### 2 commen ts were often written verbatim while other times they were summarized

, as required.

EFED’s purpose of the document is to respond to technical/science

- related questions and comments. Comments of a regulatory nature will be addressed in the Final Work Plan (FWP).

The Agency appreciates the submitted information on monitoring data on permethrin

concentrations in wat er and sediment provided by the California water quality boards and

associations. This information will be used as appropriate in the Registration Review ecological

risk assessment for the chemical

, as well as t he data on use and usage submitted by M cLaughlin

G ormley K ing Company and the P ermethrin D ata G roup II

.

The comments were addressed in the following order ( Table 1 ) :

Table 1. Submitters of Comments on the “ Environmental Fate and Ecological Risk

Assessment Preliminary Problem Formulation in Support of Registration Review for

Permethrin ”

Abbreviation Submitter CRWQCB CV California Regional Water Quality Control Board, Central Valley Region CRWQCB SFB California Regional Water Quality Control Board, San Francisco Bay Region CASQA California Stormwater Quality Association

Tri

- TAC Tri

- TAC

NAFA National Alfalfa & Forage Alliance

MGK McLaughlin Gormley King Company

PDGII Permethrin Data Group II

### 3 Submitter: California Regional Water Quality Control Board, Central Valley Region

1

. CRWQCB CV Comment: The 2010 Clean Water Act §303(d) listings in Central Valley, CA contains 13 stream segments (10 in urban site s and 3 in agricultural site s) that exceed water quality standards due to pyrethroids in the sediments that are toxic to Hyalella azteca . This list was recently partially approved by the Agency and will be approved “shortly” following the resolution of un related additional listings. Permethrin has been implicated as a contributor to the toxicity observed. While all the pyrethroid

- impaired bodies of water are in Sacramento, open literature articles document the presence of pyrethroids all throughout CA.

EFED Response: EFED has confirmed that the §303(d) listings were partially agreed upon with the Agency (letter from Alexis Strauss, Director of Water Division, Region IX, to Tom Howard, Executive Director of State Water Resources Control Board). T he Agen cy’s Region IX sought public comments and a final decision was issued by October 11, 2011 (letter from Alexis Strauss, Water Division Director to Tom Howard, State Water Resources Control Board (see the following site: http://www.epa.gov/region9/water/tmdl/california.html which was accessed 10/21/2011) . EFED will include information on 303(d) listings in the Registration Review

e cological risk assessment. However, the preliminary EFED problem formulation for permethrin

reflect ed the current list of 303(d) impaired bodies of water. A s mentioned in the problem formulation, ten additional bodies of water were in draft form and not yet finalized.

2

. CRWQCB CV Comment: An attachment was provided with a list of pyrethroid retail products

avai lable based on a July, 2005 shelf survey of San Francisco Bay area warehouse and hardware stores. For permethrin , there were around 32 products o n the list.

EFED Response: EFED will consider these and other permethrin containing products at the time

of the Registration Review e cological risk assessment.

3

. CRWQCB CV Comment s : The board p rovided o pen literature and other articles as attachments:

Attachment 2 : “ Statewide Investigation of the Role of Pyrethroid Pesticides in Sediment Toxicity in California’s Urban Waterways,” a literature article by Holmes et al. 2008 ( Environ. Sci. Technol. 2008,
42, 7003

– 7009).

Attachment 6 : “Sediment Toxicity in Agricultura l Areas of California and the Role of Hydrophobic

Pesticides ,” a literature article by Weston et al. 2008 ( p ublished in: Synthetic Pyrethroids: Occurrence and Behavior in Aquatic Environments. Gan, J., Spurlock, F., Hendley, P. and Weston, D. (editors). Am erican Chemical Society Symposium Series 991, American Chemical Soci ety, Washington, D.C. pp. 26

- 54, 2008).

Attachment 7 : “ Monitoring Urban Pesticide Runoff in Northern California, 2009

– 2010,” a recent article by Ensminger & Kelley 2011 (Report 264, CA EPA, CA Department of Pesticide Regulation, Environmental Monitoring Branch, Surface Water Protection Program, July 2011, 34 pp.)

Attachment 8 : “Dietary Segregation of Pelagic and Littoral Fish Assemblages in a Highly Modified Tidal Freshwater Estuary,” a literature article by Grimaldo et al. 2009 (Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science 1:200

– 217, 2009).

### 4 Attachment 9 : “ Urban and Agricultural Sources of Pyrethroid Insecticides to the Sacramento

- San Joaquin

Delta of Calif ornia,” a literature article by Weston & Lydy 2010 ( Environ. Sci. Technol. 2010

, 44, 1833

– 1840).

Attachment 12 : “ Aquatic Toxicity Due to Residential Use of Pyrethroid Insecticides,” a literature article by Weston et al. 2005 ( Environ. Sci. Technol

. 2005

, 39, 9778

- 9784).

EFED Response s : The Agency appreciates the submission of the above referenced studies.

Some of t h ese and other publications were initially considered in the preparation of the Problem Formulation for permethrin. Further review of open scientific literature and other relevant articles will be conducted as part of the Registration Review e cological risk assessment.

4

. CRWQCB CV Comment s : Tables containing permethrin sediment monitoring data were submitted :

Attac hment 3 : “ Urban creek sediments sampled in the East Bay, CA. ” Permethrin, sampled in six sites ranged from undetected (U) to 56.0 ng/g or equivalent to 0

- 0.99 toxic units (TUs)

.

Attachment 4 : “Urban creek sediments sampled in and around Nashville, TN.” Permethrin was sampled in 14 sites and detected in four of them at concentrations ranging from undetected (U) to 12.73 ng/g or 0

- 0.05 TUs

.

Attachment 14 : “Urban creek sediments sampled in and around Sacramento, CA.” Permethrin, sampled in 11 sites was detected in all but one of the sites. Concentrations ranged from undetected (U) to 171.3 ng/g or 0

- 0.42 TUs.

EFED Response: The Agency appreciates the submission of the se report tables . They provide

information on the prevalence of permethrin in sediment samples in California and will be

considered at the time of the Registration Review ecological risk assessment.

5

. CRWQCB CV Comment : T he following documents were submitted: “Water Quality Criteria Report (WQC) for Permethrin” (Fojut , Rering & Tjeerdema

, 2011), Appendix B1 (Data Summary Sheets)

and “ Responses to Public Comments and Peer Review s” ( Attachments 5, 10 and 11

“Aquatic life in the Sacramento River and San Joaquin River basins should not be affected )

. This comprehensive report was prepared by U

. C

. Davis for CRWQCB CV , dated September 2011

. A multiplicity of ecological effects studies were evaluated and classified using specified data evaluation

criteria. Factors such as bioconcentration, sediment and air concentrations, and possible impact of other pesticides were evaluated and considered . In brief , t he description of the final c riteria is as follows:

unacceptably if the four

- day average concentration of permethrin does not exceed 0.002 μg/L (2 ng/L) more than once every three years on the average and if the one

- hour average concentration does not exceed 0.01 μg/L (10 ng/L) more than once every three years on the average. Mixtures of permethrin and other pyrethroids should be considered in an additive manner .”

EFED Response: The Agency also appreciates the submission of the report , as it contains a comprehensive review of open literature aquatic to xicity studies and information on species sensitivity distributions for permethrin and mixtures with other pyrethroids . As indicated in the Problem Formulation document, the Agency may further describe risks in the upcoming assessment using methods such a s the species sensitivity distributions analogous t o those in the submitted report

.



### Submi tter : California Regional Water Quality Control Board, San Francisco Bay Region

### 5 6

. C RWQC B SFB C omment: Pesticides used in accordance with label directions are causing toxicity in our urban water bodies. For example, Kirker Creek recently was listed under Clean Water Act §303(d) as impaired by pyrethroids. Permethrin was found in sediments of two out of s ix Bay area creeks sampled , at concentrations up to 12.2 μ g/kg, and found to contribute to toxicity in those creeks.

EFED Response: As indicated above, EFED will include relevant information on 303(d) listings

in the Registration Review ecological risk a ssessment. However, the preliminary EFED problem formulation for permethrin reflect ed the current list of 303(d) impaired bodies of water at the time

of its issuance

.

7

. CRWQC B SFB Comment: Based on our understanding of the current schedule, the Office of Pesticide Programs and Office of Water (OPP/OW) common effects assessment methodology will be available in time to use for this risk assessment. We support use of this updated methodology. To protect aquatic life designated uses, it is important that exposure periods and exposure frequencies used in ecological effects assessments include time periods consistent with those used by OW.

EFED Response: At this time, the OPP/OW common effects methodology framework is under development and a time line to include an integrated methodology in OPP's risk assessment process has not been established. The focus of the OPP/OW common effects methodology project has been on characterizing effects of stressors on aquatic organisms. OPP appreciates CRWQCB 's comme nt about consideration of duration of exposure. EPA will consider this comment in the continued development of the common effects methodology.

8

. CRWQC B SFB Comment: CRWQCB SFB encourages the EPA to develop a set of urban scenarios that better represents realistic urban pesticide use and runoff conditions. The current urban impervious surface scenario, which uses a 0.25

- acre residential lot scenario, does not adequately represent today’s urban environment. Urban watersheds, where pesticides including permethrin are used in a variety of applications, have mixed uses that include dense residential with small lot sizes, multifamily, and

commercial land uses

– these all have significantly mor e impervious area per acre than the current urban impervious surface scenario. In addition, urban soils are highly compacted. The current scenario underestimates the mass of pesticide runoff in urban areas.

