### UNITED STATES ENVIRONMENTAL PROTECTIONAGENCY WASHINGTON, 

### D.C. 20460
OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES 

### PC 

### code: 05700 1 

### DP Barcode: D295631 

### MEMORANDUM SUBJECT: Responseto Comments for MGK-264 Risk Assessment TO: Cathryn O'Connell Special Review and Reregistration Division (7508P) 

### FROM: William P. Eckel, Ph.D. Environmental Risk Branch I1 2 

### Environmental Fate and Effects Division (7507P) THRU: Tom Bailey, Ph.D. 

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# \>w-- Chief, Environmental Risk BranchW Environmental Fate and Effects Division (7507P) DATE: January 5,2007
This memorandum provides EFED's responses to comments on the MGK-264 risk assessment. This response is for comments received in October, 2006. Please note that one comment from Country Sanitation Districts of Los Angeles County requires a response from SRRD. If you have any questions,please contact me (WPE) at 305-6451.



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### Comment 2 from California Regional Water Quality Control Board

Comment3 

### from Country Sanitation Districts of Los Angeles County Comment Recommend additionalhevised label language for use in drains, shampoos, and professional and consumer products. Develop urban runoff model that is empirical not mechanistic Request to include the model in the revised eco assessment. Improve the sewer discharge model 

### with OW'S information

Identify priorities for MGK-264 DCI and list of data gaps. 

### Response The suggested language appears reasonable.
EPA has developed residential and impervious surface scenariosfor the PRZM-EXAMS model to addressthis issue. The model may be applied when MGK-264 comes up for Registration Review. The Down-the-Drain model is part of E-Fast, and was developed by OPPT. That office would need to make any revisions. Wastewater treatment and sewage sludge disposal are the responsibility of the Office of Water Data to support urban runoff modeling may not be necessary given the developmentof residentiaYimpervioussurface scenarios for PRZMEXAMS. Data to support "down the drain" assessments, especially sewage sludge, are the responsibility ofthe Office ofWater and OPPT. Surface water monitoring data may be requested after the submission of data to fill toxicity and fate data gaps. Development of Water Quality Criteria is done by the Office ofWater.



### Comment Disagree with EPA's use of stream dilution factors because not all facilities in the country dilution credits 

### in the NPDES permits for environmental reasons.
EPA should use E-FAST to calculate a median surface water concentration without dilution factor for use 

### as the chronic concentration in the risk analysis. For acute concentration, EPA should calculate a surface water concentration assuming a local high-end scenario appropriate for the pesticide (likeusing a shampoo). Develop an improved wastewater discharge methodologyusing April 2006 version of E-FAST. Toxicity data for formulatedproduct: acute and chronic, freshwater and estuarinelmarinefish, invertebrate and whole sediment toxicitytests. This is needed to evaluate down-the-drain assessment. 

### Response "Down-the-Drain" is part of E-Fast, and is maintained by OPPT. Any modificationswould need to be made by that office. "Down-the-Drain" is part of E-Fast, and is maintained by OPPT. Any modifications would need to be made by that office.

"Down-the-Drain" is part of E-Fast, and is maintained by OPPT. Any modificationswould need to be made by that office. Formulated product data is needed to evaluate the toxicityof the synergized mixture.

### Comment 4 

### from MGK Company Request that aquatic toxicity label statements be added to all labels if the data requested indicatesthis is appropriate. Requests to work with OPP and OW to develop wastewater discharge methodology for evaluating impacts to aquatic organisms from sewer discharges during reg-review. EPA will evaluate the need for these label statements when the needed data are submittedand reviewed.



### SRRD to respond



### Comment 5 

### from CASQA Comment MGK does not support use of MGK-264 in wide area outdoor uses, so MGK Co. believes the eco risks are even less than EPAs current risk assessment. Based on use patterns, prior to requiring mixture data, look for monitoring data detects ofMGK-264 in the environment. 

### Response The actual ecological risks may be lesser or greater than stated. There is much uncertaintyin the current assessmentbecause of the numerous data gaps. Mixture data are needed for labeling statements, and to determineif monitoring is needed.



### Comment Potential negative impact of 

### pyrethroids/pyrethrins/synergists to urban creeks. 

### Subject Ecological 

### Response EPA acknowledgesthe possibilitythat MGK-264 may synergize other contaminants. Further research is needed to determineif this is a widespread phenomenon.