Docket Number EPA-HQ-OPP-2010-0684 

www.regulations.gov

Cyfluthrins Summary Document 

Registration Review: Initial Docket 

September, 2010 

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TABLE OF CONTENTS 

 Page # 

I. Preliminary Work Plan (PWP) 9 

II. Fact Sheet 13 

III. Summary of Data Gaps 19 

 

This Preliminary Work Plan and Fact Sheet summarize the Environmental Protection Agency’s 

current position based on the following documents: 

1. EFED Registration Review Problem Formulation for Cyfluthrin and Beta-cyfluthrin, July 29, 

2010. 

2. Cyfluthrin and Beta-cyfluthrin Human Health Assessment Scoping Document in Support of 

Registration Review, July 1, 2010. 

3. Cyfluthrin and Beta-cyfluthrin Screening Level Usage Analysis (SLUA), September 28, 

2009. 

4. Usage/Use Report Package in Support of Registration Review for Cyfluthrin (128831),

January 26, 2010. 

 

5. Cyfluthrins: Review of Human Incidents, May 20, 2010 

All supporting documents for the registration review of cyfluthrin and beta-cyfluthrin are located in 

docket EPA-HQ-OPP-2010-0684 at www.regulations.gov. 
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I. PRELIMINARY WORK PLAN – Cyfluthrin and Beta-cyfluthrin 

Introduction

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. 

All pesticides distributed or sold in the United States (U.S.) generally must be registered by the 

Environmental Protection Agency (EPA or the Agency), based on scientific data showing that they 

will not cause unreasonable risks to human health or the environment when used as directed on 

product labeling. 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 of no unreasonable adverse effects to human health or the environment. Changes 

in science, public policy, and pesticide use practices will occur over time. Through the registration 

review program, the Agency periodically reevaluates pesticides to make sure that as change occurs, 

products in the marketplace can be used safely. Information on this program is provided at: 

http://www.epa.gov/oppsrrd1/registration_review/ . 

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. The Agency will consider benefits information and data as required by FIFRA. The 

public phase of registration review begins when the initial docket is opened for each case. The 

docket is the Agency’s opportunity to state what it knows about the pesticide and what additional 

risk analyses and data or information it believes are needed to make a registration review decision. 

After reviewing and responding to comments and data received in the docket during this initial 

comment period, the Agency will develop and commit to a final work plan and schedule for the 

registration review of cyfluthrin and beta-cyfluthrin. 

Cyfluthrin and beta-cyfluthrin are pyrethroid insecticides. They are both mixtures of eight 

isomers of the same compound. Cyfluthrin is composed of comparable percentages of eight isomers, 

whereas beta-cyfluthrin is an enrichment of the four most efficacious isomers. Cyfluthrin and betacyfluthrin products are registered for use on agricultural sites, residential indoor/outdoor areas, 

turf/ornamentals, pets/pet houses, poultry processing plant premises, recreational/golf areas, tobacco, 

and for use as an outdoor wood protection treatment. The first cyfluthrin registration was approved 

in 1987, while the first beta-cyfluthrin registration was approved in 1995. As a result, Reregistration 

Eligibility Decisions (REDs) have not been conducted for these compounds. 

Anticipated Risk Assessment and Data Needs

The Agency intends to require data needed to conduct a comprehensive ecological risk assessment, 

including an endangered species risk assessment, and to update and revise the human health risk 

assessment for all uses of cyfluthrin and beta-cyfluthrin. Below is a summary of the issues relevant 

to the registration review of cyfluthrin and beta-cyfluthrin and the data the Agency anticipates 

requiring. 
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Ecological Risk:

 The most recent ecological risk assessments on cyfluthrin and beta-cyfluthrin were 

conducted in 2007, 2006, 2004, and 2001 as a result of several new agricultural uses being 

added to the product labels. 

 The Agency has not conducted an ecological risk assessment that supports a complete 

endangered species determination for cyfluthrin or beta-cyfluthrin. The ecological risk 

assessment planned during registration review will allow the Agency to determine whether 

cyfluthrin and beta-cyfluthrin’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 (FWS) 

and/or National Marine Fisheries Service (NMFS) (the Services), as appropriate. 

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

risk assessment, including an endangered species assessment for cyfluthrin and betacyfluthrin. 

