2 • 835.430 0: Aerobic aquatic metabolism

• 835.4400: Ana erobic aquatic m etabolism

• 850.1300: Aquatic invertebrate life cycle (freshwater)

• 850.1400: Fish Early

- Life Stage (saltwater)

• 850.2300: Avian Reproduction (bobwhite quail)

• 850.3030: Honey bee t oxicity of residues on foliage

• 850.4100: Seedling emergence

• 850.4150: Ve ge tative vigor

• 850.6200: Analytical method in water and sediment

• Special study: Acute oral honey bee adult toxicity

EFED Response : The environmental fate data has been received and is undergoing review.

EFED will review the ecotoxicity data when they ar e submitted.

Syngenta Comment 2: RQs for Aquatic Organisms The risk quotients for non

- target aquatic organisms calculated in the last assessment are highly

conservative because much of the environmental fate data were from older studies that no longer

meet acceptability criteria. Therefore the modeling assumed abamectin to be stable in the environment. Syngenta has submitted new environmental fate studies which will allow for

r efinement to the aquatic exposure modeling.

EFED Response : EFED will review the submitted environmental fate data and will use them for modeling in the registration review risk assessment if they are found to be suitable for quantitative use

.

Syngenta C omment 3: Adsorption/Desorption Data

A more recent adsorption/desorption study was submitted (MRID 49071002) and the results from this study should be included in the risk assessment.

EFED Response : The adsorption/desorption study has been received and is undergoing

review. If the data are found to be useful , they will be considered for use in the registration

review risk assessment.

Syngenta Comment 4: Mysid Shrimp NOAEC

The NO A EC value for the mysid shrimp should be 0.0035 μg ai/L rather than 0.00035 μg ai/L

.

EFED Response : The stated NOAEC of 0.00035 μg ai/L was based on reproduction when compared to the negative control. The NOAEC of 0.0035 μg ai/L was based on survival. The study was originally classified as supplemental. However, while reviewing the data for these comments, a new evaluation of the study was conducted and it was determined that the survival data were acceptable but the reproduction data were invalid. A solve nt effect on reproduction was noted that may have confounded the results.

As stated in the study report, there was a statistically significant difference between reproductive success (offspring/female/reproductive day) in the negative control and solven t control (p=0.038). The solvent used in the study was acetone at a concentration of 5.7 μL/L. Reproductive success in the solvent control was reduced by 30% compared to the negative3 control. As a result of this difference, the reviewer c ould not determi ne whether effects on reproductive success observed were due solely to exposure to the test substance. Compared to the solvent control, decreases in reproductive success were apparent at some test

concentrations but these differences were not statisticall y significant. Compared to the negative control, statistically significant effects on reproductive success were observed at two test concentrations, 0. 000 76 μ g/L and 0

. 003 5 μg/L (p<0.05)

. If the negative control is used as the comparison group, the NOAEC for reproductive success in the study is 0.00035 μg/L. The apparent solvent effect on reproductive success makes this endpoint unreliable for use in quantitative risk assessment.

In contrast, survival was not affected by the solvent. The NOAEC based on survival, as stated in the original DER, is 0.00 35 μg/L.

Syngenta Comment 5: Earthworm LC 50 The 28

- d LC 50 for earthworms should be 28 ppm rather than 18 ppm.

EFED Response : The stated 28

- d LC 50 of 18 ppm, calculated using probit regression, is

accurate. The calculations are detailed in the DER.

Syngenta Comment 6 : Use Table Syngenta has submitted a document to the registration review docket summarizing abamectin

food/feed uses from multiple re gistrants

.

EFED Response : EFED will refer to this document when constructing maximum use scenarios for the registration review risk assessment.

Syngenta Comment 7 : Endangered Species Assessment Methods Syngenta has submitted a document to the registration review docket summarizing the types of

refinements that should be considered for a n endangered species assessment.

EFED Response : EFED has received the document and will take Syngenta’s recommendations under advisement when conducting the end angered species assessment.