EFED Response: The justification of the use of a 1⁄4

- acre residential lot wa s based on a past American Housing Survey (AHS), dated 2006; however, in this response it is updated with data

from the latest “ American Housing Survey of the U.S. : 2009, ” from the Census Bureau (AHS)

, which was accessed 9 /30/11 at the following site: http://www.census.gov/housing/ahs/data/index.html

. The latter survey was issued in March 2011

, and covers data for the year 2009

. In order to test the assumpt ion of the 1⁄4

- acre lot as the best representation for residential housing , the AHS data for suburban homes that list total number of houses by lot size and by square footage of house was evaluated (Table 1

- 3 at the AHS website

above

, was provided as an Exc el spreadsheet entitled “ Size of Unit and Lot

– All Housing Units ” )

. With a total of 130,112,000 total units reported nationally for all suburban areas, 25,008 ,000 units (the largest class at 19 %) were on lots between 1/8 acre and 1⁄4 acre, while 17,825 ,000 units (the

third largest class at 14 %) were on lots between 1⁄4 acre and 1⁄2 acre. Overall, these two lot size categories cover 33% of all housing units. The second largest class was for units between 1 to 5

acres (15%) and the fourth largest class was for units less than 1/8 acre (11%)

. Overall, the

median lot size was 0.26 acre. T he vast majority of the houses were one unit structures, with 95,216,000 units (73%). This analysis suggests that the 1⁄4

- acre lot is a reasonable approximation

### 6 of suburban p esticide use. As indicated in the Problem Formulation, “ Alternative assumptions for percent impervious surfaces, percentage of use site treated, and percentage of overspray may be considered in order to characterize the assumptions of the ecological risks assessment in the context of the individual exposure assessment and risk conclusions. ” EFED may evaluate further CRWQCB SFB’s comment and may determine whether additional scenarios are needed.

9

. CRWQC B SFB Comment: The board’s comment a ttachment is a Final Project Report entitled

“ Investigations of Sources and Effects of Pyrethroid Pesticides in Watersheds of the San Francisco Estuary

. ” ( Lowe S., B. Anderson

, and B. Phillips, 2007

, Final Project Report: Investigations of Sources

and Effects of Pyrethroid Pesticides in Watersheds of the San Francisco Bay Estuary. Proposition 13

PRISM Grant # 041355520

, SFEI Contribution #523

, San Francisco Estuary Institute, Oakland, CA; 269 pp.)

EFED Response: The Division appreciates the submissio n of th is report. EFED will include all relevant information derived from the report at the time of the Registration Review ecological

risk assessment.



### Submitter: California Stormwater Quality Association

1 0

. CASQA Comment: It is essential that the registration process adequately consider potential water quality impacts, so that such impacts are prevented before they result in CWA Section 303(d) impaired waters listings.

EFED Response: At the time of the Registration Revi ew ecological risk assessment, all relevant 303(d) listings will be considered.

11

. CASQA Comment: CASQA encourages EFED to follow refinements to the existing modeling approach for urban impervious scenario:

1. Recognize applications to urban land uses within the conceptual model, and separately include “landscaped” (pervious) areas and “impervious” areas as urban source categories, at a level equivalent to agricultural soil (shown currently as “Soil” on the conceptual model diagram).

2. Recognize that with in urban areas, pesticides are often applied directly and intentionally to impervious surfaces, and that applications to impervious surfaces are considered to be the controlling factor in urban runoff contributions to receiving water toxicity. The model

di scussion in the Problem Formulation currently seems to consider pesticide applications to impervious surfaces to be the unintended result of spray drift only.

3. The computational methods should distinctly account for appropriate wash

- off fractions from

urban impervious surfaces vs. landscaped (pervious) surfaces; discussion of impervious

surface runoff coefficients was provided in a fact sheet that was attached to the comments (see below)

. 4. Account for the distinct physical characteristics of urban storm drain age conveyance systems, which rapidly convey water and pollutants to receiving waters.

EFED Response s : EFED points out that a s part of the risk mitigation in the revised Permethrin

Re

- registration Eligibility Decision (RED , USEPA 2009 , Document ID EPA 738

- R

- 09

- 306,

available at http://www.epa.gov/oppsrrd1/REDs/permethrin

- red

- revised

- may2009.pdf and

### 7 accessed 10/21/2011 ), for products to be used in and around buildings a nd other structures ( i.e.

, likely having impervious surfaces): “All outdoor applications must be limited to spot or crack

and

- crevice treatments

t reatment to soil or vegetation around structures; except for the following allowed uses :

a pplications to law ns, turf, and other vegetation; and,

a pplications to building foundations, up to a maximum height of 3 feet

. Other than applications to building foundations, all outdoor applications to impervious surfaces such as sidewalks, driveways, patios, porches and structural surfaces (such as windows, doors, and eaves) are limited to spot and crack

- and

- crevice applications, only.”

Thus, legal pyrethroid applications over impervious surfaces have been limited to a high extent.

1. The Problem Formulation shows applications over impervious surfaces in its conceptual model (not just soil or pervious surfaces ). Modeling will include currently published categories of impervious areas in different urban areas of the country (based on NL CD) in order to establish a range of EECs from highly dense residential areas with high ratio of impervious to pervious

surfaces to low density residential areas with low ratio of impervious to pervious surface).

2. Labeled pesticide application will be categ orized into two categories and modeled separately. The suggested categories are: applications where drift is the main source for pesticide reaching impervious surfaces ( e.g. , labeled application to turf or landscaped areas)

, and direct application to impe rvious surfaces.

3. For direct applications over impervious surfaces, the portion of the pesticide “available for run off” is directly related to wash off factors established for various types of impervious surfaces ( e.g. , asphalt, concrete and others). T he fraction of the rate ( percent or %) used for impervious

s urface modeling will be equal to that expected to be washed off from the type of impervious

surfaces. At the present time, EFED is reviewing a washoff study for cypermethrin submitted by the Pyrethr oid Working Group ( PWG

, MRID 48072902)

, and another study that included 17 pyrethroi d products , including permethrin formulations will be submitted by the PWG in the near

future . Both studies may

4. Storm drains ( i.e. , pipe conveyances designed to collect and transport surface stormwater through drainage inlets), convey the water through closed conduits to receiving waters. Conduit systems are often comprised of di fferent material types

, lengths, shapes, and sizes of storm drain pipes. Furthermore, they are connected by structures such as manholes, junction boxes, etc

. This type of structure is not contemplated in the combination of residential (or rights

- of

- way) plus impervious scenarios. EFED may explore alternative ways to address this issue. be used to characteriz e the washoff potential from impervious surfaces if appropriate

.

1 2

. CASQA Comment: CASQA encourages OPP to pursue development of a pr otocol for quantitative assessment of cumulative impacts of pesticide mixtures, as this appears to be a significant factor contributing to the observed toxicity in urban creeks.

EFED Response: EPA understands the desire for developing a risk assessment p rotocol that specifically addresses cumulative impacts of pesticide mixtures, such as the pyrethroids. As indicated in the Preliminary Problem Formulation document, the Agency believes that conducting a prospective ( i.e. , predictive) ecological risk asses sment of pesticide mixtures would require a

substantial amount of information regarding the temporal and spatial extent of pesticide usage within a watershed, which is currently lacking. This information is needed to accurately predict (or screen) pestici de concentrations in a waterbody because different pesticides will be applied at different times and locations within any given watershed. In addition, a watershed

- based model would also need to be developed and reviewed for this particular application in order to capture

### 8 the temporal and spatial dynamics of multiple pesticide uses and applications. Although a prospective cumulative ecological risk assessment methodology is subject to these and other challenges related to exposure and effects assessment, the Agency believes that available monitoring data for pyrethroids do offer some potential to evaluate cumulative ecological risk in a retrospective manner, as suggested in the Preliminary Problem Formulation document. T he Agency will consider monitoring data of pyrethroid mixtures

, such as concentrations in

sediments

, in the context of their potential to provide insight into ecological risks of pyrethroid mixtures to the extent that simplified assumptions regarding their combined toxicity ( additivity)

are scientifically supported.

1 3

. CASQA Comment: CASQA request s that the work plan be modified to indicate OPP’s intent to work with OW and to utilize the outcomes of the common effects assessment methodology project in permethrin registration review. T o facilitate integration with OW regulatory programs, they request that the work plan be modified to provide exposure estimates for time periods consistent with those used by OW in addition to the time periods ordinarily used by OPP.

EFED Response: See r esponse to similar comment from CRWQCB (Comment #7) above.

1 4

. CASQA Comment: CASQA urges OPP to continue to obtain and incorporate the extensive amount of new information being generated by CDPR through its pyrethroid reevaluation process.

EFED Response: The Agency encourages both CASQA and the registrant to submit all available useful information for consideration for the Registration Review ecological risk

assessment. The Agency has been actively working with CDPR to coordinate its Regis tration Review with CDPR pyrethroid reevaluation process. This includes review of protocols and studies that are submitted by the registrant to CDPR.

1 5

. CASQA Comment: Attachment: “ Impervious Surface Coefficients: A Tool for Environmental Analysis and Management, ” California Office of Environm ental Health Hazard Assessment.

According to the attachment, a set of impervious surface coefficients, representing the average amount of impervious cover (IC) in each of the major land use categories (LUC s ) in C A , have been developed. ICs were based on data collected from Sacramento, Irvine, and Santa Cruz, and they reflect the average percent of IC for any single LUC. When combined with information on the total area of each LUC, the

total amount of IC within a ny defined area can be estimated. Data a re provided for ten Commercial/ General LUCs and the percent impervious surface coefficients ( ISCs ) range from 2% for open space to 91% for heavy industrial. Residential ISCs are calculated using a regression equat ion. Finally, four categories of road ISCs range from 47% for rural to 96% for suburban. Using these data, the IC ( e.g. , acres) can be calculated for current or future IC for a developed (or to be developed) area.

EFED Response: EFE D appreciates this submission, and it will be evaluated for potential use to

characterize the percentages of impervious surface cover for various residential, industrial and /or

rural scenarios.