The following anticipated studies should be conducted on cyfluthrin: 

Environmental fate data gaps

 GDLN 835.1230– Leaching and Adsorption/Desorption (TGAI) 

 GDLN 835.4100 – Aerobic Soil Metabolism (TGAI, 2 Soils) 

 GDLN 835.4200 – Anaerobic Soil Metabolism (TGAI) 

 GDLN 835.6100 – Environmental Chemistry Method and Independent Laboratory 

 Validation for soil (Footnote 7) 

 GDLN 835.6200 – Environmental Chemistry Method and Independent Laboratory 

 Validation for Water and Sediment (Footnote 7) 

Ecological toxicity data gaps

 GDLN 850.2100 – Avian Oral Toxicity (passerine species) (TGAI) 

 GDLN 850.2300 – Avian Reproductive Study 

 GDLN 850.1025 – Oyster Acute Toxicity (saltwater, cyfluthrin TEP only) 

 GDLN 850.1035 – Mysid Acute Toxicity (saltwater, cyfluthrin TEP only) 

 GDLNs 850.4100 & 850.4150 – Seedling Emergence & Vegetative Vigor (Tier II) 

 GDLNs 850.4400 – Aquatic Vasular Plant Growth –Lemna spp. Tier II 

 Non-GDLN – Aquatic Invertebrate Acute Toxicity (Hyalella azteca) 

 GDLNs 850.1790 – Whole sediment: chronic invertebrates freshwater and marine 

The following anticipated studies should be conducted on beta-cyfluthrin: 
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Environmental fate data gaps

 GDLN 835.4100 – Aerobic Soil Metabolism (TGAI, 4 Soils) 

 GDLN 835.4300 – Aerobic Aquatic Metabolism (TGAI) 

 GDLN 835.4400 – Anaerobic Aquatic Metabolism (TGAI) 

 GDLN 835.6100 – Environmental Chemistry Method and Independent Laboratory 

 Validation for soil (Footnote 7) 

 GDLN 835.6200 – Environmental Chemistry Method and Independent Laboratory 

 Validation for Water and Sediment (Footnote 7) 

Ecological toxicity data gaps

 GDLN 850.1350 – Invertebrate Life Cycle, mysid 

 GDLNs 850.4100 & 850.4150 – Seedling Emergence & Vegetative Vigor (Tier II) 

 GDLNs 850.4400 – Aquatic Vasular Plant Growth –Lemna spp. Tier II 

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 (E-FAST) 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 can be conducted on 

either cyfluthrin or beta-cyfluthrin. The Agency is recommending that these studies be conducted 

on cyfluthrin. 

o Leachability from Treated Wood 

o POTW Effluent Monitoring 

o POTW Treatability Study 

Please refer to the “EFED Registration Review Problem Formulation for Cyfluthrin and Betacyfluthrin (July 29, 2010),” for a more detailed discussion of the anticipated ecological risk 

assessment and data needs.

Human Health Risk: 

 The most recent human health risk assessment was conducted in 2007 in association with 

new uses on grasses, alfalfa, and sugar beets. The mammalian toxicity is very similar for 

cyfluthrin and beta-cyfluthrin, and the combined toxicology database for cyfluthrin and betacyfluthrin is considered to be complete except for an immunotoxicity study. 

 Subsequent to the last risk assessment, the Agency identified age-dependent pharmacokinetic 

factors associated with all pyrethroid insecticides that might lead to uncertainty regarding 

effects in children. The Agency anticipates re-evaluating the points of departure (POD) and 

uncertainty factors used for human health risk assessment during registration review. 

 

 The dietary exposure database is adequate to support the existing registrations and tolerances. 

No new residue chemistry data are expected to be needed. A new drinking water assessment 
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may be conducted during registration review. Further, a revised dietary risk assessment may 

be conducted to include updated percent crop treated estimates, updated monitoring data, 

changes in toxicological endpoints, and revised estimated drinking water concentrations. 

 As a result of the revisions to the Agency’s Residential Standard Operating Procedures 

(SOPs), the parameters and algorithms for dermal, inhalation, and hand-to-mouth exposure 

calculations may change. These changes could result in significantly different exposure 

estimates for indoor and outdoor uses. Therefore, during registration review, a new 

residential exposure assessment is anticipated. 

 The potential changes mentioned above (toxicological endpoints, dietary exposure estimates, 

residential exposure estimates) have led to a determination that an updated aggregate risk 

assessment may be needed. 

 A revised occupational handler and postapplication assessments may need to be conducted 

based on updated doses and endpoints for dermal and inhalation risk assessments. 

 During registration review, the tolerance expressions should be revised so that they address 

both coverage and measurement. Please see the human health scoping document for more 

details. 

