UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D.C., 20460

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

PC Code: 016331 DP Barcode: 426301

MEMORANDUM

DATE:

SUBJECT:

TO:

FROM:

Through: March 24, 2015

Response to Comments Submitted by Sumitomo Chemical Company Regarding the Proposed Decision Document and Environmental Fate and Ecological Risk Assessment for Momfluorothrin

Julie Chao, Risk Manager Reviewer Kahle Davis, Product Manager Team 3 Marietta Echeverria, Branch Chief Invertebrate

- Vertebrate Branch 1 Registration Division (7505P) 

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Nathan Miller, Biologist

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## '"3:}{-\) Mark Corbin, Branch Chief**~** Monica Wait, Risk Assessment Process Leader**~** 

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In response to the "Environmental Fate and Ecological Risk Assessment for the Section 3 New Chemical Registration of the Pyrethroid Insecticide Momfluorothrin" (Document ID EPA-HQOPP-2013-0478-0014 in www.regulations.gov ), Sumitomo Chemical Company ("Sumitomo") provided comments during the public comment period (EPA-HQ-OPP-2013-0478-0018). The
purpose of this memorandum is to address those comments and respond to technical/sciencerelated questions and comments as they pertain to the data reviews and the ecological risk
assessment document. In summary, EFED does not concur with Sumitomo's comments 1, 2, 3, and 5 pertaining to data acceptability. Comment 4 will be addressed separately by the Health Effects Division. EFED appreciates the editorial corrections identified in comments 6 and 7 and will incorporate these suggestions within any future momfluorothrin risk assessments.

Page 1of5Page 2 of 5

Sumitomo Comment 1. Midge lifecycle data evaluation record : The 49

- day midge lifecycle test (MRID 49019968) is described as "Supplemental" because of the statistically significant difference for development rate. However, the study is considered "Acceptable" (NOEC = 0.035 mg/kg) as the following reasons:

 The study was conducted according to the international test guideline s and the results were appropriately evaluated using the appropriate control (solvent control in this case).

 The development rate of solvent control (0.0367) was faster than that of control (0.0343 ) and the solvent control (i.e., better performance ) were used for evaluation (i.e., conservative analysis).

 The results of the definitive test are consistent with the preliminary range

- finding test (i.e. emergence rate is the most sensitive parameter rath er than development rate and EC50 of emergence rate would lay down 0.03

- 0.75 mg/kg).

EPA Response: EFED classified MRID 49019968 supplemental

, for qualitative use only, because it does not establish a definitive no

- effect endpoint suitable for use in risk
assessment. From the DER:

For midge emergence, based on time weighted average concentrations, the NOAEC was established to be 0.03 0 mg a.s. / kg and the LOAEC was established to be 0.0 73 mg a.s./ kg

. The EC 50 for percent emergence was calculated to be 0.14 mg/kg, with corresponding 95% confidence intervals of 0.10 to 0.17 mg/kg, using the probit method. The NOAECs for male, female, and male

- fe male combined development rate data were established to be < 0.013, 0.03, and < 0.013 mg/kg, respectively (LOAECs of 0.013, 0.073, and 0.013 mg/kg, respectively). Male development rate was not promoted by more than 10% in comparison to the negative contro l [Note that EFED policy is to make statistical comparisons to the negative control ( USEPA, 2008 ) ] , and solvent interference may have contributed to the reported significance at all treatment concentrations, considering an Equal Variance t Two

Sample Test which determined development rate in the solvent control to be significantly promoted compared to the negative control. Since no concentration tested resulted in > 50% promotion (or inhibition) of development rate, the EC 50 values were empirically estimat ed to be > 0.17 mg/kg, the highest concentration statistically analyzed.

NOAEC: < 0.013 mg a.s./kg LOAEC: 0.013 mg a.s./kg Most sensitive endpoint: Male development rate, combined male

- female development rate

Sumitomo Comment 2. Aquatic nonvascular plant data evaluation record : The 96

- hour aquatic non

- vascular plant study (MRID 49019991) is described as "Supplemental" because of potential interference from the co

- solvent. However, the study is considered "Acceptable" (96hr

IC50 >4.8 mg/L) a s the fo llowing reasons.

 The study was conducted according to the international test guideline s and the results were appropriately evaluated using the solvent control (OECD test guideline 201 saysPage 3 of 5

that "When solvents are used to prepare the test solutions, the so lvent controls rather than the controls without solvents should be used in calculation of percent inhibition").

 As stated in the report, no significant difference was detected between control and solvent control for any endpoints.

 The 96hr

- IC50 value (i.e. , >4.8 mg/L) are not changed if the control or solvent control is used for the evaluation.

 The results of the definitive test are consistent with the preliminary range

- finding test.

EPA Response: EFED classified MRID 49019991 supplemental

, for qualitative use only, because the study design did not employ four replicates per treatment level as stipulated in the guideline, and a solvent effect confounds interpretation of treatment response. Further, undissolved test substance was observed at the highest treatment concentration which makes the true exposure concentration for that treatment level uncertain. As the [study design] adheres to the OECD guidelines, which stipulates that three replicates are sufficient, this does not affect the acce ptability of the study in the PMRA’s perspective. However, the PMRA agrees with the EPA that the other noted deficiencies influence the usefulness of the study.

EPA Classification: Supplemental, for qualitative use only PMRA Classification: Acceptable

IC 50 : Could not be determined Most sensitive endpoint: N.A.

NOAEC: 0.37 mg a.i./L Most sensitive endpoints: Cell density

Sumitomo Comment 3. Avian reproduction study data evaluation record : Classification of supplemental should be corrected to acceptable because there was no effect on birds treated with the test item in the reproduction study with bobwhite (MRID 49019979).

