Docket Number: EPA-HQ-OPP-2009-0637 

www.regulations.gov

Deltamethrin Final Work Plan 

Registration Review 

September 2010 

3

DELTAMETHRIN FINAL WORK PLAN 

Introduction: 

This is the Environmental Protection Agency’s (EPA’s) Final Work Plan for the 

registration review of deltamethrin. This work plan includes the expected registration 

review timeline. The work plan also addresses public comments received concerning the 

Preliminary Work Plan in the Summary Document, which was posted in the 

deltamethrin registration review docket (EPA-HQ-OPP-2009-0637), and any other 

comments concerning the initial docket postings. The Summary Document provided 

information on what EPA knows about the pesticide and what additional risk analyses 

and data or information the Agency believes are needed to make a registration review 

decision. 

The Agency is implementing the registration review program pursuant to Section 3(g) of 

the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each 

registered pesticide every 15 years to determine whether it continues to meet the FIFRA 

standard for registration. Changes in science, public policy, and pesticide use practices 

will occur over time. The registration review program is intended to make sure that, as 

the ability to assess risk evolves and as policies and practices change, all registered 

pesticides continue to meet the statutory standard. The public phase of registration 

review begins when the initial docket is opened for each case. Information on this 

program is provided at: http://www.epa.gov/oppsrrd1/registration_review/. 

Deltamethrin is a pyrethroid registered for use on cotton, sorghum, artichokes, pears and 

a variety of vegetable, fruit, and tree nut crops for the control of a broad spectrum of 

pests including mites, ants, weevils, and beetles. It is also registered for use in residential 

and industrial applications for the control of cockroaches, pests of stored commodities, 

and other nuisance or destructive insects. A deltamethrin pet collar is registered for the 

control of fleas and ticks. Deltamethrin was first registered in the U.S. in 1994, and 

products containing deltamethrin were first marketed in the United States in 1997. 

Deltamethrin is also a metabolite of the pyrethroid pesticide tralomethrin, so that 

deltamethrin may occur as a result of the applications of tralomethrin. Since the 

deltamethrin PWP was issued, the tralomethrin registrant has requested to voluntarily 

cancel all uses of tralomethrin. More information on tralomethrin can be accessed via 

www.regulations.gov under Docket ID OPP-2010-0116. 

Comments Received on Preliminary Work Plan: 

Multiple comments were received during the 60-day public comment period on the 

Preliminary Work Plan. These comments are summarized in this document and changes 

to the work plan set out in the Preliminary Work Plan are explained. In the Preliminary 

Work Plan, EPA also solicited comments on three specific topics: environmental justice, 

water body impairment, and trade irritants. No comments or information were received 

during the comment period concerning environmental justice or trade irritants. 
4

Comments were received from three commenters regarding water body impairment. As a 

result of comments additional data are required for deltamethrin and are described below. 

For further discussion on these comments please see the Summary of Comments and 

Agency Responses section below. 

Anticipated Risk Assessment and Data Needs:

The Agency expects to require data needed to update and revise the ecological risk 

assessment for deltamethrin (including an endangered species risk assessment) and the 

human health risk assessment. 

Ecological risk 

The most recent assessment for deltamethrin was conducted in 2007, prompted by a 

proposal for a new tolerance for flax. The 2007 assessment references a 2002 

assessment, and the 2002 assessment in turn references a 1994 assessment: 

 “EFED Section 3 Registration of Deltamethrin for use on Flax and Results from 

the Submission of a 6(a)2 Adverse Effects Daphnid Study,” USEPA, September 

27, 2007. 

 “Tolerance Petition for Uses of Deltamethrin (PC Code 097805) on Field Corn, 

Sorghum, Soybeans, Sunflowers, Bulb Vegetables, Cucurbit Vegetables, Leafy 

Vegetables, Fruiting Vegetables, Carrots, Potatoes, Radishes, Artichokes, 

Cauliflower, Broccoli, Cabbage, Mustard Greens, Tree Nuts, Stone Fruits, and 

Pome Fruits (DP Barcode D262498) Incremental Ecological Effects Risk 

Assessment Due to the New Uses,” USEPA, August 6, 2002. 

 “Ecological Effects Branch Review of Deltamethrin,” USEPA, January 17, 1994.

