2

overall persistence in the environment. Due to the very low solubility of cyfluthrin and 

beta-cyfluthrin, there is also concern with respect to the results of the batch equilibrium 

study. There is uncertainty concerning the potential for adverse aquatic effects, including 

benthic environments, for acute, chronic and endangered species risk based on fate 

transport involving drift and run-off, and persistence. There is uncertainty concerning the 

potential for adverse terrestrial effects for acute and endangered species risk to birds, 

terrestrial invertebrates and plants based on fate transport, drift, binding to the soil, and 

persistence. In addition, there are ecological data gaps that need to be addressed for 

cyfluthrin and beta-cyfluthrin. For cyfluthrin, this includes acute effects to passerine 

birds, acute effects to freshwater fish and estuarine/marine organisms, chronic effects to 

benthic organisms, and toxicity to terrestrial and aquatic plants. For beta-cyfluthrin, data 

gaps include chronic effects to aquatic invertebrates and toxicity to terrestrial and aquatic 

plants. The potential for adverse effects to pollinators and other beneficial insects from 

use of cyfluthrin and beta-cyfluthrin appears to be high. 
3

Environmental Fate and Ecological Risk 

Assessment Problem Formulation in 

Support of Registration Review for 

Cyfluthrin and Beta-cyfluthrin 

Cyfluthrin Beta-cyfluthrin 

Unstated stereochemistry, 

consists of eight isomers 

July 29, 2010 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

US Environmental Protection Agency 
4

Prepared by: 

Amanda Solliday, Biologist 

José L. Meléndez, Chemist 

Secondary Review: 

Keith Sappington, Senior Scientist 

Mah T. Shamim, Ph.D., Branch Chief 

Environmental Risk Branch V 
5

Table of Contents 

1. Purpose........................................................................................................................ 9 

2. Problem Formulation ............................................................................................... 9 

2.1. Nature of Regulatory Action............................................................................... 10 

2.2. Previous Risk Assessments and Scientific Advisory Panels ................................. 10 

3.1. Mechanism of Action............................................................................................. 21 

3.2. Overview of Pesticide Usage ............................................................................... 22 

In addition to the classical agricultural use sites, cyfluthrin and beta-cyfluthrin have 

multiple other uses. Cyfluthrin and beta-cyfluthrin may be used in multiple urban 

environments. Many of these uses are classified as outdoor residential such as 

ornamental lawns and turf, recreation area lawns, ornamental and/ or shade trees, 

ornamental herbaceous plants, ornamental woody shrubs and vines, paths/ patios, 

paved areas (private roads/ sidewalks), pet living/ sleeping quarters, and residential 

lawns. Tables 3.4a and 3.4b provide a summary of the terrestrial nonagricultural use 

sites for cyfluthrin and beta-cyfluthrin, respectively. Application methods vary. Many 

of these uses could involve substantive exposure to wildlife, specifically, aquatic 

organisms, and they will be assessed accordingly (e.g., commercial/ industrial lawns, 

residential lawn, golf course turf, ornamental lawns and turf, recreation areas and 

residential lawns). (Note that there are fewer non-food uses for beta-cyfluthrin than for 

cyfluthrin.) Another use that will be evaluated is wood protection treatment 

(outdoors)...................................................................................................................... 30 

In addition, there are several other indoor non-food or indoor residential use sites for 

both cyfluthrin and beta-cyfluthrin, like for example, 

commercial/institutional/industrial premises/equipment (indoor), dairies/cheese 

processing plant premises (nonfood contact), eating establishments, food processing 

plant premises (nonfood contact), food stores/ markets/ supermarkets premises, 

hospitals/ medical institutions premises and household/ domestic dwellings. Cyfluthrin 

and beta-cyfluthrin also have greenhouse uses............................................................. 32 

It is important to recognize that the active ingredient and the synergist have differing fate 

properties and therefore would be expected to occur in the environment at different times 

and at different concentrations than present in the end use product. Consequently, it is 

necessary to have toxicology data which allows the assessment of the level of synergy as 

the ratio of the pesticide and synergist vary in the environment. Datasets which allow the 

calculation of the ‘pesticide-synergist interaction’ are often not available. EFED 

recognizes the limitations inherent in this approach and is looking into the acquisition of 

data that would allow the evaluation of the effect of both synergist and active ingredient 

when present in the ecosystem. Evaluating the potential toxic effects of the synergist 

include evaluating ecological effects data generated using end-use products and the active 

ingredient in the presence of synergists, in addition to data for the active ingredient alone. 

At this time, EFED typically has data for individual active ingredients, as well as for the 

synergists alone, but few data are available from which to draw conclusions regarding the 

potential effect of the combination. As stated above, the Agency is evaluating its options 

for obtaining data appropriate for this type of evaluation................................................. 33 

3.3. Environmental Fate and Transport......................................................................... 34 

4. Receptors ................................................................................................................. 40 

4.1. Aquatic and Terrestrial Effects.......................................................................... 40 
6

4.2. Incident Database Review................................................................................... 48 

4.3. Ecosystems Potentially at Risk ........................................................................... 51 

6. Conceptual Model ................................................................................................ 53 

6.1. Risk Hypothesis.................................................................................................. 53 

6.2. Conceptual Diagram.......................................................................................... 54 

Indoor uses can result in discharges of cyfluthrin and beta-cyfluthrin into sewer systems 

and subsequently into publicly owned treatment works (POTWs), and to aquatic 

ecosystems. These discharges of cyfluthrin and beta-cyfluthrin will be included in the 

assessment as a possible route of exposure to the environment. Exposure estimates could 

be used to evaluate potential effects to ecological entities. The conceptual model for 

potential risks of cyfluthrin or beta-cyfluthrin to aquatic organisms due to various indoor 

uses of the chemical that could potentially end up in a “drain” is depicted in Fig. 6.2. 

The stressor is the chemical of concern, cyfluthrin and beta-cyfluthrin. It is noted that the 

transport pathway is wastewater flow, the exposure media is the treatment facility, but the 

exposure point or route, receptor and attribute changes for aquatic organisms are similar 

to the conceptual model for agricultural and urban applications (as depicted in Fig. 6.1a).

........................................................................................................................................... 57 

7. Analysis Plan ........................................................................................................ 58 

7.1. Stressors of Concern .............................................................................................. 59 

7.2. Measures of Exposure.......................................................................................... 59 

7.3. Measures of Effect ................................................................................................. 61 

7.4. Integration of Exposure and Effects ...................................................................... 62 

7.5. Deterministic and Probabilistic Assessment Methods........................................... 62 

7.6. Endangered Species Assessments.......................................................................... 63 

7.7. Drinking Water Assessment .................................................................................. 64 

7.8. Endocrine Disruptor Screening Program ......................................................... 64 

7.9. Preliminary Identification of Data Gaps .......................................................... 65 

7.9.1. Fate................................................................................................................. 65 

7.9.2 Effects.............................................................................................................. 69 

Trimble, A.J, D.P. Weston, J.B. Belden, and M.J. Lydy. 2009. Identification and 

Evaluation of Pyrethroid Insecticide Mixtures in Urban Sediments. Environ Toxicol & 

Chem 26 (8) pp. 1687–1695. ........................................................................................ 82 

9. Fate and Eco-Toxicity Bibliography ....................................................................... 84 

Environmental Fate Cyfluthrin..................................................................................... 84 

161-1 Hydrolysis............................................................................................ 84 

161-2 Photodegradation-water................................................................... 84 

161-3 Photodegradation-soil...................................................................... 84 

162-1 Aerobic soil metabolism .................................................................. 85 

162-4 Aerobic aquatic metab...................................................................... 85 

163-1 Leach/adsorp/desorption................................................................. 85 

163-3 Volatility - field.................................................................................... 86 

164-1 Terrestrial field dissipation ............................................................. 86 

165-2 Field rotational crop.......................................................................... 87 

165-4 Bioaccumulation in fish ................................................................... 87 

202-1 Drift field evaluation.......................................................................... 87 

850.7100 Data reporting for environmental chemistry methods...... 87 
7

Environmental Fate Beta-Cyfluthrin............................................................................ 88 

162-4 Aerobic aquatic metabolism ........................................................... 88 

Ecological Effects Cyfluthrin......................................................................................... 88 

71-1 Avian Single Dose Oral Toxicity ...................................................... 88 

71-2 Avian Dietary Toxicity......................................................................... 88 

71-4 Avian Reproduction............................................................................. 89 

71-5 Simulated or Actual Field Testing ................................................... 89 

72-1 Acute Toxicity to Freshwater Fish................................................... 89 

72-2 Acute Toxicity to Freshwater Invertebrates.................................. 91 

72-3 Acute Toxicity to Estuarine/Marine Organisms ........................... 92 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study ... 93 

72-5 Fish Full Lifecycle Study .......................................................................... 94 

72-7 Simulated or Actual Field Testing ................................................... 94 

123-2 Aquatic plant growth......................................................................... 94 

141-1 Honey bee acute contact ................................................................. 95 

141-2 Honey bee residue on foliage......................................................... 95 

850.1790 Chironomid Sediment Toxicity Test....................................... 95 

Appendix A. PRD data request justification tables................................................... 97 

Appendix C. Open Literature Information.................................................................. 118 

The following is a cursory search of the available literature on cyfluthrin, betacyfluthrin and synthetic pyrethroids in general, mostly about their prevalence/ 

occurrence, and about their toxicity to aquatic invertebrates and sediment dwelling 

organisms (which also pertains to Section 4.1). It is not intended to be exhaustive. In 

the relatively recent past there has been an increased awareness of the prevalence and 

toxicity of cyfluthrin, and other synthetic pyrethroids, in sediment environments of 

urban and agricultural sites, particularly in California. .............................................. 118 

Cyfluthrin is among the constituents monitored by the National Water Quality 

Assessment (NAWQA), maintained by the U.S. Geological Survey. Two kinds of 

parameters (types of samples) are reported. One is “Cyfluthrin_ water_ filtered_ 

recoverable_ micrograms per liter,” with a reported percent of samples with this 

parameter of 9.7 (report units of μg/L). The other is “Cyfluthrin_ solids_ recoverable_ 

dry weight_ micrograms per kilogram,” with a reported percent of samples with this 

parameter of 0.1 (report units of μg/Kg)..................................................................... 120 

Multiple articles from the literature document the presence of synthetic pyrethroids, 

including cyfluthrin, in both urban and agricultural sediments. Weston et al. 2005, 

studied the presence of synthetic pyrethroids in Roseville, CA, selected as a typical 

suburban development. Sediments from creeks that drain subdivisions of single-family 

homes were found to be toxic to Hyalella azteca. The sediments were tested for 

several pesticides, including 7 pyrethroids. Bifenthrin was present in all the sediment 

samples. It was considered to be the primary cause of the toxicity towards the 

organism, with additional contributions of the pyrethroids cyfluthrin and cypermethrin. 

The maximum concentration of cyfluthrin was found to be 169 ng/g dry weight, for a 

tributary of Kaseberg Creek, in sampling site 11. It was detected in 12 out of 24 

sediment samples. The authors indicate that the presence of synthetic pyrethroids was 

not likely to be due to agricultural uses. In Placer County, the use of synthetic 

pyrethroids for agricultural purposes was reported to amount to around 1%............. 120 
8

Amweg et al. 2006b also studied synthetic pyrethroids in urban areas of California and 

Tennessee. Bifenthrin was found to be the major contributor to the toxicity of 

sediments sampled in California to Hyalella azteca, due to its high reported 

concentrations and toxicity. Cypermethrin, cyfluthrin, deltamethrin and lambdacyhalothrin may have contributed to the toxicity in some of the sites. The 

concentrations of cypermethrin and cyfluthrin were typically higher than for other 

synthetic pyrethroids (usually 2-30 ng/g), but the bifenthrin and permethrin 

concentrations were the highest. On the other hand, in Tennessee only a few samples 

contained synthetic pyrethroids and none of the samples were toxic to Hyalella azteca. 

The differences between the two sites were attributed to different climate, types of 

residential development and pesticide use practices................................................... 120 

Holmes et al. 2008 presented the occurrence and toxicity of the synthetic pyrethroids 

throughout the state of California’s urban creek sediment samples. First, 90 samples 

were screened for toxicity to Hyalella azteca, of which around one third caused 

significant toxicity to the organism. Later, 30 sample locations were selected for the 

final study. Of the 30 samples, 25 were toxic to Hyalella azteca at 23oC and all 30 

samples were toxic at 15oC (the synthetic pyrethroids often show higher toxicity at 

lower temperatures, as indicated above). Seven of eight pyrethroids were detected in 

the sediment samples. Fenpropathrin was not detected in any of the samples, and 

deltamethrin and esfenvalerate were detected infrequently; but bifenthrin was present 

in all the 30 samples (2.19 to 219 ng/g dry weight). Permethrin was the second most 

detected pyrethroid and cyfluthrin was detected in 16 samples, with a highest 

concentration of 127 ng/g dry weight. The results suggested an important role of the 

synthetic pyrethroids in California’s urban creeks sediment toxicity. Bifenthrin 

accounted for around two thirds of the toxicity on an average basis, with cyfluthrin and 

cypermethrin also playing an important role in the pyrethroid toxicity statewide. .... 121 
 9

1. Purpose 

The purpose of this problem formulation is to provide the foundation for the ecological 

risk assessment being conducted for the registered uses of cyfluthrin and beta-cyfluthrin. 

As such, it articulates the purpose and objectives of the risk assessment, evaluates the 

nature of the problem, and provides a plan for analyzing the data and characterizing the 

risk (USEPA, 1998). Additionally, this problem formulation is intended to identify data 

gaps, uncertainties and potential assumptions needed to address those uncertainties in 

characterizing the ecological risk associated with the registered uses of cyfluthrin and 

beta-cyfluthrin. 

Cyfluthrin is a Type II synthetic pyrethroid insecticide that is registered for numerous 

agricultural, non-agricultural and residential uses, such as (but not limited to) alfalfa, 

almond, apple, beans, brassica (head and stem) vegetables, carrots, citrus, corn, cotton, 

cucurbit vegetables, fruiting vegetables, grapes, hops, leafy vegetables, legume 

vegetables, lettuce, peach, peanuts, peas, pome fruits, potato, root and tuber vegetables, 

sorghum, soybeans, stone fruits, sugarcane, sunflower, tomato, tree nuts, wheat, airport/ 

landing fields, animal kennels/ sleeping quarters, barns, warehouse premises, industrial 

lawns, eating establishments, food processing plant premises, golf course turf, 

greenhouses, domestic dwellings, rights-of-way, ornamental and/ or shade trees, 

ornamental lawns, tobacco and wood protection to buildings. Type II pyrethroids are 

characterized by the cyano moiety in their chemical structure (Type I pyrethroids do not 

contain this moiety, see Mechanism of Action for additional distinctions between the two 

types). Cyfluthrin is a mixture of eight possible isomers. 

Beta-cyfluthrin consists of four of the eight possible isomers of cyfluthrin, which are the 

more potent isomers of cyfluthrin. Thus, its application rate is usually lower than that for 

cyfluthrin. The environmental fate and ecological effects properties of cyfluthrin and 

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

registrations are separate from cyfluthrin, the environmental fate and ecological database 

for beta-cyfluthrin has been largely supplemented by available data for cyfluthrin. 

Beta-cyfluthrin is registered also on numerous agricultural, non-agricultural and 

residential uses such as (but not limited to) alfalfa, apple, beans, brassica (head and stem) 

vegetables, broccoli, cabbage, canola, carrot, cashew, citrus, corn, cotton, peas, cucurbit 

vegetables, fruiting vegetables, grass forage/ fodder/ hay, hops, leafy vegetables, legume 

vegetables, lettuce, mustard, pastures, peach, peanuts, pear, pecan, pepper, pome fruits, 

potato, plum, rangeland, root and tuber vegetables, sorghum, soybeans, stone fruits, 

sugarcane, sunflower, tomato, tree nuts, wheat, sugarbeets, tobacco, agricultural/ farm 

premises, animal kennels/ sleeping quarters, automobiles, barns, Christmas tree 

plantations, commercial/ industrial lawns, fencerows/ hedgerows, greenhouse – empty, 

hospitals/ medical institutions premises, domestic dwellings, ornamental and/ or shade 

trees, ornamental lawns and turf, paths/ patios, paved areas, recreation area lawns, 

residential lawns and wood protection treatment to buildings. 

2. Problem Formulation 
 10

 2.1. Nature of Regulatory Action 

This report summarizes the Environmental Fate and Effects Division’s (EFED) Problem 

Formulation for the Registration Review of cyfluthrin and beta-cyfluthrin. Previous risk 

assessments were completed for the uses of these chemicals, which serve as the basis for 

this assessment. 

The Food Quality Protection Act (FQPA) of 1996 mandated the EPA to implement a new 

program, i.e., registration review (http://www.epa.gov/oppsrrd1/registration_review/). All 

pesticides distributed or sold in the United States generally must be registered by the 

EPA. The decision to register a pesticide is based on the consideration of scientific data 

and other factors showing that it will not cause unreasonable risks to human health, 

workers, or the environment when used as directed on product labeling. The registration 

review program is intended to ensure 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 and the environment. 

Changes in science, public policy, and pesticide use practices will occur over time. 

Through the new registration review program, the Agency periodically reevaluates 

pesticides to make sure that as change occurs, products in the marketplace can be used 

safely. 

As part of the implementation of the new Registration Review program pursuant to 

Section 3(g) of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the 

Agency is beginning its evaluation to determine whether cyfluthrin and beta-cyfluthrin 

continue to meet the FIFRA standard for registration. This problem formulation for the 

environmental fate and ecological risk assessment chapter in support of the registration 

review is intended for the initial docket opening the public phase of the review process. 

2.2. Previous Risk Assessments and Scientific Advisory Panels 

Previous Assessments 

Recent risk assessments conducted on cyfluthrin and beta-cyfluthrin, indicated risk 

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

concerns for organisms living in the benthos. 

In June and July 2007, EFED issued three incremental risk assessments (an assessment 

for uses for which the risk for cyfluthrin are similar to those previously identified) for 

proposed new uses of cyfluthrin (D331952+), beta-cyfluthrin (D332314+), and cyfluthrin 

and beta-cyfluthrin (D340740+). The first new use risk assessment for cyfluthrin, 

covered its use of the chemical on grasses; the second new use risk assessment for betacyfluthrin covered its uses on grasses, Crop Group #15 (cereal grains except rice) and 

Crop Group #16 (forage, fodder and straw of cereal grains); finally, the third new use risk 

assessment for cyfluthrin and beta-cyfluthrin covered the increased application rate for 

alfalfa (maximum application rate 0.175 lb a.i./A/season for cyfluthrin and 0.35 lb 

a.i./A/season for beta-cyfluthrin). All three reviews relied upon previously issued 

assessments (e.g. high application rates for sweet corn at a rate of 0.44 lb a.i./A/season, 
 11

and cotton at a rate of 0.5 lb a.i./A/season). These assessments concluded that the 

potential risks associated with newly proposed crops or maximum application rates were 

within the range of risks identified by previously issued risk assessments and overall risks 

should be similar. 

Also in June 2007, the EFED issued an incremental risk assessment for the proposed new 

use of PONCHO BETA (EPA Reg. No. 264-1056), a product containing both, 

chlothianidin and beta-cyfluthrin, for the use for seed treatment on sugar beet seeds 

(D335254). The single application rate for the chemical beta-cyfluthrin is 0.0125 lb 

a.i./A, and the risks were based on a previously issued assessment for the use of 

cyfluthrin on tobacco, with a similar application rate. It was indicated that“generally, 

seed treatments result in less risk to aquatic organisms due to a lower potential for 

exposure since the seed is normally covered and there is little or no pesticide drift. Also, 

application rates per acre are usually lower than normal spray treatments.” A seed 

leaching study was required for clothianidin and beta-cyfluthrin. 

Prior to this assessment, in 2006, a risk assessment was issued for the use of cyfluthrin on 

tobacco (D316313). The application rate for tobacco is 0.0044 lb a.i./A, with a single 

application allowed. This is only a small fraction of the application rate on several other 

crops. Regarding risk to terrestrial and aquatic organisms, it was concluded that there 

was a potential for non-target aquatic organisms (freshwater and estuarine/ marine, fish 

and invertebrates) to be exposed to cyfluthrin via off target spray drift and/ or runoff into 

surface water. The results indicated that chronic levels of concern (LOCs) were exceeded 

for estuarine/ marine invertebrates with a risk quotient (RQ) of 1.35. For the proposed 

maximum application rate on tobacco, the acute or chronic RQs for benthic invertebrates 

did not exceed the LOCs. Also, there were no acute or chronic risks to birds or mammals 

from a single application of cyfluthrin to tobacco. Cyfluthrin is very highly toxic to 

honey bees on an acute contact basis, therefore, risk was assumed. Risks to aquatic and 

terrestrial plants were not assessed because data were not available. Nonetheless, due to 

cyfluthrin’s mode of action and lack of incidents pertaining phytotoxicity for the 

chemical or other pyrethroid pesticides, there were no phytotoxicity concerns stated in 

the risk assessment. The environmental fate and ecological effects databases were 

considered mostly complete, but an aerobic aquatic metabolism study was required. In 

addition, it was indicated that acute freshwater and chronic estuarine/ marine sediment 

studies were received as follows. The studies are currently in review. 

MRID 46591507 Cyfluthrin – Toxicity to Midge (Chironomus tentans) During a 

10-Day Sediment Exposure. 

MRID 46591506 Cyfluthrin – Toxicity to Estuarine Amphipods (Leptocheirus 

plumulosus) During a 28-Day Sediment Exposure. 

Finally, the tobacco risk assessment also provided a fate characterization for cyfluthrin. 

In short, it was indicated that cyfluthrin is moderately persistent in the environment 

(terrestrial field dissipation half-lives 18 to <32 days; aerobic soil metabolism 73.5-94.8 

days; anaerobic soil metabolism of the order of about 30 days), and practically immobile 

(Kds ranged from 1116 to 1793 mL/g, KOC's ranged from 73,480 to 124,000 mL/gOC). 
 12

[Note: According to the currently used mobility classification (FAO 2000), cyfluthrin is 

considered immobile to hardly mobile.] It was also pointed out that the primary routes of 

dissipation for cyfluthrin are hydrolysis in alkaline media (half-life 2.1 days), and 

aqueous and soil photolysis (respective half-lives of 4.5 and 5.6 days). Cyfluthrin is 

resistent to hydrolysis in acidic and neutral media. It binds strongly to soil suggesting 

little potential to leach to subsurfaces and to contaminate ground water. Nonetheless, 

cyfluthrin appeared to have a high potential to reach surface waters by spray drift or in 

runoff events accompanied by erosion, with cyfluthrin bound to particulate and organic 

matter in the water column. It was also indicated that the chemical has the potential for 

deposition in the benthos, accumulating with repeated use. Cyfluthrin was not expected 

to volatilize, based on its moderately low Henry's Law constant, low vapor pressure and 

binding capacity. This chemical bioaccumulates moderately (854X for total residues, 

whole fish), with relatively rapid depuration (observed DT50 for depuration ≤3 days). 

Degradates observed in the studies included DCVA, FPB-ald and FPB-acid, all of which 

are product of pyrethroid ester cleavage. 