 Based on the Agency’s review of existing pyrethroid data, EPA has come to the conclusion 

that the DNT is not a particularly sensitive study for comparing the sensitivity of young and 

adult animals to pyrethroids. EPA has recently determined that, as an alternative to the 

generation and submission of a new DNT study, pyrethroid registrants may instead choose to 

cite the six previously submitted DNT studies for pyrethroid pesticides. The Agency is also 

investigating the need for additional experimentation, specific to the mode of action and 

pharmacokinetic characteristics of pyrethroids, to evaluate the potential for increased 

susceptibility of young organisms. Additional information can be found on EPA’s website: 

http://www.epa.gov/oppsrrd1/reevaluation/pyrethroids-pyrethrins.html. 

 The Agency will make a decision regarding changes to any database uncertainty/safety 

factors for the cyfluthrins following receipt of the remaining required toxicity data, 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. 

 Cyfluthrins are members of the pyrethroid class of insecticides. EPA has developed a draft 

science policy document on the proposed common mechanism of toxicity for naturallyoccurring pyrethrins and synthetic pyrethroids, which was supported by the FIFRA Scientific 

Advisory Panel (SAP). Upon finalization of this science policy, the pyrethroids will be 

subject to a cumulative risk assessment under the FQPA. 
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 The Agency anticipates requiring the following data in order to conduct a complete human 

health risk assessment for cyfluthrin and beta-cyfluthrin. The Agency recommends 

conducting this study with cyfluthrin: 

o GDLN 870.7800 – Immunotoxicity Study 

 Please refer to the “Cyfluthrin and Beta-Cyfluthrin Human Health Assessment Scoping Document in 

Support of Registration Review (July 1, 2010),” available in the docket, for a detailed discussion of the 

anticipated human health risk assessment and data needs for cyfluthrin and beta-cyfluthrin. 

Other Anticipated Data Needs: 

 OPPTS GLN 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, and 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 post-application agricultural scenarios. This list should 

not be construed as a list of known or likely endocrine disruptors. 

Cyfluthrins are among the group of 58 pesticide active ingredients on the initial list to be screened 

under the EDSP. For information on the status of the orders issued under the EDSP for each 

chemical, please visit our website at http://www.epa.gov/endo/ and click on the "Status of EDSP 

Orders/DCIs" in the Highlights Box. Additional information on the EDSP, including the policies 
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and procedures, the list of 67 chemicals, the test guidelines and the Tier 1 screening battery, can also 

be found at this website. 

Other data needs

Agricultural Health Study 

Cyfluthrins are among several agricultural chemicals included in the Agricultural Health Study 

(AHS). The AHS began in 1993 and is a collaboration of the National Institute of 

Environmental Health Sciences (NIEHS), the National Cancer Institute (NCI), the EPA, and the 

National Institute for Occupational Safety and Health (NIOSH). Designed as a large, long-term 

epidemiological study, the AHS collects and analyzes data on the health and work practices of 

nearly 90,000 farmers and their families in Iowa and North Carolina who enrolled in the study 

before any disease developed. The study focuses particularly on farmers' exposure to 50 

chemicals including many of the most widely used pesticides. As data are collected over a 

period of years, scientists can compare overall health outcomes for people who differ in whether 

they have had exposure to various chemicals. While these comparisons cannot conclusively 

demonstrate how exposure affects health, they can show some statistical associations. More 

information on the AHS can be found at: http://aghealth.nci.nih.gov. 

Timeline

 

The Agency has created the following estimated timeline for the completion of the cyfluthrin and 

beta-cyfluthrin registration review. 

Registration Review for Cyfluthrin and Beta-cyfluthrin – Projected Registration Review 

Timeline

Activities Estimated Date 

Opening the docket 

Open Docket and Public Comment Period 2010 – September 

Close Public Comment 2010 – November 

Case Development 

Final Work Plan 2011 – February 

Issue DCI 2011 – October – 

December 

Data Submission 2013 – October – 

December 

Open Public Comment Period for Draft Risk Assessments 2015 – April -June 

Close Public Comment Period 2015 –JulySeptember 

Registration Review Decision 

Open Public Comment Period for Proposed Registration Review 

Decision 

 2015 – October – 

December 

Close Public Comment Period 2016- Jan. – Mar. 
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Registration Review Decision and Begin Post-Decision Follow-up 2016 

Total (years)1 6 

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

time estimate. 