The Agency has not conducted a risk assessment that supports a complete endangered 

species determination for deltamethrin. The ecological risk assessment planned during 

registration review will allow the Agency to determine whether deltamethrin’s use has 

“no effect” or “may affect” federally listed threatened or endangered species (listed 

species) or their designated critical habitats. When an assessment concludes that a 

pesticide’s use “may affect” a listed species or its designated critical habitat, the Agency 

will consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries 

Service (the Services), as appropriate. 

The Agency anticipates requiring the following data in order to conduct a complete 

ecological risk assessment, including an endangered species assessment, for deltamethrin:

• Guideline # 835.4300 Aerobic Aquatic Metabolism 

• Guideline # 835.4400 Anaerobic Aquatic Metabolism 

• Guideline #s 835.6100 & 6200 Environmental Chemistry Methods and 

Independent Laboratory Validations for Soil, Water and Sediment 

• Guideline # 850.2100 Passerine Acute Avian Oral 

• Guideline # 850.1400 Fish Early Life Stage (saltwater) 
5

• Guideline # 850.1500 Fish Life Cycle (saltwater) 

• Guideline # 850.1350 Aquatic Invertebrate Life-Cycle (saltwater) 

• Guideline # 850.1790 Whole sediment, chronic invertebrates freshwater and 

marine 

• Guideline # 850.4150 & 4250 Vegetative vigor and Seedling emergence, Tier I/ 

Tier II 

• Guideline # 850.4400 Aquatic Vascular Plant Growth-Lemna spp. Tiers I/II 

• Guideline # 850.5400 Algal toxicity test, Tier I/II 

• Non-guideline Aquatic Invertebrate Acute Toxicity (Hyalella azteca)

The following data would be used to inform removal percentages by waste water 

treatment, which is an input to the Exposure and Fate Assessment Screening Tool’s (EFAST) down-the-drain module. The Office of Pesticide Programs will continue to 

confer with the Office of Water with the goal of refining our down-the-drain assessment 

for registration review. These studies should be conducted on deltamethrin. 

o POTW Effluent Monitoring; 

o POTW Treatability Study. 

Please refer to the document “Environmental Fate and Ecological Risk Assessment 

Problem Formulation in Support of Registration Review for Deltamethrin, March 23, 

2010,” for a more detailed discussion of anticipated ecological risk assessment data 

needs.

Human Health Risk 

The most recent assessment for deltamethrin was conducted in 2009, prompted by a 

proposal for a new tolerance for flax. The assessment is documented in: 

 “Tier I Estimated Drinking Water Concentrations of Deltamethrin for the Use in 

the Human Health Risk Assessment: IR-4 Tolerance Petition for the Use of 

Deltamethrin on Flax,” USEPA, April 24, 2007. 

 “Deltamethrin--Response to Tolerance Petition for Use on Flax,” USEPA, August 

13, 2009. 

Additional analyses are discussed in: 

 “Deltamethrin--Human Health Assessment Scoping Document in Support of 

Registration Review,” USEPA, February 17, 2010. 

This latter document includes an aggregate risk assessment that incorporates residential 

uses not covered by the 2009 assessment, and documents some aggregate risk estimates 

of concern. The Agency believes that a refined assessment utilizing additional data and 

new assessment methodologies may reduce some of these risk estimates relative to 

conservative, default data and methodologies. For some residential uses with very low 
6

MOEs, refinement of the risk assessment is not likely to reduce risk estimates below 

levels of concern, and the Agency is currently working with affected registrants to 

mitigate the risks. 

• The existing residue chemistry database for deltamethrin is adequate for risk 

assessment purposes. 

• The Agency is investigating the need for additional experimentation, regarding 

the pharmacokinetics of pyrethroids and the potential for increased susceptibility 

of young organisms. The Agency will revisit its decision on the need for an 

FQPA or other database uncertainty/safety factors following receipt of the toxicity 

data the Agency expects to require, and following a final determination of the 

potential for increased susceptibility of infants and children to pyrethroid 

pesticides based on the results of all available data. 

• Aside from the potential outcome of the research described above, the toxicology 

database for deltamethrin is essentially complete, with the exception of the 

immunotoxicity data. The Agency expects to require an immunotoxicity study 

(Guideline # 870.7800). 