In 2004, the EFED issued a risk assessment for several proposed new uses as follows: 

tree nuts, grapes and peanuts, wheat, leafy vegetables, fruiting vegetables, cucurbits, 

leafy brassica, pome fruit, stone fruit. In addition, the registrant seeked to establish IR-4 

tolerances for the use of cyfluthrin on tuberous and corm vegetables (crop Subgroup 1C), 

turnip greens, dried shelled peas and beans (except soybeans), grass hay, and grass forage 

(D274813+). Regarding the risk to terrestrial organisms, it was concluded that there were 

no acute or chronic risks to birds from applications of cyfluthrin. However, for small 15-

35 g mammals, acute LOCs were slightly exceeded for single and multiple application 

scenarios. As in the case for the assessment for use on tobacco, risk was assumed for 

nontarget terrestrial insects; and for semi-aquatic and terrestrial plant, data were not 

required. 

In the 2004 assessment, most acute, chronic, restricted use and endangered species LOCs 

were exceeded for aquatic organisms (freshwater and estuarine/marine fish and 

invertebrates). Acute RQs based on rainbow trout ranged from 1.5 to 39 while chronic 

RQs ranged from 0.45 to 30. For freshwater invertebrates, the results indicated that acute 

RQs for daphnia ranged from 4 to 107 and for crayfish ranged from 1.7 to 43. Chronic 

RQs for daphnia ranged from 1.3 to 61. For estuarine/marine fish, acute RQs based on 

sheepshead minnow ranged from <0.01 to 0.70 while chronic RQs ranged from 0.10 to 

12. For estuarine/marine invertebrates, the results indicated that acute RQs for mysids 

ranged from 48 to 1214 and for shrimp surrogate crayfish ranged from 1.7 to 43. Chronic 

RQs for mysids ranged from 45 to 2130. In addition, based on the risk of cyfluthrin to 

fish, exposed amphibians were also assumed to be at risk due to a portion of their lifecycle being spent in aquatic environments, particularly the early life stages that are 

primarily aquatic and where respiration is dependent on gills (such as tadpoles) or where 

later adult stages retain external gill structures (primitive salamanders). It was indicated 

that amphibians often inhabit shallow litoral areas where incoming runoff concentrations 

of cyfluthrin may be the highest. 

In 2001, the EFED issued an incremental risk assessment for the use of cyfluthrin on 

Southern peas (D271494). Conclusions were based on the previously issued assessment 
 13

of the same or similar use in the year 2000 (see below). 

In 2000, the EFED also conducted an assessment for the use of cyfluthrin on leafy 

vegetables (lettuce, mustard greens, cauliflower and broccoli), soybeans, corn (pop, field, 

and seed), dry peas, pigeon peas, chick peas, and lentils (D256960+). The following was 

stated in the review: “Cyfluthrin poses a risk to freshwater and estuarine/marine fishes 

and invertebrates based on the highest suggested application rates for all proposed 

commodities based on corn (pop, seed, and field), leafy vegetables, and soybeans. Levels 

of concern (LOCs) for freshwater fishes and freshwater invertebrates and estuarine/ 

marine invertebrates were exceeded on an acute and chronic basis. Chronic data for the 

freshwater rainbow trout showed LOC exceedance while chronic data for the fathead 

minnow did not show an exceedance of LOCs when multiple applications of cyfluthrin 

was used. Semi-aquatic and terrestrial plant data is not required due to the results of 

previous phytotoxicity testing with a pyrethroid surrogate (cypermethrin) which showed 

no evidence of phytotoxicity. Based on the registrant submitted studies, cyfluthrin 

appears to be poorly mobile and moderately persistent in the environment. Because of 

cyfluthrin’s low mobility, it should not reach ground water in significant quantities, but 

does have the potential for surface water contamination through drift and erosion where it 

will become sorbed mainly on sediment.” 

1999 Scientific Advisory Panel 

A FIFRA Scientific Advisory Panel (SAP) in 1999 examined the sediment toxicity and 

fate of synthetic pyrethroids. In response to a question regarding whether sediment 

toxicity data on one pyrethroid (cypermethrin) could be used to predict sediment toxicity 

to all pyrethroids, the panel generally supported the method of using data from a few 

pyrethroids to extrapolate information on toxicity to other pyrethroids. Also, the new 

CFR Part 158 requirements include sediment toxicity tests and these studies are 

considered particularly important for ecological risk assessment of all synthetic 

pyrethroids, including cyfluthrin and beta-cyfluthrin. 

The SAP commented on the use of Kd or KOC to estimate concentrations of synthetic 

pyrethroids in sediments, recommending that the Agency reconsider KOC as a measure of 

the binding potential of synthetic pyrethroids to sediment and soil because the use of Kd

alone limits extrapolation to experimental conditions while KOC allows estimates 

partitioning across a wide variety of soil/sediment types (USEPA 1999). The Panel 

expressed concern that standard methods used to measure sorption may not be applicable 

to highly hydrophobic compounds due to high solids to water ratio, consideration of the 

character of the organic matter, presence of dissolved organic carbon, use of nonrepresentative soils and sediments as sorbents, and improper methods used to measure 

organic carbon. 

While the biota-sediment accumulation factor is a widely accepted method of assessment 

of bioaccumulation in sediments, the Panel indicated that the bioconcentration data for 

Daphnia and Hyalella should be sufficient to predict bioconcentration of pyrethroids. 

Finally, the Panel indicated that use of a solid phase microextraction (SPME) method to 

determine the dissolved concentration in water could be used to account for sorption of 
 14

pyrethroids to organic carbon and colloids present in the water column in the 

measurement of bioconcentration factors. 

In 2003 and in response to the comments from the SAP on pyrethroids, EFED requested 

the following studies on cyfluthrin and three other synthetic pyrethroids: cypermethrin, 

esfenvalerate and bifenthrin (memorandum dated 12/22/03, Rexrode & Meléndez): 

850.1735: 10-day Sediment (freshwater)

- Test organism: Hyalella azteca and Chironomus dilutus. 

- Duration: 10 days, endpoint is survival. 

EPA/600/R01/020: Chronic Estuarine/Marine Sediment Testing

- 28 day test on Leptocheirus plumulosus. 

- Percentage of neonates that survive as adults. 

- Growth rate. 

- Reproduction (#eggs/ female, etc.). 

- Behavior. 

A chronic 65-day freshwater test was also requested only for cypermethrin. 

EPA/600/R-991064: Chronic Freshwater Sediment Testing 

- 65 day test on Chironomus dilutus. 

- Survival. 

- Growth rate. 

- Reproduction (# eggs/ female, time to oviposition, proportion of females 

ovipositing, % hatch).

2009 Scientific Advisory Panel

OPP presented a “Proposed Common Mechanism Grouping for the Pyrethrins and 

Synthetic Pyrethroids to a FIFRA SAP in June 2009. OPP proposed two subgroups 

based on Type I or Type II effects related to sodium current tails and neurobehavioral 

impact, with esfenvalerate and fenpropathrin showing symptoms of both types. 

Cyfluthrin and beta-cyfluthrin are Type II synthetic pyrethroids, which means they are 

cyano-substituted in the alpha position. The panel indicated that substances with mixed 

characteristics could be included in both groups (see p. 18 of SAP minutes, USEPA 

2009). This mechanism of action assessment was performed by HED/OPP and 

presented to the SAP to determine if a cumulative assessment is required for the synthetic 

pyrethroids. However, EFED does not currently conduct cumulative assessments. EFED 

does not currently have the methodology to conduct similar cumulative risk assessments 

for all of the (non-human) biological entities for which EFED has responsibility. 

Although EFED agrees that an assessment of cumulative risk would be a desirable goal, 

EFED does not believe the current state of the science can address this issue 

quantitatively. The ecological risk assessment for cyfluthrin and beta-cyfluthrin will 

consider open literature, modeling and other lines of evidence, as available, to 

qualitatively address the potential for cumulative effects in the risk assessment. 
 15

Information on the 2009 SAP is available in the docket (with non-copyright material 

available at http://www.regulations.gov) under EPA-HQ-OPP-2008-0489. 

Open Literature Information 

There are multiple articles in the open literature that indicate concern over cyfluthrin, 

beta-cyfluthrin and other pyrethroids’ toxicity towards benthic and other non-target 

aquatic organisms. Also, the articles illustrate cyfluthrin’s prevalence in the 

environment. Please, refer to the Appendix C for further details. 

Aquatic Life Criteria and Aquatic Life Benchmarks 

The Clean Water Act requires the Agency to publish water quality criteria that accurately 

reflect the latest scientific knowledge on the kind and extent of all identifiable effects on 

health and welfare which might be expected from the presence of pollutants in any body 

of water, including ground water. While these recommended criteria do not, in 

themselves, impose any requirements, states and authorized tribes can use them to 

develop water quality standards. An Aquatic Life Ambient Water Quality Criteria 

document has not been published for cyfluthrin or beta-cyfluthrin 

(http://www.epa.gov/waterscience/criteria/). 

Based on toxicity values revised by the EPA, the OPP publishes aquatic life benchmarks 

for freshwater species, based on the most sensitive species from the most recent risk 

assessments. For cyfluthrin and beta-cyfluthrin, no aquatic life benchmarks have been 

published 

(http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm#benchmarks). 

Impaired Water Bodies 

Cyfluthrin and beta-cyfluthrin are not individually 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_grou

p_id=885. However, the pyrethroids as a group have been identified as a cause for 

impairment for three water bodies in Central Valley, California: Del Puerto Creek, 

Ingram Creek Site (from confluence with Hospital Creek to Highway 33 crossing) and 

second Ingram Creek Site (from 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_gr

oup_id=885&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 (refer to:

http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm), in order to 
 16

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

3. Stressor Source and Distribution

Cyfluthrin (Tables 3.1a) is a synthetic pyrethroid insecticide and acaricide. Its structure 

has three rings, two phenyl rings attached to each other by an oxygen atom, and a 

cyclopropyl ring. It is a Type II synthetic pyrethroid (it is cyano-substituted in the alpha 

position). The chemistry of cyfluthrin may be dictated by its ester moiety. It would be 

expected to hydrolyze as the pH increases; this is confirmed from the hydrolysis study, 

where cyfluthrin was stable at pH 5, nearly stable at pH 7 and showed a half-life of 2.1 

days at pH 9. The structure of the molecule has three chiral centers that could result in a 

total of 23

 or 8 isomers. Cyfluthrin has 2,2-dichloroethenyl and it is 2,2-dimethyl 

substituted in the cyclopropane ring. 

Beta-cyfluthrin (Tables 3.1a) is a mixture of four of the isomers of cyfluthrin. 

Chemically, it is the (R)-alcohol-(1S)-cis-acid, (R)-alcohol-(1S)-trans-acid, (S)-alcohol-

(1R)-cis-acid and (S)-alcohol-(1R)-trans-acid out of eight isomeric esters. 

In general, the physicochemical and environmental fate properties of cyfluthrin and betacyfluthrin are expected to be similar to each other. Information about the identification 

of cyfluthrin and beta-cyfluthrin is provided in Table 3.1a. A summary of 

physicochemical properties of cyfluthrin and beta-cyfluthrin is included in Table 3.1b. 
 17

Table 3.1a. Identification information for cyfluthrin and beta-cyfluthrin 

CHEMICAL CYFLUTHRIN BETA-CYFLUTHRIN 

PARAMETER VALUE(S) (units) SOURCE VALUE(S) (units) SOURCE

CAS Chemical 

Name 

cyano(4-fluoro-3-

phenoxyphenyl)methyl 3-(2,2-

dichloroethenyl)-2,2-

dimethylcyclopropanecarboxylate 

Cyfluthrin data sheet, at: 

http://www.alanwood.net/pestic

ides/cyfluthrin.html 

(accessed 04/21/10) 

cyano(4-fluoro-3-

phenoxyphenyl)methyl 3-(2,2-

dichloroethenyl)-2,2-

dimethylcyclopropanecarboxylate 

Beta-cyfluthrin data sheet, at: 

http://www.alanwood.net/pestic

ides/beta-cyfluthrin.html 

(accessed 04/21/10) 

PC Code 128831 OPP Databases 118831 OPP Databases 

IUPAC Chemical 

Name 

(RS)-α-cyano-4-fluoro-3-

phenoxybenzyl 

(1RS,3RS;1RS,3SR)-3-(2,2-

dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate 

or

(RS)-α-cyano-4-fluoro-3-

phenoxybenzyl (1RS)-cis-trans-3-

(2,2-dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate 

Cyfluthrin data sheet, at: 

http://www.alanwood.net/pestic

ides/cyfluthrin.html 

reaction mixture comprising the 

enantiomeric pair (R)-α-cyano-4-

fluoro-3-phenoxybenzyl (1S,3S)-3-

(2,2-dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate 

and (S)-α-cyano-4-fluoro-3-

phenoxybenzyl (1R,3R)-3-(2,2-

dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate in 

ratio 1:2 with the enantiomeric pair 

(R)-α-cyano-4-fluoro-3-

phenoxybenzyl (1S,3R)-3-(2,2-

dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate 

and (S)-α-cyano-4-fluoro-3-

phenoxybenzyl (1R,3S)-3-(2,2-

dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate 

or

reaction mixture comprising the 

enantiomeric pair (R)-α-cyano-4-

fluoro-3-phenoxybenzyl (1S)-cis-3-

(2,2-dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate 

and (S)-α-cyano-4-fluoro-3-

phenoxybenzyl (1R)-cis-3-(2,2-

dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate in 

ratio 1:2 with the enantiomeric pair 

(R)-α-cyano-4-fluoro-3-

phenoxybenzyl (1S)-trans-3-(2,2-

dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate 

and (S)-α-cyano-4-fluoro-3-

phenoxybenzyl (1R)-trans-3-(2,2-

dichlorovinyl)-2,2-

dimethylcyclopropanecarboxylate 

Beta-cyfluthrin data sheet, at: 

http://www.alanwood.net/pestic

ides/beta-cyfluthrin.html 
 18

Table 3.1a. Identification information for cyfluthrin and beta-cyfluthrin 

CHEMICAL CYFLUTHRIN BETA-CYFLUTHRIN 

PARAMETER VALUE(S) (units) SOURCE VALUE(S) (units) SOURCE

Chemical Structure 

(from chemical’s 

data sheet) 

Unstated stereochemistry;

It consists of 8 isomers
 19

Table 3.1b. Summary of physicochemical properties of cyfluthrin and beta-cyfluthrin

PARAMETER VALUE(S) (units) SOURCES

CAS Reg. No. 

68359-37-5 (unstated stereochemistry) 

Cyfluthrin is a mixture of all possible isomers. 

86560-92-1 (diastereoisomer I) 

86560-93-2 (diastereoisomer II) 

86560-94-3 (diastereoisomer III) 

86560-95-4 (diastereoisomer IV) 

Beta-cyfluthrin is comprised mainly of 

diastereoisomers II and IV. 

FAO/WHO Specifications1

and Cyfluthrin (157)/Betacyfluthrin (228), Draft 

Review Prepared by 

Australian Quarantine and 

Inspection Service2

Stereochemistry 

Diastereoisomer I: (1R,3R,1R + 1S,3S,1S = 1:1; cis) 

Diastereoisomer II: (1R,3R,1S + 1S,3S,1R = 1:1; cis) 

Diastereoisomer III: (1R,3S,1R + 1S,3R,1S = 1:1; trans) 

Diastereoisomer IV: (1R,3S,1S + 1S,3R,1R = 1:1; trans) 

FAO/WHO Specifications 

Composition 

Diastereoisomer Cyfluthrin Beta-cyfluthrin 

I 23-27% ≤2.0% 

II 17-21% 30.0-40.0 

III 32-36% ≤3.0% 

IV 21-25% 57.0-67.0 

FAO/WHO Specifications 

Molecular Formula C22H18Cl2FNO3 Cyfluthrin’s data sheet 

Molecular Weight 434.29 TOXNET/ HSDB3

Melting Point 

60oC; 

64.40 diastereoisomer I; 80.71 diastereoisomer II; 65.04 

diastereoisomer III; 106.19 diastereoisomer IV 

TOXNET/ HSDB 

FAO/WHO Specifications 

 Boiling Point (oC) Not measurable; weight loss above 160°C; decomposition 

>220°C 

FAO/WHO Specifications 

pKa (20 oC) 

NA; Dissociation characteristics: cyfluthrin does not show 

basic or acidic characteristics in water 

EC Review Report for the 

Active Substance Cyfluthrin 

and Beta-cyfluthrin4

Solubility (20oC) 

2.32 x 10-3 mg/L or ppm or 2.32 ppb at 20o

C

pH 3/pH 5: 2.5/2.2 ug/L diast. I; 2.1/1.9 ug/L diast. II; 3.2/2.2 

ug/L diast. III; 4.3/2.9 ug/L diast. IV* 

*The material used was a defined mixture of four 

diastereoisomeric enantiomer pairs. 

‘Not Soluble’ 

Bolded value is considered representative for cyfluthrin. 

Laskowski 2002, 

FAO/WHO Specifications 

FAO, 2000 

Vapor Pressure 

(20-25oC) 

1.5 x 10-8 mmHg at 25°C 

2.1 x 10-9 mmHg at 20°C 

@20°C 9.6 x 10-7 Pa diast. I 

1.4 x 10-8 Pa diast II 

2.1 x 10-8 Pa diast. III 

8.5 x 10-8 Pa diast. IV 

@25°C 2.1 x 10-6 Pa diast. I 

3.4 x 10-7 Pa diast II 

4.7 x 10-7 Pa diast. III 

2.0 x 10-7 Pa diast. IV 

‘Non-volatile under field conditions’ (≤9.98 x 10-7 mmHg) 

Laskowski 2002 

FAO/WHO Specifications 

USEPA, 2008 

 

1

http://www.fao.org/ag/AGP/AGPP/Pesticid/Specs/docs/Pdf/new/cyfluthr.pdf and 

http://www.fao.org/ag/AGP/AGPP/Pesticid/Specs/docs/Pdf/new/beta_cyf.pdf (accessed 05/05/10). 2

http://www.fao.org/fileadmin/templates/agphome/documents/Pests_Pesticides/JMPR/Evaluation07/Cyflutr

hin.pdf (accessed 05/05/10). 3

http://toxnet.nlm.nih.gov/. 4

http://ec.europa.eu/food/plant/protection/evaluation/existactive/list1-29_en.pdf and 

http://ec.europa.eu/food/plant/protection/evaluation/existactive/list1-32_en.pdf (accessed 05/05/10). 
 20

Table 3.1b. Summary of physicochemical properties of cyfluthrin and beta-cyfluthrin

PARAMETER VALUE(S) (units) SOURCES

Henry’s Law Constant 3.7 x 10-6 atm-m3

/mol (estimated from vapor pressure at 

25°C and water solubility at 20°) Laskowski, 2002 

Octanol-Water Partition 

Coefficient 

(20 and 22°C) 

KOW (log KOW) 

9.33 x 105 (5.97)* 

6.00 diast. I; 5.94 diast. II; 6.04 diast. III; 5.91 diast. IV* 

6.18 diast. II; 6.18 diast IV at 22°C 

*The material used was a defined mixture of four 

diastereoisomeric enantiomer pairs. 

Laskowski, 2002 

FAO/WHO Specifications 

Octanol-Air Partition 

Coefficient 

KOA (log KOA) 

Constant Law sHenry'

RTK

K

K

K OW

AW

OW

OA  = 6.17 x 109

 (9.79) 

Calculated using KOW = 9.33 x 105

 and HLC = 3.7 x 10-6

atm-m3

/mol; the temperature was assumed to be 25°C. 

EPIWEB est.: 1.47 x 1010 – 7.52 x 1011 (10.164-11.876) 

Calculated Value 

EPIWEB v.4.0 Estimate 

KAW (log KAW) 

KAW = Cair/Cwater = HLC/RT = 1.51 x 10-4 (-3.82) 

EPIWEB estimate: KAW = 1.18 x 10-6 (-5.926) 

‘Slightly volatile from a water surface’ 

Calculated 

EPIWEB v.4.0 

USEPA, 2008 

Cwater/Cair 





 







  6

air

water

10GMW P

760RT S

C

C = 6,612 (unitless) 

‘Slightly volatile from a water surface’ 

Calculated 

USEPA, 2008 

OH Radical Reaction 

Half-life 

0.856 days 

(Assumptions: 12-hr days; 1.5 x 106 OH/cm3) EPIWEB v.4.0 Estimate 

Biomagnification 

Potential 

Presumption: If log KOA > 5, log KOW > 2 and the rate of 

chemical transformation is low, the chemical may 

biomagnify in terrestrial food chains**

For cyfluthrin, log KOA> 5, log KOW> 2. However, its rate 

of transformation is moderate in the environment and 

appears to be moderately rapid in fish, with moderate to 

rapid depuration indicated. Therefore, it appears that 

cyfluthrin may have a low potential to biomagnify in 

terrestrial food chains. 

**Gobas et al. 2003 and 

Armitage & Gobas, 2007 

support this presumption 

utilized here only as a broad 

reference to determine the 

potential for 

biomagnification. 

Bolded value is considered representative for cyfluthrin.

Cyfluthrin has a high molecular weight of 434.29 g/mol. It also has a small solubility 

(only 2.32 ppb) and a high octanol/ water partition coefficient (KOW = 9.33x105). Based 

on its octanol/ water partition coefficient, it appears that cyfluthrin has the potential to 

bioaccumulate/ bioconcentrate (KOW ≥ 1000) in fish and other aquatic organisms. With a 

vapor pressure of 1.5 x 10-8 mmHg, it is considered “non-volatile under field conditions.” 

Due to its very small solubility (2.32 ppb), its calculated Henry’s Law Constant is 

moderately low (3.7 x 10-6 atm-m3

/mol). In addition, its Cwater/Cair is 6612, which 

classifies it as “slightly volatile from a water surface” (USEPA 2008). Cyfluthrin could 

have a potential to volatilize slightly from wet surfaces. The potential to volatilize may 

be greatly attenuated in the environment by its tendency to bind to organic matter (e.g., 

soils, sediments, or organic matter and particulate in natural water). For cyfluthrin, the 

log KOA range is 9.79 – 11.88 (calculated and EPIWEB v.4.0 estimates), the log KOW is 

5.97 and the rate of transformation is moderate in the environment and appears to be 

moderate in fish (the majority of the residues observed in fish were the parent 

compound), with moderately rapid depuration (observed depuration DT50 of 

approximately 3 days). Therefore, it appears that cyfluthrin may have a low potential to 

biomagnify substantially in terrestrial food chains, based on the presumption made by 

Gobas et al. and Armitage & Gobas, in 2003 and 2007 articles, respectively. 
 21

Nevertheless, the possibility of biomagnification has not been quantified. Even though 

EFED has not adopted an official reference or guideline to distinguish chemicals that 

biomagnify, Gobas et al. and Armitage & Gobas’ presumption was utilized here as a 

general or broad reference to detect the potential for biomagnification in terrestrial food 

chains for these chemicals. 

Even though various degradates were observed in the laboratory studies (e.g. FPB-acid 

and DCVA), it was found that they were the result of the rupture of the ester bond of the 

parent molecule. It is believed that the toxicity of the resulting molecules is substantially 

reduced compared to the parent because they presumably have lost the neurotoxic mode 

of action. Table 3.1c shows the chemical structures of cyfluthrin’s major degradation 

products. At this time, they are not considered stressors of concern in this problem 

formulation. As part of the forthcoming risk assessment, available information on the 

toxicity of these degradates will be considered to confirm this assumption. 