Guidance for Commenters

The public is invited to comment on EPA’s preliminary registration review work plan and rationales. 

The Agency will carefully consider all comments, as well as any additional information or data 

provided in a timely manner, prior to issuing a final work plan for the cyfluthrin and beta-cyfluthrin 

case. 

Trade Irritants

Through the registration review process, the Agency intends to solicit information on trade irritants 

and, to the extent feasible, take steps toward facilitating irritant resolution. Growers and other 

stakeholders are asked to comment on any trade irritant issues resulting from lack of Maximum 

Residue Limits (MRLs) or disparities between U.S. tolerances and MRLs in key export markets, 

providing as much specificity as possible regarding the nature of the concern. 

Environmental Justice

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have atypical, 

unusually high exposure to cyfluthrin and beta-cyfluthrin compared to the general population. 

Please comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure, compared to the general population. 

Water Quality

Cyfluthrin and beta-cyfluthrin are not identified as a cause of impairment for any water bodies listed 

as impaired under section 303(d) of the Clean Water Act, based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885. 

However, the pyrethroids as a group have been identified as a cause for impairment for three water 

bodies in Central Valley, CA: Del Puerto Creek, first Ingram Creek Site (confluence with Hospital 

Creek to Hwy 33 crossing) and second Ingram Creek Site (confluence with San Joaquin River to 

confluence with Hospital Creek). 

Nonetheless, no Total Maximum Daily Load (TMDL) criteria have been developed for cyfluthrin or 

beta-cyfluthrin, based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=88
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5&p_pollutant_group_name=PESTICIDES. More information on impaired water bodies and 

TMDLs can be found at http://www.epa.gov/owow/tmdl/. The Agency invites submission of water 

quality data for these pesticides. To the extent possible, data should conform to the quality standards 

in Appendix A of the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and 

Other Water Quality Data in OPP’s Registration Review Risk Assessment and Management Process

(see: http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm) in order to ensure 

they can be used quantitatively or qualitatively in pesticide risk assessments. 

Other Information

Stakeholders are also specifically asked to provide information and data that will assist the Agency 

in refining risk assessments, including any species-specific ecological effects determinations. The 

Agency is interested in receiving the following information: 

1. Confirmation on the following label information. 

a. sites of application 

b. formulations 

c. application methods and equipment 

d. maximum application rates 

e. frequency of application, application intervals, and maximum number of applications 

per season and per year 

f. geographic limitations on use 

2. Use or potential use distribution (e.g. geographical distribution of relevant uses). 

3. Use history. 

4. Median and 90th percentile reported use rates (lb/A, lb 1K sq.ft) from usage data – national, 

state and county. 

5. Application timing (date of first application and application intervals) by use – national, 

state, and county. 

6. Usage/use information for non-agricultural uses. 

7. Directly acquired county-level usage data (not derived from state level data). 

a. maximum reported use rate (lb/cc) from usage data – county 

b. median and 90th percentile number of applications – county 

c. total pounds per year – county 

d. the year the pesticide was last used in the county/sub-county area 

e. the years in which the pesticide was applied in the county/sub-county area 

8. Typical application interval (days). 

9. State or local use restrictions. 

10. Ecological incidents specific to cyfluthrins (non-target plant damage and avian, fish, 

reptilian, amphibian, mammalian mortalities, and bee or beneficial insect mortalities) not 

already reported to the Agency. 

11. Monitoring data, including existing or ongoing Publically Owned Treatment Works 

(POTWs) effluent monitoring data for the pyrethroids be submitted to the Agency. 
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Next Steps

After the 60-day comment period closes, the Agency will consider and respond to any comments 

received in a timely manner and then expects to issue a Final Work Plan in February of 2011 for 

cyfluthrin and beta-cyfluthrin. 
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II. FACT SHEET 

Background Information

 Cyfluthrin and beta-cyfluthrin share the same registration review case number: 7405. 

 Cyfluthrin PC Code: 128831; beta-cyfluthrin PC code: 118831. Both share CAS # 68359-

37-5. 

 Cyfluthrin was first registered in 1987, and beta-cyfluthrin was first registered in the United 

States in 1995. As a result, no Reregistration Eligibility Decisions (REDs) were conducted 

for these compounds. 

 Technical registrant: Bayer Crop Science LP. 

 As of September, 2010, for cyfluthrin, there are 92 Section 3 registrations; for betacyfluthrin, there are 29 Section 3 registrations and 4 special local need (SLN) registrations. 

