Barbara Madden, Team Leader (RM Team 5)

RIMUERB/RD (7505P)

FROM: David Lieu, Chemist Trainee

ERB4/EFED (7507P)

THRU: Greg Orrick, Environmental Scientist

Elizabeth Behl, Chief

ERB4/EFED (7507P)

This memo includes a drinking water exposure assessment for proposed uses of 

acetamiprid on red clover (grown for seed only), grapes and tomatoes in greenhouses. These 

proposed uses do not exceed those previously assessed in June 21, 2005 (DP BARCODE 

303582), which were based on acetamiprid maximum use patterns for citrus fruit (surface water)

and tree nuts (groundwater). The use pattern for citrus fruit included the highest single 

application rate (i.e., 0.25 lb a.i./A, applied twice per season at 7-day intervals). The use pattern

for tree nuts included the highest application rate per season (i.e., 0.18 lb a.i./A, applied four 

times per season at 14 day intervals). The proposed use on clover in ID, OR, and WA only has a 

maximum application rate of 0.075 lb a.i./A applied once a season. The proposed use on grapes 

and other climbing small fruits (except fuzzy kiwifruit)(within crop sub-group 13-07F) has a 

maximum application rate of 0.1 lb a.i./A, applied twice at 14 day intervals. The proposed use on 

greenhouse grown tomatoes has a maximum application rate of 0.075 lb a.i./A applied twice per 

crop. All use patterns are summarized in Table 1. Because previous exposure estimates (Table 2) 

were based on maximum application rates that were greater than the proposed maximum 

application rates for these uses, we recommend that these tier I estimates of exposure be used in 

support of human health risk assessment.
2

Table 1. Summary of acetamiprid use patterns for different crops proposed

Product 

Name

EPA 

Reg. 

No.

Single 

App. 

Rate (lbs. 

a.i./A)

Number 

of Apps.

Seasonal 

App. 

Rate (lbs. 

a.i./A)

Interval 

Between 

Apps. 

(days) App. Method

Clover (for use in ID, 

OR, and WA only)

Assail 70 WP 8033-23 0.075 1 0.075 None Aerial spray

Assail 30 SG 8033-36 0.075 1 0.075 None Aerial spray

Grapes and other 

Climbing Vine Small 

Fruits (except Fuzzy 

Kiwifruit) (within Crop 

Sub-Group 13-07F)

Assail 70 WP 8033-23 0.1 2 0.2 14 Aerial spray

Assail 30 SG 8033-36 0.1 2 0.2 14 Aerial spray

Greenhouse-grown 

Tomatoes (mature 

plants) TriStar 30 SG 8033-94 0.075 2 0.15 N/A

Chemigation/soil 

drenching

Citrus fruits (used in 

previous assessments)

Assail 70 WP 8033-23 0.25 2 0.55* 7 Aerial spray

Assail 30 SG 8033-36 0.25 2 0.55* 7 Aerial spray

Tree Nuts (within Crop 

Group 14) (including

Pistachio)

Assail 70 WP 8033-23 0.18 4 0.72 14 Aerial spray

Assail 30 SG 8033-36 0.18 4 0.72 14 Aerial spray

* The seasonal application rate for citrus fruits is 0.55 lb a.i./A; however the modeled application rate was only 0.50 lb a.i./A due 

to limitations imposed by the indivisibility of 0.55 by 0.25.

Table 2. Tier I 1-in-10-year EDWCs in surface water and ground water for acetamiprid.

Drinking Water Source Maximum Use Pattern Exposure EDWC

Surface water Citrus fruit Peak 20.1 ppb

Annual average 4.9 ppb

Ground water Tree nut Peak & annual average 1.6 ppt

It is also recommended that the label for TriStar 30SG specify the maximum application 

rate (in lbs a.i./A) for a single application use on greenhouse-grown tomatoes. The proposed 

label only implies such a rate. A clearly stated value on the label would prevent confusion and 

promote consistency.