Table 3.1c. Major Transformation Products of Cyfluthrin and Beta-cyfluthrin 

Common 

Name Chemical Name Structure 

DCVA 

3-(2,2-dichlorovinyl)-2,2-

dimethyl-cyclopropanecarboxylic 

acid 

Cl

Cl

O

OH

3CH CH3

FPB-ald 

4-fluoro-3-phenoxybenzaldehyde 

or 

3-phenoxy-4-fluorobenzaldehyde 

O

F

O

FPB-acid 

4-fluoro-3-phenoxybenzoic acid 

or 

3-phenoxy-4-fluorobenzoic acid O

F

O

OH

3.1. Mechanism of Action 

Both, cyfluthrin and beta-cyfluthrin are neural toxic insecticides acting through direct 

contact and ingestion. The insecticidal effect of pyrethroids is characterized by a rapid 

“knock down,” or paralysis, of insects. All pyrethroids act as axonic poisons, affecting 

both the peripheral and central nervous systems, and share similar modes of action. The 

primary biological effects of cyfluthrin, beta-cyfluthrin and other pyrethroids on insects 

and vertebrates reflect an inhibition of the correct firing of neurotransmitter deliver 

signals from one cell to another via nerve membrane inhibition of the voltage-gated Ca2+
 22

(calcium ion) channels coupled with a stimulatory effect on the voltage-gated Na+

(sodium ion) channels. The pyrethroids (including cyfluthrin and beta-cyfluthrin) share 

similar modes of action, and are considered axonic poisons that affect both the peripheral 

and central nervous system. 

It is now well established that severe neurological symptoms of poisoning with 

pyrethroids in mammals and insects are the result of modification of the Na+

 channels 

activity (cellular pores through which Na+ ions are permitted to enter the axon to cause 

excitation) (Matsumura, 1985). Advanced electrophysiological experiments using 

voltage clamp and patch clamp, together with ligand-binding and ionic flux experiments, 

have unveiled unique actions of pyrethroids of keeping the Na+

 channel in the open state 

for an extremely long period, sometimes as long as several seconds. This modification of 

Na+

 channel properties leads to hyperactivity of the nervous system. This action leads to 

spontaneous depolarizations, augmented neurotransmitter secretion rate and 

neuromuscular block, which ultimately results in paralysis of the insect. 

Pyrethroids have also been shown to suppress GABA and glutamate receptor-channel 

complexes and voltage-activated Ca2+ channels, but the toxicological significance of 

these actions is uncertain. Relative to physiological responses, researchers have 

designated two types of pyrethroids, Type I (e.g., bifenthrin, resmethrin, permethrin) and 

Type II (e.g., cypermethrin, deltamethrin, fenvalerate, cyfluthrin and beta-cyfluthrin). 

Type I pyrethroids action is mainly associated with compounds that cause nerve 

excitation symptoms typified by the appearance of repetitive firing of axons in the 

peripheral nervous system and a negatively correlated temperature reversible knockdown 

property (Clark & Matsumura, 1987). In insects, the type II pyrethroids predominantly 

cause ataxia and uncoordinated movement. 

3.2. Overview of Pesticide Usage

Cyfluthrin and beta-cyfluthrin have numerous uses. A summary of agricultural use 

patterns for cyfluthrin and beta-cyfluthrin, based on a set of labels for cyfluthrin and all 

labels for beta-cyfluthrin, are shown Tables 3.2a and 3.2b. 

Table 3.2a. Summary use information for cyfluthrin based on BAYTHROID® 2 Emulsifiable 

Pyrethroid Insecticide (Reg. No. 264-745), RENOUNCE® 20WP Insecticide (Reg. No. 264-784) and 

LEVERAGE® 2.7 Suspension Emulsion Insecticide (Reg. No. 264-770) labels. For use on corn, labels 

with Reg. Nos. 264-811, 264-812, 264-813 and 264-839 were also evaluated.

USE 

SINGLE 

APP. RATE 

(lbs. a.i./A) 

NUMBER 

OF APPS. 

SEASONAL 

APP. RATE 

(lbs. a.i./A) 

INTERVAL 

BETWEEN 

APPS. (days) 

APPLIC. 

METHOD PHI (days) 

Corn (field corn, popcorn, seed corn, 

teosinte) – foliar applications 

or Corn – soil applications at plant

or Corn – soil applications at plant – 

granular formulation 

0.044 

0.044

0.0073 

4 

1 

0.175 7 G, A, ULV, 

Soil 

Applications 

Grain and 

fodder – 

21; green 

forage – 0 

Sweet Corn (FoliarApplications)/ (Soil 

Application – one application allowed) 

0.044 10 0.44 2 G, A, ULV 0 

Cotton 0.05 10 0.5 3 G, A, ULV 0 

Peanut 0.044 3 0.131 10 G, A, ULV 14 
 23

Table 3.2a. Summary use information for cyfluthrin based on BAYTHROID® 2 Emulsifiable 

Pyrethroid Insecticide (Reg. No. 264-745), RENOUNCE® 20WP Insecticide (Reg. No. 264-784) and 

LEVERAGE® 2.7 Suspension Emulsion Insecticide (Reg. No. 264-770) labels. For use on corn, labels 

with Reg. Nos. 264-811, 264-812, 264-813 and 264-839 were also evaluated.

USE 

SINGLE 

APP. RATE 

(lbs. a.i./A) 

NUMBER 

OF APPS. 

SEASONAL 

APP. RATE 

(lbs. a.i./A) 

INTERVAL 

BETWEEN 

APPS. (days) 

APPLIC. 

METHOD PHI (days) 

Sorghum 0.044 3 0.131 10 G, A, ULV 14 

Soybean 0.044 4 0.175 7 G, A, ULV 45 

Sugarcane 0.044 6 0.263 7 G, A, ULV 15 

Sunflower 0.044 3 0.131 7 G, A 30 

Tobacco 0.0044 1 0.0044 N/A G Apply up to 

7 days 

following 

transplanting

Wheat 0.038 2 0.076 3 G, A, ULV 30 

Brassica (Cole) Leafy Vegetables: 

broccoli, broccoli raab (rapini), Chinese (gai 

lon) broccoli, Brussels sprouts, cabbage, 

Chinese (bok choy) cabbage, Chinese (napa) 

cabbage, Chinese mustard (gai choi) 

cabbage, cauliflower, cavalo broccoli, 

collards, kale, kohlrabi, mizuna, mustard 

greens, mustard spinach, rape greens, and 

turnip greens

0.05 4 0.2 7 G, A 0 

Cucurbits: balsam apple, balsam pear, 

bitter melon, chayote, Chinese cucumber, 

Chinese waxgourd, citron melon, cucumber, 

gherkin, edible gourd (includes various), 

muskmelon (includes cantaloupe, honeydew 

melon and others), pumpkin, summer 

squash (includes zucchini and others), 

watermelon, Winter squash (includes 

calabaza, and others)

0.044 4 0.175 7 G, A 0 

Fruiting Vegetables: eggplant, 

groundcherry, pepino, pepper (includes bell 

pepper, chilipepper, cooking pepper, 

pimento, sweet pepper), tomatillo, tomato

0.044 6 0.263 7 G, A 0 for 

tomato and 

7 for other 

crops 

Leafy Vegetables: amaranth, arugula, 

cardoon, celery, Chinese celery, celtuce, 

chervil, Chrysanthemum, corn salad, cress, 

dandelion, dock, endive, Florence fennel, 

lettuce (head and leaf), New Zealand 

spinach, orach, parsley, purslane, radicchio, 

rhubarb, spinach, Swiss chard, vine spinach

0.05 4 0.2 7 G, A 0 

Dried Shelled Legume Vegetables: 

adzuki beans, blackeyed pea, broad bean, 

catjan, chickpea, cowpea, crowder pea, field 

bean, field pea, guar, kidney bean, lablab 

bean, lentil, dry lima bean, lupin (various), 

moth bean, mung bean, navy bean, pigeon 

pea, pinto bean, rice bean, tepary bean, urd 

bean

0.05 2 0.1 14 G, A 7 

Southern Pea 0.033 5 0.165 5 G, A 3 

Potato and Other Tuberous and Corm 

Vegetables: arracacha, arrowroot, 

artichoke, edible canna, cassava, chayote 

root, chufa, dasheen, ginger, leren, potato, 

sweet potato, tanier, true yam, turmeric, 

yam bean

0.044 6 0.263 5 G, A 0 
 24

Table 3.2a. Summary use information for cyfluthrin based on BAYTHROID® 2 Emulsifiable 

Pyrethroid Insecticide (Reg. No. 264-745), RENOUNCE® 20WP Insecticide (Reg. No. 264-784) and 

LEVERAGE® 2.7 Suspension Emulsion Insecticide (Reg. No. 264-770) labels. For use on corn, labels 

with Reg. Nos. 264-811, 264-812, 264-813 and 264-839 were also evaluated.

USE 

SINGLE 

APP. RATE 

(lbs. a.i./A) 

NUMBER 

OF APPS. 

SEASONAL 

APP. RATE 

(lbs. a.i./A) 

INTERVAL 

BETWEEN 

APPS. (days) 

APPLIC. 

METHOD PHI (days) 

Root Vegetables (except sugarbeet): 

gardenbeet, edible burdock, carrot, celeriac, 

turnip-rooted chervil, chicory, ginseng, 

horseradish, turnip-rooted parsley, parsnip, 

radish, Oriental radish, rutabaga, salsify 

(various), skirret, turnip

0.044 5 0.22 7 G, A 0 

Citrus** calamondin, citrus citron, citrus 

hybrids (includes chironja, tangelo), 

grapefruit, kumquat, lemon, lime, mandarin 

(tangerine), orange, pummelo, satsuma 

mandarin, white sapote and other cultivars 

and/or hybrids of these 

**California and Arizona, only. 

0.1 1 0.1 N/A G, A 0 

Grape: table grape, raisin, wine and 

muscadine grape 

(Product LEVERAGE® 2.7) 

0.05 

0.07 

4 

1 

0.2 

0.07 

14 

N/A 

G, A 3 

Hop 0.05 5 0.25 14 G, A 7 

Pome Fruit: apple, crabapple, loquat, 

mayhaw, pear, Oriental pear, quince

0.044 1 0.044 N/A G, A 7 

Stone Fruit: apricot, cherry, nectarine, 

peach, plum, plumcot, prune (fresh and 

dried)

0.044 2 0.088 14 G, A 7 

Tree Nut Crops: almond, beechnut, Brazil 

nut, butternut, cashew, chestnut, chinquapin, 

filbert, hickory nut, macadamia nut, pecan, 

pistachio, walnut (black and English)

0.044 1 0.044 N/A G, A 14 

Alfalfa, alfalfa grown for seed 0.044, 

0.088 per 

cutting 

8 0.35 5 G, A, ULV 7 

Grass (pasture, rangeland, grass for seed, 

grass for hay, grass in mixed-stands with 

alfalfa)

0.044 per 

app. 

4 0.176 5 G, A, ULV Pregrazing 

interval: 

0-7 

Table 3.2b. Summary use information for beta-cyfluthrin, based on BAYTHROID® XL (Reg. No. 

264-840), LEVERAGE® 360 Insecticide (Reg. No. 264-1104) and PONCHO BETA (Reg. No. 264-1056) 

labels.

USE 

SINGLE 

APP. RATE 

(lbs. a.i./A) 

NUMBER 

OF APPS. 

SEASONAL 

APP. RATE 

(lbs. a.i./A) 

INTERVAL 

BETWEEN 

APPS. (days) 

APPLIC. 

METHOD PHI (days) 

Corn (field corn, popcorn, seed corn); 

Corn (soil applications)

0.022 4 0.088 7 G, A, ULV, 

Soil 

Applications 

Grain and 

fodder – 

21; green 

forage – 0 

Sweet Corn (FoliarApplications)/ 

(Soil Application – at plant) 

0.022/ 

0.022 

10 0.44 2 G, A, ULV 0 

Cotton 0.025 10 0.25 3 G, A, ULV 0 

Peanut 0.022 3 0.066 10 G, A, ULV 14 

Sorghum 0.022 3 0.066 10 G, A, ULV 14 
 25

Table 3.2b. Summary use information for beta-cyfluthrin, based on BAYTHROID® XL (Reg. No. 

264-840), LEVERAGE® 360 Insecticide (Reg. No. 264-1104) and PONCHO BETA (Reg. No. 264-1056) 

labels.

USE 

SINGLE 

APP. RATE 

(lbs. a.i./A) 

NUMBER 

OF APPS. 

SEASONAL 

APP. RATE 

(lbs. a.i./A) 

INTERVAL 

BETWEEN 

APPS. (days) 

APPLIC. 

METHOD PHI (days) 

Soybean 0.022 4 0.088 7 G, A, ULV 45 

Sugarcane 0.022 6 0.132 7 G, A, ULV 15 

Sunflower 0.022 3 0.066 7 G, A 30 

Tobacco 0.0022 1 0.0022 N/A G Apply 7 

days 

following 

transplanting

Brassica (Cole) Leafy Vegetables: 

broccoli, broccoli raab (rapini), Chinese (gai 

lon) broccoli, Brussels sprouts, cabbage, 

Chinese (bok choy) cabbage, Chinese (napa) 

cabbage, Chinese mustard (gai choi) 

cabbage, cauliflower, cavalo broccoli, 

collards, kale, kohlrabi, mizuna, mustard 

greens, mustard spinach, rape greens, and 

turnip greens

0.025 4 0.1 7 G, A 0 

Cucurbits: balsam apple, balsam pear, 

bitter melon, chayote, Chinese cucumber, 

Chinese waxgourd, citron melon, cucumber, 

gherkin, edible gourd (includes various), 

muskmelon (includes cantaloupe, honeydew 

melon and others), pumpkin, summer 

squash (includes zucchini and others), 

watermelon, Winter squash (includes 

butternut squash, calabaza, and others)

0.022 4 0.088 7 G, A 0 

Fruiting Vegetables: eggplant, 

groundcherry, pepino, pepper (includes 

bellpepper, chilipepper, cooking pepper, 

pimento, sweet pepper), tomatillo, tomato

0.022 6 0.132 7 G, A 0 

Leafy Vegetables: amaranth, arugula, 

cardoon, celery, Chinese celery, celtuce, 

chervil, Chrysanthemum, corn salad, cress, 

dandelion, dock, endive, Florence fennel, 

lettuce (head and leaf), New Zealand 

spinach, orach, parsley, purslane, radicchio, 

rhubarb, spinach, Swiss chard, vine spinach

0.025 4 0.1 7 G, A 0 

Dried Shelled Legume Vegetables: 

adzuki beans, blackeyed pea, broad bean, 

catjan, chickpea, cowpea, crowder pea, field 

bean, field pea, guar, kidney bean, lablab 

bean, lentil, dry lima bean, lupin (various), 

moth bean, mung bean, navy bean, pigeon 

pea, pinto bean, rice bean, tepary bean, urd 

bean

0.025 2 0.05 14 G, A 7 

Southern Pea 0.017 5 0.083 5 G, A 3 

Potato and Other Tuberous and Corm 

Vegetables: arracacha, arrowroot, 

artichoke, edible canna, cassava, chayote 

root, chufa, dasheen, ginger, leren, potato, 

sweet potato, tanier, true yam, turmeric, 

yam bean

0.022 6 0.132 5 G, A 0 

Root Vegetables (except sugarbeet): 

garden beet, edible burdock, carrot, celeriac, 

turnip-rooted chervil, chicory, ginseng, 

horseradish, turnip-rooted parsley, parsnip, 

radish, Oriental radish, rutabaga, salsify 

(various), skirret, turnip

0.022 5 0.11 7 G, A 0 
 26

Table 3.2b. Summary use information for beta-cyfluthrin, based on BAYTHROID® XL (Reg. No. 

264-840), LEVERAGE® 360 Insecticide (Reg. No. 264-1104) and PONCHO BETA (Reg. No. 264-1056) 

labels.

USE 

SINGLE 

APP. RATE 

(lbs. a.i./A) 

NUMBER 

OF APPS. 

SEASONAL 

APP. RATE 

(lbs. a.i./A) 

INTERVAL 

BETWEEN 

APPS. (days) 

APPLIC. 

METHOD PHI (days) 

Citrus** calamondin, citrus citron, citrus 

hybrids (includes chironja, tangelo), 

grapefruit, kumquat, lemon, lime, mandarin 

(tangerine), orange, pummelo, satsuma 

mandarin, white sapote and other cultivars 

and/or hybrids of these 

**California and Arizona, only. 

0.05 1 0.05 N/A G, A 0 

Grape: table grape, raisin, wine and 

muscadine grape/ 

For the product LEVERAGE® 360

0.025 

0.05 

4 

1 

0.1 

0.05 

14 G, A 3 

Hop 0.025 5 0.125 14 G, A 7 

Pome Fruit: apple, crabapple, loquat, 

mayhaw, pear, Oriental pear, quince

0.022 1 0.022 N/A G, A 7 

Stone Fruit: apricot, cherry, nectarine, 

peach, plum, plumcot, prune (fresh and 

dried)

0.022 2 0.044 14 G, A 7 

Tree Nut Crops: almond, beechnut, Brazil 

nut, butternut, cashew, chestnut, chinquapin, 

filbert, hickory nut, macadamia nut, pecan, 

pistachio, walnut (black and English)

0.022 1 0.022 N/A G, A 14 

Alfalfa 0.022 

0.044 per 

cutting 

8 0.175 5 G, A, ULV 7 

Grass (pasture, rangeland, grass for seed, 

grass for hay, grass in mixed-stands with 

alfalfa)

0.022/ app. 

0.022/ 

cutting 

4 0.089 5 G, A, ULV 0 

Sugar beet, seed treatment ~0.0125 1 ~0.0125 N/A Seed 

Treatment 

N/A 

As mentioned previously at the top of Tables 3.2a and 3.2b, there are several end use 

agricultural products containing cyfluthrin and beta-cufluthrin like BAYTHROID® XL 

(Reg. No. 264-840), BAYTHROID® 2 Emulsifiable Pyrethroid Insecticide (Reg. No. 264-745), 

RENOUNCE® 20WP Insecticide (Reg. No. 264-784) and PONCHO BETA (Reg. No. 264-1056). 

In general, for a given crop, the application rate for beta-cyfluthrin is around half that for 

cyfluthrin. For agricultural products, application methods include aerial or ground spray 

(foliar) and ULV. In addition, soil applications are possible, particularly for corn. The 

labels for cyfluthrin and beta-cyfluthrin require a buffer zone of 10 ft around certain 

bodies of water, such as lakes, reservoirs, rivers, permanent streams, marshes or natural 

ponds, estuaries and commercial fish farm ponds, so as to allow growth of a maintained 

vegetative filter strip. The agricultural products should not be applied by ground 

equipment within a distance of 25 ft, or by aerial equipment within a distance of 150 ft, 

or by ULV within a distance of 450 ft from freshwater or estuarine/ marine bodies of 

water (e.g. lakes, reservoirs, rivers, permanent streams, marshes or natural ponds, 

estuaries and commercial fish farm ponds). 

For corn, granular formulations are available that may be applied as a band, T-band or in 

furrow applications, soil incorporated (it appears that the minimum incorporation depth is 
 27

1 inch). The buffer zone is 60 ft from adjacent bodies of water. The granular 

formulations also contain O-[2-(1,1-Dimethylethyl)-5-pyrimidinyl]-O-ethyl O-(1-

methylethyl) phosphorothioate, an organophosphate insecticide, commonly named 

phostebupirim. Cyfluthrin and beta-cyfluthrin may be co-formulated with imidacloprid, 

in the products LEVERAGE® 2.7 Suspension Emulsifiable Insecticide and 

LEVERAGE® 360 Insecticide. For beta-cyfluthrin, the product PONCHO® BETA is 

coformulated with chlothianidin, for the use on sugar beet seeds. 

The Label Use Information System (LUIS report) & Usage/Label Use Reports for 

cyfluthrin (provided by BEAD) was based on a partial listing of labels, due to the large 

number of labels available for review; use data is not based on an exhaustive review of 

the entire population of labels. Section 3 labels or major producers’ labels, along with all 

State and Local Needs (SLNs) labels, are included in the LUIS report. These data 

represent the major uses of this chemical. For beta-cyfluthrin, all labels were included in 

the LUIS report. 

The usage of cyfluthrin, from the Screening Level Usage Analysis (SLUA) is provided in 

Table 3.3. The table is arranged in alphabetical order of crops. According to the table, 

the major agricultural uses for cyfluthrin, crops for which 5000 or more pounds active 

ingredient are applied, are alfalfa, corn, cotton, soybeans, potatoes, oranges and sweet 

corn. For cotton and corn, for which the pounds applied are 60,000 and 30,000, 

respectively, the average percent crop treated is 5, and maximum percent crop treated are 

moderately low (10-15%). The crop for which the percent crop treated is the highest is 

potatoes, for which these percentages may reach moderately high values (25 and 35%, for 

the average and maximum, respectively). 

Table 3.3. Screening-Level Estimates of Agricultural Uses of Cyfluthrin (SLUA, 

dated 09/28/09). 

Percent Crop Treated 

Crop lbs a.i. Avg. Max. 

Alfalfa 10,000 <2.5 5 

Apples <500 <2.5 5 

Artichokes <500 <1 <2.5 

Beans, Green <500 <2.5 5 

Broccoli <500 <2.5 <2.5 

Cabbage <500 5 15 

Cantaloupes <500 <2.5 <2.5 

Carrots <500 10 25 

Cauliflower <500 5 10 

Celery <500 <2.5 <2.5 

Cherries <500 <2.5 <2.5 

Corn 30,000 5 10 

Cotton 60,000 5 15 

Cucumbers <500 <1 <2.5 
 28

Table 3.3. Screening-Level Estimates of Agricultural Uses of Cyfluthrin (SLUA, 

dated 09/28/09). 

Percent Crop Treated 

Crop lbs a.i. Avg. Max. 

Dry Beans/Peas <500 <1 <2.5 

Grapefruit <500 <2.5 5 

Grapes <500 <1 <2.5 

Hazelnuts (Filberts) <500 20 25 

Lemons <500 5 15 

Lettuce 1,000 5 10 

Onions + <500 <1 <2.5 

Oranges 5,000 5 15 

Peaches <500 <1 <2.5 

Peanuts 1,000 5 10 

Pears <500 <2.5 <2.5 

Pecans <500 <1 <2.5 

Peppers 1,000 15 25 

Pistachios <500 5 15 

Potatoes 10,000 25 35 

Pumpkins <500 <2.5 <2.5 

Rice <500 <1 <2.5 

Sod (NPUD '02) + <500 5 N/C 

Sorghum 2,000 <1 <2.5 

Soybeans 7,000 <1 <2.5 

Spinach <500 5 5 

Squash <500 5 10 

Sugarcane 1,000 <2.5 5 

Sunflowers 1,000 <2.5 5 

Sweet Corn 6,000 10 25 

Tobacco <500 <1 <2.5 

Tomatoes 2,000 5 10 

Watermelons <500 <1 <2.5 

Wheat 2,000 <1 <2.5 

All numbers are rounded. '<500' indicates less than 500 pounds of active ingredient. '<2.5' indicates less 

than 2.5 percent of crop is treated. '<1' indicates less than 1 percent of crop is treated. ‘+’ Crops not known 

to be listed on active end use product registrations or as Section 18 emergency exemptions when the report 

was run. The sources of the SLUA include the USDA-NASS, Private Pesticide Market Research, the 

National Pesticide Use Database (NPUD 2002) of the CropLife America Foundation and California 

Department of Pesticide Regulation (CDPR) data. The information reflects amalgamated data developed 

by the Agency and are in a releasable format. 

There is no similar SLUA for beta-cyfluthrin. According to the LUIS report, no usage 
 29

data was found for this chemical (as of January 2010). 

