### UNfTED STATES E VIRONMENTAL PROTECTION AGENCY WASHINGTON D

.C. , 20460

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION



### PC Code: 128888 DP Barcode: 423503

December 02, 2014 MEMORANDUM SUBJECT:



### TO:

FROM: Response to Comments Regarding the Lactofen Registration Review Preliminary Risk Assessment that Were Submitted During the Registration Review Proposed Interim Decision Public Comment Period Kelly Ballard, Chemica l Review Manager Neil Anderson , Chief Risk Management and Implementation Branch I Pesticide Reevaluation Division {7508P) 

# 1J
Brian Kiernan, Biologist

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# 'i Andrew Shelby, Physical Scientist 

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## I"( Mark Corbin, Branch Chief Environmental Risk Branch VI Environmental Fate and Effects Division (7507P)

The Environmental Fa, te and Effects Division (EFED) has reviewed the comments submitted by Valent U .S.A. Corporation, dated 9/22/14, regarding the proposed interim registration review decision on the herbicide lactofen (PC code 128888). The comments on the EFED Preliminary Risk Assessment (PRA) component are addressed in this document. Valent makes a number of comments critiquing EFED's risk assessment models and procedures as well as several specific comments

. Valent expressed concern that the PRA relied on only high
-end and marginal (Section 24c, Special Local Needs registrations) use patterns (e.g. Florida fruiting vegetables) in describing potential risk from lactofen uses. EFED responds that while the highest risk estimates result from some of the more l imited use patterns, the PRA described risk estimates from all use patterns identified on the labels. The more limited uses tended to have higher application rates, resulting in higher risk estimates, but EFED describes the spatial limitations of the high-application use patterns in the PRA, and will continue to note these limitations in the upcom ing endangered and threatened (Listed) species risk assessment. Further , Valent states that "the Agency did not conduct an assessment of aquatic exposure following the use of the product in soybeans" (p 5 of the 9/22/14 comment). EFED's response is that indeed all use patterns were considered in the assessment of aquatic risk, but that since no risk to aquatic animals was identified for any of the registered use patterns, there was no need to list out individual use patterns.The exception to the finding of low risk to aquatic animals was for ch ronic fish exposure under high-UV light conditions based on the fact lactofen is a light dependent peroxidizing he rbicide {LDPH); the document extensively describes both the conditions {high UV light) and the taxon for which the finding is valid (fish via chronic exposure)

. EFED will adhere to the appropriate guidance at the time of the listed species risk assessment regarding the LDPH issue

. Risk estimates for aquatic plants were bounded i n the assessment (e.g." RQs ranging from 1.36 to 3

.70"), and the PRA specifically stated that the LOC was exceed for aquatic plants for all scenarios. Valent also comments on effects endpoints used in the PRA, specifically for terrestrial plants {MRIDs 47919602 and 47919601) and avian reproduction (MRID 48223101)

. EFED went back to the data evaluation records (DERs) for these studies and confirmed that the correct endpoints were drawn from the DERs

. However, EFED disagrees with Valent's suggestion that the original study author's reported values be used in risk assessment rather than the conclusions from EFED's DERs. EFED independently evaluates submitted studies and applies consistent statistical procedures to all data submitted, includ ing lactofen. Results f rom these internal analyses are used in selecting endpoints for the risk assessment. The DERs from these lactofen studies should have been sent to Valent at the t ime of the reviews (early 2012), but should be made available for Valent's review. One additional specific comment was that the model T-H ERPS should have been used in the assessment. EFED responds that the model, which modifies T-REX to account for dietary and metabolic differences between birds and re pti le and te rrestria l-phase amphibians, is by**guidanc~,** not used in screening-level risk assessments. The model cou ld have been used in a refinement to the risk assessment, however such refinements were not requested to support the lactofen inte rim registration review decision. The listed species risk assessment process is still be ing determined, but the accepted methodology w i ll be applied at the time of that assessment. General Comments on EFED Risk Assessment Approaches and Methods Valent makes numerous comments on the methods, tools and assumptions used by EFED in assessing risk to non-target species from pesticides. These methodological comments are generally broke n down into broad categories of model sufficiency, model assumptions, use pattern relevance, and characterization of exposure values. As a general response, it should be noted that EFED's exposure assessment methods, tools and assumptions have evolved over time and have been well documented and peer reviewed. Where appropriate, EFED attempts to characterize the relevance of res ults from exposure outputs. EFED also notes that the tools, methods and models employed in risk assessments are not static and are constantly evolving and where appropriate, the general methodological comments noted by Valent will be considered.