### Submitter: Tri

- TAC

### 9 1 6

. Tri

- TAC Comment: Permethrin from products for pets, for the treatment of fabrics and for head

lice treatment can reach P ublicly O wned T reatment W orks (POTWs). Based upon these uses, it appears

that t he fate of permethrin is likely in water and solid emissions ( i.e. , biosolids) from POTWs . Effluent from the POTW will typically be discharged into creeks, rivers, estuaries, or the ocean. The receiving bodies of water may have little flow ( i.e. , “effluent dominated” waters). Recycled wastewater has growing use for irrigation, toilet flushi ng, industrial use, and groundwater recharge. Biosolids may be reused in agriculture or in urban gardens or disposed of in landfills.
 Tri

- TAC is concerned about potential effluent toxicity to aquatic organisms from pyrethroid discharges to POTWs, as foun d in Weston & Lydy (2010), 1

 POTWs are subject to National Pollutant Discharge Elimination System (NPDES) permits

under the Federal Clean Water Act. whom found pyrethroids and toxicity

to H

. azteca in secondary and tertiary POTW effluent samples.

EFED Re sponse: E valuation of E

- FAST’s “down

- the

- drain” (DTD) module results indicate d

that for the high end scenario, the stream dilution factor (SDF) is 1.00, which appears to be the

minimum allowed value

. The SDF is the volume of the receiving stream flow divided by the volume of the wastewater treatment facility effluent flow. The high end scenario (or 10 th
percentile) concentration represents small receiving streams. A SDF of 1.00 represents “effluent

dominate d” surface bodies of water

. These results may be compared against SDFs on the order

of 20

- 24 for the average (50 th percentile) concentration that represents midsized stream flows

. Currently, EFED is conferring with Office of Pollution Prevention and Toxi cs ( OPPT

. the office that developed the model) to depict and select representative EECs more accurately

.

Regarding the issue of biosolids, EFED stated in the Problem Formulation t hat, “ The Agency is actively evaluating the extent to which ecological risk from permethrin via land application of biosolids should be addressed in its forthcoming environmental fate and ecological risk assessment and by extension, any additional data that may be required.”

The Agency acknowledges the concern about non

- compliance with the Federal Clean Water Act (CWA). OPP is actively working with the O ffice of W ater (OW) in harmonizing the methodologies for risk assessment and development of OW’s water quality criteria to ad dress

some of these concerns.

17

. Tri

- TAC Comment : Tri

- TAC supports the use of Agenc y ’s standard tool for DTD assessments, Exposure and Fate Assessment Screening Tool (E

- FAST) Version 2.0, but has concerns with the way that OPP has applied the model. T ri

- TAC recommend s that the anticipated refinements to the model that are mentioned in the review be incorporated in the DTD assessment. In the past, OPP and OW have used different exposure periods and exposure frequencies in their ecological effects assessments. If these factors are not being addressed in the OPP/OW Common Effects Assessment Methodology project, we request that OPP work with OW to develop a means of avoiding regulatory inconsistencies. One option would be to modify OPP pesticide runoff models to provide exposure estimates for multiple time periods, including time periods consistent with those used by OW.

EFED Response: See response to similar comment from CRWQCB above (Comment #7)

.

1 Weston, D. P. and M.J. Lydy. (2010). Urban and Agricultural Sources of Pyrethroid Insecticides to the

Sacramento

- San Joaquin Delta of California. Environ. Sci. Technol

. 44 : 1833

– 1840.

### 10 18

. Tri

- TAC Comment: Available POTW monitoring data for other pyrethroids should be extrapolated to provide input into E

- FAST for the DTD assessment. If influent, effluent, and biosolids POTW monitoring data are not available in time for the permethrin risk assessment or if available data are insufficient to account for the variety of POTW treatment processes and operational parameters uti lized nationwide, EPA should use conservative assumptions for permethrin removal during wastewater

treatment in the DTD assessment.

EFED Response: EFED may use available monitoring data in the Registration Review ecological risk assessment

. [ See also re sponse to next comment (Comment #19)

. ] However

, the

Division has also requested a bench scale POTW treatability study for permethrin. It is expected that the study will provide information about removal of permethrin from POTWs . As indicated previously in the problem formulation, “Part of the design of this study will need to address factors that the commenters present ( such as the effect of differences in POTW design and operation on removal efficiencies) to the extent practicable. This may involve dif ferences in experimental conditions and/or the use of POTW simulation models to address these concerns. The ability to extrapolate the bench scale results to results from available POTW monitoring data

will also be evaluated.”

19

. Tri

- TAC Comment: A potentially valuable study is currently in development for POTW monitoring in collaboration among the P WG , CDPR and Tri

- TAC in CA . Tri

- TAC requests including this study in the Agency’s review.

EFED Response: EFED believes that this comment refers to the influent/effluent monitoring that CDPR requested for eight pyrethroids undergoing Reevaluation

. In March 31, 2011 the Agency submitted comments on the proposed POTW sampling protocol to CDPR. The findings of this study will be evaluated in the upcom ing Registration Review ecological risk assessment.

2 0

. Tri

- TAC Comment: Land application is a frequently used method for recycling biosolids. Since pyrethroids adsorb strongly to organic matter, a portion of permethrin entering POTWs will likely

part ition into biosolids. As such, the permethrin environmental risk assessment should address biosolids as well as effluent. The analysis of this partitioning has largely been missing from prior studies. We have heard that the Agency is open to including t his component of your review and are pleased.

EFED Response: Regarding the assessment of biosolids it was stated in the problem

formulation that “ [ t ] he Agency is actively evaluating the extent to which ecological risk from permethrin via land application of biosolids should be addressed in its forthcoming environmental fate and ecological risk assessment and by extension, any additional data that may be required. As part of this evaluation, OPP is working closely with the Office of Water which regulates land application of biosolids under the Clean Water Act.”

2 1

. Tri

- TAC Comment: Acute and chronic toxicity data for freshwater and estuarine/marine fish and invertebrates are necessary to perform the DTD and biosolids assessments. Tri

- TAC recommends th at EPA issue data requirements for permethrin that fill any gaps in available data. The data requirements for permethrin should mimic the data requirements for pyrethroids undergoing registration review, which are the minimum necessary for a scientificall y sound environmental risk assessment.

POTWs need the Agency’s assistance to protect surface water from contamination from pesticides. POTWs are required by NPDES permits to meet effluent toxicity standards; however, our agencies do not

### 11 have the authority to directly regulate the use of pestic ides. Tri

- TAC requests that necessary aquatic toxicity data be obtained and the DTD assessment and a biosolids assessment be performed as part of EPA’s registration review for permethrin.

EFED Response: Similar to other pyrethroid problem formulations, the toxicity data requested for permethrin follow the Part 158 Ecological Effects data requirements . Based upon by permethrin ’s physical properties, use patterns and previously demonstrated toxicity to aquatic organisms, additional data was requested in th e problem formulation for acute effects of the technical product to freshwater invertebrates ( Hyalella azteca ), oysters and aquatic plants, as well as chronic toxicity information for the technical product on estuarine/marine invertebrates in the

water col umn and benthic freshwater and estuarine/marine invertebrates. In addition, acute toxicity information on permethrin for freshwater invertebrates ( Hyalella azteca ) and freshwater fish are requested for an end

- use product with the synergists PBO and MGK. Th ese requested studies will supplement the currently available acute information on permethrin technical and

end

- use product toxicity (without PBO or MGK) to freshwater invertebrates ( Daphnia magna ), estuarine/marine invertebrates, freshwater and estuarine/ marine fish and the chronic effects of permethrin technical to freshwater invertebrates and freshwater fish

. Therefore, EFED believes the necessary aquatic toxicity data are being requested for the forthcoming registration review of permethrin.

It is also noted again that the DTD module of E

- FAST is not designed to evaluate

estuarine/marine fish and invertebrate risks. This module was designed to address only freshwater receiving bodies of water.

Regarding biosolids p lease refer to the response to Tri

- TAC ’s Comment #16 above

.

Submitter: National Alfalfa & Forage Alliance



### 2 2

. NAFA Comment: Permethrin is a critically important insect management tool which has broad spectrum control of a number of alfalfa hay and seed pests including, alfalfa weevil, aphids (pea, blue alfalfa, alfalfa, and spotted), caterpillars (alfalfa, armyworms, cutworms, loopers) a nd lygus bug. It is an integral part of alfalfa and alfalfa seed producers’ ability to control these insect pests. NAFA goes on to list the advantages of permethrin which are: it has a low mammalian toxicity, it has a short pre

- harvest

interval

, and it is inexpensive if generic brands are used.

EFED Response: The issue of the weight carried out by permethrin’s costs and benefits is

outside the scope of EFED. The response to this comment is deferred to PRD.



### Submitter: McLaughlin Gormley King Company

2 3

. MGK Comment: The submitter provided a letter with an appendix summar izing maximum use rates and use sites by product type for MGK permethrin products. The Appendix A is entitled “Permethrin Product Use Site and Rate Summary for McLaughlin Gormley King Company

. ” The table indicates the maximum rates and limitations ( e.g. , retr eatment interval if available) for the following

s ample uses:

### 12 Indoor surface treatment; indoor broadcast for total release fogger; i ndoor space spray; outdoor premises treatment (turf, building surface treatment and fire ant); on animal ( e.g. , livestock,

h orses, ponies, dogs, cats, poultry, sheep); wood destroying pest; livestock premise treatment; residential systems; clothing repellent; lice and louse eggs, bedbugs; carpet upholstery broadcast; plants, home gardens

Furthermore, a provided Excel file ha d two spreadsheets with product descriptions, and maximum rates

for each one. The documents also give which active ingredients are formulated with permethrin in MGK products. Information for around 29 products is provided

.

EFED Response: EFED appreciates MGK ’s submission. It appears that it will be helpful in determining use rates for many of the uses to be assessed in the Registration Review ecological

risk assessment.



### Submitter: Permethrin Data Group II

The PDGII divided its comments into two separate submissions or parts, which are identified as a and b

.



### a

. Permethrin Data Group II Comments on the Permethrin Registration Review

2 4

. PDGII Comment

- PDGII will conduct and submit new studies to sup port the following requirements:

**•** 835.1230 Batch Equilibrium Adsorption/Desorption ;

**•** 835.2240 Aqueous Photolysis

**•** 835.4300 Aerobic Aquatic Metabolism

**•** Non

- guideline Leachability from Treated Wood

**•** Non

- guideline POTW Treatability Study

EFED Response : EFED concurs with PDGII on the submission of the new ly conducted studies

.