The U.S. Geological Survey (USGS) pesticide agricultural use maps (Fig. 3.1) show 

regional scale patterns in use intensity within the United States. The USGS pesticide 

maps are based on State level estimates of pesticide use rates for individual crops, which 

have been compiled by the National Center for Food and Agricultural Policy (NCFAP) 

for 1999 through 2004, and on the 2002 Census of Agriculture for county crop acreage 

crop. According to the map, the major agricultural use for cyfluthrin is cotton with 

46.96% of the use, followed by corn, alfalfa hay and potatoes with 6.72-19.41% of the 

use. Other crops with >1% of the use included sweet corn, citrus fruits, tomatoes, 

sorghum and lettuce. One crop, with reported percent of the use <1% is sunflower seed. 

As expected, there is a general agreement between the SLUA and the USGS map. The 

map shows a generalized use of cyfluthrin for agricultural purposes throughout the 

country, with highest uses in the cornbelt and the cotton belt. It also shows potential uses 

in estuarine/ marine regions of the US. Multiple agricultural uses are approved for 

cyfluthrin, other than the ones in the map, as indicated above in the Table 3.2a. 

At the present time, there is no similar agricultural map for beta-cyfluthrin. 
 30

Fig. 3.1. Estimated Use of Cyfluthrin in 2002 

Note of Caution: The pesticide use maps available (http://water.usgs.gov/nawqa/pnsp/usage/maps/compound_listing.php?year=02 ) show the 

average annual pesticide use intensity expressed as average weight (in pounds) of a pesticide applied to each square mile of agricultural land in 

a county. The area of each map is based on state-level estimates of pesticide use rates for individual crops that were compiled by the CropLife 

Foundation, Crop Protection Research Institute during based on information collected during 1999 through 2004 and on 2002 Census of 

Agriculture county crop acreage. The maps do not represent a specific year, but rather show typical use patterns over the five year period 1999 

through 2004. Use intensity rates are expressed as the pounds applied per square mile of mapped agricultural land in a county. The area of 

mapped agricultural land for each county was obtained from an enhanced version of the 1992 USGS National Land Cover Data (NLCD). The 

key limitations of the data used to produce these maps include the following: (1) state use coefficients represent an average for the entire state 

and consequently do not reflect the local variability of pesticide management practices found within states and counties, (2) pesticide use 

estimates are not for a specific year, but represent typical use patterns for the five year period, (3) state pesticide use coefficients may not have 

been available for all states where a pesticide may have been applied to agricultural land, and therefore, are not displayed on the maps, (4) the 

county crop acreage is based on the 2002 Census of Agriculture and may not represent all crop acreage because of Census nondisclosure rules, 

and (5) agricultural land area used to calculate the pesticide use intensity and display the data was derived from 30-meter satellite remote 

sensing data that may over estimate or underestimate the actual agricultural land area. The maps are not intended for making local-scale 

estimates of pesticide use, such as estimates at the county level. Please refer to Method for Estimating Pesticide Use for a detailed discussion of 

how the pesticide use data were developed. 

In addition to the classical agricultural use sites, cyfluthrin and beta-cyfluthrin have 

multiple other uses. Cyfluthrin and beta-cyfluthrin may be used in multiple urban 

environments. Many of these uses are classified as outdoor residential such as 

ornamental lawns and turf, recreation area lawns, ornamental and/ or shade trees, 

ornamental herbaceous plants, ornamental woody shrubs and vines, paths/ patios, paved 

areas (private roads/ sidewalks), pet living/ sleeping quarters, and residential lawns. 

Tables 3.4a and 3.4b provide a summary of the terrestrial nonagricultural use sites for 

cyfluthrin and beta-cyfluthrin, respectively. Application methods vary. Many of these 

uses could involve substantive exposure to wildlife, specifically, aquatic organisms, and 
 31

they will be assessed accordingly (e.g., commercial/ industrial lawns, residential lawn, 

golf course turf, ornamental lawns and turf, recreation areas and residential lawns). (Note 

that there are fewer non-food uses for beta-cyfluthrin than for cyfluthrin.) Another use 

that will be evaluated is wood protection treatment (outdoors). 

Table 3.4a. Uses Classified as Terrestrial Non-Food or Outdoor for Cyfluthrin 

Use 

Max. App. Rate/ 

units

Max. No. 

Apps./ Year 

Max. App. 

Rate per 

Year 

Min. App. 

Int./ days 

agricultural/farm structures/buildings and equipment 0.0044 lb 1K sq.ft NS NS NS 

airports/landing fields 

0.0100 lb 1K sq ft 

0.0042 lb/ mound NS NS AN, NS 

animal kennels/sleeping quarters 0.0100 lb 1K sq ft NS NS AN 

animals (laboratory/research) 0.0100 lb 1K sq ft NS NS 7 

automobiles, taxis, limousines, recreational vehicles, & tires 0.0100 lb 1K sq ft NS NS 7 

barns/barnyards/auction barns 0.0085 lb 1K sq ft NS NS 10, NS 

commercial storages/warehouses premises 0.0100 lb 1K sq ft NS NS AN, 7 

commercial/industrial lawns 0.0100 lb 1K sq ft NS NS 7, AN 

commercial/institutional/industrial premises/equipment (outdoor) 0.0100 lb 1K sq ft NS NS 7, AN 

golf course turf 0.0031 lb 1K sq ft 6/ 1 yr NS NS 

greenhouse-empty 0.0100 lb 1K sq ft NS NS 7 

household/domestic dwellings outdoor premises 

0.0088 lb 1K sq ft 

0.0042 lb/ mound 6/ 1 yr NS 7, AN, NS 

industrial areas (outdoor) 

0.0088 lb 1K sq ft 

0.0042 lb/ mound NS NS 7, NS 

livestock feed lots 4.579E-06 lb/ sq ft NS NS AN 

meat processing plant premises (nonfood contact) 0.0100 lb 1K sq ft NS NS 7 

nonagricultural outdoor buildings/structures 

0.0100 lb 1K sq ft 

0.0042 lb/ mound NS NS NS, AN, 7 

nonagricultural rights-of-way/fencerows/hedgerows 0.0100 lb 1K sq ft NS NS 7, 30, AN 

ornamental and/or shade trees 0.0100 lb 1K sq ft NS NS AN, 7, 30 

ornamental ground cover 0.0040 lb 1K sq ft NS NS 7, 30 

ornamental herbaceous plants 0.0040 lb 1K sq ft NS NS AN, 7, 30 

ornamental lawns and turf 0.0100 lb 1K sq ft 6/ 1 yr, NS NS AN, 7, NS 

ornamental nonflowering plants 0.0100 lb 1K sq ft 6/ 1 yr, NS NS AN, 7, 30, NS 

ornamental woody shrubs and vines 0.0040 lb 1K sq ft 6/ 1 yr, NS NS AN, 7, 30, NS 

paths/patios 

0.0100 lb 1K sq ft 

0.0042 lb/ mound NS NS NS, 7, AN 

paved areas (private roads/sidewalks) 

0.0088 lb 1K sq ft 

0.0042 lb/ mound NS NS 7, NS 

pet living/sleeping quarters 0.0100 lb 1K sq ft NS NS 7, AN 

recreation area lawns 0.0044 lb 1K sq ft 6/ 1 yr, NS NS 7, NS 

recreational areas 0.0088 lb 1K sq ft NS NS 7, NS 

residential lawns 0.0042 lb 1K sq ft 6/ 1 yr, NS NS NS 

tobacco 0.0044 lb/A 1 

0.0044 

lb/A/cc 7 

wood protection treatment to buildings/products outdoor 

0.0085 lb 1K sq ft 

0.0011 lb sq ft NS NS NS 

wood protection treatment to forest products (unseasoned) 0.0088 lb 1K sq ft NS NS 7 

zoos 0.0100 lb 1K sq ft NS NS 7, AN 

NS = Not Specified; AN = As Needed; cc = crop cycle. Data obtained from LUIS Report. 

Table 3.4b. Uses Classified as Non-Food or Outdoor for Beta-cyfluthrin 

Use 

Max. App. Rate/ 

units

Max. No. 

Apps./ Year 

Max. App. 

Rate per 

Year 

Min. App. 

Int./ days 

agricultural/farm premises 0.0042 lb 1K sq ft NS NS NS, 10 

barns/barnyards/auction barns 0.0042 lb 1K sq ft NS NS NS 

Christmas tree plantations 0.025 lb/A NS 0.125 lb/cc AN 

commercial/industrial lawns 0.0022 lb 1K sq ft 6/ 1 yr NS AN 

commercial/institutional/industrial premises/equipment (outdoor) 0.0044 lb 1K sq ft NS NS NS, 7 

fencerows/hedgerows 0.0044 lb 1K sq ft NS NS NS, 7 
 32

Table 3.4b. Uses Classified as Non-Food or Outdoor for Beta-cyfluthrin 

Use 

Max. App. Rate/ 

units

Max. No. 

Apps./ Year 

Max. App. 

Rate per 

Year 

Min. App. 

Int./ days 

household/domestic dwellings outdoor premises 0.0042 lb 1K sq ft NS NS NS, 7 

ornamental and/or shade trees 0.0015 lb 1K sq ft NS NS 

NS, 7, 14, 30, 

AN 

ornamental ground cover 0.0015 lb 1K sq ft NS NS NS, 7 

ornamental herbaceous plants 0.0015 lb 1K sq ft NS NS NS, 7, 14, AN 

ornamental lawns and turf 0.0022 lb 1K sq ft 6/ 1 yr NS NS, AN 

ornamental nonflowering plants 0.0015 lb 1K sq ft NS NS NS, 7, 14 

ornamental woody shrubs and vines 0.0015 lb 1K sq ft NS NS NS, 7, 14 

paths/patios 0.0044 lb 1K sq ft NS NS NS, 7 

paved areas (private roads/sidewalks) 

Not specified, RTU 

formulation NS NS NS 

recreation area lawns 0.0022 lb 1K sq ft 6/ 1 yr NS AN 

residential lawns 0.0022 lb 1K sq ft 6/ 1 yr, NS NS 7, NS, AN 

tobacco 0.0022 lb/A 1/ cc 0.0022 lb/ cc NS 

wood protection treatment to buildings/products outdoor 

NS, various 

formulations NS NS 7, NS 

NS = Not Specified; AN = As Needed; cc = crop cycle. Data obtained from LUIS Report. 

In addition, there are several other indoor non-food or indoor residential use sites for both 

cyfluthrin and beta-cyfluthrin, like for example, commercial/institutional/industrial 

premises/equipment (indoor), dairies/cheese processing plant premises (nonfood contact), 

eating establishments, food processing plant premises (nonfood contact), food stores/ 

markets/ supermarkets premises, hospitals/ medical institutions premises and household/ 

domestic dwellings. Cyfluthrin and beta-cyfluthrin also have greenhouse uses. 

For the indoor uses, the Division has conducted environmental risk assessments for a few 

chemicals for Re-registration Eligibility Decisions. In an open literature study (Weston 

and Lydy 2010), several synthetic pyrethroids were observed in effluents after secondary 

treatment from POTWs in the Sacramento-San Joaquin Delta. In the study, bifenthrin 

was the most frequently detected pyrethroid. Cyfluthrin was found in 6% of the 

municipal wastewater treatment plant effluents (POTWs) tested in the Sacramento-San 

Joaquin Delta (18 samples), at a maximum concentration of 1.7 ng/L, and it exceeded the 

Hyalella azteca EC50 of 1.9 ng/L in 0% of the samples. This study indicates there is a 

potential for synthetic pyrethroids to reach surface waters via exposure from 

contaminated drains, and even after treatment in plants (for further information about this 

study, see Section 3.4). The EFED will evaluate the potential for exposure to aquatic 

organisms from the various indoor uses of cyfluthrin and beta-cyfluthrin (see also further 

information below).

Toxicity data on environmental mixtures of cyfluthrin or beta-cyfluthrin with other 

pesticides may be presented, if available, as part of the ecological risk assessment. It is 

expected that the toxic effect of cyfluthrin or beta-cyfluthrin, in combination with other 

pesticides used in the environment, is likely to be a function of many factors including 

but not necessarily limited to: (1) the exposed species, (2) the co-contaminants in the 

mixture, (3) the ratio of cyfluthrin or beta-cyfluthrin and co-contaminant concentrations, 

(4) differences in the pattern and duration of exposure among contaminants, and (5) the 

differential effects of other physical/ chemical characteristics of the receiving waters (e.g.

organic matter present in sediment and suspended water). Quantitatively predicting the 
 33

combined effects of all these variables on mixture toxicity to any given taxa with 

confidence is beyond the capabilities of the available data and methodologies. However, 

a qualitative discussion of implications of the available pesticide mixture effects data 

regarding the confidence of risk assessment conclusions will be addressed as part of the 

uncertainty analysis. 

Piperonyl butoxide (PBO) and MGK-264 are commonly used in formulations with 

pyrethroids. PBO acts as a potentiator in both mammals and insects because the 

pyrethroid is not metabolized and excreted as quickly in its presence (Barile 2004; 

Hodgson & Smart 2001). Exposure to pyrethroids along with PBO increases the toxicity 

of the pyrethroids (Amweg & Weston 2007; Weston & Lydy 2010). MGK-264, another 

potentiator/synergist used with pyrethroids, has similar effects as those observed for 

piperonyl butoxide (Hodgson & Smart 2001). 

A total of 4 current product registrations exist for cyfluthrin formulations with PBO: 

 Cyfluthrin, PBO and Pyrethrins: # 279-3404, #499-462, #9444-183, #9444-226 

Beta-cyfluthrin is not co-formulated with PBO or MGK in any currently active 

registrations. 

The Agency routinely assesses potential exposure to formulations by examining acute 

exposure due to spray drift or direct applications to water and comparing the estimated 

exposure to available acute toxicity data on the formulation. The spray drift associated 

with the cyfluthrin uses containing synergists will be minimal, as all cyfluthrin products 

with PBO or MGK are registered for residential or structural uses only. Therefore, a 

quantitative assessment of the potential aquatic exposure to the formulation containing 

MGK synergists will not be conducted. Piperonyl butoxide and/or MGK-264 from other 

pyrethroid applications (e.g. the application of an adulticide containing PBO), could 

interact with cyfluthrin and beta-cyfluthrin in the environment. Available literature data 

also suggest the potential for synergism in the environment (Amweg et al. 2006, Weston 

et al. 2006, Amweg & Weston 2007, and Brander et al. 2009). Therefore, potential 

interactions will be discussed qualitatively in the risk assessment. EPA is currently 

evaluating options on how to gather data on pyrethroid end use products co-formulated 

with a synergist. 

It is important to recognize that the active ingredient and the synergist have differing fate 

properties and therefore would be expected to occur in the environment at different times 

and at different concentrations than present in the end use product. Consequently, it is 

necessary to have toxicology data which allows the assessment of the level of synergy as 

the ratio of the pesticide and synergist vary in the environment. Datasets which allow the 

calculation of the ‘pesticide-synergist interaction’ are often not available. EFED 

recognizes the limitations inherent in this approach and is looking into the acquisition of 

data that would allow the evaluation of the effect of both synergist and active ingredient 

when present in the ecosystem. Evaluating the potential toxic effects of the synergist 

include evaluating ecological effects data generated using end-use products and the active 

ingredient in the presence of synergists, in addition to data for the active ingredient alone. 
 34

At this time, EFED typically has data for individual active ingredients, as well as for the 

synergists alone, but few data are available from which to draw conclusions regarding the 

potential effect of the combination. As stated above, the Agency is evaluating its options 

for obtaining data appropriate for this type of evaluation. 

3.3. Environmental Fate and Transport 

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. [Phenyl-14C]-

radiolabeled compound was utilized in most instances. 

A summary of environmental fate/ transport properties for cyfluthrin and beta-cyfluthrin 

is included in Table 3.5. 
 35

Table 3.5. Summary of the environmental fate and transport properties of cyfluthrin and 

beta-cyfluthrin. 

 PARAMETER VALUE(S) (units) SOURCE COMMENT 

 Hydrolysis Half-life 

 [pH 5, 7, 9; (25 oC)] 

Stable at pH 5, nearly stable at pH 7, 

t1/2 = 2.1 days at pH 9; major degradation 

product FPB-ald 

MRID: 00131493, 

00137539, 45022101 

Supplemental data shows that the 

half-life was 9 days in natural 

waters from the Rhine river. Major 

product was FPB-acid. Water’s pH 

was 7.7-8.3. 

 Aqueous Photolysis Half-life 

 (pH 5) 

t1/2 = 4.5 days linear; 

t1/2 = 0.7 days nonlinear; 

degradation products: 

FPB-acid and FPB-ald 

MRID: 00149595, 

45022102 

Value obtained using natural 

sunlight 

 Soil Photolysis Half-life t1/2 = 5.6 days; 

degradation product: FPB-ald 

MRID: 00137543, 

00157043 

Dark control corrected; using 

natural sunlight 

 Aerobic Soil Metabolism Halflife  L t1/2 = 73.5 days 

SL t1/2 = 94.8 days 

major degradate: FPB-acid 

MRID: 00131494 – 

 Anaerobic Soil Metabolism 

 Half-life 

t1/2 ~ 30 days; 

degradate FPB-acid declined 

MRID: 00131494 Study lasted 60 days. 

 Aerobic Aquatic Metabolism 

 Half-life 

t1/2 = 32.9 and 42.0 days for two German 

systems. Degradates DCVA, FPB-acid and 

FPB-ald 

MRID: 46824101 (20.4 & 22.0 days for two Dutch 

systems, but the quality of these 

half-lives was considered very low.)

 Anaerobic Aquatic Metabolism 

 Half-life 

No Study Available NA Study is required. 

 Soil Partition Coefficient (Kd) 

 Organic Carbon Partition 

 Coefficient (KOC) 

 For Cyfluthrin

Adsorption:

Soil Kd KOC

German LS 1116 124000 

US LS 1244 180300 

US CL 1321 118000 

German SiL 1793 73500

Desorption:

Soil Kd KOC

German LS 1448 161000 

US LS 974 141000 

US CL 1307 117000 

German SiL 1705 69900

KOC in mL/gOC and Kd in mL/g. 

Immobile to hardly mobile. 

There is a linear relationship between the soil 

organic carbon content and the Kd values (r2

 = 

0.92). 

MRID: 00131495, 

00137544, 45022103 

In supplemental studies, TLC data 

for cyfluthrin on six different soils 

were submitted. Using the Helling 

and Turner mobility classification 

system, cyfluthrin was classified as 

immobile in the six test soils. To 

help EFED develop a Kd input for 

modeling, the registrant later 

submitted a supplemental study to 

the Agency which contained a 

single Kd value for one soil of 810 

mL/g. 

 Soil Partition Coefficient (Kd) 

 Organic Carbon Partition 

 Coefficient (KOC) 

 For trans-DCVA

Adsorption:

Soil KF KFOC

Sand ND ND 

Silty Clay 0.46 18 

Sandy Loam 0.16 19 

Sandy Loam 0.54 48

Desorption:

Soil KF KFOC

Sand ND ND 

Silty Clay 0.91 36 

Sandy Loam 0.36 44 

Sandy Loam 0.72 64

ND = Not determined 

MRID: 43424901 Provides information to partially 

fulfill the data requirement. 

 Terrestrial Field Dissipation 

 Half-life 

NC: t1/2 (in surface soil) = 18.1 days; was only 

detected in top 6 in soil layer. 

CA (Fresno) cotton site: t1/2 reported to be 4.3 

days (using 0-7 day data; or 23.8 days if 0-14 

day data are used), cyfluthrin was not detected 

after day 29 post-treatment; residues remained 

in top 6 in soil layer, except for two individual 

samples. FPB-acid and DCVA were detected 

in this study. 

AZ, FL, KS, GA, OR, MS, Canada:

DT50 < 32 days 

MRID: AN 259211, 

44822901, 42794801 

Study 42794801 was screened only 

and a full review will be provided at 

a later time. 
 36

Table 3.5. Summary of the environmental fate and transport properties of cyfluthrin and 

beta-cyfluthrin. 

 PARAMETER VALUE(S) (units) SOURCE COMMENT 

 Bioaccumulation in Fish 

 (BCF) 

Maximum BCF=854X for whole fish, with 

moderate depuration. The only major residue 

was the parent. The depuration time appears 

to be ≤3 days. 

MRID: 00143143 – 

Cyfluthrin and beta-cyfluthrin are Type II synthetic pyrethroids (they are cyano 

substituted in the alpha position. Cyfluthrin and beta-cyfluthrin have a 2,2-

dichloroethenyl, and they are 2,2-dimethyl substituted in the cyclopropane ring. The 

database for cyfluthrin has been used as a surrogate fate database for beta-cyfluthrin 

since they are structurally related. Even though they are Type II pyrethroids that 

characteristically show more stability to photolysis, submitted laboratory data suggest 

that the primary routes of dissipation are aqueous and soil photolysis (4.5 and 5.6 days, 

respectively) and hydrolysis in alkaline media (2.1 days). Cyfluthrin and beta-cyfluthrin 

are moderately persistent in the environment and immobile (aerobic soil metabolism 

73.5-94.8 days, aerobic aquatic metabolism 32.9-42 days). The terrestrial field 

dissipation data confirm the pattern observed in the laboratory studies with half-lives and 

DT50’

s in the range of 18-32 days, which would indicate that the chemical follows mix 

routes of dissipation in the field. The KOC’s ranged from ~73,000-180,000 mL/gOC, 

indicating low mobility. Like other pyrethroids, cyfluthrin and beta-cyfluthrin bind 

strongly to soils suggesting a low potential to leach to subsurfaces and to contaminate 

groundwater. The moderate persistence of the chemical, the high soil affinity and very 

low solubility indicate that the chemicals have a high potential to reach surface waters in 

runoff events accompanied by erosion occurring during periods of weeks to months after 

application. Residues could also reach surface waters via spray drift. Once the chemicals 

reach surface waters, there is potential impact to water quality, which appears to be 

mostly due to parent compound. The fate of cyfluthrin in anaerobic environments is 

uncertain. Cyfluthrin and beta-cyfluthrin are likely to partition with sediments in bodies 

of water. Since cyfluthrin may be applied repeatedly, the material may build up in 

sediments and affect benthic communities. Cyfluthrin and beta-cyfluthrin are moderately 

bioaccumulative with moderately rapid rates of depuration (estimated half-depuration 

time ≤3 days). Major metabolites observed in laboratory studies include cis- and transDCVA, FPB-acid and FPB-ald (Table 3.1c). These compounds result from the 

hydrolysis of the ester bond of the parent compounds. 

Transport 

The potential impact to water quality from the use of cyfluthrin appears to be mostly due 

to the parent compound. Laboratory studies show that cyfluthrin is moderately persistent 

under most environmental conditions making the compound available for runoff. 

Although the potential for mobility appears low, the likely means of cyfluthrin movement 

from a crop site to an adjacent body of water would be runoff accompanied by erosion, as 

well as spray drift. Laboratory studies predict that once the chemical reaches surface 

waters, it may persist for moderate periods of time (relatively stable at pH 7). Even 

though cyfluthrin undergoes photolysis in water, its lypophilicity and affinity with 

particulate should make it unavailable to photolysis in a short period. In addition, 
 37

photolysis will be limited only to clear shallow waters or the upper layers of the water 

column. Cyfluthrin does not seem to be a significant threat to ground water quality under 

most conditions. While laboratory conditions show that cyfluthrin is moderately 

persistent, the very low mobility observed in the laboratory reduces substantially the 

concern that there would be a potential of the compound to reach ground water. Some 

supplemental studies indicate that the potential degradates cis- and trans-DCVA could 

leach to ground waters. Conclusions with respect to the mobility of these degradates are 

limited by the available data. 