 Pesticide Re-evaluation Division Contact: Yan Donovan (Donovan.yan@epa.gov). 

 Registration Division Contact: Olga Odiott (odiott.olga@epa.gov). 

Use and Usage Information

(For additional details, please refer to “Usage/Use Report Package in Support of Registration 

Review for Cyfluthrin (128831), January 26, 2010” and “Cyfluthrin and beta-cyfluthrin Screening 

Level Usage Analysis (SLUA), September 28, 2009” in the cyfluthrin and beta-cyfluthrin docket.

 Cyfluthrin and beta-cyfluthrin are a Type II pyrethroid insecticide registered for a variety of 

agricultural, non-agricultural and residential uses.

 For cyfluthrin, the majority of the usage is on agricultural crops such as cotton (60,000 lbs 

ai), corn (30,000 lbs ai), alfalfa and potato (10,000 lbs ai) in the year 2009.

 For beta-cyfluthrin, California DPR usage data indicates that the majority of usage is in 

residential settings, such as structural pest control (11,346 - 6,153 lbs ai), landscape 

maintenance (1,846-398 lbs ai), from 2006-2008, respectively. Overall, the trend seems to be 

decreased over the three years.

Recent and Pending Actions

 There are no pending actions for cyfluthrin or beta-cyfluthrin. 

Ecological Risk Assessment Status

The following are key findings from the most recent ecological risk assessments regarding the 

environmental fate, ecological effects and risks of cyfluthrin and beta-cyfluthrin. 

Please refer to “EFED Registration Review Problem Formulation for Cyfluthrin and Betacyfluthrin,” July 29, 2010, located in the docket, for a detailed discussion. 

Ecological Risks: 
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 The most recent ecological risk assessments on cyfluthrin and beta-cyfluthrin were 

conducted in 2007, 2006, 2004, and 2001. These assessments indicated risk concerns for 

freshwater and estuarine/marine organisms. In addition, there were risk concerns for 

organisms living in the sediment. 

Fate Discussions: 

 The majority of the environmental fate studies for these chemicals were conducted with 

cyfluthrin, which comprises all eight isomers. The environmental fate properties of 

cyfluthrin and beta-cyfluthrin are expected to be similar to each other.

 Based on the environmental fate properties, cyfluthrin and beta-cyfluthrin are hydrophobic 

and range from hardly mobile to immobile in four soils. The chemical will bind strongly to 

the soil surfaces. The primary routes of dissipation are aqueous and soil photolysis, and 

hydrolysis in alkaline media. Metabolism appears to be a moderate route of dissipation for 

these chemicals. The terrestrial field dissipation data confirm the pattern observed in the 

laboratory studies indicating that the chemical follows mixed routes of dissipation in the 

field. Laboratory studies showed that cyfluthrin is moderately persistent and, therefore, 

available for runoff through erosion as well as spray drift.

Ecological effects: 

 For terrestrial species, cyfluthrin and beta-cyfluthrin are practically nontoxic to birds, 

moderately toxic to mammals, and highly toxic to terrestrial invertebrates on an acute basis. 

Chronic effects were seen in rats at levels as low as 150 ppm and at 250 ppm for birds. No 

terrestrial plant data have been submitted to the Agency.

 For aquatic species, numerous aquatic studies have been submitted to the Agency, some of 

which were conducted with beta-cyfluthrin. Both are classified as very highly toxic to 

aquatic organisms based on data for aquatic vertebrates and invertebrates. An acceptable 

toxicity study with green algae suggests that cyfluthrin has low toxicity to nonvascular 

aquatic plants. No vascular aquatic plant data has been submitted to the Agency. 

Human Health Risk Assessment Status

The following are key findings from the human health risk assessments conducted for cyfluthrin and betacyfluthrin registered uses. Please refer to the “Cyfluthrin and Beta-cyfluthrin Human Health Assessment 

Scoping Document in Support of Registration Review,” July 1, 2010, located in the docket for a detailed 

discussion of the human health risk assessment status. 

Hazard Characterization: 
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 The toxicity profile was sufficient for characterization of potential carcinogenic, mutagenic, 

developmental, and reproductive effects in the most recent risk assessments. Cyfluthrin and 

beta-cyfluthrin are classified as “not likely to be carcinogenic to humans.” 

 The acute oral toxicity of both cyfluthrin and beta-cyfluthrin ranges from Toxicity Category I 

to III, depending on the administration vehicle. Inhalation toxicity categories also varied by 

vehicle from Category II to III. Toxicity was low (Category IV) via the dermal route. 