2 5

. 835.4100 Aerobic Soil Metabolism

– PDGII proposes to submit this study utilizing cold parent material (as opposed to radiolabeled material).

EFED Response : Paragraph (e)(1) of the OCSPP 835.4100/835.4200 guidance for Aerobic and Anaerobic Soil Metabolism studies specifically indicates that the use of a radiolabeled material is

recommended “ for studying the pathway of transformation and for establishing a mass balance .” [Emphasis was added.] Thus , in order to establish a pathway, pattern of formation and decline of the degradates, and obtain suitable mass balance s , EFED recommends that the test material be

radiolabeled.

2 6

. 835.4200 Anaerobic Soil Metaboli sm

– PDGII believes that a new anaerobic soil metabolism study will not give substantial new information because the previous study shows persistence of permethrin under anaerobic conditions. Furthermore, the anaerobic aquatic metabolism that PDGII will s ubmit should be more relevant to surface water exposure estimates

.

### 13 EFED Response : These studies are required for the proper characterization of the environmental fate of permethrin in anaerobic soils

. Based on the characteristics of permethrin (which binds tightly to soils and sediments), it seems unlikely that the chemical would reach subsurfaces to a high degree; however, permethrin has aquatic uses and thus potential to reach anaerobic soils due

to adulticide treatment. T he single available study l asted only 60 days of anaerobic incubation, a period during which permethrin decreased from 81.7% AR to 68.1% AR (decreasing only 13.6% AR during this period

, and making the half

- life highly unreliable ) (the required anaerobic period is one year)

. Also, b oth trans

- DCVA and m

- PBA increased throughout the study . Additional degradation half

- life information and data about these degradates are needed.

27

. 835.4400 Anaerobic Aquatic Metabolism

– PDGII suggests the submission of two ongoing studies that are being performed for CDPR

.

EFED Response : EFED agrees with the submission of two C DPR studies.

28

. 835.6100 & 835.6200 Environmental Chemistry Methods (ECMs) and Independent Laboratory

Va lidations (ILVs), for Soil, Water and Sediment

– PDGII is proposing to use the following two available studies to support this data requirement: 47053001 and 47053002

.

EFED Response : As indicated in the problem formulation, EFED will evaluate these two s tudies for their suitability and determine the ir acceptab i l ity for soil, water and sediment

.

29

. 850.1010 Acute Toxicity Freshwater Invertebrates and 850.1020 Acute Toxicity H

. azteca (using highest ratios of PBO and MGK

- 264)

– It appears that there are some inconsistencies in comparing the summary document and the problem formulation. PDGII asks for clarification on this data requirement.

EFED Response : Acute water column toxicity data on permethrin technical and typical e nd

- use products (TEPs) with PBO and MGK

- 264 are requested for H

. azteca , using Guideline 850.1020 ( Gammarus acute toxicity test guideline) as the basis for conducting the tests . As appropriate

modifications to the 850.1020 guideline will be necessary for testing of H. azteca , the registrant is encouraged to submit a protocol to the Agency prior to conducting the acute test of H. azteca

.

3 0

. 850.1025 Oyster Acute Toxicity Test (shell deposition) ; 850.1075 Acute Freshwater Fish Toxicity (TEP) (using highest ratios of PBO and MGK

- 264); 850.1350 Aquatic Invertebrate Life

Cycle (saltwater) ; 850.2100 Avian Acute Oral Toxicity T est (passerine species) : The PDGII indicated that they will conduct and submit these studies

.

EFED Response : EFED concurs with PDGII on the submission of the newly conducted studies.

3 1

. 850.4100 Seedling Emergence and 850.4150 Vegetative Vigor

– A waiver for this data requirement was submitted based on the fact that FMC (original registrant for permethrin) generated efficacy data for numerous crops. No phytotoxicity was observed to alfalfa, asparagus, beans, cabbage, sweet and field corn, cucumber, lettuce, pepper, plum, potato, pumpkin and tomato. PDGII does not believe that a new study would generate add itional useful data.

### 14 EFED Response : Among other data quality requirements, these terrestrial plant studies would

need to address the potential adverse effects examined in our typical seedling emergence and vegetative vigor studies, such as germination, g rowth and phytotoxic damage. Also, the studies must demonstrate that permethrin was applied at or above the maximum labeled application rates

with a minimum 14

- day post

- application observation period. T he field trials recently submitted to

t he Agency are d esigned for residue chemistry (OCSPP Series 860 Guidelines) . Although these

data do provide additional lines of evidence regarding the potential phytotoxic effects of permethrin, the studi es do not meet the same objectives a s a standard seedling emergence and/or vegetative vigor study. In addition, the 8 major and 149 minor permethrin plant incidents that have been reported indicate that plant damage may occur following use of this chemical . Data that will provide quantitative information on the potential e ffects of permethrin exposure to terrestrial plants , including any inhibition of germ ination, reduction in growth and observed phytotoxicity, are needed for the upcoming ecological risk assessment.

3 2

. 850.4400 Aquatic Plant Growth (aquatic vascular plant toxicity), Tier II

– Another waiver for this data requirement was submitted. PDGII indicates that the above mentioned studies indicated no phytotoxicity to numerous crops and also argues that only small amounts of permethrin would reach adjacent bod ies of water because permethrin does not have aquatic uses and such amounts would not be bioavailable to macrophytes because permethrin binds to sediments.

EFED Response : Similar to the response for C omment #31 above, these field trials do not

address the same questions as our standard aquatic plant toxicity tests. Data that will provide quantitative information on the potential phytotoxic effects of permethrin exposure to aquatic vascular plants , including any reductions in growth or observed phytotoxicity , are needed for the upcoming ecological risk assessment.

Regarding the aquatic uses for this chemical , EFED confirms that permethrin does have aquatic

uses ( as a mosquito adulticide )

. In addition, chemicals that bind to sediments still hav e the potential for exposure to aquatic plant root systems, as well as contact with the shoot portions of macrophytes in the form of dissolved and particulate organic matter.

3 3

. 850.5400 Aquatic Plant Growth ( a lga e ) Tier II

– PDGII is evaluating existing studies to determine if they meet the data requirement and will submit them at the time of the DCI.

EFED Response : Once submitted, EF ED will evaluate these studies for their suitability according to current guideline requi rements.



### b

. Comments on EPA’s Summary Document and Problem Formulation Supporting Registration Review

3 5

. PDGII Comment: Labels from FMC, Valent, and United Phosphorus were reviewed and were

considered representative of the majority of the agricultural, residential and professional labels, so a subset of all registered uses was reviewed. This approach should be robust for the purposes of a screening level assessment, because the other registered use la bels should essentially be copies of FMC, Valent, or United Phosphorous labels, with the same use rates, interval between application s, and seasonal

rates

. N o dust formulation labels were reviewed in PDGII’s analysis. However, of the 9 registered dust

fo rmulations, they found that all are labeled for home lawn and garden use only, so the extent of exposure to them is expected to be much less than if they were agricultural uses, as EPA’s table implies.

### 15 EFED Response: A substantial subset of labels w as ut ilized to prepare the use and usage information in the LUIS report. The labels evaluated represent all use patterns, maximum single application rates, and all formulation types. EFED did not intend to “imply” that the extent of exposure of any of the use s was greater or smaller than others. The table presented the maximum rates if available for all agricultural and non

- agricultural uses. For the uses that are limited to home and gardens only, EFED currently has a specific scenario (residential), which i s run in tandem with the impervious scenario to derive suitable EECs

.

3 6

. PDGII Comment: EPA states that the Label Use Information System (LUIS ) report and Usage/

La bel Use Reports for Permethrin were based on a partial listing of labels d ue to the large number of permethrin labels . S ection 3 labels or major producers’ labels, along with all State and Local Needs (SLN ) labels were incorporated in the LUIS report. However, that report is not included as an appendix

to the Problem Formulati on or in the R egistration R eview docket, making it difficult to evaluate the information presented in the Problem Formulation. EPA states that these data represent major uses for

this chemical. PDGII believes that EPA’s approach of identifying “represent ative” agricultural and non

agricultural labels will not be acceptable to the Services. A more detailed analysis and summary of all permethrin labels may be needed if formal consultation on endangered species is requested by EPA.

EFED Response: This app roach was used in the past for endangered species risk assessments ( e.g. , the C alifornia R ed L egged F rog /S an F rancisco B ay and the V alley E lderberry L onghorn

B eetle permethrin assessments). As said above, t he LUIS report was based on a subset of labels

that account for all the chemical’s uses

. Permethrin has over 700 product labels of which a substantial subset was extracted

. In general, th e full LUIS report is not included in the docket

, but it includes all use patterns, maximum single application ra tes, and all formulation types

.

37

. PDGII Comment: EPA does not state the objectives of its summary of the permethrin uses, but it is expected that the information is to be used to support a screening

- level ecological risk assessment, as well

as any refinements that might be needed for an endangered species effects determination. T he critical

information for these activities would include: an evaluation of the inherent risk to non

- target organisms of the different formulations ( e.g. , granular, sprays , and dusts) and associated application sites and methods; and a summary of mitigation measures on the labels.

EFED Response: EFED acknowledges that identifying and tabulating all the multiplicity of uses of permethrin is challenging. T he referenced se ction of the Problem Formulation is an “overview” of use and usage of permethrin , but the complete use and usage is given in the LUIS

report

. EFED stated in the document the main mitigation measures that were imposed in the labels, which resulted from the Reregistration Eli gi bility Decision ( e.g. , buffer zones and vegetative buffer strips). In the upcoming Registration Review ecological risk assessment, EFED will not only account for these measures of mitigation, but also include differences which result from applications of different formulations, use sites, and application methods.