Degradation and Metabolism 

The hydrolysis of cyfluthrin was pH dependent. It was fast in alkaline media (stable, 

essentially stable and 2.1 days at pH’s 5, 7 and 9 respectively). In a supplemental study 

conducted on filtered Rhine River water (pH 7.7-8.3), in the dark, cyfluthrin hydrolyzed/ 

degraded with a half-life of 9 days. An important route of dissipation for this chemical 

may be aqueous photolysis with a non-linear half-life of 0.7 days/ linear 4.5 days in an 

aqueous solution under natural sunlight. The major degradates were FPB-acid (4-fluoro3-phenoxybenzoic acid) and FPB-ald (4-fluoro-3-phenoxybenzaldehyde). Soil 

photodegradation may also be an important route of dissipation for cyfluthrin and betacyfluthrin. In soil, photodegradation followed a half-life of 5.6 days (dark control 

corrected). The only phenyl-labeled degradate was FPB-ald (up to 8% of the applied). It 

is assumed that the degradate DCVA [3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid] is formed in the hydrolysis and the aqueous photolysis 

studies. DCVA is stable to hydrolysis at pH’s 4, 7 and 9 (European Commission, 

Appendix 2). 

The aerobic soil metabolism appears to play a lesser role in the dissipation of cyfluthrin 

with half-lives in a loam soil and a sandy loam soil, of 73.5 and 94.8 days, respectively. 

There was some formation of carbon dioxide and the only fluoro-phenyl degradate 

detected at appreciable amounts was FPB-acid (7% of the applied). In an anaerobic soil 

metabolism study, using aged loam, flooded and purged with nitrogen and based on two 

points, a half-life of around 30 days was obtained. Two degradates detected at the end of 

the initial aerobic incubation, FPB-acid and cyfluthrin-amide (minor degradate), declined 

during the anaerobic phase. The degradate DCVA was identified in a 100-day aerobic 

soil metabolism study at >10% of the applied, as indicated by the European Commission 

(Appendix 2). In aerobic soil metabolism studies at 25°C at 40% MWHC, the DT50 

range for DCVA was 12-62 days (mean 24 days, median 16 days, 2 soils, 4 isomers). It 

is indicated that DT50FPBacid < DT50DCVA. 

In aerobic aquatic metabolism studies, conducted on beta-cyfluthrin, based on first order 

linear regression analysis, the half-lives of cyfluthrin in the total systems were 32.9 and 

42.0 days for two German systems, and 20.4 and 22.0 days for two Dutch systems. The 

quality of the results of the Dutch systems is regarded as low, and those half-lives should 

not be used for modeling. Three degradates were identified in the aerobic aquatic 

systems. In the German systems, DCVA was a maximum of 47.63% at 28 days. In the 

Dutch systems, FPB acid was a maximum of 44.5% at 11 days, and FPB-ald) was a 

maximum of 15.7% at 1 day. No anaerobic aquatic metabolism studies are available at 
 38

this time. 

Sorption and Mobility 

Cyfluthrin is hydrophobic and was hardly mobile to immobile in four soils (Kd range 

1116 to 1793 mL/g; KOC range 73,000 to 180,000 mL/gOC; measurements made at single 

concentrations, FAO mobility classification, FAO 2000). The chemical will bind 

strongly to the soil surfaces. There was a linear relationship between the soil organic 

carbon content and cyfluthrin Kd values (r2 = 0.92). The soils included German loamy 

sand and silty loam, and US loamy sand and clay loam. At least, some of the degradates 

formed from the cleavage of the carboxylate ester are expected to be more mobile than 

the parent. Supplemental data available to the Agency, indicates that the degradate 

DCVA is mobile to moderately mobile in neutral to alkaline soils (KOC range 14 to 356 

mL/gOC, FAO mobility classification). 

Even though cyfluthrin may be applied aerially, by ground or ULV, and drift is possible, 

the chemical appears to be relatively non-volatile (vapor pressure 1.5 x 10-8 mmHg, 

Henry’s Law Constant 3.7 x 10-6 atm-m3/mol). Furthermore, cyfluthrin readily binds to 

soils or partitions with suspended matter and sediment. Thus, volatilization would be 

greatly reduced. 

Field Dissipation 

Cyfluthrin, applied on Fairmont, NC sandy soil (sand 90.8%, depth 0-6 inches, 0.33% 

OM), cropped with cotton, at a rate of 0.55 lb a.i./A, dissipated from the field with a halflife of 18 days (r2

 = 0.94, n = 8), or with a DT50 of <32 days. Residues were detected 

only in the top 6” soil layer. No residues were detected below the top 6” of soil depth 

(sandy loam, 0.33% OM). There were two single detects of Cl2CA (≤0.012 ug/g), and 

eight, mostly single detects of FPBA (≤0.016 ug/g). All values were close to the 

analytical detection limits. Cyfluthrin dissipated from a cotton site in Fresno, California 

with a registrant-reported half-life of 4.3 days (using 0-7 day data; or 23.8 days if 0-14 

day data are used, but the data point for 14 days was higher than for 7 days). Cyfluthrin 

was not detected after day 29 post-treatment. The DT50 was ca. 3 days. Residues 

remained in top 6 in soil layer, except for two individual samples. FPBA and DCVA 

were detected in this study. This study was screened only, but a full review will be 

conducted at a later time. 

In other terrestrial field dissipation studies, in AZ, FL, KS, GA, OR, MS and Canada 

different soils, with different organic matter content showed that cyfluthrin (in the form 

of Baythroid 24% EC), sprayed at 1 kg a.i./ha dissipated with DT50’s of <32 days. In 

these studies, soil sampling intervals, spaced by 30-32 days were inadequate and 

prevented accurate half-life calculations. Besides the parent, residues of DCVA and 

FPB-acid were detected in some studies. Cyfluthrin was detected in the 6-12” cores at 

levels less than 0.13 mg/Kg in five out of the seven studies. 

Bioaccumulation 

Based on the octanol/ water partition coefficient, cyfluthrin shows a high potential to 

bioaccumulate (KOW = 9.33 x 105

). The bioconcentration factor in whole rainbow trout 
 39

was moderate (854x, whole fish). Residues were depurated at moderately rapid rates in 

untreated water (apparent depuration half-life of approximately ≤3 days). Accumulated 

residues were found mostly in non-edible tissues, and the only residue detected at high 

levels was the parent compound. 

Transformation Products 

The fate and transport characterization is also summarized for the various degradation 

products formed by each process for the studies reviewed in Table 3.6. 

Table 3.6. Summary of degradate formation from degradation of cyfluthrin. 

DEGRADATE and MAXIMUM CONCENTRATION 

 STUDY TYPE SOURCE F-PB-acid (% app) F-PB-ald (% app) DCVA (% app) 

 Hydrolysis MRID: 00131493, 

00137539, 45022101 

– 11% at 35 days at pH 

7, 89% at 21 days at 

pH 9 

– 

 Aqueous Photolysis MRID: 00149595, 

45022101, 45022102 

37% at day 14 18% at day 7 – 

 Soil Photolysis MRID: 00137543, 

00157043 

– 18% at days 5-6 – 

 Aerobic Soil Metabolism MRID: 00131494 10% at 10 days – >10% in 100-day 

studies 

 Anaerobic Soil Metabolism MRID: 00131494 10% at 30 days of 

aerobic incubation 

(time of flooding) 

– – 

 Aerobic Aquatic Metabolism MRID: 46824101 44.5% at 11 days 15.7% at 1 day 47.63% at 28 days 

 Terrestrial Field Dissipation MRID: AN 259211, 

42794801, 44822901 

<0.07 mg/Kg in the 0-

6” cores 

– 0.16 mg/Kg at 30 days

Major degradates identified in laboratory studies are FPB-acid, FPB-ald and DCVA 

result from the rupture of the ester linkage of the synthetic pyrethroid. FPB-acid was 

identified in the aqueous photolysis, aerobic soil metabolism, and anaerobic soil 

metabolism studies at 10-37% of the applied at 10-30 days after treatment. FPB-ald was 

observed at significant amounts in photolysis/ photodegradation studies at 18% of the 

applied of the applied (5-7 days posttreatment) and in hydrolysis studies (up to 89% of 

the applied at pH 9, but only 11% at pH 7). DCVA was identified in supplemental 

aerobic soil metabolism studies (>10% of the applied). The degradate DCVA was also 

identified in field studies at up to 0.16 mg/Kg. 

There is uncertainty with respect to the available data on the cyclopropane side of the 

ester linkage and cold analyses were not performed on the possible degradates resulting 

from the rupture of this linkage. There is evidence of the formation of DCVA, but there 

is no further information on the possible degradation pathways. There are limited data 

about the mobility and persistence of FPB-ald, FPB-acid and DCVA. While it appears 

that DCVA is much more mobile than the parent compound and has the potential to reach 

ground waters in vulnerable sites, there are limited data about its mobility. DCVA has 

been detected in laboratory studies at >10% of the applied. 

Uncertainties

The environmental fate database for parent cyfluthrin and beta-cyfluthrin was previously 

considered adequate to perform a screening level assessment of the chemical. However, 

the following uncertainties were noted. There is uncertainty related to the anaerobic soil 

metabolism study. The half-life was very roughly estimated, based on two data points. 
 40

Also, the fate of cyfluthrin in anaerobic aquatic environments is uncertain. 

Studies using radiolabeling on the cyclopropane side of the ester linkage were not 

conducted and cold analyses were not performed. Consequently, there were no analyses 

for potential cyclopropane containing degradates that may have originated from the 

cleavage of the carboxylate ester linkage, such as DCVA. At this time, most of the data 

available are on the fluorophenyl ring only. 

EFED has limited data about the environmental fate (mobility and persistence) of 

degradates of cyfluthrin, FPB-ald, FPB-acid, cyfluthrin amide, and cis/ trans-DCVA. 

The limited data available indicate that DCVA is mobile to moderately mobile and has 

the potential to reach ground waters in vulnerable sites. However, this potential would be 

limited by the amounts of DCVA produced in the soils because cyfluthrin degrades 

slowly. It appears that DCVA is not highly toxic to mammals (communication with 

Carol Christensen, Health Effects Division, 07/01/2004). As part of the risk assessment, 

the EFED will conduct an ECOTOX search for information about the possible toxicity of 

the degradates of cyfluthrin as it will be further indicated below. 

The mobility (batch equilibrium) data available for cyfluthrin was obtained at a single 

concentration. EFED has available Kd and KOC values, but no Freundlich KF and KFOC

values (no isotherms available). 

4. Receptors 

4.1. Aquatic and Terrestrial Effects 

The receptor is the biological entity that is exposed to the stressor (EPA, 1998). Due to 

the outdoor uses of cyfluthrin and beta-cyfluthrin, the types of receptors that may be 

exposed include both aquatic and terrestrial receptors, such as birds, reptiles, mammals, 

amphibians, freshwater and estuarine/marine fish, non-target terrestrial & aquatic 

invertebrates and terrestrial & aquatic plants. This list may not be comprehensive. Spray 

drift and runoff exposures are expected for both ground and aerial applications of 

cyfluthrin. Consistent with the process described in the Overview Document (USEPA, 

2004), this risk assessment uses a surrogate species approach in its evaluation of 

cyfluthrin. Toxicological data generated from surrogate test species, which are intended 

to be representative of broad taxonomic groups, are used to extrapolate to potential 

effects on a variety of species (receptors) included under these taxonomic groupings. 

Tables 4.1 and 4.2 provide a summary of the taxonomic groups and the surrogate species 

tested to help understand potential acute ecological effects of pesticides to these nontarget taxonomic groups. In addition, the tables provide a preliminary overview of the 

potential acute toxicity of cyfluthrin and beta-cyfluthrin, by providing the acute toxicity 

classifications. 

Terrestrial Species 
 41

A summary of sensitive terrestrial toxicity data from registrant-submitted studies is 

provided in Table 4.1. Based on the available acute data, cyfluthrin is classified as 

practically nontoxic to birds, moderately toxic to mammals, and highly toxic to terrestrial 

invertebrates. Avian reproductive studies indicate reproductive effects at 250 mg/kg diet 

(NOAEC<250 mg/kg diet). A mammalian reproduction study with cyfluthrin showed 

adverse effects on pup body weight at 150 ppm (NOAEL=50 ppm). All endpoints are 

provided in terms of the active ingredient (ai) unless otherwise specified. 

Mammals

Mammalian toxicity data suggest that this compound is moderately toxic to small 

mammals on an acute basis (rat LD50 <100 mg/kg bw and mouse LD50 = 291 mg/kg bw) 

(Accession #072008 and 004334). Reproductive effects were based on decreased pup 

bodyweight observed at a LOAEC of 150 ppm (NOAEC = 50 ppm) (Accession 

#072009). For mammalian toxicity in the final risk assessment, EFED will coordinate 

with HED to determine the most sensitive endpoints for acute and chronic studies. In an 

acute oral study conducted to examine beta-cyfluthrin effects on rats, the LD50=960 

mg/kg bw (males) and LD50=1150 mg/kg bw (females) (MRID 44251101). Based on the 

submitted data, beta-cyfluthrin appears to have lower toxicity to mammals than 

cyfluthrin. 
 42

Birds

The available toxicity data suggests that cyfluthrin appears to be practically non-toxic on 

an acute basis to avian species based on a bobwhite quail (Colinus virginianus) single 

dose LD50 of >5000 mg/kg bw (00131498, acceptable) and an 8-day dietary LC50 of 

>5000 mg/kg diet for the bobwhite quail and mallard duck (Anas platyrynchos) 

(00131500 and 0013501, both acceptable). 

Reproductive tests with mallard ducks indicated effects at 250 mg/kg diet (NOAEC <250 

mg/kg diet). In one test conducted with mallards, a high percentage of eggs cracked were 

observed at 250 mg/kg diet, the lowest level tested (MRID 00145331, supplemental). 

This effect was not seen at the higher treatment levels, however. Other adverse effects 

shown at the 1000 and 4000 mg/kg diet levels include a reduction in the number of eggs 

laid, eggs set, fertilized eggs, 3-week viable embryos, hatchlings and 14-day survivors. 

Due to low control reproductive performance, including low embryo viability, hatchling 

number and 14-day survivorship, the results of this study are classified as supplemental. 

In another one-generation reproductive study conducted on mallard ducks, cyfluthrin 

statistically showed no adverse effects to reproduction at the highest concentration tested 

when compared to control birds (NOAEC = 250 mg/kg diet) (MRID 00158782, 

supplemental). In this study, no statistical differences in reproductive parameters 

between the controls and treatments were determined at any concentration tested (10, 50 

and 250 mg/kg diet). Response variables examined include eggs laid, eggs cracked, eggs 

set, viable embryos, 3-week embryos, hatchlings and 14-day survivors per hen. 

Pathological results showed an increase in egg yolk peritonitis and regressing ovary at 

levels as low as 10 mg/kg diet (lowest level tested). In this study, control bird 

reproduction appeared to be impaired, as indicated by a low number of eggs laid, embryo 

viability and hatching rate compared to guideline criteria. 

Two studies were submitted for bobwhite quail, yielding less sensitive reproductive 

endpoints than the mallard studies. The NOAEC = 900 and 1000 mg/kg diet, for MRIDs 

00152829 (acceptable) and 00145330 (supplemental), respectively. Effects observed 

include low body weight gain in males and low 14-day survivorship at 4000 mg/kg diet 

level. 

Terrestrial Invertebrates

Cyfluthrin is highly toxic to nontarget terrestrial invertebrates. A 48-hour acute contact 

study on honeybees (Apis mellifera) with cyfluthrin technical produced an LD50 = 0.037 

μg/bee (MRID 00153638, acceptable). A 10-day honey bee residual toxicity study with 

cyfluthrin 2 EC (Baythroid) indicated that the formulated product is also highly toxic to 

nontarget terrestrial invertebrates, with and EC50 of 0.045 μg/bee (MRID 00162586). 

Terrestrial Plants

No terrestrial plant data have been submitted to the Agency for cyfluthrin. 
 43

Table 4.1. Summary of most sensitive endpoints from submitted terrestrial toxicity studies for cyfluthrin 

and beta-cyfluthrin. 

Species 

(common 

name)

Taxa 

Represented

Endpoint Concentration 

Test 

Substance 

(% a.i.) 

MRID and 

classification 

Acute 

Toxicity 

Classification 

Rattus 

norvegicus 

(Laboratory 

Rat) 

LD50

Cyfluthrin: <100 

mg/kg bw 

Beta-cyfluthrin: 960 

mg/kg bw (male) 

1150 mg/kg bw 

(female) 

tech 

Accession 

#072008 

Acceptable 

44251101 

Acceptable 

Mus musculus 

(Laboratory 

mouse) 

LD50

291 mg/kg bw (male) 

609 mg/kg bw 

(female) 

tech 

Accession 

#004334 

Acceptable 

Moderately 

toxic 

Rattus NOAEL 50 ppm 

norvegicus 

(Laboratory 

Rat) 

Mammals 

LOAEL 150 ppm 

tech 

Accession 

#072009 

Acceptable 

NA 

Colinus 

virginianus 

(Bobwhite 

quail) 

LD50 >5000 mg/kg bw 87 001314981 Practically 

non-toxic 

Anas 

platyrynchos 

(Mallard duck) 

and 

Colinus 

virginianus 

(Bobwhite 

quail) 

LC50 >5000 mg/kg diet 87 

001315002 

001315012 

Practically 

non-toxic 

NOAEC <250 mg/kg diet Anas 

platyrynchos 

(Mallard duck)

Birds, terrestrialphase 

amphibians, and 

reptiles 

LOAEC 250 mg/kg diet 

94% 

001453313

Supplemental 

NA 

Apis mellifera

(Honey bee) 

Terrestrial 

invertebrates LD50 0.037 μg/bee 93% 

00153638 

Acceptable 

Highly toxic 

1

 Original review classified the study as acceptable, completed in 1983 by W. Faatz. Study not required at 

this time because a cursory review indicates that the study is acceptable, but may be required pending 

additional data evaluation. 

2

 Data need additional review. Original reviews classified the study as acceptable, completed in 1984 by W. 
 44

Faatz. Study not required at this time because a cursory review indicates that the study is acceptable, but 

may be required pending additional data evaluation. 

3

 This endpoint is based on the most sensitive registrant-submitted study available. However, in this study, 

the endpoint is non-definitive. Another study conducted on mallard ducks with lower treatment 

concentrations (10-250 mg/kg diet) showed no reproductive effects at any treatment levels. 

NA=not applicable 

Aquatic Species 

A summary of sensitive aquatic toxicity data from registrant-submitted studies is 

provided in Table 4.2. Numerous aquatic studies have been submitted to the Agency, 

some of which were conducted with beta-cyfluthrin. Appendix B includes a table 

detailing all aquatic toxicity data submitted to the Agency. Cyfluthrin and betacyfluthrin are classified as very highly toxic to aquatic organisms based on data for 

aquatic vertebrates and invertebrates. Chronic effects were also seen in all aquatic taxa at 

levels ranging from 0.00040 – 0.63 μg a.i./L. 

 

Freshwater

Cyfluthrin technical is highly toxic to freshwater fish, with a 96-hour LC50 = 0.68 μg 

a.i./L (MRID 00131502). Beta-cyfluthrin technical is also highly toxic to freshwater fish, 

with a 96-hour LC50 = 0.068 μg a.i./L in the most sensitive acute test conducted on 

rainbow trout (Oncorhynchus mykiss) (MRID 45375002). In an acute test with cyfluthrin 

EC (2%), the 96-hour LC50 = 0.295 μg a.i./L for rainbow trout (MRID 41558002, 

supplemental). A freshwater fish early-life stage study for cyfluthrin technical resulted in 

an NOAEC of 0.010 μg a.i./L and LOAEC of 0.018 μg a.i./L for rainbow trout based on 

reduced growth and behavioral effects (MRID 00155898, supplemental). In a fish full life 

cycle test with cyfluthrin, fathead minnow (Pimephales promelas) showed reduced 

survival and hatching success at 0.25 μg a.i./L, with a NOAEL = 0.14 μg a.i./L (MRID 

41450401, acceptable). 

Daphnia magna is used as the test species for freshwater invertebrates for both acute and 

chronic effects. Acute toxicity values for daphnids suggest that cyfluthrin technical is 

very highly toxic to freshwater invertebrates, with a 48-hour EC50 of 0.141 μg a.i./L 

(MRID 00131504). An acute 48-hour study examining beta-cyfluthrin technical effects to 

daphnids produced an EC50 = 0.29 μg a.i./L (MRID 45426701). A 48-hour study 

conducted with the formulated product (Tempo, 25% a.i.) showed higher toxicity to 

daphnids, with an EC50 of 0.025 (MRID 41558003). Chronic toxicity to invertebrates is 

represented through Daphnia magna life cycle studies. In a daphnid chronic life-cycle 

test with cyfluthrin, the NOAEC = 0.00174 μg/L and the LOAEC = 0.0157 μg/L based 

on adverse effects to growth, survival and # of young (MRID 00151442, acceptable). In 

this study, cyfluthrin showed significant degradation, due to hydrolysis at the high pH (8 

to 8.5). Based on results from thin layer chromatography analysis, it was determined that 

approximately 37% of the total carbon-labelled residues were the parent compound. 

Therefore, the mean-measured concentrations were adjusted to reflect the percentage of 

cyfluthrin in the final endpoint calculations (endpoints based on mean-measured 14C 

concentrations alone were NOAEC=0.020 μg/L and LOAEC=0.041 μg/L). 

For freshwater benthic organisms, a 10-day toxicity study with midges (Chironomus 
 45

tentans) has been submitted (MRID 46591507, in review). Based on preliminary results 

from this study, cyfluthrin is very highly toxic to freshwater benthic organisms and the 

LC50=0.44 μg a.i./L based on mean-measured pore water concentrations and LC50=290 

μg a.i./kg sediment based on bulk sediment concentrations. 

Estuarine/Marine

Estuarine/marine fish are represented by the sheepshead minnow (Cyprinodon 

variegatus). Acute toxicity studies indicates that cyfluthrin is very highly toxic to 

estuarine/marine fish, with an LC50 = 4.05 μg a.i./L for the technical material (MRID 

00146485, acceptable). The most sensitive sheepshead minnow early life stage study 

submitted by the registrant resulted in a 39-day NOAEC = 0.025 μg a.i./L and a LOAEC 

= 0.084 μg a.i./L, based on reduced juvenile survival. Another early life stage study has 

been submitted, yielding less sensitive endpoints based on treatment-related mortality 

(NOAEC=0.27 μg a.i./L and LOAEC = 0.63 μg a.i./L) (MRID 00158784, this study is 

currently unreviewed). 

Estuarine/marine aquatic invertebrates are represented by the mysid shrimp (Mysidopsis 

bahia) and eastern oyster (Crassostrea virginica) with toxicity studies indicating 

cyfluthrin is very highly toxic to both. Cyfluthrin technical produced an LC50= 0.0024 

μg a.i./L in an acute toxicity study with mysid shrimp (MRID 40069501). In an acute 

study with mysid shrimp, the 96-hour LC50 = 0.0022 μg a.i./L for beta-cyfluthrin 

technical (MRID 45426709, acceptable). In a study with the eastern oyster, the 96-hour 

EC50 was 2.69 μg a.i./L for cyfluthrin technical (MRID 00158783, acceptable). A 

chronic study with estuarine/marine invertebrates has also been submitted for cyfluthrin 

technical. In a 28-day life cycle study with mysid shrimp, the NOAEC = 0.00017 μg 

a.i./L and LOAEC = 0.00040 μg a.i./L based on adverse effects to growth and survival 

(MRID 00158785, supplemental). This study was deemed supplemental due to 

fluctuations in the test concentrations throughout the study. 