• The Agency anticipates conducting a new dietary risk assessment in registration 

review to incorporate updated drinking water estimates, information on dietary 

consumption, and usage information. In order to better understand postapplication residential exposure, the Agency expects to require data on the 

transfer of deltamethrin residues from pets wearing deltamethrin flea collars to 

humans. The Agency anticipates developing a refined aggregate assessment for 

combined exposures from food, drinking water, and residential exposures. 

• The Agency anticipates conducting a new occupational risk assessment in 

registration review, which would utilize any new and relevant toxicological 

endpoints, exposure data, policies, and incident data as appropriate. 

• Deltamethrin is an animal and environmental metabolite of another pyrethroid 

insecticide, tralomethrin. In recent assessments, the human toxicology endpoint 

selected for tralomethrin was derived from the same study as that used in 

assessing the risks associated with deltamethrin use, and the dietary risk 

assessment for deltamethrin accounted for tralomethrin use. Since the 

deltamethrin PWP was issued, the tralomethrin registrant has requested to 

voluntarily cancel all uses of tralomethrin. Depending on the outcome of the 

voluntary cancellation process the Agency may or may not include tralomethrin in 

any risk assessments. More information on tralomethrin can be accessed via 

www.regulations.gov under Docket ID OPP-2010-0116. 

• In 1997, tolerances for tralomethrin and deltamethrin were reassessed in response 

to a general policy change in which time limitations for tolerances were deleted. 

For this FQPA reassessment, exposures associated with the use of both 
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tralomethrin and deltamethrin were combined. The basis for this approach was 

that tralomethrin is rapidly metabolized by animals to deltamethrin (as a result of 

debromination) and the toxicology profiles of deltamethrin and tralomethrin are 

virtually identical. Since the tralomethrin registrant is pursuing voluntary 

cancellation of tralomethrin, future tolerance expressions and dietary assessments 

for deltamethrin may be modified to account for this change. 

• Deltamethrin is a member of the pyrethroid class of insecticides. This class also 

includes permethrin, cypermethrin, cyfluthrin, tau-fluvalinate, bifenthrin, 

fenpropathrin, and lambda-cyhalothrin, among others. EPA developed a draft 

science policy document on the proposed common mechanism of toxicity for 

naturally-occurring pyrethrins and synthetic pyrethroids (Draft Science Policy 

Paper: Common Mechanism Grouping for the Pyrethrins and Synthetic Pyrethroid 

Pesticides, May 19, 2009, available in the docket at 

http://www.regulations.gov/search/Regs/home.html#documentDetail?R=0900006

4809a62df ). The FIFRA Scientific Advisory Panel (SAP) supported the draft 

science policy (Minutes from the SAP meeting on the Evaluation of the Common 

Mechanism of Action of the Pyrethroid Pesticides, September 9, 2009, available 

in the docket at 

http://www.regulations.gov/search/Regs/home.html#documentDetail?R=0900006

480a1f8d7). EPA will finalize the policy document on the pyrethroid common 

mechanism of toxicity taking into account the recommendations of the SAP. 

Pesticides with a common mechanism of toxicity are subject to cumulative risk 

assessment under the FQPA. Research is on-going by EPA’s Office of Research 

and Development (ORD) to make improvements to the Stochastic Human 

Exposure and Dose Simulation (SHEDS) probabilistic exposure model, which are 

important for the cumulative risk assessment. EPA ORD is also developing 

physiologically-based pharmacokinetic models for several pyrethroids. The status 

of both of these research modeling efforts will be reviewed by the FIFRA SAP in 

July, 2010. For information regarding EPA’s efforts to evaluate the risk from 

pyrethroids, see http://www.epa.gov/oppsrrd1/reevaluation/pyrethroidspyrethrins.html. 

• During registration review, the tolerance expression for deltamethrin in 40 CFR § 

180.435 will be reviewed to ensure that it appropriately covers the metabolites 

and degradates of deltamethrin and that it specifies the residues to be measured 

for each commodity. Any proposed revisions would be to the chemical 

description rather than the individual tolerance levels. 