38

. PDGII Comment: EPA groups emulsifiable concentrate, water soluble bag and granule s in one table; dusts are presented separate ly

. The potential for offsite movement of the two spray formulations, the granule, and the dusts differ and it may be inappropriate to ignore these differences. The drift potential for granules is negligible, and if applied in

- furrow, runoff will be markedly reduced. S pray formulations can be applied as a foliar spray or applied directly to the soil at planting, pre

- emergence, or

pre

- plant incorporated, as is the granule. Other things being equal, a foliar spray application will have a greater potential for drift and runoff than a spray or granule applied to the soil. The granules can also be

### 16 applied aerially, but other than being captured in corn whorls, should leave minimal residue on foliar

surfaces. For a foliar application, some of the permethrin could reach the soil surface; adsorption to foliar

surfaces will differ from that on soil su rfaces and could modify runoff. It is recommended that EPA perform separate analyses for granular and spray formulations and for foliar and soil applied methods to

ensu re that appropriate estimates of residues and offsite movement are made.

EFED Response: EFED acknowledges the differences in the potential for offsite transport for

different permethrin formulations and application methods and will consider the PDGII com ment when assessing permethrin in the Registration Review ecological risk assessment. Generally, when a screening

- level risk assessment is conducted, the most conservative scenarios are

modeled. In addition, for endangered species assessments for Registra tion Review, different application methods and formulations, and possible refinements are also considered.

39. PDGII Comment: Some unusual or specialized labels allow treatment of many matrices, often with little indication of maximum treatment rates. It will be difficult for EPA to assess these, even with their experience, and more difficult for the Services to evaluate them. For many of them, no risk s cenarios are

available. One advantage is that labels do limit applications that might formerly have been made on impervious surfaces where urban and suburban runoff would have been a problem prior to those limitations; only spot or crack and crevice appli cations may be made to such surfaces. These products may be used as a residual surface treatment on walls and ceilings. Most of these are indoor uses. The outdoor uses are limited to the lower three feet of walls and directions specify that sprays are n ot to be made to the point where the material would run off from the treated site.

EFED Response: In past assessments, EFED has made estimates of the application rates for

numerous unusual scenarios. EFED is aware of, and will consider the above stated mitigation measures at the time the Registration Review ecological risk assessment is done (note d also a response to CASQA’s C omment #11 above)

.

4 0

. PDGII Comment: Mosquito cide uses are intended to remain in the air for a significant period of

time and not deposit out; while drift may be enhanced

, deposition resulting from that drift will be reduced. Mosquito adulticides may be applied to the air column over a variety of crops, all of which are on permethrin agricultural labels, but the rate of 0.007 l b a.i./A is far lower than the maximum crop rates of 0.1 lb a.i./A and higher. Thus, the mosquito use of permethrin will not add, for all practical purposes, to the residues from crop applications of agricultural formulations. This public health use is o nly allowed under the authority of federal, state, local, or tribal governments and a pplicators must be certified or under the direct supervision of certified applicators.

EFED Response: Previous risk assessments have shown that there may be RQs that exc eed one

or more of the LOCs for the adulticide uses . It is important to reassess the m with the most up to date label requirements. Despite that the application rate is low, multiple applications are allowed

and the minimum interval between applications i s only 1 day (high pest pressure) . The seasonal application rate is 0.18 lb a.i. /A. Furthermore, in addition to agricultural crop uses, adulticide applications are also allowed over regions that could have extensive impervious surfaces

. EFED acknowledge s th e mosquitocide application restrictions ( e.g. , made by certified applicators )

.

4 1

. PDGII Comment: Termiticide applications, which are very important for structural pest control, may present difficulties, but permethrin products are to be applied only by state licensed and trained individuals, injected well into non

- saturated soils or covered, and not a pplied when precipitation is

### 17 occurring, along with other provisions to reduce exposure away from treated areas. Other underground treatments such as to cables and other utilities, will have very limited potential exposure, other than to

fossorial animals. Premise treatments, such as public health and other applications to a wide variety of structures, walls, and their immediate surroundings still require buffers to keep runoff away from water.

EFED Response: EFED a cknowledges the above mentioned informa tion and will evaluate it, along with labels for termiticide applications, for possible uses with potential for exposure to non

target wildlife , such as fossorial and/or aqu atic animals , aquatic plants, etc.

4 2

. PDGII Comment: In the narrative following the Environmental Hazard Statements, EPA discusses the fact that permethrin labels require a 10

- ft buffer zone around certain water bodies. However, the narrative does not indicate, as the agricultural labels do, that this 10 ft area is to be unc ultivated so as to leave a vegetated buffer strip; vegetated buffer strips are more efficient at reducing runoff than a simple

buffer zone that may or may not be bare ground. Furthermore, there is a specific statement for protection

of bees. The labels f or the crop applications have a wide range of specifications to reduce spray drift

from ground or aerial applications. The language on the Pounce EC, WP, and even 1.5G labels is

identical and covers wind speed and direction, temperature inversion, droplet size, as well as additional requirements for ground and air applications. The Permethrin Task Force suggests that EPA consider these measures when developing Estimated Environmental Concentrations (EECs) for permethrin. Also,

these measures need to be c onsidered by EPA and the Services if it is necessary to craft Reasonable and

Prudent Alternatives and Measures for listed species.

EFED Response: EFED is aware of these mitigation measures and will consider the m at the time of the ecological risk assessment is completed

, as appropriate

.

4 3

. PDGII Comment: T en representative Task Force labels were reviewed and summarized in tabular

form to facilitate a comparison with EPA’s Tables 3.2 and 3.5

. According to PD GII, i t appear s that the labels selected by EPA in Table 3.2 were substantially similar to the POUNCE 3.2 EC label.

PDGII compared the POUNCE 3.2 EC label with EPA’s Table 3.2 with the following findings: A

difference between EPA’s tables and the POUNCE 3.2 EC label was that EPA often concluded that chemigation, airblast, and even soil incorporation application methods could be used. FMC’s crop

- level descriptions usually specified ground or air, and perhaps airblast or ULV. There was general statement about the chemigation uses on the POUNCE 3.2 EC label, but this statement often did not tie back to the

crop

- level instructions. For example, EPA states that alfalfa could be treated by chemigation and by soil incorporation, but the POUNCE 3.2 EC label on ly mentions ground or air, and makes no mention of chemigation or soil incorporation. There were a few differences in the crops listed in EPA’s Table 3.2

and the POUNCE 3.2 EC label. EPA includes anise, beans, S wiss chard, kohlrabi, okra, fennel, pecans, raspberries, blueberries, and strawberries, rhubarb, and watercress, Christmas tree plantations, rights

- of

way/fencerows/hedgerows, patios/patios and paved areas , and public health uses, which do not appear to

be on the POUNCE 3.2 EC label. Some of these differences may be due to Section 24(c) labels, which

were not reviewed for PDGII’s analysis

. EPA does not limit the uses on collards and turnips to specific states, but the FMC label does. T he Problem Formulation does not indicate which products were u sed to develop the table of non

- agricultural uses

. The rangeland use is on the POUNCE 3.2 EC label, with a specified rate of 0.01 lb a.i./A and is allowed only in the state of New Mexico. In contrast, EPA lists the rangeland use in Table 3.2 as 0.1 lb a. i./A.

EFED Response: A comparison of POUNCE 3.2 EC label against EFED’s table s is not appropriate because the LUIS report summarized in the review incorporates several labels

.

### 18 Inspection of the LUIS report indicated that both chemigation and soil incorporation are allowed application methods for alfalfa. Further, according to the report, a nise, beans, Swiss chard, kohlrabi, okra, fennel, pecans, raspberries, blueberries, straw berries, rhubarb , watercress, Christmas tree plantations, rights

- of

- way/fencerows/hedgerows, patios/patios and paved areas

, and public health uses are all registered uses for permethrin. EFED acknowledges that uses on collards and turnips ar e restricted t o specific states and confirms that the uses on rangeland

include a maximum rate of 0.1 lb a.i./A , as stated in EFED’s table

.

4 4

. PDGII Comment: While usage data indicate considerable home and garden use, it should be noted that this use is typically spread out more than in agricultural areas because only some homeowners will

use a particular product and only on limited parts of their property. T hus any off

- site exposure would be much more limited than in agricultural areas. Use on lawns and landscaping plants would result in permethrin being adsorbed to plant materials, rather than to soils as in cropland areas, and thus less

available to runoff on soil particulate matter. The commercial and other wide area urban uses of permethrin have labels that dictate no applications during rain and no spraying of plants or articles to the point of dripping or runoff, reducing the potential for transport of a n adsorptive material. L abels limit applications to impervious surfaces to crack and crevice applications, and prohibit use in sewers or sewer

drains.

EFED Response: The comment is acknowledged and will be considered at the time of the Registration Revi ew ecological risk assessment (n ote also a response to CASQA’s C omment #11 above)

.

4 5

. PDGII Comment: EPA has some very high use rates for termiticide treatments in th e T able 3.5 , and it is not clear how, for example, the 180 lb a

. i

. /A use rate for pre

- construction treatment was arrived at. On its face, a use rate this high would seem to imply considerable potential for exposure. But for the termiticide uses, the products are mixed with considerable amounts of soil and then covered and buried. Instructions require that treated areas must not be left open, and applications are not allowed when precipitation is occurring or when soils are frozen or saturated. Only persons licensed and trained are allowed to apply permethrin products a s termiticides.

EFED Response: These rates were obtained directly from BEAD’s report and a footnote with a reference to the specific use was included in the Problem Formulation for unusually high application rates ( e.g. , used for soil treatment (preconst ruction) or soil treatment (rodding)

– injection equipment) . EFED acknowledges uses that may involve lower exposure potential and the measures of mitigation taken for of the termiticide uses. It is noted that t hese rates were

obtained from BEAD's LUIS re port. BEAD converts all application rates into lb a.i./A regardless of the labeled unit of measurement. EFED realizes that the pre

- construction treatment with the mitigation referenced by PDGII is applied to buildings, structures, and their immediate

sur roundings only, and that the lb a.i./A unit measurement may not be appropriate for this use scenario. Additionally, EFED will consider the specific application restrictions when assessing the exposure from this use, which may result in lower exposure scena rios.