Aquatic Plants

A 96-hour toxicity test with the green algal species Scenedesmus subspicatus was 

submitted for cyfluthrin, but the test was determined to be invalid due to low test 

substance solubility and absence of analytically-determined concentrations (MRID 

41450402). Another study with green algae (Pseudokirchneriella subcapitata, formerly 

known as Selenastrum capricornutum) has been submitted for cyfluthrin (MRID 

43984901). The reported EC50 > 181 μg a.i./L and NOAEC = 181 μg a.i./L in this study, 

based on Day 0 soluble measured concentrations. No studies have been submitted for 

aquatic vascular plants. 

Toxicity of Degradates

Four aquatic toxicity studies have been submitted for degradates of cyfluthrin, FPB ALD 

and DCVA. Both degradates appear to be less toxic than the parent compound based on 

acute toxicity studies with freshwater fish and invertebrates. Studies with rainbow trout 

resulted in a 96-hour LC50 = 792 μg a.i./L for FPB ALD and LC50>14.7 mg a.i./L for 

DCVA (MRIDs 00158554 and 00158557). Acute 48-hour studies with Daphnia magna 

resulted in an EC50=1.3 mg a.i./L for FPB ALD and EC50=25 mg a.i./L for DCVA 
 46

(MRIDs 00158555 and 00158556). Therefore, the parent compound is expected to be the 

primary stressor of concern. 

Table 4.2. Summary of most sensitive endpoints from submitted aquatic toxicity studies for 

cyfluthrin and beta-cyfluthrin 

Species 

(common name) 

Taxa 

Represented 

Endpoint Duration

(hours) 

 Mean 

concentration 

(μg a.i./L) 

MRID 

Study 

Classification 

Acute 

Toxicity 

Classification 

LC50 96 

Cyfluthrin: 

0.68 

Betacyfluthrin: 

0.068 

00131502 

Acceptable 

45375002 

Supplemental 

Very highly 

toxic 

NOAEC 0.010 

Oncorhynchus 

mykiss 

(Rainbow trout) 

Freshwater 

fish and 

aquatic-phase 

amphibians

LOAEC 

58 (days) 0.018 

00155898 

Supplemental NA 

Crassostrea 

virginica 

(Eastern oyster)

EC50 96 2.69 00158783 

Acceptable 

EC50 48 

Cyfluthrin: 

0.025 

Betacyfluthrin: 

0.29 

41558003 

Acceptable 

45426701 

Supplemental 

Very highly 

toxic 

NOAEC 0.0074 

Daphnia magna 

(Water Flea) 

Freshwater 

Invertebrates 

LOAEC 

 21 

(days) 0.0157 

00151442 

Acceptable 

NA 

Chironomus tentans 

(Midge) 

Freshwater 

Benthic 

Invertebrates 

LC50 10 (days) 

0.44 (pore 

water) 

290 μg a.i./kg 

sediment 

(bulk 

sediment) 

46591507 

In review 

Very highly 

toxic 

LC50 96 4.05 

00146485 

Acceptable 

Very highly 

toxic 

NOAEC 0.025 

Cyprinodon 

variegatus

(Sheepshead 

minnow) 

Estuarine/ 

Marine Fish 

LOAEC 

39 (days) 0.084 

00158781 

Supplemental NA 
 47

Table 4.2. Summary of most sensitive endpoints from submitted aquatic toxicity studies for 

cyfluthrin and beta-cyfluthrin 

Species 

(common name) 

Taxa 

Represented 

Endpoint Duration

(hours) 

 Mean 

concentration 

(μg a.i./L) 

MRID 

Study 

Classification 

Acute 

Toxicity 

Classification 

LC50 96 

Cyfluthrin: 

0.0024 

Betacyfluthrin: 

0.0022 

40069501 

Acceptable 

45426709 

Acceptable 

Very highly 

toxic 

NOAEC 0.00017 

Mysidopsis bahia 

(Mysid shrimp) 

Estuarine/ 

Marine 

Invertebrates 

LOAEC 

28 (days) 0.00040 

00158785 

Supplemental 

NA 

Leptocheirus 

plumulosus 

(Amphipod) 

Estuarine/ 

Marine 

Benthic 

Invertebrates 

LC50

(survival) 

EC50

(growth) 

28 (days) 

35 

36 

46591506 

In review 

Very highly 

toxic 

Green algae 

(Pseudokirchneriella 

subcapita) 

Aquatic 

Plants EC50 96 >181 

43984901 

Acceptable 

Practically 

nontoxic 

ECOTOX 

Available open literature will be used to evaluate the potential direct effects of cyfluthrin 

and beta-cyfluthrin to the terrestrial receptors identified in this section. This includes 

toxicity data on the technical grade active ingredient, and when available, formulated 

products. 

At this time, a full and complete ECOTOX search has not been performed, but will be 

conducted prior to issuance of any Data Call-in. The open literature studies will be 

identified through EPA’s ECOTOX database (http://cfpub.epa.gov/ecotox/), which 

employs a literature search engine for locating chemical toxicity data for aquatic life, 

terrestrial plants, and wildlife. The evaluation of data can also provide insight into the 

direct and indirect effects of cyfluthrin and beta-cyfluthrin on biotic communities from 

loss of species that are sensitive to the chemical and from changes in structure and 

functional characteristics of the affected communities. 

Open literature toxicity data for other ‘target’ insect species (not including bees, 

butterflies, beetles, and non-insect invertebrates including soil arthropods and worms), 

which include efficacy studies, are not currently considered in deriving the most sensitive 
 48

endpoint for terrestrial insects. Efficacy studies do not typically provide endpoint values 

that are useful for risk assessment (e.g., NOAEC, EC50, etc.), but rather are intended to 

identify a dose that maximizes a particular effect (e.g., EC100). Therefore, efficacy data 

and non-efficacy toxicological target insect data will not be included in the ECOTOX 

open literature search. 

4.2. Incident Database Review 

A preliminary review on May 20, 2010 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 betacyfluthrin. A search for incidents involving cyfluthrin and beta-cyfluthrin was also 

conducted in the American Bird Conservancy’s Avian Incident Monitoring System 

(AIMS). These incidents are summarized in Table 4.3. This total excludes incidents 

classified as ‘unlikely’ and only includes those incidents with certainty categories of 

‘highly probable’, and ‘probable’ and ‘possible’ (for EIIS) and ‘certain’, ‘highly likely’, 

‘likely’, ‘probable’, and ‘possible’ (for AIMS). In the EIIS and AIMS databases, the 

“unlikely” category is used when a chemical is not likely to be responsible for the 

incident. For example, an ‘unlikely’ classification might be applied in situations where a 

given chemical is practically nontoxic to the category of organism killed and/ or there is 

evidence that another pesticide or stressor likely caused the incident. Incidents classified 

as ‘unlikely’ for cyfluthrin and beta-cyfluthrin will not be included in this Problem 

Formulation or the ecological risk assessment conducted for Registration Review. 

 

A total of eight reported ecological incidents associated with the use of cyfluthrin have 

been reported to the Agency. No incidents associated with beta-cyfluthrin were found in 

the EIIS database. This is likely due to the fact that enantioselective methods are required 

for differentiating cyfluthrin and beta-cyfluthrin. Therefore, cyfluthrin incidents cannot 

be ruled out as possible beta-cyfluthrin incidents. 

Five incidents were reported for aquatic animals and three are 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. The certainty that the incidents were associated with cyfluthrin exposure was 

considered highly probable for two incidents, probable for four incidents and possible for 

two incidents. See Table 4.3 for summary of the incidents. 

The AIMS database contains no incidents involving cyfluthrin and beta-cyfluthrin. 

Table 4.3. Wildlife Incidents Associated with Cyfluthrin

Incident 

Number 

Taxa 

Involved Magnitude Year 

Location 

(County, 

State) Use 

Legality 

of Use 

Certainty 

Category1 Residue 
 49

Table 4.3. Wildlife Incidents Associated with Cyfluthrin

Incident 

Number 

Taxa 

Involved Magnitude Year 

Location 

(County, 

State) Use 

Legality 

of Use 

Certainty 

Category1 Residue 

I004564-

0011 

Koi fish 

(Cyprinus 

carpio) 

5 1996 CA Building 

Spray RU Highly Probable No 

I003621-

001 

Bluegill 

(Lepomis 

macrochirus) 

unknown 1996 Not 

reported 

Not 

reported M Probable No 

I003351-

021 

Crayfish 

(Decapoda) 

and snail 

(Gastropoda) 

hundreds 1994 Placer, 

CA 

Not 

reported UN Probable No 

I013927-

001 

Flathead 

catfish 

(Pylodictis 

oilvaris), 

grass carp 

(Ctenopharyn

godon idella) 

and 

largemouth 

bass 

(Micropterus 

salmoides) 

400 2003 Imperial, 

CA 

Agricultural UN Probable 

220-390 

ppb in 

gill 

tissue, 

0.33 

ppb in 

water 

I009427-

006 

Crayfish 

(Decapoda) Unknown 1999 Madison, LA 

Aerial to 

cotton RU Possible No 

I016940-

010 

Corn (Zea 

mays) 30 acres 2005 Imperial, CA Aerial M Highly probable 

0.15-7.2 

ppm in 

plant 

tissue 

I001728-

001 

Unknown 

ornamentals Unknown 1993 WA Commercial lawn RU Probable 

Yes, 

levels 

not 

reported 

I013550-

002 Potatoes 65 acres 2001 Kent, DE Aerial RU Possible No 

1

Incidents classified as ‘unlikely’ are excluded; RU = Registered Use; M = Misuse; UN = Unknown 
 50

Aquatic Incidents Involving Cyfluthrin 

 Incident # I004564-001 – A fishkill in two ornamental ponds occurred due to cyfluthrin 

use in California in 1996. Cyfluthrin (TEMPO) dust was sprayed on the side of a 

building to control wasps. Around five days after application, approximately five koi 

fish (Cyprinus carpio) began to die in ponds 20-30 feet away. Water samples taken 20 

days after application contained 2 ppb cyfluthrin. No analyses were conducted on the 

fish tissues. This incident is listed as “highly probable” for a registered use of 

cyfluthrin. 

 Incident # I003621-001 – After a heavy rainfall, cyfluthrin (Aztac 2.1%) washed into a 

stream where hundreds of bluegill (Lepomis macrochirus) were subsequently killed. 

The incident occurred in 1996. No water or tissue samples were taken. This incident is 

listed as “probable” for an intentional misuse of cyfluthrin. 

 Incident # I003351-021 – Cyfluthrin was the probable cause of the death of hundreds 

of crayfish (Decapoda) and snails (Gastropoda) in California in 1994. No other data 

were reported. This incident is listed as “probable” for cyfluthrin. It is unknown if the 

incident was due to a registered use or misuse. 

 Incident # I013927-001 – Cyfluthrin was the probable cause of a fish kill in California 

in 2003, reported the California Department of Fish & Game. Cyfluthrin and 

chlorpyrifos were aerially applied to an agricultural field adjacent to the site of the kill. 

Approximately 400 fish died, including 320 flathead catfish (Pylodictis oilvaris), 60 

grass carp (Ctenopharyngodon idella) and 20 largemouth bass (Micropterus 

salmoides). Two water samples were analyzed, and chlorpyrifos was found in both 

water samples (0.08 and 11.7 ppb) and cyfluthrin was found in one sample (0.33 ppb). 

Analyses of fish gills ranged from 220-390 ppb cyfluthrin and 660-2100 ppb 

chlorpyrifos. The report states that “there was probably some dilution of the water 

between the time of application of the pesticides and the time of sampling”. This 

incident is listed as “probable” for cyfluthrin. It is unknown if the incident was due to a 

registered use or misuse. 

 Incident # I003351-021 – Cyfluthrin (Baythroid) was the possible cause of death to an 

unknown number of crayfish (Decapoda) in Lousiana in 1999. Both cyfluthrin and 

profenofos were aerially applied to cotton fields 100 yards from 200 acres of ponds. 

The Lousiana Department of Agriculture took water samples 8 hours after the 

application and found neither chemical (LOD= 1.4 ppb for cyfluthrin and LOD=1.48 

ppb for profenofos). Bayer Cropscience, the registrant, said the incident may be due to 

low dissolved oxygen levels. This incident is listed as “possible” for a registered use of 

cyfluthrin. 

Terrestrial Plant Incidents Involving Cyfluthrin 
 51

 Incident # I016940-010 – A crop duster experienced mechanical problems and 

discharged cyfluthrin (Baythroid) and dimethoate (Prokil) onto a corn field (Zea mays). 

A few days later the corn field showed burn symptoms in 30 acres of the crop. Around 

7,500 pounds of the crop were sampled for residues, and the two chemicals were found 

in 2,500 pounds (the grower voluntarily disposed of this portion). The analysis showed 

0.15 to 7.2 ppm of cyfluthrin and 0.96 to 119.2 ppm of dimethoate. This incident is 

listed as “highly probable” for a misuse of cyfluthrin. 

 Incident # I001728-001 – In Washington state, a commercial applicator sprayed 

cyfluthrin in a yard, which resulted in drift to a neighbor’s garden. Damage to unknown 

species of ornamentals ensued. The type and magnitude of the damage was not 

reported. Soil samples from the neighbor’s garden tested positive for cyfluthrin (levels 

not reported). This incident is listed as “probable” for a registered use of cyfluthrin. 

 Incident # I013550-002 – A Delaware potato grower aerially applied cyfluthrin 

(Baythroid), chlorothalonil (Bravo Ultrex) and spinosad (Spin Tor 2SC) to 65 acres of 

his crop, and damage to the plants occurred within 2 days. The Department of 

Agriculture investigated and determined there was glyphosate contamination in the 

containers. This incident is listed as “possible” for a registered use of cyfluthrin. 

Incident reports for non-target organisms typically provide information only on mortality 

events and plant damage incidents. Except for phytotoxic effects in terrestrial plants, 

sublethal effects for organisms such as reduced growth or impaired reproduction are 

rarely reported. EPA’s changes in the registrant reporting requirements for incidents in 

1998 may account for a reduced number of reported incidents. Registrants are now only 

required to submit detailed information on ‘major’ fish, wildlife, and plant incidents. 

Minor fish, wildlife, and plant incidents, as well as all other nontarget incidents, are 

generally reported aggregately and are not included in EIIS. In addition, there have been 

reductions in state monitoring efforts due to lack of resources. 

In the risk assessment, these incidents will be further evaluated to determine if they 

represent current patterns of use for cyfluthrin and/ or beta-cyfluthrin. Examples of 

additional considerations are mitigation (e.g., reduced application rates), product 

cancellations, and changes in use patterns that have occurred since the date of the 

reported incidents. 

As it has been indicated earlier, cyfluthrin is among the constituents monitored by the 

National Water Quality Assessment Data Warehouse, (NAWQA) maintained by the U.S. 

Geological Survey; furthermore, multiple articles from the literature document the 

presence of synthetic pyrethroids like cyfluthrin and/ or beta-cyfluthrin in both urban and 

agricultural water and sediments (refer to Section 3.4). 

4.3. Ecosystems Potentially at Risk 

Cyfluthrin and beta-cyfluthrin may be applied on a variety of food crops, including (but 

not limited to) alfalfa, tree nuts, pome fruits, brassica (head and stem) vegetables, fruiting 
 52

vegetables, leafy vegetables, legume vegetables and root and tuber vegetables. In 

addition, they may be used in numerous non-food sites (e.g. ornamental and/ or shade 

trees and ornamental lawns). Thus, the ecosystems at risk may be extensive in scope, and 

as a result it may not be possible to identify specific ecosystems during the development 

of a baseline risk assessment. In general terms, terrestrial ecosystems potentially at risk 

due to the use of cyfluthrin and beta-cyfluthrin, could include the treated field and areas 

immediately adjacent to the treated field that may receive drift or runoff. Areas adjacent 

to the treated field could include cultivated fields, fencerows and hedgerows, meadows, 

fallow fields or grasslands, woodlands, riparian habitats and other uncultivated areas. 

Due to the potential persistence of cyfluthrin and beta-cyfluthrin, they are expected to 

drift and/or runoff due to application to food crops, resulting in possible exposure to 

aquatic ecosystems. Aquatic ecosystems potentially at risk due to the use of cyfluthrin 

and beta-cyfluthrin include water bodies adjacent to, or down stream from, the treated 

field and might include impounded bodies such as ponds, lakes and reservoirs, or flowing 

waterways such as streams or rivers. For uses in coastal areas, aquatic habitat also 

includes marine ecosystems, such as estuaries. 

5. Assessment Endpoints 

Assessment endpoints are defined as “explicit expressions of the actual environmental 

value that is to be protected.” Defining an assessment endpoint involves two steps: 1) 

identifying the valued attributes of the environment that are considered to be at risk; and 

2) operationally defining the assessment endpoint in terms of an ecological entity (i.e., a 

community of fish and aquatic invertebrates) and its attributes (i.e., survival and 

reproduction). Therefore, selection of the assessment endpoints is based on valued 

entities (i.e., ecological receptors), the ecosystems potentially at risk, the migration 

pathways of pesticides, and the routes by which ecological receptors are exposed to 

pesticide-related contamination. The selection of clearly defined assessment endpoints is 

important because they provide direction and boundaries in the risk assessment for 

addressing risk management issues of concern. Changes to assessment endpoints are 

typically estimated from the available toxicity studies, which are used as the measures of 

effects to characterize potential ecological risks associated with exposure to pesticides, 

such as cyfluthrin and beta-cyfluthrin. 

To estimate exposure concentrations, the ecological risk assessment considers 

applications at the maximum application rate to fields that have vulnerable soils. The 

most sensitive toxicity endpoints are used from surrogate test species to estimate 

treatment-related direct effects on acute mortality and chronic reproductive, growth and 

survival assessment endpoints. Toxicity tests are intended to determine effects of 

pesticide exposure on birds, mammals, fish, terrestrial and aquatic invertebrates, and 

plants. These tests include short-term acute, sub-acute, and reproduction studies and are 

typically arranged in a hierarchical or tiered system that progresses from basic laboratory 

tests to applied field studies. The toxicity studies are used to evaluate the potential of a 

pesticide to cause adverse effects, to determine whether further testing is required, and to 

determine the need for precautionary label statements to minimize the potential adverse 

effects to non-target animals and plants. 
 53

An open literature search will be conducted to determine any relevant endpoints. The 

search will focus on survival, growth and reproductive effects for aquatic and terrestrial 

effects of cyfluthrin and/ or beta-cyfluthrin. More sensitive endpoints from acceptable 

open literature studies will be included in this risk assessment. 

 6. Conceptual Model

For a pesticide to pose an ecological risk, it must reach ecological receptors in 

biologically significant concentrations. An exposure pathway is the means by which a 

pesticide moves in the environment from a source to an ecological receptor. For an 

ecological pathway to be complete, it must have a source, a release mechanism, an 

environmental transport medium, a point of exposure for ecological receptors, and a 

feasible route of exposure. 

A conceptual model provides a written description and visual representation of the 

predicted relationships between cyfluthrin or beta-cyfluthrin, potential routes of 

exposure, and the predicted effects for the assessment endpoint. A conceptual model 

consists of two major components: risk hypothesis and a conceptual diagram (USEPA, 

1998). 

6.1. Risk Hypothesis 

Risk hypotheses are specific assumptions about potential adverse effects (i.e., changes in 

assessment endpoints) and may be based on theory and logic, empirical data, 

mathematical models, or probability models (USEPA 1998). For this assessment, the risk 

is stressor-initiated, where the stressor is the release of cyfluthrin and beta-cyfluthrin into 

the environment. The following risk hypotheses are presumed for this screening-level 

assessment: 

Cyfluthrin and beta-cyfluthrin, when used in accordance with registered labels, 

will likely lead to off-site movement of the compound via runoff, spray drift, and 

eroded soil leading to exposure of nontarget plants and animals. Based on 

information on the environmental fate, mode of action, direct toxicity and 

potential indirect effects, EFED assumes that registered uses of cyfluthrin and 

beta-cyfluthrin have the potential to cause reduced survival, growth, and 

reproduction to non-target terrestrial and/ or aquatic animals and plants. 

Cyfluthrin and beta-cyfluthrin, when used indoors, in accordance with current 

labels, may result in off-site movement of the compound via wash-off into surface 

waters via drains and treatment plants, leading to exposure of nontarget aquatic 

animals and plants. This potential exposure pathway may result in adverse 

effects upon the survival, growth, and/or reproduction of non-target aquatic 

animals and plants.

 

The conceptual model is a generic graphic depiction of the risk hypothesis. It includes 
 54

the potential pesticide or stressor (cyfluthrin, beta-cyfluthrin and possible metabolites), 

the source of the pesticide and/or transport pathways, exposure media, exposure point, 

biological receptor types, and attribute changes. 

6.2. Conceptual Diagram

The conceptual site model is a generic graphic depiction of the risk hypothesis, and 

assumes that the insecticides cyfluthrin and beta-cyfluthrin, which are Type II synthetic 

pyrethroids, having multiple outdoor agricultural and non-agricultural uses, are capable 

of affecting aquatic and terrestrial animals provided that environmental concentrations 

are sufficiently elevated as a result of proposed label uses. Based on an examination of 

the physicochemical properties of cyfluthrin and beta-cyfluthrin, the fate and disposition 

in the environment, and mode of application, a conceptual model was developed that 

represents the possible relationships between the stressors, ecological receptors, and the 

assessment endpoints. Through a preliminary iterative process of examining available 

data, the conceptual model (i.e., the representation of the risk hypothesis) may be refined 

to reflect the likely exposure pathways and the organisms that are most relevant and 

applicable to this assessment (see Figures 6.1a and 6.1b, below). They include the 

potential pesticide or stressor (cyfluthrin and/ or beta-cyfluthrin, but the presence of 

toxicologically important metabolites cannot be ruled out), the sources and/ or transport 

pathways, exposure media and exposure points, biological receptor types and attribute 

changes. 

In order for a chemical to pose an ecological risk, it must reach ecological receptors in 

biologically significant concentrations. An exposure pathway is the means by which a 

pesticide moves in the environment from a source to an ecological receptor. For an 

ecological exposure pathway to be complete, it must have a source, a release mechanism, 

an environmental transport medium, a point of exposure for ecological receptors, and a 

feasible route of exposure. In addition, the potential mechanisms of degradation/ 

transformation (i.e., which degradation/ transformation products may form in the 

environment, in which media, and how much) must be understood, especially if for the 

chemical, its metabolites/ transformation products are of greater toxicological concern 

than the parent compound. The assessment of ecological exposure pathways, therefore, 

includes an examination of the source and potential migration pathways for constituents, 

and the determination of potential exposure routes. 

Under the possible uses of cyfluthrin and beta-cyfluthrin, the sources and mechanisms of 

release of the compound are from ground or aerial spray or ULV applications. Note that 

this conceptual model also considers agricultural applications as well as certain nonagricultural applications. Surface runoff from the areas of application is assumed to 

depend on factors such as topography, irrigation, and rainfall events. Direct deposition 

may result in contamination of food items that may be consumed by terrestrial organisms. 