EPA Response: EFED does not concur with Sumitomo’s assertion that there was no effect on birds treated with the test item in this avian reproduction test. The Executive Summary of the DER for MRID 49019979 explains the basis for the study classification :

“ This study, while scientifically sound, is classified as supplemental because it does not establish a definitive overall no

- effect concentration. Adult female weight gain was significantly reduced compared to the control at the lowest test concentration; therefore, the concentration response relationship for female weight gain resulting from dietary exposure to momfluorothrin cannot be determined.

NOAEC: < 241mg a.s./kg diet LOAEC: 241 mg a.s./kg diet Most sensitive endpoint: Female weight gain ”Page 4 of 5

Because of t he significant effects to female weight gain, EFED does not concur with Sumitomo, and no changes will be made to the study classification within the risk
assessment.

Sumitomo Comment 4

. Two generation rat reproduction study : Comments were submitted in regards to the appropriate NOAEC and LOAEC from the two generation rat reproduction study (MRID 49020018 ).

EPA Response: EFED concurs with Sumitomo’s comments , as confirmed by the Health Effects Division’s review of this study

. The two generation rat reproduction study NOAEL and LOAEL should have been reported as 500 mg/kg diet and 1500 mg/kg diet respectively, based on significantly decreased body weights in both sexes of the F1 and F2 pups . F uture momfluorothrin risk assessments will reflect the cor rect endpoints and exposure duration

.

Sumitomo Comment 5

. Avian acute oral toxicity test with zebra finch data evaluation record : T w o birds [were] replaced due to [regu rgitation ] . However, one was replaced only 7 minutes after dosing and the other was replaced 40 minutes after dosing. And the replaced birds were adequately observed during rest of test period. Therefore, we consider it not appropriate to classify the study to supplemental based on these events.

In this context, the following should b e corrected. Page 41 4.3.2 Effects Uncertainties 1st sentence in 3rd paragraph: “a NOAEC” should read “a LD50”, and “at the lowest dose tested” should read “in the two treatment”.

EPA Response: EFED does not concur with Sumitomo’s assertion. The Exec utive Summary of the DER for MRID 49019973 explains the basis for the study’s classification:

“ The 14

- day acute oral toxicity of momfluorothrin (S

- 1563) to the zebra finch ( Poephila guttata ) was determined in the laboratory, with groups of 10 birds per treatment exposed to 0 (negative control), 292, 486, 810, 1350, and 2250 mg a.s. /kg bodyweight. The study authors replaced two birds (one in the 292 mg ai/kg bw treatment, and one in the 486 mg ai/kg bw treatment) that regurgitated the dose during the tes t. EFED treats these replaced birds as mortalities [(USEPA, 2012)] . The 14

- day LD 50 was estimated to be above 2250 mg

a.s. /kg bw, the highest dose applied. The no

- mortality and the no

- observed

- adverse

- effect

levels (NOAEL) were less than the lowest dose tested (i.e., < 292 mg a.s. /kg bw).

LD 50 : > 2250 mg a.s. /kg bw NOAEL: < 292 mg a.s. /kg bw

This study is classified as supplemental because of replacement of birds that regurgitated in the 292 and 486 mg ai/kg bw treatments , but is considered suitable f or quanti tative use in risk assessment.”Page 5 of 5

Sumitomo Comment 6

. Summary table of submitted te rrestrial toxicity studies for

m omfluorothrin in Appendix B of the ecological risk assessment : We consider it appropriate to add tables for rats acute dermal toxicity study (MRID 49020098) and rats chronic toxicity test (MRID 49020020) to Table 2 of page 56 of the risk assessment.

EPA Response: These studies were omitted from the summary table of Appendix B as they

are not routinely considered for ecological risk assessment but rather by the HED’s human health risk assessment.

Sumitomo Comment 7

. Other minor comments : Sumitomo comments that the adult honey bee acute contact toxicity endpoint reported in the EFED risk assessment as 0.2 μg a.i./ bee should instead be reported as 0.21 μg a.i./bee. Table numbering and other editorial corrections are presented.

EPA Response: EFED does not agree with the assertion that the toxicity endpoint for the adult honey bee acute contact toxicity study is erroneously reported, but concurs with the other proposed Sumitomo corrections regarding spelling, table numbering, and phenothrin/ d

phenothrin active ingredient identification

. While the study authors reported a contact LD 50 of 0.21 μg a.i./bee, EFED’ s independent statistical analysis using the data provided by the laboratory via the study report established a different LD 50 threshold than was reported by the study author. In the statistical analysis appended to the DER (MRID 49019985)

, the 48

- hour

ac ute contact LD 50 is identified as 0.201 μg a.i./bee, with 95% lower and upper confidence limits of 0.171 and 0.233 μg a.i./bee, respectively.

Corrections to table numbering and minor editorial comments will be addressed in any future momfluorothrin risk a ssessments.

References:

USEPA. 2008. Guidance for the Use of Dilution

- Water ( Negative ) and Solvent C ontrol s in Statistical Data Analysis for Guideline Aquatic Toxicology Studies. Memorandum from Donald Brady, Director, to the Environmental Fate and Effects Division. September 25, 2008.

USEPA. 2012

. Guidance for Use When Regurgitation is Observed in Avian Acute Toxicity Studies with Passerine Species . Memorandum from Donald Brady, Director, to the Environmental Fate and Effects Division. April 9, 2012. Available online at: http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/terres trial_biology_te ch_team/tbtt_regurg_acute_passerine.htm