Cyfluthrin and beta-cyfluthrin are slight eye (Category III) and dermal (Category IV) 

irritants, but neither is a dermal sensitizer. 

 In the most recent risk assessment, neurotoxic endpoints were chosen for all exposure 

scenarios, with the exception of the inhalation exposure which route-specific studies were 

used. The point of departure (POD) for the short-term inhalation exposure was chosen from 

the 28-day rat inhalation study and is based on decreased body weight. The POD for 

intermediate- and long-term inhalation exposure is based on decreased body weight and body 

weight gain observed in the 90-day inhalation study in rats. A dermal study is available, but 

was not used for endpoint selection because developmental effects were not evaluated in that 

study. 

Dietary exposure: 

 The most recent acute and chronic aggregate dietary (food and drinking water) risk 

assessments for cyfluthrin and beta-cyfluthrin used the Dietary Exposure Evaluation Model 

(DEEM-FCIDTM Version 2.03). This model incorporates consumption data from the 

USDA’s Continuing Survey of Food Intakes by Individuals taken between 1994 and 1996 

along with a supplemental children’s survey taken in 1998. The acute and chronic dietary 

risk assessments were both refined and risks were not of concern. 

Residential and Recreational exposure and Risk: 

 All residential exposure assessments for cyfluthrin and beta-cyfluthrin were conducted using 

the 1997 version of HED’s Residential Exposure SOPs for residential exposure assessment, 

and there were no risks of concern. The residential assessments combined the two potential 

residential exposure scenarios (indoor carpet and outdoor lawn) for a single worst-case 

residential exposure component. 

Aggregate Risk: 

 In the 2007 risk assessment performed for cyfluthrin and beta-cyfluthrin, EPA determined 

that acute, short-term, intermediate-term, and chronic aggregate risk assessments were 

appropriate and risks were not of concern. Acute and chronic aggregate risks included food 

and water, while short-term and intermediate-term aggregate risk included food, water, and 

residential exposures. For both short-term and intermediate-term scenarios, EPA estimated 

aggregate risks to the general U.S. population, infants (< 1 year), and children (1 – 2 years). 
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Occupational Risk: 

 In 2002, occupational handler and post-application dermal/inhalation exposures were 

assessed for the use of cyfluthrin on a variety of agricultural crops (vegetable crops, field 

crops, etc.) and grain storage uses. In 2007, occupational risks to workers engaged in 

production of alfalfa and grasses as well as risk to workers engaged in seed treatment 

operations were assessed. Baseline PPE and additional PPE (i.e., chemical resistant gloves 

and a dust/mist respirator) were recommended based on risk findings. 

Cumulative assessment: 

Cyfluthrin and beta-cyfluthrin are members of the pyrethroid class of insecticides. This class also 

includes permethrin, cypermethrin, bifenthrin, tau-fluvalinate, bifenthrin, fenpropathrin, and lambdacyhalothrin, among others. EPA developed a draft science policy document on the proposed 

common mechanism of toxicity for naturally-occurring pyrethrins and synthetic pyrethroids 

(Proposed common mechanism grouping for the pyrethrins and pyrethroids, draft, May 19, 2009; 

http://www.regulations.gov/search/Regs/home.html#documentDetail?R=09000064809a62df ). This 

document was supported by the FIFRA Scientific Advisory Panel (SAP) and is available in the 

docket 

(http://www.regulations.gov/search/Regs/home.html#documentDetail?R=0900006480a1f8d7). EPA 

will finalize the policy document on the pyrethroid common mechanism of toxicity taking into 

account the SAP comments. 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 was the subject of a FIFRA SAP 

held in July, 2010. For information regarding EPA’s efforts to evaluate the risk to pyrethroids, see 

http://www.epa.gov/oppsrrd1/reevaluation/pyrethroids-pyrethrins.html. 