Spray drift results in contaminated adjacent areas, including bodies of water. Notice that 

leaching to groundwater is not considered an important source because cyfluthrin and 

beta-cyfluthrin are relatively immobile. Due to cyfluthrin and beta-cyfluthrin’s potential 

for volatilization, atmospheric transport cannot be ruled out. Despite the fact that 
 55

cyfluthrin and beta-cyfluthrin show a moderate Henry’s Law Constant, that would 

suggest some potential for volatilization, and it is moderately persistent in various 

environmental media, the hydroxyl radical reaction half-life for the chemical is 0.86 days 

(EPI Suite v.4.0 estimate). The short (atmospheric) half-life suggests that the potential 

for atmospheric transport for cyfluthrin and beta-cyfluthrin is relatively low and that this 

source of the chemical is of low importance, compared to spray drift, runoff and/ or direct 

contact after application. 

For aquatic receptors, the major point of exposure is through direct contact with the water 

column, sediment, and pore water (gill/ integument) contaminated with spray drift (from 

spray application) and/or runoff from treated areas. Indirect effects to aquatic organisms 

(fish, amphibians and aquatic invertebrates) can also occur through impact to various 

food chains. It was established earlier in this document that cyfluthrin and betacyfluthrin have the potential to bioaccumulate/ bioconcentrate. The representative 

aquatic receptors are certain freshwater and estuarine/ marine fish, invertebrates, and, in 

certain cases, aquatic plants. The major point of exposure for terrestrial animals is 

consumption of food contaminated with residues such as grass, foliage, and small insects. 

For plants, the point of exposure is direct contact or root uptake. The representative 

terrestrial receptors are mammals, birds and terrestrial plants. The attribute changes used 

to assess risk to terrestrial receptors depend on the type of test (e.g., reduced survival, 

growth, or reproduction for animals and seedling emergence and vegetative vigor for 

plants). It should be noted, that these species do not cover all the possible species in the 

animal and plant kingdoms; certain taxa are considered as surrogates for other taxa. For 

example, fish are considered surrogates for aquatic phase amphibians. Other attribute 

changes are related to the food chain and habitat integrity. Changes in the food chain 

include, for example, reduction in prey and modifications in primary constituent elements 

(PCEs). PCEs are physical and biological features essential to the conservation of the 

listed species. Changes in habitat integrity include, for example, reduction in primary 

productivity. 

This conceptual model also shows some details about biomagnification for a chemical 

(see piscivorous birds and mammals in Fig. 6.1a). Cyfluthrin and beta-cyfluthrin have a 

very high KOW and according to its physicochemical and fate properties, there would be a 

potential for bioaccumulation/bioconcentration in aquatic organisms; however, the 

potential for biomagnification in terrestrial organisms, though at the screen level appears 

low, is uncertain and has not been quantified. 

Cyfluthrin and beta-cyfluthrin show a very low solubility, a very high KOW and also high 

KOCs. These properties suggest that the chemical partitions with the sediments, and with 

organic matter, suspended in the water bodies. Cyfluthrin and beta-cyfluthrin are likely 

to concentrate and persist in the sediments, especially after repeated exposures 

(applications). Such sediments could serve as repositories of the chemical for extended 

periods of time and could potentially be toxic to sediment dwelling organisms, affecting 

the food chain. These issues will also be assessed in the risk assessment for cyfluthrin 

and beta-cyfluthrin. 
 56

Figure 6.1a. Conceptual model depicting stressors, exposure pathways, and 

potential effects to aquatic organisms from the use of cyfluthrin or beta-cyfluthrin 

on agricultural and certain non-agricultural sites 

Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk. 

PCE=primary constituent element 

**Route of exposure includes only ingestion of fish and aquatic inverts. 

Stressor 

Source 

Receptors 

Attribute 

Change 

Cyfluthrin or beta-cyfluthrin applied to agricultural 

or non-agricultural use site 

Spray drift 

Aquatic animals 

Invertebrates 

Vertebrates 

**Piscivorous mammals 

 and birds 

Individual 

organisms 

Reduced survival 

Reduced growth 

Food chain 

Reduction in algae and 

 vascular plants 

Reduction in prey 

Modification of PCEs 

 related to prey availability 

Habitat integrity 

Reduction in primary 

 productivity

Reduced cover 

Community change 

Modification of PCEs related to 

 habitat 

Surface water/ 

Sediment 

Runoff

Aquatic Animals

Invertebrates 

Vertebrates 

Exposure 

Media 

Uptake/gills 

or integument 

Ingestion Ingestion 

Atmospheric 

transport 

Wet/dry deposition 

Soil Leaching to 

Groundwater 

Uptake/gills 

or integument 

Aquatic Plants 

Non-vascular 

Vascular 

Uptake/cell, 

roots, leaves Riparian plants

terrestrial 

exposure 

pathways; see 

Figure 6.1b 
 57

Figure 6.1b. Conceptual model depicting stressors, exposure pathways, and 

potential effects to terrestrial organisms from the use of cyfluthrin or betacyfluthrin on agricultural and certain non-agricultural sites 

Dotted lines indicate exposure pathways that have a low likelihood of contributing to ecological risk. 

PCE=primary constituent element 

 

Indoor uses can result in discharges of cyfluthrin and beta-cyfluthrin into sewer systems 

and subsequently into publicly owned treatment works (POTWs), and to aquatic 

ecosystems. These discharges of cyfluthrin and beta-cyfluthrin will be included in the 

assessment as a possible route of exposure to the environment. Exposure estimates could 

be used to evaluate potential effects to ecological entities. The conceptual model for 

potential risks of cyfluthrin or beta-cyfluthrin to aquatic organisms due to various indoor 

uses of the chemical that could potentially end up in a “drain” is depicted in Fig. 6.2. 

The stressor is the chemical of concern, cyfluthrin and beta-cyfluthrin. It is noted that the 

transport pathway is wastewater flow, the exposure media is the treatment facility, but the 

exposure point or route, receptor and attribute changes for aquatic organisms are similar 

to the conceptual model for agricultural and urban applications (as depicted in Fig. 6.1a). 

Stressor 

Source 

Attribute 

Change 

Cyfluthrin or beta-cyfluthrin applied to agricultural 

or non-agricultural use site

Direct 

application Spray drift 

Terrestrial 

vertebrates 

Terrestrial 

invertebrates 

Individual 

organisms 

Reduced survival 

Reduced growth 

Reduced reproduction

Food chain 

Reduction in prey and food

Modification of PCEs 

 related to prey availability 

Habitat integrity 

Reduction in primary productivity

Reduced cover 

Community change 

Modification of PCEs related 

 to habitat 

Terrestrial plants 

grasses/ forbs, fruit, seeds 

(trees, shrubs) 

Runoff 

Terrestrial 

vertebrates 

Exposure Media 

& Receptors Soil 

Ingestion 

Ingestion 

Ingestion

Dermal uptake/Ingestion

Atmospheric 

transport 

Root uptake/contact 

Wet/dry deposition

Ingestion

Leaching to

Groundwater Irrigation 

water 
 58

Figure 6.2. Conceptual model for potential risks of cyfluthrin and beta-cyfluthrin to 

aquatic organisms for various indoor uses of the chemical that could potentially end 

up in the “drain.” 

 

7. Analysis Plan 

In order to address the risk hypothesis, the potential for adverse effects on the 

environment is estimated. Usage, environmental fate and transport, and ecological 

effects of cyfluthrin and beta-cyfluthrin are characterized and integrated to assess the 

risks. This is accomplished using a risk quotient (ratio of exposure concentration to 

effects concentration) approach. Although risk is often defined as the likelihood and 

magnitude of adverse ecological effects, the risk quotient-based approach does not 

provide a quantitative estimate of likelihood and/ or magnitude of an adverse effect. 

However, as outlined in the Overview Document (USEPA 2004), the likelihood of effects 

to individual organisms from particular uses of a chemical is estimated using the probit 

dose-response slope and either the level of concern (discussed below) or the actual 

calculated risk quotient value. 

This analysis plan will be revisited and may be revised depending on the data available in 

Stressor Cyfluthrin and Beta-cyfluthrin Applications 

that Could Potentially End Up “Down-the-drain” 

Source/ 

Transport 

Pathways 

Wastewater flow 

Source/ 

Exposure 

Media 

Treatment Facility 

Discharges into Surface 

Waters 

Exposure 

Route 

Gill/ 

 Integument 

Uptake 

Receptors 

Attribute 

Changes 

Aquatic 

Invertebrates, 

Vertebrates 

Individual 

Vertebrates and 

Invertebrates

Reduced survival 

or reproduction 

Plant Population

Reduced 

population 

growth 

Aquatic 

Plants 

Uptake/ 

Adsorption
 59

the open literature and the information submitted by the public or the registrant in 

response to the opening of the Registration Review docket. 

7.1. Stressors of Concern 

The focus of this assessment is on the parent materials, cyfluthrin and beta-cyfluthrin. 

However, the Agency will review available studies to identify degradate(s) of potential 

toxicological concern (e.g., DCVA, FPB-acid and FPB-ald). 

Toxicity data for environmental mixtures of cyfluthrin and beta-cyfluthrin with other 

pesticides (those mixtures occurring in the environment following application), if 

available, may be presented as part of the ecological risk assessment. Cyfluthrin and 

beta-cyfluthrin may be applied in tank mixtures with other products approved for use on 

registered crops. It is expected that the toxic effect of cyfluthrin and beta-cyfluthrin, in 

combination with other pesticides used in the environment, is likely to be a function of 

many factors including, but not necessarily limited to (1) the exposed species, (2) the cocontaminants in the mixture, (3) the ratio of cyfluthrin and/ or beta-cyfluthrin and cocontaminant concentrations, (4) differences in the pattern and duration of exposure 

among contaminants, and (5) the differential effects of other physical/ chemical 

characteristics of the receiving waters (e.g. organic matter present in sediment and 

suspended water). Quantitatively predicting the combined effects of all these variables 

on mixture toxicity to any given taxa with confidence is beyond the capabilities of the 

available data and methodologies. However, a qualitative discussion of implications of 

the available pesticide mixture effects data on the confidence of risk assessment 

conclusions will be addressed as part of the uncertainty analysis. 

7.2. Measures of Exposure 

In order to estimate risks of cyfluthrin and beta-cyfluthrin exposures in aquatic and 

terrestrial environments, all exposure modeling and resulting risk conclusions will be 

made based on maximum application rates for the current use patterns. Measures of 

exposure are based on aquatic and terrestrial models that predict estimated environmental 

concentrations of cyfluthrin and beta-cyfluthrin using maximum labeled application rates 

and methods, as well as any mitigation measures specifically indicated on the label. The 

models used to predict aquatic EECs are the Pesticide Root Zone Model coupled with the 

Exposure Analysis Model System (PRZM/EXAMS). Also, to estimate exposure related 

to releases of cyfluthrin and beta-cyfluthrin from domestic wastewater treatment plants, 

the Exposure and Fate Assessment Screening Tool’s (EFAST2) down-the-drain module 

will be used. The model used to predict terrestrial exposure to birds and mammals is TREX. The model used to derive EECs relevant to terrestrial and wetland plants is 

TerrPlant. The potential for bioaccumulation for the chemical is assessed using the 

KABAM model, as well the results from bioconcentration in fish studies (e.g. the 

bioconcentration factors). KABAM is used to estimate potential bioaccumulation of 

hydrophobic organic pesticides in freshwater aquatic ecosystems and risks to mammals 

and birds consuming aquatic organisms which have bioaccumulated these pesticides. All 

of these models are parameterized using relevant reviewed registrant-submitted 
 60

environmental fate and transport data. 

PRZM (v.3.12.2, May 2005) and EXAMS (v.2.98.4.6, April 2005) are screening 

simulation models coupled with the input shell PE5.pl (August, 2007) to generate daily 

exposures and 1-in-10 year EECs of cyfluthrin and beta-cyfluthrin, that may occur from 

spray drift and runoff to surface water bodies adjacent to application sites. PRZM 

simulates pesticide application, movement and transformation on an agricultural field and 

the resultant pesticide loadings to a receiving water body via runoff, erosion and spray 

drift. The EXAMS model simulates the fate of the pesticide and resulting concentrations 

in the water body. The standard scenario used for ecological pesticide assessments 

assumes application to a 10-hectare agricultural field that drains into an adjacent 1-

hectare water body that is 2 meters deep (20,000 cubic meters volume) with no outlet. 

PRZM/ EXAMS is used to estimate screening-level exposure of aquatic organisms to 

cyfluthrin and/ or beta-cyfluthrin and/ or their transformation products, should they be of 

concern. The measure of exposure for aquatic species is the 1-in-10 year return peak or 

rolling mean concentration. The 1-in-10 year peak is used for estimating acute exposures 

of direct effects to aquatic organisms. The 1-in-10-year 60-day mean is used for assessing 

chronic exposure to fish and aquatic-phase amphibians. The 1-in-10-year 21-day mean is 

used for assessing aquatic invertebrate chronic exposure. 

Given the aquatic toxicity of cyfluthrin and beta-cyfluthrin and their likelihood to occur 

in sediment, the Agency will also consider the potential exposures resulting from benthic/ 

sediment concentrations (EECs). Pore water concentrations are commonly used to 

predict toxicity of non-ionic substances in sediments and characterize exposure to 

organisms that spend time in or near sediments (Di Toro et al. 1991; US EPA 2002). 

PRZM/ EXAMS estimates 1-in-10-year peak and 21-day mean EECs for pore water. 

To estimate exposure related to releases of cyfluthrin and beta-cyfluthrin from domestic 

wastewater treatment plants, the Agency will rely on the Office of Pollution Prevention 

and Toxics (OPPT) model, Exposure and Fate Assessment Screening Tool (EFAST, 

version 2.0, or EFAST2, 2007). From this model, the Agency will use the “Down-theDrain” module, which is designed for releases to domestic wastewater treatment. It is 

suitable for all the sources of cyfluthrin and beta-cyfluthrin that could potentially be 

exposed through a “down-the-drain” scenario. The model provides screening level 

estimate concentrations of chemicals in surface water that may result from household 

uses and the disposal of consumer products into wastewater using a few simple input 

parameters (production volume and fraction of the chemical removed during wastewater 

treatment) (please, refer to Section 7.9.1 for data being required for this analysis; a 

POTW treatability study is being required for these chemicals). 

Exposure estimates for terrestrial animals assumed to be in the target area are derived 

using the T-REX model (version 1.3.1, 12/07/2006). For pesticides such as cyfluthrin 

and beta-cyfluthrin, which can be applied as a dust, this includes the amount of pesticide 

per square foot, used in LD50 per square foot risk assessment calculations. EECs for 

terrestrial plants inhabiting dry and wetland areas are derived using TerrPlant (version 

1.2.2, 12/26/2006). This model uses estimates of pesticides in runoff and in spray drift 
 61

(assumed to be 0% for granulars) to calculate EECs. EECs are based upon solubility, 

application rate and minimum incorporation depth. 

As indicated in Table 3.1 and its associated text in Section 3, cyfluthrin and betacyfluthrin appear to have a potential to bioaccumulate in aquatic organisms, based on its 

high KOW (9.33 x 105) and persistence in water and sediments. Due to its metabolism and 

relatively rapid depuration, it appears that cyfluthrin and beta-cyfluthrin have a low 

likelihood to biomagnify in aquatic and terrestrial organisms (i.e., a form of 

bioaccumulation where concentrations increase from prey to predators due to dietary 

exposure). However, this potential has not been quantified. The potential for 

bioaccumulation and biomagnification of cyfluthrin and beta-cyfluthrin in aquatic food 

webs will be examined in the risk assessment. Because cyfluthrin and beta-cyfluthrin 

have a fairly high KOW (9.33 x 105) and the chemical may be persistent in water and 

sediments, there is a potential for bioaccumulation. The maximum bioconcentration 

factor was 854x for whole fish and depuration rate is moderate (half depuration time of 3 

days, MRID 00143143). Bioaccumulation will be assessed using the results from 

bioaccumulation in fish studies, as well as the (KOW (based) Aquatic BioAccumulation 

Model (KABAM, v.1.0, 2009), adjusting for biotransformation rates. KABAM is used to 

estimate potential bioaccumulation of hydrophobic organic pesticides in freshwater 

aquatic ecosystems and risks to mammals and birds consuming aquatic organisms which 

have bioaccumulated these pesticides. Currently, EFED does not have the modeling 

capabilities to quantitatively evaluate bioaccumulation and biomagnification in terrestrial 

food webs5. Therefore, EFED will address these exposure routes qualitatively. 

7.3. Measures of Effect 

Ecological effects data are used as measures of direct and indirect effects to biological 

receptors. Data are typically obtained from registrant-submitted studies or from literature 

studies identified by ECOTOX. The ECOTOX database provides more ecological effects 

data in an attempt to bridge existing data gaps. ECOTOX is a source for locating single 

chemical toxicity data and potential chemical mixture toxicity data for aquatic life, 

terrestrial plants, and wildlife. ECOTOX was created and is maintained by the USEPA, 

Office of Research and Development, and the National Health and Environmental Effects 

Research Laboratory's Mid-Continent Ecology Division. 

The acute measures of effect used for animals in this assessment are the LD50, LC50 and 

EC50. LD stands for "Lethal Dose", and LD50 is the amount of a material, given all at 

once, that is estimated to cause the death of 50% of the test organisms. LC stands for 

“Lethal Concentration” and LC50 is the concentration of a chemical that is estimated to 

kill 50% of the test organisms. EC stands for “Effective Concentration” and the EC50 is 

 

5

 USEPA. 2009a. SAP Minutes No. 2009-01. A Set of Scientific Issues Being Considered by the 

Environmental Protection Agency Regarding: Selected Issues Associated with the Risk Assessment Process 

for Pesticides with Persistent, Bioaccumulative and Toxic Characteristics October 28 - 31, 2008. FIFRA 

Scientific Advisory Panel Meeting, Held at the Environmental Protection Agency Conference Center, 

Arlington, Virginia (http://epa.gov/oscpmont/sap/meetings/2008/october/minutes.pdf) 
 62

the concentration of a chemical that is estimated to produce a specific effect in 50% of 

the test organisms. Endpoints for chronic measures of exposure for listed and non-listed 

animals are the NOAEL/NOAEC and NOEC. NOAEL stands for “No ObservedAdverse-Effect-Level” and refers to the highest tested dose of a substance that has been 

reported to have no harmful (adverse) effects on test organisms. The NOAEC (i.e., “NoObserved-Adverse-Effect-Concentration”) is the highest test concentration at which none 

of the observed effects were statistically different from the control. The NOEC is the NoObserved-Effects-Concentration. For non-listed plants, only acute exposures are 

assessed (i.e., EC25 for terrestrial plants and EC50 for aquatic plants); for listed plants 

either the NOAEC or EC05 is used. 

Information on the potential effects of cyfluthrin and beta-cyfluthrin on non-target 

animals is also collected from the Ecological Incident Information System (EIIS). The 

EIIS is a database containing adverse effect (typically mortality) reports on non-target 

organisms where such effects have been associated with the use of pesticides. 

Information on incidents involving avian species is also provided through the Avian 

Monitoring Information System (AIMS), which is maintained by the American Bird 

Conservancy. 

Where available, sub-lethal effects observed in both registrant-submitted and open 

literature studies will be evaluated qualitatively. Such effects may include behavioral 

changes (e.g., lethargy and changes in coloration). Quantitative assessments of risks, 

though, are limited to those endpoints that can be directly linked to the Agency’s 

assessment endpoints of impaired survival, growth and reproduction. 

The assessment of risk for direct effects to non-target organisms makes the assumption 

that the toxicity of cyfluthrin and beta-cyfluthrin to birds is similar to terrestrial-phase 

amphibians and reptiles. The same assumption is made for fish and aquatic-phase 

amphibians. 

7.4. Integration of Exposure and Effects 

Risk characterization is the integration of exposure and ecological effects characterization 

to determine the potential ecological risk from the use of pesticides and the likelihood of 

direct and indirect effects to non-target organisms in aquatic and terrestrial habitats. The 

exposure and toxicity effects data are integrated in order to evaluate the risks of adverse 

ecological effects on non-target species. For the assessment of risks, the risk quotient 

(RQ) method is used to compare exposure and measured toxicity values. EECs are 

divided by acute and chronic toxicity values. The resulting RQs are then compared to the 

Agency’s Levels of Concern (LOCs) (USEPA 2004). These criteria will be used to 

indicate when cyfluthrin and beta-cyfluthrin’s uses, as directed on the label, have the 

potential to cause adverse direct or indirect effects to non-target organisms. In addition, 

incident data from the EIIS will be considered as part of the risk characterization. 

7.5. Deterministic and Probabilistic Assessment Methods 
 63

The quantitative assessment of risk will primarily depend on the deterministic pointestimate based approach described in the risk assessment. An effort may also be made to 

further qualitatively describe risk using probabilistic tools that the Agency has developed. 

These tools have been reviewed by FIFRA Scientific Advisory Panels 

(http://www.epa.gov/scipoly/sap/index.htm) and have been deemed as appropriate means 

of refining assessments where deterministic approaches have identified risks. 

7.6. Endangered Species Assessments 

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), 

the Agency will evaluate risks to Federally-listed threatened and/or endangered (listed) 

species from registered uses of cyfluthrin and beta-cyfluthrin. This assessment will be 

conducted in accordance with the Overview Document (USEPA 2004), provisions of the 

ESA, and the Services’ Endangered Species Consultation Handbook (USFWS/NMFS, 

1998). No previous endangered species assessment has been conducted for cyfluthrin or 

beta-cyfluthrin. 

The assessment of effects associated with the registration of cyfluthrin and betacyfluthrin is based on an action area. The action area is considered to be the area directly 

or indirectly affected by the federal action, as indicated by the exceedance of Agency 

Levels of Concern (LOCs) used to evaluate direct or indirect effects. The Agency’s 

approach to defining the action area under the provisions of the Overview Document 

(USEPA 2004) considers the results of the risk assessment process to establish 

boundaries for that action area with the understanding that exposures below the Agency’s 

defined LOCs constitute a no-effect threshold. For the purposes of this assessment, 

attention will be focused on the footprint of the action (i.e., the area where cyfluthrin and 

beta-cyfluthrin application occurs), plus all areas where offsite transport may result in 

potential exposure that exceeds the Agency’s LOCs. Specific measures of ecological 

effect that define the action area for listed species include any direct and indirect effects 

and/ or potential modification of its critical habitat, including reduction in survival, 

growth, and reproduction as well as the full suite of sub-lethal effects available in the 

effects literature. Therefore, the action area extends to a point where environmental 

exposures are below any measured lethal or sub-lethal effect threshold for any biological 

entity at the whole organism, organ, tissue, and/ or cellular level of organization. In 

situations where it is not possible to determine the threshold for an observed effect, the 

action area is not spatially limited and is assumed to be the entire United States. 

Currently, EFED does not assess risk to non-target insects. Results of acceptable studies 

are used for recommending appropriate label precautions. Based on the results of a 

single study in honey bees (LD50 of 0.037 μg a.i./bee, MRID 00153638), cyfluthrin is 

classified as highly toxic on an acute contact basis. This study suggests that the acute 

toxicity to non-target beneficial endangered insects may also be of concern should 

exposure occur. 

Toxicity data are not available for terrestrial plants, and risks associated with cyfluthrin 

and beta-cyfluthrin exposure to terrestrial plants cannot be assessed. In the past, it had 
 64

been indicated that a review of cyfluthrin and beta-cyfluthrin’s mode of action (neural 

toxin) suggested that direct toxicity to plants would not be an issue of concern. However, 

incidents involving terrestrial plants have been reported to the Agency. These data are 

requested, according to the Part 158 data requirements. 