The Agency anticipates needing the following data in order to conduct a complete 

human health risk assessment for deltamethrin: 

• Guideline # 870.7800 Immunotoxicity 

• Special Study, Pet Collar Residue Transfer 
8

Please refer to the document “Deltamethrin. Human Health Assessment Scoping 

Document in Support of Registration Review,” February 17, 2010 for a more detailed 

discussion of human health risk estimates and anticipated human health risk assessment 

data needs. 

Other Data Needs 

• Guideline # 830.7050 UV/Visible Light Absorption – this study is a new data 

requirement under 40 CFR part 158 (Product Chemistry Data Requirements) for 

registration of a pesticide (food and non-food uses). The Agency anticipates 

requiring this study to obtain basic information about the compound’s 

identity/composition and the wavelengths at which the compound may be 

susceptible to photochemical degradation.

Endocrine Disruptor Screening Program

As required under FFDCA section 408(p), EPA has developed the Endocrine Disruptor 

Screening Program (EDSP) to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the 

Administrator may designate.” The EDSP employs a two-tiered approach to making the 

statutorily required determinations. Tier 1 consists of a battery of 11 screening assays to 

identify the potential of a chemical substance to interact with the estrogen, androgen, or 

thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier 1 screening and 

are found to have the potential to interact with E, A, or T hormonal systems will proceed 

to the next stage of the EDSP where EPA will determine which, if any, of the Tier 2 tests 

are necessary based on the available data. Tier 2 testing is designed to identify any 

adverse endocrine related effects caused by the substance, and establish a quantitative 

relationship between the dose and the E, A, or T effect. 

Between October 2009 and February 2010, EPA issued test orders/data call-ins for the 

first group of 67 chemicals, which contains 58 pesticide active ingredients and 9 inert 

ingredients. This list of chemicals was selected based on the potential for human 

exposure through pathways such as food and water, residential activity, and certain postapplication agricultural scenarios. This list should not be construed as a list of known or 

likely endocrine disruptors. 

Deltamethrin is not among the group of 58 pesticide active ingredients on the initial list 

to be screened under the EDSP. Under FFDCA sec. 408(p) the Agency must screen all 

pesticide chemicals. Accordingly, EPA anticipates issuing future EDSP orders/data callins for all Registration Review cases, including those for which EPA has already opened 

a Registration Review docket for a pesticide active ingredient. 

For further information on the status of the EDSP, the policies and procedures, the list of 

67 chemicals, the test guidelines and the Tier 1 screening battery, please visit our 

website: http://www.epa.gov/endo/. 
9

Timeline: 

EPA has created the following estimated timeline for completion of the registration 

review for deltamethrin. 

Projected Deltamethrin Registration Review Timeline 

Activities Estimated Date 

Opening the docket 

Open Docket and Public Comment Period 2010 – March 

Close Public Comment 2010 – May 

Case Development 

Final Work Plan 2010 – August 

Issue DCI 2011 – April - June 

Data Submission 2013 – April - June 

Open Public Comment Period for Preliminary Risk Assessments 2014 – Oct. – Dec. 

Close Public Comment Period 2015 – Jan. - March 

Registration Review Decision 

Open Public Comment Period for Proposed Registration Review 

Decision 

 2015 – April - June 

Close Public Comment Period 2015 – July – Sept. 

Final Registration Review Decision and Begin Post-Decision 

Follow-up 

 2016 

Total (years)* 6 

* An assessment of the potential cumulative risk from the pyrethroid class of insecticides may impact this 

time estimate.

Summary of Comments and Agency Responses: 

The deltamethrin registration review docket was open for a 60-day comment period 

beginning on March 31, 2010. During the comment period, multiple comments were 

received. Some of the comments received prompted changes in the work plan. 

Comments received regarding data requirements and comments received that necessitated 

changes to the deltamethrin work plan are addressed below. Please see Deltamethrin. 

Response to Comments on the Human Health Assessment Scoping Document, dated 

August 12, 2010, and Preliminary Workplan and Response to Comments on the 

Registration Review – Environmental Fate and Ecological Risk Assessment Problem 

Formulation in Support of Registration Review for Deltamethrion (PC Code 097805; DP 

Barcode D379665, dated August 18, 2010, located in docket number EPA-HQ-OPP2009-0637, for EPA’s responses to other comments received. 