4 6

. PDGII Comment: T here are numerous livestock and animal premise uses, including feedlots, where there may be heavy concentrations of livestock. A large proportion of animal treatments will be spot

treatments, and indoor treatments of animals or premises. Outdoor agricultural premises will typically be

associated with barns and other animal houses. While these may be made outdoors, they are not made in

natural habitats, nor are they typically made near such ha bitats where most non

- target organisms would

### 19 occur. Use in feedlots would likely be insignificant relative to the waste products generated by the

animals themselves. The most likely exposure scenario for threatened and endangered species would be

livesto ck treated on rangeland or pastureland, which does occur, but is not the kind of area where either the livestock or the pests to be controlled are concentrated.

EFED Response: In the past, t he Division has evaluated livestock uses for only a few chemicals

. Based upon a preliminary screening

- level assessment, EFED will determine whether further refinements to the proposed scenarios is warranted.

47

. PDGII Comment: Agricultural Usage

– A limitation of EPA’s Screening Level Usage Analysis is that it does not explicitly consider the time trends of permethrin usage. To complement EPA’s agricultural usage analysis, usage data from Doane’s were obtained from FMC for 2010. Those data showed that the top 8 crops were: pistachios (23%), corn (16%), lettuce (10%), soybeans (10%), potatoes (7%), sweet corn (5%), almonds (4%), and spinach (4%). Celery made up 3% of the total, while peaches, cucumbers, pumpkins and alfalfa made up 2% of the total. Another 8 uses made up 1% of the total each,

and 15 uses made up less than 1% of the total each. To further complement EPA’s agricultural usage analysis, data were obtained for 2007 to 2009 from the CA Pesticide Use Reporting (PUR) database ( http://calpip.cd pr.ca.gov/main.cfm ). These data are presented alphabetically by agricultural use in Table

1 of the PDGII submission

. Total permethrin agricultural use (as measured by pounds of active ingredient ) decreased by 29% from 2007 to 2008, and increased slightl y (4%) from 2008 to 2009. Each year, the top ten crops accounted for >90% of permethrin use. The highest use crop was pistachios (33

- 40%), followed by almonds (11

- 14%), lettuce head (11

- 13%), lettuce leaf (10

- 12%), spinach (4

- 6%), celery (3

- 6%), corn (3

- 4%), walnuts (2

- 3%), tomatoes (1

- 3%), and onion (1

- 2%). A wide range of crops made up <1% of the total each.

EFED Response: The Division appreciates the submission of these data. It will aid to identify major agricultural crops of interest during the process of the Registration Review ecological risk

assessment

. EFED notes that one limitation of the usage data presented in PDGII’s table is that it includes only the state of CA.

48

. PDGII Comment: Urban Usage

– In its Proble m Formulation, EPA did not perform an analysis for the urban usage of permethrin. Urban usage is broadly defined as essentially all nonagricultural pesticide usage, including applications to residences, commercial buildings, institutions, parks, golf cour ses, and rights

- of

- way
, structural, landscape maintenance, public health, vertebrate, commodity fumigation, and regulatory. The most detailed data on nonagricultural permethrin use are available from the CA PUR

. The PDGII provided in formation in Table 2 of the submission

. The CA PUR data rely on responses from professional applicators, but permethrin is also purchased and used by homeowners. I nformation was

summarized for 2007 to 2009 and data were presented alphabetically by nonagricultural use. Tota l permethrin non

- a gricultural use decreased by 11% from 2007 to 2008, and decreased by an additional

29% from 2008 to 2009. Each year, structural pest control accounted for >90% of non

- agricultural use. The next highest non

- agricultural uses were landscap e maintenance (6

- 9%), and public health pest control (<1

- 1%). All other non

- agricultural uses made up <1% of the total each. T otal permethrin non

agricultural use was 50 to over 100% higher than agricultural use, depending upon the year under

considerati on from 2007

- 2009

.

EFED Response: The Division appreciates the submission of these data. It will help identify major non

- agricultural uses of interest during the process of the Registration Review ecological

risk assessment

. It also helps to inform trends of usage of permethrin over time.

### 20 49

. PDGII Comment: Ecotoxicity: EPA has not conducted a full analysis of the available data, including data available in its ECOTOX database and other sources. Drawing on the extensive database of the PWG, an analysis was conducted on the studies that EPA relied upon in the Problem Formulation,

as well as additional studies that could be used in a refined assessment. The PWG database was also

searched to distinguish studies that might be used to fulfill data gaps identified by EPA. Additional

studies on non

- target insects and on plants were also identified from EPA’s ECOTOX database. These studies could be relevant for performing a refined ecological risk assessment.

With regard to t oxicity data for terrestrial insects, the Problem Formulation indicates that open literature toxicity data will be considered in the upcoming risk assessment. EPA also provides a rationale for exclusion of efficacy studies, but none for exclusion of non

- e fficacy studies. We note that the ECOTOX database includes median lethal dose (LD 50 ) values for more than 70 other species of insects in addition to honeybees, which may be relevant to a refined assessment.

The Problem Formulation indicates that no terre strial plant data are available to the EPA for permethrin. The ECOTOX database includes toxicity data for over 50 species of terrestrial plants, which may be

relevant to a refined assessment.

Appendix H (ECOTOX Database for Permethrin) of the longhorn be etle risk assessment (EPA 2010)

contains no studies from 2010. However, the current ECOTOX database does contain studies from 2010 that most likely had not been entered into ECOTOX when Appendix H was compiled. The Permethrin Task Force requests that EPA continue to examine ECOTOX for new studies that may be useful for a

refined risk assessment.

EFED Response: A full ECOTOX search will be conducted prior to the final risk assessment for Registration Review, and the available studies identified for permethrin will be evaluated for suitability in quantifying ecological risk of the chemical. EFED welcomes submissio n of any studies that the registrants believe may fulfill the data gaps for permethrin in the context of a data waiver request

.

5 0

. PDGII Comment: Using the PWG’s aquatic toxicity database, the data used by EPA in their

Problem Formulation were evaluated to insure that they were from reliable and relevant studies and that the endpoints were correct. The studies in the PWG’s aquatic toxicity database have been reviewed and evaluated for reliability and relevance. Based upon these evaluations, th e Permethrin Task Force suggests

that the 48

- hour median effect concentration (EC 50 ) of 0.075 μg/L for the Daphnia magna acute study (MRID 00043736)

, is more appropriate than the 96

- hour EC 50 of 0.039 μg/L presented in the Problem

Formulation. According to test guideline OPPTS 850.1010, the purpose of the definitive test is to

determine the 24

– and 48

– h EC 50 values.

Additionally, an a cceptable study for the bluegill ( Lepomis macrochirus ) is available (Bentley 1974; MRID 00110657) and is more suitable fo r risk assessment than the s upplemental study (Hill et al. 1976; MRID 00042128). The Bentley (1974) study is preferable since it used statistics to calculate the median lethal concentration (LC 50 ) and reported the control performance (100% survival).

EFE D Response: EFED agrees that the 48

- hour EC 50 value should be used for the acute study

with Daphnia magna , instead of the 96

- hour EC 50 value (MRID 00043736). In this particular study, the test organisms were fed after 48 hours , and the control immobilization was greater than 10% at 96 hours, indicating test organism stress that is not chemical

- related (13% immobilization

### 21 was observed in the negative control at 96 hours, compared to 0% immobilization in the negative

control at 4 8 hours).

Thank you for providing a review of available data for bluegill. We are aware of several strengths and limitations in the bluegill study referenced in the permethrin problem formulation (MRID 00042128). Some of the study’s strengths include the use of measured concentrations, flow

through conditions, the availability of raw data and use of concurrent controls. However, we recognize that some of study limitations include absence of control response reporting, relatively high co

- solvent concentrat ions and use of graphical m ethods for LC 50 determination. Some of these limitations can be addressed (such as recalculating statistics for LC 50 ), but others do not appear to be repairable, such as use o f high co

- solvent concentration and lack of control da ta

. The bluegill study suggested by the PDGII (MRID 00110657 ) is not considered useful for risk

assessment purp oses and was invalidated because the percent active ingredient of the test substance was not reported and water quality measurements were not taken during the study.

For the final risk assessment of permethrin, the Agency will re

- evaluate its choice of the acute toxicity endpoint for freshwater fish in the contex t of all available information, including data from the open literatur e which have yet to be reviewed, and the associated strengths and limitations of the bluegill study used for risk quotient calculations in previous permethrin ecological assessments (MRID 00042128).

5 1

. PDGII Comment: The Problem Formulation says the assessment will use the surrogate species approach, and that surrogate test species “are intended to be representative of broad taxonomic groups.” The surrogate species approach is the only option for ecological risk assessment because data are

a vailable for only a small number of species. However, the breadth of the taxonomic groups to which surrogate data are applied should be kept to a minimum. Species sensitivity is more similar for more closely related taxonomic groups, and becomes less sim ilar with increasing taxonomic distance.

In the case of permethrin, for example, there is a wide difference in sensitivity between taxonomic groups of aquatic invertebrates. In particular, mollusks are much less sensitive than arthropods, and therefore, toxicological data for arthropods should not be extrapolated to mollusks. While it may be appropriate to lump all aquatic invertebrates into a single category in the initial stage of the assessment, risks to these two important groups should be clearly d istinguished at the first level of refinement. This is especially important because of the large number of threatened and endangered species of mollusks. We note that the taxonomic categories in the Office of Pesticide Programs (OPP) Pesticide Ecotoxicit y Database distinguish between crustaceans, insects, and mollusks, and that the data in the OPP Pesticide Ecotoxicity Database confirm the large difference in sensitivity of crustaceans and mollusks.