Human Studies: 

Past cyfluthrin risk assessments rely in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide to determine their dermal and inhalation exposure. Many such 

studies, involving exposure to many different pesticides, comprise generic pesticide exposure 

databases such as the Pesticide Handlers Exposure Database (PHED) and the Agricultural Reentry 

Task Force (ARTF) Database. EPA has reviewed all the studies supporting these multi-pesticide 

generic exposure databases, and has found no clear and convincing evidence that the conduct of any 

of them was either fundamentally unethical or significantly deficient relative to the ethical standards 

prevailing at the time the research was conducted. All applicable requirements of EPA’s Rule for 

the Protection of Human Subjects of Research (40 CFR Part 26) have been satisfied, and there is no 

regulatory barrier to continued reliance on these studies. 
17

Incidents

Ecological:

 A preliminary review of the Ecological Incident Information System (EIIS, version 2.1), 

which is maintained by the Agency’s Office of Pesticide Programs indicates reported 

ecological incidents associated with the use of cyfluthrin and beta-cyfluthrin. A search for 

incidents involving cyfluthrin and beta-cyfluthrin was also conducted in the American Bird 

Conservancy’s Avian Incident Monitoring System (AIMS). 

 A total of eight reported ecological incidents have been reported to the Agency. These 

reports did not make distinctions between cyfluthrin and beta-cyfluthrin. This is likely due 

to the fact that analytical methods used were unable to distinguish cyfluthrin from betacyfluthrin. Therefore, cyfluthrin incidents cannot be ruled out as possible beta-cyfluthrin 

incidents. 

 Five incidents were reported for aquatic animals and three were reported for terrestrial plants. 

All incidents were reported between 1993 and 2005. Four of the incidents were associated 

with registered uses of cyfluthrin, two were associated with uses where it was undetermined 

if the use was a registered use, and two incidents were associated with misuse. 

Human Health: 

 Both the OPP Incident Data System (IDS) and the Centers for Disease Control and 

Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) Sentinel 

Event Notification System for Occupational Risk-Pesticides (SENSOR) databases were 

consulted. 

 In general, incidents involving cyfluthrin were of low, moderate and high severity; the most 

frequently reported symptoms were related to the dermal, respiratory, neurological, 

gastrointestinal, and ocular systems. The majority of cases involved subject exposure at 

home while applying the product indoors or outdoors; however there were cases that 

occurred in occupational settings while mixing, loading, applying, or reentering the treated 

fields, as well as inadvertent exposure to bystanders. 

 For cyfluthrin (PC Code 128831), 274 cases were identified between 2002 and 2009. The 

incidents appear to be decreasing over time. The number of incidents in 2009 is 

approximately 1/3 of the number reported in 2002. Cyfluthrin incidents occurred both 

indoors and outdoors, and as a result of applying a product or being exposed after 

application. Many incidents appeared to occur due to misuse such as failure to read the 

labels, failure to use protective clothing and mask, lack of awareness of adverse effects, 

overuse of a product, failure to ventilate, or a leak/spill resulting in direct contact. 

 For beta-cyfluthrin (PC Code 118831), 112 cases were identified between 2002 and 2009. 

The incident trend appears to be increasing. 

Tolerances and International Harmonization
18

Where possible, EPA strives to harmonize the US Tolerances and Maximum Residue Limits (MRLs) 

in key export markets. A table with US tolerances, Canada MRLs, Mexico MRLs and Codex MRLs 

for cyfluthrin and beta-cyfluthrin in registered raw agricultural commodities is provided in 

Attachment 6 of the Cyfluthrin and beta-cyfluthrin Human Health Assessment Scoping Document in 

Support of Registration Review (July 1, 2010). 

For both cyfluthrin and beta-cyfluthrin, Mexico adopts U.S. tolerances and/or Codex MRLs for its 

export purposes. 

Both Codex and Canada have established MRLs for cyfluthrin. In most cases, the Codex and 

Canadian MRLs differ from each other as well as from the U.S. tolerance. Canada has not 

established MRLs for beta-cyfluthrin. The Codex MRLs for beta-cyfluthrin are equivalent to the 

Codex MRLs for cyfluthrin. In most cases, they differ from the U.S. tolerances. 

In registration review, the Agency will reconsider the U.S. tolerances and will harmonize them with 

Codex MRLs when the data warrant harmonization. 

Data Call-In Status 

 There have been no data call-ins associated with cyfluthrin or beta-cyfluthrin.

 Labels 

 Active Section 3 labels for cyfluthrin and beta-cyfluthrin can be obtained from the Pesticide 

Product Label System (PPLS) website: http://oaspub.epa.gov/pestlabl/ppls.home.
19

III. Summary of Data Gaps – Cyfluthrin and Beta-cyfluthrin 

The tables below summarize all outstanding data needs for cyfluthrin and beta-cyfluthrin in 

Section I of this document (Preliminary Work Plan). 