This document makes final the work plan for the deltamethrin registration review 

process. 
10

Comments by Tri-TAC/East Bay Municipal Utility District and County Sanitation 

Districts of Los Angeles County [EPA-HQ-OPP-2009-0637-0013 and EPA-HQ-OPP2009-0637-0018] (Note: These comments are substantially similar are thus addressed 

together)

Comment 1: The submitters stated that the deltamethrin work plan does not identify 

indoor uses as a possible route of aquatic exposure and would like it to reflect impacts on 

urban water quality from sewer discharge from the indoor uses of deltamethrin. They 

indicate that some of the indoor uses of deltamethrin include surface treatment (aerosols, 

foggers or sprays), treatment of carpets and of animal kennels and pet sleeping quarters, 

pet collars, and sewer treatments could result in indoor discharges into sewer systems 

when treated surfaces are washed with water which is disposed of down-the-drain. 

Contaminated disposal water may arise from treated surfaces washed with water; carpet 

cleaning water; rinse water from mops, rags or brushes used to clean treated surfaces; or 

pet bathe rinse waters. Pesticide discharged in water via these routes (down-the-drain) 

may reach publically owned treatment works (POTWs), and subsequently be discharged 

into the environment in effluent and/ or in biosolids from POTWs. Submitters stated that 

EPA should evaluate potential impacts from deltamethrin in both POTW effluents and 

biosolids (which may be subsequently applied to land) as part of the risk assessment. 

Stress was placed on the fact that adsorption to biosolids and volatilization/ stripping are 

“cross-media transfer” processes as opposed to “removal mechanisms.” They indicate 

that the potential impacts of such processes should be addressed in the ecological risk 

assessment. Submitters also cited a study which found that pyrethroids are not 

completely removed or degraded during wastewater treatment and are present in final 

POTW effluent. 

Response 1: The Agency agrees that indoor uses can result in discharges of deltamethrin 

residues into sewer systems and will be included in the assessment as a possible route of 

exposure to the environment. Assumptions will be used to quantify the potential loading 

to drainage systems. Discharge of deltamethrin into the environment via effluent will be 

considered to the best degree possible in the assessment. However, deltamethrin in 

biosolids is not anticipated to be assessed during registration review. At this time, the 

Agency does not have a methodology to assess the exposure resulting from application of 

biosolids to land. The Agency has begun discussions with other EPA Offices to explore 

methodology to make quantitative estimates of exposures due to biosolids applied to 

land. EPA recognizes the potential exposure from down-the-drain sources of pyrethroids, 

and will continue to investigate ways of more accurately reflecting these sources in fate 

and ecological exposure assessments. 

Comment 2: Tri-TAC and the Districts recommended that additional data should be 

requested to inform the risk assessment. They supported the data call-in for aquatic 

toxicity data and recommended that the Agency imposed stringent conditions on issuing 

waivers and withhold registration decisions until required toxicity data are submitted. 

 

Response 2: The Agency has requested chronic toxicity data for estuarine/marine fish 

and invertebrates. Furthermore, chronic whole sediment toxicity data are necessary to 
11

establish the effects assessment of pyrethroids such as deltamethrin towards benthic 

communities. Besides the data required in the preliminary problem formulation, the 

Agency will also call for an acute (96-hour) Hyallela azteca water column toxicity study 

to better characterize the acute route of exposure for the most sensitive aquatic 

invertebrate species. More information regarding EPA’s future request for this study is 

included in this document after the “Next Steps” section of the document. 

The Agency will use the E-FAST down-the-drain model or a more refined version of the 

model for assessment of wastewater effluent exposure. However, modifications to the 

model are currently being discussed. EPA will utilize all the data available in 

determining the potential for deltamethrin to reach ecological receptors through 

wastewater effluent. To that end, the Agency is requesting that any existing or ongoing 

pyrethroid POTW effluent monitoring data be submitted. 

Comment 3: The submitters commented on the costs of toxicity bioassays required by 

NPDES permits, the costs of chemicals monitoring and other related costs, the costs of 

removing a toxicant and the costs related to maintain or upgrade POTWs. 

Response 3: The Office of Pesticide Programs does not have jurisdiction over the cost of 

these procedures. 