Other relevant and reliable studies that could be used in a refined risk assessment are presented in Table 4 (freshwater) and Table 5 (marine) of PDGII’s submission

. As evidenced by the assigned MRID numbers and EPA ratings, many of the studies in Table 4 and Table 5 have been rated by EPA and found to be

Ac ceptable or Supplemental. The data presented in Table 4 and Table 5 will be useful in a refined aquatic

risk assessment that accounts for all available, high

- quality data, rather than only the lowest endpoints as used in the screening

- level assessment.

E FED Response: It is EFED’s policy to select an acute and a chronic endpoint from the available test data within each of these very broad taxonomic groups for risk estimation. As a conservative measure, t he selection is made from the most sensitive species tested within that organism group ( see Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs , U SEPA , 2004)

. Additional toxicity data within a broad taxonomic group can

### 22 provide insight on relative species sensitivity within that group, and can be a useful tool for risk

characterization. A summary of the lowest data endpoints was presented in the problem

formulati on. A ll available toxicity data for permethrin will be considered , as appropriate, in the upcoming Registration Review ecological risk assessment. In addition, the totality of aquatic toxicity data may be evaluated in the context of one or more species se nsitivity distribution s in order to provide additional characterization of ecological risk.

5 2

. PDGII Comment: In the Summary, there is a requirement for study 850.1010 with a typical end

- use product. The Summary appears to be silent about the species or the formulation to be tested. There is

also a requirement for study 850.1020 to be done with H. azteca and combination products containing piperonyl butoxide and MGK

- 264. In the Problem Formulation, t here is a requirement for study 850.1010, and it is specified that this study should be done with H. azteca and combination products containing piperonyl butoxide and MGK

- 264. There is also a requirement for study 850.1020 on page 82,

and a footnote 4 for this study on page 83. The footnote specifies that the test species should be H.

azteca , but is silent about the test substance. If study 850.1020 is done according to the requirements of the Work Plan, it would seem that it is a duplication of 850.1010

. The Permethrin Task Force requests that EPA clarify the test species and test substance(s) for studies 850.1010 and 850.1020.

EFED Response: As listed in Table 7.2 of the problem formulation, the registrant has previously submitted studies for permethrin technical under Guideline 850.1010 with Daphnia magna as the test species (MRIDs 00043736, 00110662, 00110663). No additional studies with thi s guideline are requested at this time. Acute toxicity data on permethrin technical and typical end

- use products with PBO and MGK

- 264 are requested for H

. azteca , using Guideline 850.1020 as the basis for developing the tests. As appropriate modifications to the 850.1020 guideline will be necessary for testing of H. azteca , the registrant is encouraged to submit a protocol to the Agency prior to conducting the acute test of H. azteca

.

5 3

. PDGII Comment: In the Problem Formulation EPA raises concern ab out the potential for permethrin to bioconcentrate and to bioaccumulate in aquatic organisms and to biomagnify in terrestrial organisms. EPA raises these concerns based on permethrin’s octanol / water partition coefficient, the bioconcentration factor (BCF) in the bluegill study, depuration rate from bluegills, and persistence in water and sediment. In order to assess the potential for bioaccumulation, EPA will use its K OW (based) Aquatic BioAccumulation Model, version 1.0 (KABAM). Although KABAM has been re viewed and approved by EPA’s Scientific Advisory Panel, it is nonetheless a relatively recent addition to EPA’s suite

of models. It is suggested that the model outputs from KABAM be compared with all available and relevant higher tier aquatic or terrestri al studies, as part of a model verification effort. KABAM should not be used uncritically as the basis for a screening level assessment.

EFED Response: As indicated in the Problem Formulation (p. 66), the Agency will assess permethrin bioaccumulation us ing available bioconcentration and bioaccumulation studies in

addition to KABAM. Such an approach, that couples measured and modeled estimates of bioaccumulation, was strongly endorsed by the Agency's FIFRA Scientific Advisory Panel meeting in 2008 ( http://www.epa.gov/scipoly/sap/meetings/2008/october/minutes.pdf )

. Furth e rmore, the Agency clearly recognize d the role of biotransformation in pyrethroid

bioaccumulation and indicated that KABAM

- based estimates of bioaccumulation will consider

available information on biotransformation rates of permethrin by aquatic organisms

.

### 23 5 4

. PDGII Comment: With regard t o the development of EECs for the urban use, EPA has not provided very much detail on how the “impervious” and “residential’ scenarios were developed or verified. Many terms used in EPA’s discussion of these scenarios are apparently undefined. Considering EECs for use around structures, EPA proposes to use its PRZM/EXAMS model, in a combination of scenarios that are described as “impervious” and “residential.” Given the extent of the urban residential uses of permethrin, and given what is known regarding contamination of urban water bodies by pyrethroids in general, arriving at appropriately conservative EECs will be critical for the permethrin risk

assessment. The Problem Formulation document does not provide very much detail on the assumptions

made in t he impervious or residential scenarios, or any explanation for how these scenarios were developed or verified. EPA discusses how “alternative assumptions on percent impervious surfaces, percentage of use site treated, and percentage of overspray may be considered in order to characterize the assumptions of the ecological risk assessment in the context of individual exposure and risk conclusions.” Many of the terms used in this discussion are apparently not defined in the text of the Problem

Formulation. Furthermore, it would appear that EPA has not, in fact, arrived at established assumptions for modeling of urban EECs. It is a concern when models that are apparently in development are used to support regulatory analyses.

EFED Response: Metadata file s for the impervious

, residential , and rights

- of

- way scenarios are available at: http://www.epa.gov/oppefed1/models/water/pe5_rlf.htm (accessed 10/21/2011)

. These files provide valuable in formation about these scenarios and their assumptions

. Previous comments in this document additionally partially provide responses to the PDGII comment ( e.g. , Comment #8 and Comment #11)

.

5 5

. PDGII Comment: Th e EFAST2 DTD screening level tool relies on simple inputs, such as production volume and fraction of the chemical removed during wastewater treatment, to estimate concentrations of chemicals in surface water that may result from household uses and disposal into

wastewater. In order to parameteri ze EFAST2, EPA is requiring a P OTW Treatability Study with technical permethrin. As several commenters have pointed out with regards to this requirement for bifenthrin, there is considerable variability in the performance characteristics of wastewater tre atment plants. The study design should therefore aim to mimic a reasonable worst case for the fraction of permethrin removed by wastewater treatment. Also, the risk assessment itself should consider the bioavailability of permethrin in wastewater and bio solids. This consideration is especially relevant for a pyrethroid like permethrin because of the importance of dissolved organic carbon and sediment to the bioavailability of permethrin in other systems. T hese factors should be considered in developing any EECs for permethrin in wastewater or in biosolids. The bioavailability of permethrin in these matrices needs to be taken into account to arrive at appropriately conservative EECs.

EFED Response: As stated in the problem formulation, “ [t] h e Agency received comments from stakeholders with concerns regarding the value of a POTW Treatability Study and its representativeness of numerous treatment plant designs. EFED recognizes that such differences in plant design and operation may affect remo val efficiencies, which is why it is proposing to require a POTW treatability study for permethrin, to support its EFAST2 down

- the

- drain modeling. EFED is currently working with the registrant on the design of this study to best meet the Agency’s environm ental risk assessment needs. Part of the design of this study will need to address factors that the commenters present ( i.e. , the effect of differences in POTW design and operation on removal efficiencies) to the extent practicable. This may involve diff erences in experimental conditions and/or the use of POTW simulation models to address these concerns. The ability to extrapolate the bench scale results to results from available POTW monitoring data will also be evaluated. The forthcoming environmental risk assessment would address the

### 24 uncertainty involved in the interpretation and extrapolation of results from the POTW treatability study to the national scale.”

The Agency acknowledges the substantial body of literature that indicates dissolved organic carbon and particulate organic carbon can reduce bioavailab il ity of highly hydrophobic chemicals such as permethrin. This effect is considered in the Agency's EECs developed using

PRZM/EXAMS. In relation to E

- FAST2, the Agency will consider the effect o f organic carbon should it be necessary to refine model estimates. Furthermore, the Agency also points out the

potent i al dual rol e that dissolved organic carbon ( DOC ) may have on pyrethroi d bioavailability. Specifically, while DOC is wide ly recognized as reducing pyrethroid bioavailabilit y within an

e nvironmental compartment (such as water), it also may contribute to the dissolution and transport of pyrethroids betw een environmental compartments, such as from soils/ sediments into

s treams ( Delgado

- Moreno et al

. , 2010). 2

5 6

. PDGII Comment: With regard to EECs for the cattle treatment uses, EPA appears to be proposing that 100% of applied permethrin could wash off from treated cattle. Given the binding characteristics of permethrin, this assumption is likely to be unduly conservative, and sh ould be refined. EPA also has to develop another novel EEC for the treatment of cattle with permethrin. EPA considers that there are two possible scenarios by whereby permethrin can enter aquatic ecosystems after cattle are treated. The first

scenario is that treated cattle can enter into a farm pond. The second scenario is that rainfall can wash the permethrin from the hair of the treated cattle, and permethrin could reach a farm pond via run

- off. In both cases, EPA appears to be assuming that 100% of the applied permethrin will wash off from the treated

cattle. Given the binding characteristics of permethrin to organic matter, this assumption seems overly

conservative. It is suggested that data sources be examined to arrive at an appropriatel y conservative percent of washoff.

EFED Response: Regarding the EECs for cattle treatment, this is one representative use of the

numerous uses of permethrin to treat animals. It appears to be one of the uses that could involve high exposure to aquatic h abitats. Regarding the percent wash off of permethrin, EFED is open

to evaluate further information provided by the registrant that could help refine its assessment. EFED believes that such studies may have been already provided to HED and if so, the reg istrant

should cite them . In the absence of data, conservative assumptions will be made in the context of a screening assessment

.

