OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C., 20460 

NOTE TO ISOFETAMID FILE

DATE: May 29, 2015 

SUBJECT: Isofetamid: Risk Management Decision Regarding Several Ecological Studies 

TO: Cynthia Giles-Parker, Chief 

 Fungicide Branch 

 Registration Division 

FROM: Heather Garvie 

 Fungicide Herbicide Branch 

 Registration Division 

Isofetamid is being proposed for use on almond, lettuce, grapes (Subgroup 13-07F), low growing 

berries (Subgroup 13-07G), rapeseed (Subgroup 20A), and turf (commercial and residential). 

One technical product (EPA File Symbol 71512-ER) and two end-use products [Isofetamid 

400SC Fungicide (EPA File Symbol 71512-EE) and Isofetamid Turf Fungicide (EPA File 

Symbol 71512-EG)] are being proposed for registration in the United States. The maximum 

proposed single application rate is 0.572 lb a.i./acre (grapes) and the maximum annual 

application rate proposed is 3.65 lb a.i./acre (turf). Application methods include ground spray, 

aerial spray, and chemigation. 

As part of the evaluation of this new active ingredient, the EPA discussed uncertainties in the 

risk conclusions attributed to the deficiencies associated with certain data (i.e., the daphnid 

chronic toxicity study, as well as the cyanobacteria study). Overall, based on the available data 

and predicted exposures in the environment, the EPA noted that repeating the following studies 

is not expected to alter the risk conclusions for the proposed uses, in the context of the assessed 

application rates and uses. Therefore, based on the current risk conclusions (i.e., the level of 

concern was not exceeded for the respective taxa), the EPA has determined that although these 

two studies were deemed supplemental or partially acceptable, they satisfy these two data 

requirements in support of the proposed isofetamid uses. Study-specific discussions are listed 

below regarding the rationale for not needing additional data at this time. The EPA concludes at 
this time that there are no outstanding issues from the standpoint of EPA’s proposed regulatory 

position or proposed labels that are raised by these classifications. 

‐ Daphnid Chronic Toxicity Test, OCSPP Guideline 850.1300 

‐ Cyanobacteria (Anabaena flos-aquae), OCSPP Guideline 850.5400 

 

Daphnid Chronic Toxicity Test. The only chronic toxicity data currently available for isofetamid 

and an aquatic invertebrate are for the waterflea (Daphnia magna). In the waterflea study there 

was reduced length at all test concentrations resulting in a NOAEC of <0.39 mg a.i./L. The 

effects at the 0.39 mg/L concentration were slight (the average lengths for the waterfleas in the 

control versus the waterfleas at the 0.39 mg/L concentration were 4.92 mm and 4.85 mm, 

respectively). As such, this study is classified as ‘supplemental.’ Because the 0.39 mg a.i./L is 

only 2 times the highest 21-day average EEC for the uses modeled (wet-harvested cranberry), 

there is uncertainty in this risk conclusion. While a definitive NOAEC would help address this 

uncertainty, at 0.39 mg a.i./L, no chronic risk is expected (i.e., the risk quotient is below the level 

of concern of 1). 

Cyanobacteria (Anabaena flos-aquae). Acceptable data are currently only available for three, 

instead of four, species of non-vascular aquatic plant. Due to the low toxicity of isofetamid seen 

in the three available algal studies, as well as the predicted environmental concentrations, 

additional plant data are not expected to change the current risk conclusions (i.e., no risk to nonlisted or listed plants). 

Although the two aforementioned studies were deemed supplemental or partially acceptable, 

they satisfy these two data requirements in support of the proposed isofetamid uses. 

Additionally, ISK Biosciences Corporation requested a waiver for two ecological studies: fish 

early-life stage (freshwater), guideline 850.1400; and acute fish toxicity, guideline 850.1075. 

Based on the available data and predicted exposures in the environment, the Agency believes 

that the submission of these two studies would not alter the risk conclusions for the proposed 

uses (with the exception of the proposed wet-harvested cranberry use), and in the context of the 

assessed application rates and uses, waives these studies. A more detailed discussion of these 

two studies can be found in the document titled Isofetamid: Status of Ecological Effects Data in 

Support of the Proposed Section 3 Uses, dated 5/29/15, which can be found on the isofetamid 

regulatory docket (Document ID: EPA-HQ-OPP-2013-0138).