 

Comments by the California Stormwater Quality Association (CASQA) [EPA-HQ-OPP2009-0637-14]

Comment 1: CASQA requests to include an assessment of the outdoor urban uses of 

deltamethrin by expanding the conceptual model and the analysis plan of the problem 

formulation. The modeling approach for the urban uses should include uses such as 

broadcast applications on impervious surfaces around buildings. 

Response 1: The above mentioned exposure pathway will be included in planned 

ecological risk assessment for deltamethrin. 

Comment 2: CASQA requests that both water column and sediment exposures be 

evaluated by EPA. 

Response 2: The Agency routinely uses the tier 2 coupled aquatic models PRZM/ 

EXAMS to develop EECs to be used with the toxicity tests to calculate risks quotients in 

the water column and in the pore water (of the sediment phase). As indicated above (in 

response to comment from Tri-TAC and the Districs), at this time, the EPA is requiring 

chronic whole sediment toxicity testing for all the synthetic pyrethroids undergoing reevaluation. Furthermore, acute water column testing on the aquatic invertebrate Hyalella 

azteca is also being required, as this organism is known to be particularly sensitive to 

pyrethroids. 
12

Comments by Bayer Crop Science (BCS) [EPA-HQ-OPP-2009-0637-0016]

Comment 1: BCS has indicated that the assessment of tralomethrin as a source of 

deltamethrin will not be required because they intend to cancel all uses of tralomethrin. 

Response 1: During registration review, if tralomethrin tolerances have been canceled 

and there is no longer a need to include residues resulting from the use of tralomethrin in 

any assessments, these residues will not be included. However, if for some reason the 

Agency believes that tralomethrin still needs to be accounted for in an assessment, for 

example, if tralomethrin is still in the channels of trade, then the Agency will continue to 

account for tralomethrin in the assessment. 

Comment 2: BCS submitted comments on each of the studies proposed to be required in 

the deltamethrin registration review data call-in. A summary of their comments, and 

EPA’s responses, is included below. 

Summary of BCS Comments on Proposed Deltamethrin Data Requirements and EPA 

Response 

Guideline Number BCS Comment EPA Response 

835.4300 Aerobic 

Aquatic Metabolism 

An aerobic aquatic 

metabolism study is being 

conducted and will be 

submitted. 

Acknowledged 

835.4400 Anaerobic 

Aquatic Metabolism 

BCS intends to conduct this 

study. 

Acknowledged 

835.6100, 835.6200 

Environmental 

Chemistry Methods 

and Independent 

Laboratory 

Validations for soil, 

water, and sediment 

BCS is submitting two 

Analytical Methods for soil, 

water and sediment, and 

agrees to submit the 

corresponding Independent 

Laboratory Validations. 

BCS indicates that the 

analysis of some of the 

degradates is not necessary 

due to their low toxicity 

compared to the parent 

compound. 

EPA will evaluate the submitted 

information for their suitability. 

It is the responsibility of the 

registrant to submit information to 

support their assertion that the 

degradates of deltamethrin are of 

low toxicity. 

850.2100 Passerine 

Avian Oral Toxicity 

BCS states that there is 

sufficient data available to 

characterize the toxicity of 

deltamethrin to birds and that 

the avian acute risk picture 

for deltamethrin is unlikely 

to change by the submission 

of this study because the 

chemical is relatively nontoxic to birds. 

In 2007, the Agency updated its 

data requirements in 40 CFR Part 

158 to include an acute oral 

toxicity study for passerine 

species. As stated in the problem 

formulation, passerines are 

smaller and have faster 

metabolisms than waterfowl and 

upland game bird species 

traditionally used in avian toxicity 
13

tests which could impact their 

sensitivity to chemicals. 

Therefore the toxicity of 

deltamethrin is an uncertainty at 

this time. Registrants should 

submit any information available 

to address this uncertainty. 

850.1400, 850.1500 

Fish Early Life 

Stage/Fish Life 

Cycle 

(Estuarine/Marine) 

BCS believes that the 

existing data on toxicity to 

fish is sufficient. BCS 

indicates that at most, only 

one of the studies should be 

required. They suggest to 

conduct only the early life 

stage study. 