57

. PDGII Comment: With regard to EECs for the ULV mosquito adulticide uses, it is suggested that

EPA select realistic va lues for model inputs, such as number of applications per season, application interval, spray height, and nozzle type. It is further suggested that EPA draw on available laboratory and field studies for permethrin and other ULV mosquito adulticides. Thes e studies would be used to verify model inputs and model outputs. There is considerable use of permethrin as a ULV treatment to control adult mosquitoes. In its Problem Formulation, EPA discusses the various models it plans to use to arrive

at EECs for non

- target organisms. However, that section is silent on how EPA plans to arrive at EECs for permethrin levels in water that might result from ULV applications. Contrary to conventional spray applications, t he purpose of ULV applications is to create a f og or mist of droplets that remain suspended, so that adult mosquitoes come into contact with them.

2 Delgado

- Moreno, L, L. Wu and J. Gan. 2010

. Effect of Dissolved Organic Carbon on Sorption of Pyrethroids to

Sediments

. Environ. Sci. Technol.

, 2010

, 44 (22), pp 8473

– 8478

### 25 In the past, EPA has used the AGDISP (AGricultural DISPersal) model to calculate EECs, for example in the effects determination for the Valley Elde rberry L onghorn Beetle (VELB) assessment

. There is uncertainty in the applicability of AGDISP to ULV mosquito adulticide uses, and to the authors’ knowledge, predictions of AGDISP have not been compared with measured deposition or drift of any ULV spray

. There i s a study relevant to the drift of ULV permethrin applications (Zhai & Groome [1995]; MRID 45486202). The results of this study should be compared, as possible, with model inputs

and model

- derived EECs for permethrin. Also, EPA has generally accepted the idea that, environmental

conditions being equal, drift is primarily a function of the droplet size spectrum of the spray. Chemical specific factors are less important. There are several studies that show the drift and percent deposition of

ULV applicati ons. It is suggested that EPA compare any model

- derived EECs for permethrin with the

results of the literature studies on other ULV mosquito adulticides, as a verification step for the plausibility of the model results. T he assu mptions needed for AGDISP should be realistic. In the past for other ULV adulticides, EPA has made non

- representative assumptions about numbers of applications, nozzle type, and the height at which the airplane flies. It is suggested that EPA plan to refine any

AGDISP modeling tha t is designed to produce high

- end estimates of exposure, by using realistic inputs

for these variables.

EFED Response: In past EFED chapters for the Reregistration Eligibility Decisions of mosquito adulticides, the Division initially used conservative as sumptions because labels for these chemicals were very open regarding application parameters. In the year 2005, PR Notice 2005

- 1 was issued (see the following site accessed 10/ 11 /2011 http://www.e pa.gov/PR_Notices/pr2005

- 1qa.htm ). This notice imposed significant restrictions regarding applica tion parameters for adulticides which will be taken in consideration, along with the label restriction s when the Registration Review ecological risk assessmen t is written.

A study comparing deposi tion of another pesticide (malathion) used as an adulticide was published in 2005

. 3

The registrant

- r eferenced 1995 study ( Zhai & Groome ) will be evaluated regarding application parameters and suitability of methods ( e.g. , droplet size spectrum, boom height

, particularly if aerial applications were included)

, etc . to determine whether it provides useful information that may be used to refine developed EECs in the Registration Review ecological risk assessment. The app lication parameters should be comparable to the currently required ones, as per PR Notice

2005

- 1.

58

. PDGII Comment: EPA noted that standard laboratory tests and incident reports suggest that permethrin has the potential to adversely affect honey bees. As such, EPA has held certain study requirements “in reserve” as the data relating to honey bee risk and the methods for honey bee testing are being developed. In the Problem Formulation, EPA states that “information from standard laboratory

tests and pe rmethrin incident reports suggest the potential for risks to honeybees and other beneficial

insects

. ” The Problem Formulation notes that in the assessment for the V ELB

, EPA also concluded that there are potential effects of permethrin on invertebrate poll inators of elderberry. However, due to several considerations, such as the non

- systemic nature of permethrin, available information on residues in bees, pollen, and wax, and further development of pollinator risk assessment guidelines, EPA has

decided to hold any further data requirements “In Reserve”. In the Problem Formulation, EPA

3 Mickle, R.E. 2005. Direct comparison of deposit from aerial and ground ULV applications of malathion with AGDISP predictions. REMSpC Report 2005

- 02. Study performed by REMSpC Consulting, ON, Canada and reported to Institut national de santé publique du Québec (INSPQ), Sainte

- Foy (Québec), Canada. 83 pp. ( accessed

10/06/2011 at http:/ /www.inspq.qc.ca/pdf/publications/483

- DirectComparisonMalathion.pdf ).

### 26 summarized the incident reports for terrestrial species that involved permethrin. The timeframe of the incidents is 1994 to the present. There are 3 incidents that involved permethrin and bees: I003826

- 028,

I0209998

- 040, and I012515

- 004. The first 2 incidents were caused by accidental or intentional misuse.

The third incident was rated as Possible, but the Legality of Use was rated Unknown. Permethrin has a wide variety o f uses that could result in exposure of honeybees. Yet there have only been 3 incidents of bee mortality reported since 1994. Two of those incidents were some form of misuse, and the other one has an unknown legality of use. This seems to be a very small number of incidents for a widely used compound like permethrin. Furthermore, declines in our Nation’s bee colonies have prompted a high level of scrutiny of the causes for bee mortality. It seems likely that EPA’s concern about only a small

fraction of incidents that occur are actually reported is much less likely for a high profile effect on honeybee colonies, which are tended and monitored closely by beekeepers. It is suggested the EPA keep these facts in mind as it decides what, if any, additional da ta may be required to gauge the effects of permethrin on pollinators.

EFED Response: EFED agrees that the nature and number of permethrin incidents that involve bees and other pollinators will be considered as part of any future decision regarding the need for additional data on pollinator effects or exposure. Because incident data are not systematically collected, a lack of incidents is not considered evidence that incidents do not happen. A single incident provides evidence that a labeled pesticide c a n result in an effect, such as a bee kill. The Agency will be considering the findings of the recent 2011 Pesticide Risk Asse ssment for Pollinators: Summary of a SETAC Pellston Workshop ( http://www.setac.org/sites/default/files/executivesummarypollinators_20sep2011.pdf )

, in addition to a forthcoming Scientific Advisory Panel on pollinator risk assessment

, to determine

the need for additional data.

59

. PDGII Comment: EPA is requiring studies on the toxicity of combination products of permethrin with piperonyl butoxide and MGK

- 264, to evaluate the degree of enhancement these synergists cause. To do so, EPA is requiring that formulations containing the maximum ratio of synergist to permethrin be tested, because higher ratios of synergist to permethrin are expected to increase the degree of synergism. EPA further points out that the ultimate ratios of synergist to permethrin in the environment may differ

from t he ratios in the formulations, and may alter toxicity. It is suggested that EPA consider not only the ratio of synergist to permethrin, but also the absolute amount of the synergist. It is further suggested that EPA take into account that the degree of s ynergism may not be constant for low, intermediate, or high responses ( e.g. , lethal concentrations such as LC 10 , LC 50 , or LC 90 ), even for the same ratio of synergist to permethrin.

It is well established that piperonyl butoxide and MGK

- 264 can cause greater than additive toxicity (synergism) of pyrethroids in general. EPA is requiring initial testing of formulated products containing the highest ratio of piperonyl butoxide or MGK

- 264 to permethrin, using H. azteca

. This request is

consist ent with EPA’s evolving approach for evaluating the degree of synergism that occurs for other compounds synergized by piperonyl butoxide or MGK

- 264. The rationale for requesting the highest ratio of synergist to permethrin is that there is a positive corr elation between that ratio and enhancement of toxicity. However, the degree of synergism can also be due to the absolute amount of the synergist, as

### 27 well as the ratio (Wickham 1998). 4 Also, the degree of synergism may not be uniform across the range of

r esponses ( e.g. , LC 10 , LC 50 , or LC 90 ) (Holborn 1957). 5

EPA notes that the ratio of synergist to permethrin that occurs in the environment may be quite different than the ratio that occurs in a formulated product, because the synergist and permethrin may have substantially different environmental fate properties. To address this concern, EPA will attempt to bridge results from ongoing “comprehensive” synergist testing being done at varying synergist to active ingredient ratios

. If however, this comprehensive testing should prove to be insufficient to enable scientifically defensible bridging, EPA may apply a toxicity enhancement factor to address uncertainty regarding differences in synergist

- to

- permethrin ratios in the enviro nment versus those tested in formulated products. If EPA does take this latter approach, it is suggested that not only the ratio of the synergist to permethrin be considered, but also the absolute amount of synergist. Furthermore, the degree

of enhanceme nt at toxicity levels relevant to risk assessment should also be kept in mind.

EFED Response: The Agency recognizes that the synergistic effect of PBO & MGK

- 264 on pyrethroid toxicity may be concentration and/or ratio dependent. T he ongoing "comprehensi ve" synergist testing with pyr e thrins and PBO is expected to provide additional insight into this

issue. The Agency will consider all available ev idence on the factors, such as the synergist to

a ctive ingredient ratios or absolute concentrations

, that best enable bridging the results

from combined synergist/pyrethroid toxicity tests to other pyrethroids and their application

to ecological risk assessment.

6 0

. PDGII Comment: The PDGII submitted a summary of ten labels from major producers of permeth rin products for EFED ( and BEAD ) ’s review. Besides the basic application parameters, the tables give comments under “other” category.

EFED Response: At the time of the Registration Review ecological risk assessment, EFED will

evaluate the la bels for the submitted products and verify any changes made during the time period if any, such as addition of a crop, or changes in application parameters ( e.g. , application interval, application rate and seasonal /yearly rate). EFED appreciates the submission of the summary tables for the ten permethrin products

.

4 Wickham J. 1998. The use of synergized pyrethroids to control insect pests in and around domestic, industrial, and

food

- handling premises. In Piperonyl Butoxide: The Insecticide Synerg ist, Jones DG, ed. Academic Press, London 1998, pp. 239

- 260.

5 Holborn JM. 1957. The susceptibility to insecticides of laboratory cultures of an insect species. J. Sci

. Food Agric

8:182

- 188.