Anticipated Data Requirements for Cyfluthrin 

Guideline 

Number Data Requirement 

Test 

Material 

Estimated 

Timeframe 

(Months) 

835.1230 Leaching and Adsorption/Desorption TGAI 12 

835.4100 Aerobic Soil Metabolism1 TGAI 24 

835.4200 Anaerobic Soil Metabolism2 TGAI 24 

835.6100 

(footnote 73

) 

Environmental Chemistry Method and Independent 

Laboratory Validation – soil TGAI 24+12 

835.6200 

(footnote 74

) 

Environmental Chemistry Method and Independent 

Laboratory Validation – water and sediment TGAI 24+12 

850.2100 Avian Oral Toxicity (passerine species) TGAI 12 

850.2300 Avian Reproduction Study (Mallard duck only) TGAI 24 

850.1025 Oyster Acute Toxicity, TEP 12 

850.1035 Acute Toxicity Estuarine/Marine Organisms – Mysid TEP 12 

850.4100 & 

850.4150 Seedling Emergence & Vegetative Vigor (Tier II5

) TEP 12 

850.4400 Aquatic Plant Growth (aquatic vascular plant toxicity) 

(Tier II6

) TGAI 12 

Non-GDLN Aquatic Invertebrate Acute Toxicity (Hyalella azteca) TGAI 12 

850.1790 Whole sediment: chronic invertebrates freshwater and 

marine TGAI 12 

Non-GDLN Leachability from Treated Wood TGAI 12 

Non-GDLN POTW Effluent Monitoring TGAI 12 

Non-GDLN POTW Treatability Study TGAI 12 

870.7800 Immunotoxicity Study TGAI 12 

 

1 Two additional soil studies are expected to be required for cyfluthrin. 2 Four additional soil studies are expected to be required. 

3

 40 CFR Part 158 Guideline Study 835.6100 and 835.6200 Footnote 7 states “Environmental chemistry methods used to generate data associated with 

this study must include results of a successful confirmatory method trial by an independent laboratory. Test standards and procedures for independent 

laboratory validation are available as addenda to the guideline for this test requirement.” 4

 40 CFR Part 158 Guideline Study 835.6100 and 835.6200 Footnote 7 states “Environmental chemistry methods used to generate data associated with 

this study must include results of a successful confirmatory method trial by an independent laboratory. Test standards and procedures for independent 

laboratory validation are available as addenda to the guideline for this test requirement.” 5 Registrants may opt to conduct a Tier I study, with the understanding that any adverse effects (even if <25%) may necessitate a Tier II study. A Tier 

II study will enable the Agency to conduct an endangered species assessment for nontarget plants. 6 Registrants may opt to conduct a Tier I study, with the understanding that any adverse effects (even if <25%) may necessitate a Tier II study. A Tier 

II study will enable the Agency to conduct an endangered species assessment for nontarget plants.
20

Anticipated Data Requirements for Beta-cyfluthrin 

Guideline 

Number Data Requirement 

Test 

Material 

Estimated 

Timeframe 

(Months) 

835.4100 Aerobic Soil Metabolism1 TGAI 24 

835.4300 Aerobic Aquatic Metabolism2 TGAI 24 

835.4400 Anaerobic Aquatic Metabolism TGAI 24 

835.6100 

(footnote 73

) 

Environmental Chemistry Method and Independent 

Laboratory Validation – soil TGAI 24+12 

835.6200 

(footnote 74

) 

Environmental Chemistry Method and Independent 

Laboratory Validation – water and sediment TGAI 24+12 

850.1350 Invertebrate Life Cycle, mysid TGAI 12 

850.4100 & 

850.4150 Seedling Emergence & Vegetative Vigor (Tier II) TEP 12 

850.4400 Aquatic Plant Growth , Lemna gibba TGAI 12 

 

 

1

 One additional sediment study is expected to be required for beta-cyfluthrin 2

 One additional sediment study is expected to be required for beta-cyfluthrin 3

 40 CFR Part 158 Guideline Study 835.6100 and 835.6200 Footnote 7 states “Environmental chemistry methods used to generate data associated with 

this study must include results of a successful confirmatory method trial by an independent laboratory. Test standards and procedures for independent 

laboratory validation are available as addenda to the guideline for this test requirement.” 4 40 CFR Part 158 Guideline Study 835.6100 and 835.6200 Footnote 7 states “Environmental chemistry methods used to generate data associated with 

this study must include results of a successful confirmatory method trial by an independent laboratory. Test standards and procedures for independent 

laboratory validation are available as addenda to the guideline for this test requirement.”