A chronic toxicity test is still 

required, but due to similarity in 

endpoints for the freshwater fish 

early life stage and full life cycle 

studies, an early life stage study 

for estuarine/marine fish may be 

adequate. 

850.1350 Aquatic 

Invertebrate Life 

Cycle 

BCS agrees to submit a 

mysid chronic life cycle 

study. 

Acknowledged. 

850.1790 Whole 

sediment; chronic 

invertebrates 

freshwater and 

marine 

BCS indicates it would like 

to work with the Agency, 

industry, and scientific 

experts to ensure that 

methods to evaluate toxicity 

of sediments are robust, 

rliable, and predictive. 

Acknowledged. EPA welcomes 

input regarding evaluation of 

pyrethroid toxicity to sedimentdwelling organisms. 

850.4150, 850.4250 

Vegetative Vigor 

and Seedling 

Emergence, Tier 

I/Tier II 

BCS will submit a set of 

representative Tier 1 nontarget plant studies with 

deltamethrin. However, it is 

indicated that they were not 

conducted according to GLP. 

These studies may be used as 

supplemental information in 

the risk assessment, but do 

not fulfill the guideline 

requirement. 

Acknowledged. Once submitted, 

the studies will be evaluated for 

use in the final risk assessment. 

850.4400 Aquatic 

Vascular Plant 

Growth – Lemna 

spp. Tiers I/II 

BCS asserts that because 

deltamethrin is a pyrethroid 

and non-phytotoxic, a 

toxicity study with Lemna 

spp. will not be expected to 

impact the overall risk 

assessment. 

No studies have been submitted to 

demonstrate the lack of 

phytotoxicity to aquatic vascular 

plants, there fore a study is 

required to address this 

uncertainty. 

850.5400 Algal 

toxicity test, Tier I/II 

BCS indicates that two algal 

toxicity studies have already 

been submitted to EPA. In 

EPA has received two algal 

studies from the registrant. Once 

submitted the three additional 
14

addition three other studies 

will be submitted. 

algal studies will be reviewed to 

inform the deltamethrin risk 

assessment. 

870.7800 

Immunotoxicity 

BCS acknowledges data 

deficiency and will respond 

accordingly to the DCI. 

During registration review, the 

Agency will evaluate any new 

immunotoxicity data submitted by 

BCS and will incorporate the 

results into the overall hazard 

characterization and risk 

assessment. 

Special Study: Pet 

Collar Residue 

Transfer 

BCS provided information 

received from a 

manufacturer of a pet collar 

product concerning the mode 

of action of the flea collar 

and the quantity of 

deltamethrin released. 

EPA appreciates the additional 

information provided. In its 

comment, BCS mentions a study 

in which the extent of 

deltamethrin release over time 

was confirmed. EPA would like 

for this study and any other 

pertinent information be 

submitted in response to this data 

requirement. 

830.7050 

UV/Visible Light 

Absorption 

BCS did not comment on 

this proposed study. 

None 

Comments by Physicians Committee for Responsible Medicine (PCRM) [EPA-HQ-OPP2009-0637-0015] 

Comment: PCRM would like EPA to use Organisation for Economic Co-operation and 

Development (OECD) guideline for acute avian oral toxicity, which is on the verge of 

adoption by OECD. 

Response: The Agency requires a toxicity test be conducted to estimate the acute oral 

LD50 of deltamethrin to a passerine species. PCRM recommends that the new OECD test 

guideline be used for this test because it uses considerably fewer animals than the 

traditional LD50 test described by Test Guideline 850.2100. The new OECD test 

guideline for measuring avian acute oral toxicity with a sequential dosing procedure is 

Test Guideline (TG) 223. Current policy within the Office of Pesticide Programs 

regarding the acceptance of avian acute effects studies conducted using the TG 223 

protocol states the following: 

Until the OECD TG 223 validation process is completed and the guideline 

has been approved by OECD, studies that utilize this guideline should not 

be classified; pending results of the validation, they may then be classified 

as ‘acceptable,’ assuming that they meet all other guideline requirements. 

To date the OECD has adopted the TG 223 guideline and has issued a validation report. 

At this time EFED is actively evaluating the results of the OECD validation report to 
15

determine if the TG 223 effects endpoints and dose/response information adequately 

address the purposes of the avian acute oral data requirement as described in 40 CFR Part 

158. Until the Agency’s evaluation of that validation report is completed, EFED will not 

classify avian toxicity studies performed using the TG223 protocol and the studies cannot 

be used to fulfill data requirements. Therefore, we cannot say at this time whether or not 

avian toxicity studies done under TG 223 will be acceptable to meet our data 

requirements. 

Validation work conducted on TG 223 test guideline to date has been limited to studies 

with the upland game birds (e.g., northern bobwhite). Because no work has been done to 

date to validate this guideline for passerine species, it is doubtful that we would accept 

studies done under this guideline for fulfilling requirements for passerine acute toxicity 

data unless additional validation work with passerines is done. 

Next Steps: 

o The Agency plans to issue a DCI in mid 2011, requiring the deltamethrin studies 

needed to complete the human health, ecological, and endangered species risk 

assessments.

Additional Data: 

o Comments were received regarding water body impairment. As a result of these 

comments, additional data not previously identified in the deltamethrin 

preliminary work plan are required and are described below. 

Guideline Number: Non-guideline 

Study Title: Aquatic Invertebrate Acute Toxicity (Hyalella)

Rationale for Requiring the Data 

Available information in the Agency ECOTOX database indicates that the freshwater 

amphipod, Hyalella azteca, is substantially more sensitive to pyrethroids than Daphnia 

magna, the commonly tested freshwater invertebrate. Information on the acute toxicity of 

deltamethrin to H. azteca was not identified in this problem formulation. Therefore, in 

order to ensure that risk to sensitive aquatic invertebrates are appropriately quantified, 

additional acute toxicity testing of H. azteca is needed (water column exposure, not 

sediment-spiked).

Practical Utility of the Data 

How will the data be used? 

The freshwater acute toxicity study with Hyalella would allow the Agency to analyze 

acutely toxic effects to one of the most sensitive species of freshwater aquatic invertebrates. 

The effects data would be used to determine the likelihood that acute risks can potentially 

impact aquatic communities, either by direct effects on invertebrates or by indirect effects 

by reducing the food source for their predators (e.g., fish). By refining the assessment, the 

Agency would be able to determine whether the mitigation imposed as part of the 

registration review process was appropriate due to toxicity concerns with deltamethrin. 
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How could the data impact the Agency’s future decision-making? 

If future risk assessments are performed without these data, the Agency would have to 

account for the potential increased sensitivity of Hyalella to deltamethrin using other means 

which may include using an extrapolation factor based on sensitivity differences with other 

pyrethroids. Since this extrapolation factor would involve uncertainty, it is likely that a 

conservative factor would be applied. This may impinge on the Agency’s flexibility in 

coming into compliance with the Endangered Species Act and could result in use 

restrictions for deltamethrin which are unnecessarily severe. 

Guideline Number: N/A 

Study Title: POTW Effluent Monitoring and POTW Treatability Study 

Rationale for Requiring the Data 

POTW Effluent Monitoring – Request any existing or ongoing POTW effluent monitoring data for 

the pyrethroids be submitted to the Agency. 

POTW Treatability Study – In addition, the Agency is anticipating requiring a bench scale study of 

waste water treatment. A pilot treatability study is required to better parameterize E-FAST for 

assessment of the “down-the-drain” exposure route. The pilot treatability study will characterize 

concentrations of deltamethrin in effluent, concentrations of deltamethrin in biosolids, and resulting 

removal efficiency in publically owned treatment works (POTWs) based on known concentrations of 

deltamethrin in influent. 

Practical Utility of the Data 

How will the data be used? 

These data would be used to inform removal percentages by waste water treatment, which is an input 

to the Exposure and Fate Assessment Screening Tool’s (E-FAST) “down-the-drain” module. 

How could the data impact the Agency’s future decision-making? 

Without these data, the Agency will have to make assumptions regarding the level of removal of 

deltamethrin (e.g., results of modeling from the EPIWEB v.4.0 may be used). These assumptions are 

likely to be crude and conservative. The lack of these data will limit the flexibility the Agency and 

registrants have in coming into compliance with the Endangered Species Act, and could result in use 

restrictions for deltamethrin which may otherwise be avoided, or which are unnecessarily severe.