7.7. Drinking Water Assessment 

A drinking water assessment will be conducted to support future human health risk 

assessments of cyfluthrin and beta-cyfluthrin should it be required and based on the 

newly submitted environmental fate results. The drinking water assessment will 

incorporate model estimates of cyfluthrin and/ or beta-cyfluthrin in surface and ground 

waters. Concentrations in surface waters will be estimated using FQPA Index Reservoir 

Screening Tool (FIRST, v.1.1.1, 12/18/07) (or subsequently using PRZM/ EXAMS, with 

the Index Reservoir – for description see above – if refinements are required). Ground 

water estimates of concentrations will be obtained using the Screening Concentration In 

GRound Water (SCI-GROW) model (v.2.3, July 2003). The drinking water assessment 

will also include a summary of available surface and ground water monitoring data. 

7.8. 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 dose-response 

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. 

Cyfluthrin is among the group of 58 pesticide active ingredients on the initial list to be 

screened under the EDSP. The Agency will review the EDSP Tier 1 data and any “other 

scientifically relevant information” submitted in response to test orders. Based on this 

review the Agency will determine the need for additional testing. For further information 

on the status of the EDSP, the policies and procedures, the list of 67 chemicals, the test 
 65

guidelines and the Tier 1 screening battery, please refer to the following website: 

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

7.9. Preliminary Identification of Data Gaps 

7.9.1. Fate 

After evaluation of the available data for cyfluthrin and beta-cyfluthrin, the following 

data gaps for registration review have been identified. 

835.4100 Aerobic Soil Metabolism – The Agency has aerobic soil metabolism studies 

performed in two soils for fluorophenyl-labeled cyfluthrin; no data are available with 

cyclopropyl-labeled cyfluthrin. A study performed in two soils should be submitted for 

cyfluthrin (at least, one of which should be conducted with cyclopropyl-labeledcyfluthrin). In addition, a study should be performed in four soils for beta-cyfluthrin. 

The data requirement is being required for beta-cyfluthrin as per current draft guidance 

provided in the EFED Interim Policy for Stereoisomeric Pesticides (10/26/00),6

 that 

indicates that “...an aerobic soil metabolism study (GLN 162-1/835.3300) is required as 

part of the minimal data set for enantiomeric enriched mixtures.” (Note that the current 

guideline number for the aerobic soil metabolism studies is 835.4100.) At this time, 

these data are not available to the Agency. Furthermore, there is evidence in the 

literature that the degradation of cyfluthrin and beta-cyfluthrin may be enantioselective 

(Qin et al. 2006, Li et al. 2008). Aerobic soil metabolism studies with one soil type are 

generally sufficient for the evaluation of transformation pathways. Rates of 

transformation should be determined in at least three additional soils (from Fate, 

Transport and Transformation Test Guidelines – OCSPP (formerly OPPTS) Guideline 

835.4100 & 835.4200). For all metabolism studies, domestic soils are preferred. 

835.4200 Anaerobic Soil Metabolism – The available supplemental anaerobic soil 

metabolism study, conducted on cyfluthrin, was performed with only one soil and for a 

period of roughly one month of anaerobic incubation. A new study is required. 

Anaerobic studies with one soil type are generally sufficient for the evaluation of 

transformation pathways. Rates of transformation should be determined in at least three 

additional soils (from Fate, Transport and Transformation Test Guidelines – OCSPP 

(formerly OPPTS) Guideline 835.4100 & 835.4200). For all metabolism studies, 

domestic soils are preferred. 

835.4300 Aerobic Aquatic Metabolism – Two soil/ sediment systems are available that 

were conducted with cyclopropyl-labeled cyfluthrin. The studies available that were 

conducted with fluorophenyl-labeled cyfluthrin provide only a minimum supplemental 

information.7

 A study should be conducted utilizing fluorophenyl-labeled beta-cyfluthrin 

 

6

 Available at url http://www.epa.gov/oppefed1/ecorisk_ders/stereoisomer_policy.htm . 7

 The following problems were observed in the studies: the amount of parent material at the first sampling 

interval was too low, studies were conducted at above the solubility limit, and the study was not performed 

in accordance with FIFRA GLP standards. When conducting the new study, the registrant should avoid 

these problems. 
 66

on one sediment system of marine origin. According to the OCSPP (formerly OPPTS) 

Fate, Transport and Transformation Test Guidelines (835.4300 & 835.4400)...“At least 

two sediments and their associated waters are used for both the aerobic and the anaerobic 

studies respectively...However, there may be cases where more than two aquatic 

sediments should be used, for example, for a chemical that may be present in freshwater 

and/or marine environments. Sediments should be representative of intended use sites.” 

Since both cyfluthrin and beta-cyfluthrin have the potential for use near estuarine/ marine 

areas, the required sediment system should be from estuarine/ marine environment. For 

the metabolism studies, domestic sediments are preferred. 

835.4400 Anaerobic Aquatic Metabolism – No study has been submitted. The study is 

required, and it should be conducted on beta-cyfluthrin. Three sediment systems are 

required, one of which should be of marine origin (see guideline requirement above). For 

the metabolism studies, domestic sediments are preferred. 

835.1230 Mobility Adsorption/ Desorption – The available study was performed at a 

single concentration and no Freundlich correlations or isotherms are available. A new 

study is required. According to OCSPP (formerly OPPTS) Fate, Transport and 

Transformation Test Guideline (835.1230), the main portion of the adsorption/ desorption 

study is for the “Determination of Freundlich adsorption isotherms to determine the 

influence of concentration on the extent of adsorption on soils.” The available study 

indicated that cyfluthrin is relatively immobile in the various soils tested (KOC ≥ 73,500). 

Environmental Chemistry Methods (ECMs), and Independent Laboratory 

Validations (ILVs), for Soil, Water and Sediment. ECMs associated with the 

Terrestrial Field Dissipation study (Field dissipation §158.1300; OPPTS guidelines 

835.6100, 835.6200, and 835.6300), along with successful confirmatory method trials 

(validation) by an independent laboratory (i.e. ILVs), are required. If there is risk 

concern for a given taxon, ECMs should be available for the environmental media in 

which organisms of the taxon reside. These ECMs should have limits of quantization for 

the residues of concern that are lower than the relevant toxicological levels of concern. 

Previous reviews on cyfluthrin and beta-cyfluthrin indicate that there is high concern for 

acute and chronic toxicity to aquatic animals. Certain scenarios may have triggered acute 

and chronic levels of concern for freshwater and/ or estuarine/ marine aquatic 

invertebrates and/ or for fish and/ or organisms living in the benthos. Therefore, ECMs 

for water and sediment are required in addition to the ECM for soil. The ECMs should 

include parent and those residues found in the laboratory studies that exceeded 10% of 

the applied. Based on the available data at this time, the following appear to be the 

residues of concern for each media, but this could change, based upon the results of new 

environmental fate studies: 

Soil, Water and Sediment – cyfluthrin, beta-cyfluthrin, FPB-acid, FPB-ald and DCVA 

The registrant is encouraged to submit state-of-the-art environmental chemistry methods; 

further, multi-residue methods (MRMs) for soil, water and sediment are preferred, if 

applicable. The registrant submitted one method (MRID 41511301, published in the 

Agency’s ECM website),8

 that could quantify cyfluthrin in water and sediment. In 

 

8 Available at url: http://www.epa.gov/oppbead1/methods/ecmindex.htm
 67

addition, there is one ECM and ILV that quantifies cyfluthrin and other pyrethroids in 

sediments (MRID 47053001 and 47053002). The Agency will verify the suitability of 

these methods and the appropriateness of their levels of quantization. At this time, no 

methods have been identified for the analysis of beta-cyfluthrin. A full description of the 

method validation procedures performed by an independent laboratory should also be 

submitted. It should include the following information (Corbin et al. 2006): (a) Recovery 

level(s) of the test compound(s) from the soil, water and sediment (substrates) at various 

relevant fortification level(s) using the residue analytical methodology; (b) a validated 

method sensitivity level; (c) results of the study and statistical test applied, including a 

stepwise presentation of the procedure for calculating percent recovery from the raw data; 

(d) all the data/ information necessary to independently verify the results; (e) summary of 

the results; and, (f) discussion and conclusions of the results. 

Other data needs: 

Leachability from Treated Wood – A study is required. It should be conducted 

according to the American Wood Preservers Association Standard Method of 

Determining the Leachability of Wood Preservatives (E11-06). It is strongly preferred 

that the registrant provided a protocol to be evaluated by the Agency prior to conducting 

the study. 

POTW Effluent Monitoring – Request any existing or ongoing POTW effluent 

monitoring data for the pyrethroids be submitted to the Agency. 

POTW Treatability Study – The Agency is anticipating requiring a bench scale study of 

waste water treatment, to assess the percentage removed in the biosolids by the treatment, 

the amount that would degrade during treatment, and the amount that would remain in the 

waste water. 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 (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. 

Table 7.1 lists the status of the environmental fate data requirements for cyfluthrin and 

beta-cyfluthrin. 

Table 7.1. Summary of Environmental Fate Data Requirements for Cyfluthrin and Beta-cyfluthrin

Study Identification 

Use 

Pattern1

Does EPA Have 

Data To Satisfy 

This Requirement? Bibliographic Citation 

Must Additional 

Data Be Submitted 

Under FIFRA 

3(c)(2)(B)? 

§158.1300 ENVIRONMENTAL FATE

Degradation Studies-Lab:

835.2120 Hydrolysis 1,2 Yes 00131493, 00137539, 

45022101 

No 
 68

Table 7.1. Summary of Environmental Fate Data Requirements for Cyfluthrin and Beta-cyfluthrin

Study Identification 

Use 

Pattern1

Does EPA Have 

Data To Satisfy 

This Requirement? Bibliographic Citation 

Must Additional 

Data Be Submitted 

Under FIFRA 

3(c)(2)(B)? 

835.2240 Photodegradation in 

Water 

1,2 Yes 00149595, 45022102 No 

835.2410 Photodegradation on 

Soil 

1,2 Yes 00137543, 00157043 No 

835.2370 Photodegradation in 

Air 

1,2 No Not Available No 

Metabolism Studies-Lab:

835.4100 Aerobic Soil 1,2 Yes 00131494 Yes2

835.4200 Anaerobic Soil 1,2 Yes 00131494 Yes3 

835.4300 Aerobic Aquatic 1,2 No 46824101 Yes4 

835.4400 Anaerobic Aquatic 1,2 No Not Available Yes5 

Mobility Studies:

835.1230 Leaching – 

Adsorption/ Desorption 

1,2 Yes 00131495, 00137544, 

43424901, 45022103 

Yes6 

835.1410 Volatility (Lab) 1,2 No Not Available No 

835.8100 Volatility (Field) 1,2 No Not Available No 

Dissipation Studies-Field:

835.6100 Terrestrial Field 

Dissipation 

1,2 Yes AN 259211, 44822901, 

42794801 

No7 

835.6200 Aquatic Field 

Dissipation 

1,2 No Not Applicable N/A 

835.6300 Forestry Dissipation 1,2 No Not Applicable N/A 

Ground Water Monitoring Studies:

835.7100 Ground Water 

Monitoring 

1,2 No NA Reserved 

§158.1100 SPRAY DRIFT

201-1 Droplet Size Spectrum 1,2 Yes AN 255336 No8 

202-1 Drift Field Evaluation 1,2 Yes AN 255336 No8

Other Studies: 
 69

Table 7.1. Summary of Environmental Fate Data Requirements for Cyfluthrin and Beta-cyfluthrin

Study Identification 

Use 

Pattern1

Does EPA Have 

Data To Satisfy 

This Requirement? Bibliographic Citation 

Must Additional 

Data Be Submitted 

Under FIFRA 

3(c)(2)(B)? 

Environmental Chemistry 

Methods (ECMs) and 

Independent Laboratory 

Validations (ILVs) 

1,2 Yes 41511301, 47053001, 

47053002 

Yes9

Leachability from Treated 

Wood 

1.2 No Not Available Yes10 

POTW Effluent Monitoring 

and POTW Treatability Study 

1.2 No Not Available Yes11 

1. Use Patterns: 1=Terrestrial/Food; 2=Terrestrial/Feed. 

2. A study performed in two soils should be submitted for cyfluthrin. In addition, a study should be performed on four soils 

for beta-cyfluthrin. The data requirement is being required for beta-cyfluthrin as per current draft guidance provided in the 

EFED Interim Policy for Stereoisomeric Pesticides. 

3. Data are required for cyfluthrin on four soils utilizing fluorophenyl- and cyclopropyl-labeled cyfluthrin, as per current 

guidance. 

4. A study should be conducted utilizing fluorophenyl-labeled beta-cyfluthrin on one sediment system of estuarine/ marine 

origin. 

5. A study is required for beta-cyfluthrin. 

6. The available study was conducted at only one concentration and a Freundlich isotherm could not be drawn. A new 

study is required. 

7. One of the studies is currently in review. 

8. Data requirement covered by submission of the Spray Drift Task Force. 

9. The data requirement remains unfulfilled for cyfluthrin, pending evaluation of three available studies. No data have been 

identified for beta-cyfluthrin. 

10. It is strongly preferred that the registrant provided a protocol to be evaluated by the Agency prior to conducting the 

study. 

11. Request any existing or ongoing POTW effluent monitoring data. Further, the Agency is anticipating requiring a bench 

scale study of waste water treatment, to assess the percentage removed in the biosolids by the treatment, the amount that 

would degrade during treatment, and the amount that would remain in the waste water. 

7.9.2 Effects

For registration review, the following studies are being requested to fulfill any data gaps: 

Cyfluthrin is part of the Endocrine Disruptor Screening Program; certain data has been 

required for the chemical under the program (DCI issued on 11/19/09; 90-day response 

by 02/27/10; order due date 11/19/11). 

Study Title: 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 
 70

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 dose-response 

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. 

Cyfluthrin is among the group of 58 pesticide active ingredients on the initial list to be 

screened under the EDSP. The Agency will review the EDSP Tier 1 data and any “other 

scientifically relevant information” submitted in response to test orders. Based on this 

review the Agency will determine the need for additional testing. 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 refer to the following website: 

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

Guideline Number: 850.2100 

Study Title: Passerine Acute Avian Oral 

An acute avian oral study was received for bobwhite quail. The Agency updated its data 

requirements in 40 CFR Part 158 (October 26, 2007) to include an acute oral toxicity 

study for both a passerine species and either a waterfowl or an upland game species. 

Prior to starting toxicity testing, a protocol will need to be provided for review. Many 

passerine species utilize agricultural fields, forests, residential areas and surrounding 

areas, and, therefore, have the potential to be exposed to pesticides used in agricultural, 

forest, and residential settings. It is likely that, for most pesticide use patterns, passerines 

are more likely to be exposed to pesticides than upland game species and waterfowl. 

Passerines are smaller in size and generally have faster metabolisms than the waterfowl 

and upland game bird species traditionally used in avian toxicity tests which could impact 

their sensitivity to chemicals. 

Guideline Number: 850.2300 

Study Title: Avian Reproduction Study (Mallard duck only) 

No acceptable data on reproductive toxicity to the most sensitive bird species has been 

submitted (mallard duck). The most sensitive study resulted in a nondefinitive NOAEC 

(<250 ppm) and both submitted studies had issues with control performance. A chronic 

risk assessment for birds is needed based on cyfluthrin’s use patterns and potential impact 

on birds. The avian reproduction toxicity study is justified for cyfluthrin because 1) the 

avian reproduction studies for both waterfowl and upland game bird species are standard 

data requirements for all outdoor terrestrial use patterns, 2) evidence of chronic toxicity 
 71

to mammals indicates possible chronic toxicity in birds, and 3) cyfluthrin use pattern 

indicates that chronic exposure is likely. 

Guideline Number: 850.1025 

Study Title: Oyster Acute Toxicity (saltwater, cyfluthrin TEP only) 

Guideline Number: 850.1035

Study Title: Mysid Acute Toxicity (saltwater, cyfluthrin TEP only) 

Cyfluthrin and beta-cyfluthrin have the potential to enter estuarine/marine water bodies 

based on current usage patterns that include coastal areas (see Fig. 3.1). Cyfluthrin 

technical is very highly toxic to estuarine/marine fish and invertebrates on an acute basis, 

but no information is available for cyfluthrin TEP effects on estuarine/marine species. 

Testing on Typical end-use products (TEP) 

According to the Part 158 data requirements, testing on the typical end-use product may 

be required for aquatic toxicity tests when any of the following conditions exist: 

 1. The end-use product will be introduced directly into the aquatic environment. 

2. The maximum expected environmental concentration or estimated 

environmental concentration in the aquatic environment is greater than or equal to 

one-half the LC50 or EC50 of the TGAI. 

3. An ingredient in the end-use formulation other than the active ingredient is 

expected to enhance the toxicity of the active ingredient or cause toxicity to 

aquatic organisms. 

Previous assessments on cyfluthrin indicate that the expected environmental 

concentrations in aquatic environments are well above acute 50% mortality levels for all 

estuarine/marine invertebrate species tested. Based on preliminary calculations (see 

Appendix D), the peak aquatic EEC is 1.62 μg ai/L using the PRZM/EXAMS MS cotton 

scenario. In estuarine/marine tests conducted with cyfluthrin technical, the lowest 96-

hour LC50 was 4.05 μg/L for sheepshead minnow, 0.0022 μg/L for mysid shrimp and 

2.69 μg/L for the eastern oyster. Therefore, cyfluthrin fulfills the second requirement 

(above) for TEP studies with all tested estuarine/marine invertebrate species, but not 

estuarine/marine fish. 

A Typical End-Use Product is defined in the Pesticide Assessment Guidelines 

Subdivision J Hazard Evaluation: Nontarget plants on Part 120-2(1) on Page 18 as “a 

pesticide product that is representative of a major formulation category (e.g., emulsifiable 

concentrate, granular product, wettable powder) and pesticide group (e.g., herbicide, 

fungicide, insecticide etc.) and contains the active ingredient of the applicant’s product.” 

(Holst and Ellwanger, 1982) 

Page 5 of the Pesticide Assessment Guidelines Subdivision J Hazard Evaluation: 

Nontarget plants, provides additional information on what TEP data should be tested for 

toxicity testing in the following excerpt. 

“The Agency seeks to avoid imposing a burden of duplicative testing on 
 72

applicants for registration. Therefore, where 40 CFR Part 158 specifies that the 

test substance should be a representative end-use product, testing may be 

performed using the formulation in question (end-use product being registered) or 

similar, yet representative, end-use product. It is not necessary to repeat the test 

using other similar products.” (Holst and Ellwanger, 1982). 

 

When TEP data are requested, data should be submitted for the different formulations, 

e.g., wettable powder, emulsifiable concentrate, granular, along with a rationale as to why 

the TEP is representative of other similar end-use products. Acute aquatic toxicity studies 

conducted with the Typical End-Use Product (TEP) may be used to assess effects as a 

result of exposure to spray drift only and reflect potential effects from a brief exposure to 

the formulation. Therefore, appropriate TEPs should be selected from formulations that 

are registered for agricultural uses, not residential.

Guideline Numbers: Non-guideline 

Study Title: Aquatic Invertebrate Acute Toxicity (Hyalella azteca)

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 cyfluthrin to Hyalella 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 Hyalella azteca is needed (water column 

exposure, not sediment-spiked).

Guideline Number: Non-guideline 

Study Title: Whole sediment: chronic invertebrates freshwater and marine 

No chronic sediment toxicity tests for freshwater or marine invertebrates have been 

submitted to satisfy the Agency’s updated data requirements for outdoor uses in 40 CFR 

Part 158 (October 26, 2007). For cyfluthrin, available information indicates that benthic 

organisms may be exposed via run-off or spray drift applications used in agricultural, 

forest, and residential settings. Based on preliminary calculations (see Appendix D), the 

peak sediment porewater EECs predicted for cyfluthrin (0.048 μg a.i./L) exceeds 0.1 of 

the most sensitive acute LC/EC50 (0.0022 μg/L for mysid shrimp), which satisfies one of 

the criteria for requiring chronic whole sediment toxicity testing under 40 CFR Part 158. 

Further, the expected half-life of cyfluthrin in sediment (73.5-94.8 for aerobic soil 

metabolism and 32.9-42 days for aerobic aquatic metabolism) is substantially greater than 

40 CFR Part 158 criterion of 10 days. The third set of trigger criteria for requiring 

chronic testing (Kd > 50, or log KOW >3 or KOC > 1000) is also met for cyfluthrin (e.g., Kd

values are 974-1793, log KOW is 6, and KOC values are 69900-180300). In addition, 

chronic effects were also seen in all aquatic taxa tested at levels ranging from 0.00040 – 

0.63 μg a.i./L. Finally, the potential for persistent exposure from cyfluthrin in sediment 

is also indicated by open literature studies on pyrethroids (Weston et al. 2005, Amweg et 

al. 2006 and Ding et al. 2009). 

For sediment studies involving pyrethroids, chronic whole sediment tests on Hyalella 

azteca, Chironomus tentans, and Leptocheirus plumulosus are requested. Although both 

are freshwater species, Hyalella and Chironomus differ substantially in their ecological 
 73

niche (i.e., epibenthic v. infaunal species), physiology, and there is some evidence 

suggesting Hyalella is among the more sensitive invertebrates to some pyrethroids based 

on water column tests (Anderson et al. 2006, Maund et al. 2002). Cyfluthrin has the 

potential to enter estuarine/marine water bodies based on current usuage patterns that 

include coastal areas. Therefore, testing is required for Leptocheirus plumulosus, an 

estuarine/marine sediment-dwelling invertebrate species. The previously-submitted 28-

day sediment test for cyfluthrin with Leptocheirus plumulosus (MRID 46591506) does 

not include reproductive endpoints, and does not fulfill this data requirement for 

estuarine/marine benthic invertebrates. 

Guideline Numbers: 850.4100 and 850.4150 

Study Title: Vegetative vigor and Seedling emergence, Tier I/ Tier II 

No acceptable toxicity data are currently available to assess the risk of cyfluthrin to nontarget terrestrial plants. Since cyfluthrin has residential outdoor uses, vegetative vigor and 

seedling emergence studies are required. Additionally, three incidents have been reported 

to the Agency where cyfluthrin was identified as the possible – highly probable cause of 

phytotoxic damage. Phytotoxicity data are needed to evaluate the level of pesticide 

exposure to non-target terrestrial and aquatic plants and to assess the impact of pesticides 

on endangered and threatened plants. 

Guideline Number: 850.4400 

Study Title: Aquatic Vascular Plant Growth-Lemna spp. Tiers I/II 

No studies for cyfluthrin have been submitted for vascular aquatic plants. The Agency 

has finalized its update to the data requirements in 40 CFR Part 158, which were 

promulgated on October 26, 2007. In these updated data requirements, vascular plant 

testing is required for pesticides with outdoor uses, such as cyfluthrin. 

In addition to the above mentioned data requirements for cyfluthrin, the following 

are required for beta-cyfluthrin as per the EFED Interim Policy for Stereoisomeric 

Pesticides,9 which says the following:

“OPP requires the following minimal data set using species and conditions 

(including testing laboratories) that are identical to those for the data submitted 

for the previous racemic mixture. If the toxicity values are substantially similar 

for the racemic and enantiomeric enriched mixture and do not result in 

significantly greater potential risk, then no additional ecotoxicity data are 

needed. If, however, the toxicity data for the racemic and enantiomeric enriched 

mixture differ significantly and suggests that the enriched mixture poses a 

significantly greater risk, then additional ecotoxicity data may be required on a 

case-by-case basis.” 

The data required in the interim policy is as follows: 

Avian 

 

9

 Available at http://www.epa.gov/oppefed1/ecorisk_ders/stereoisomer_policy.htm . 
 74

 Guideline 850.2100 - Acute Avian Oral -Inspection of the available results for 

cyfluthrin shows that the acute endpoint (LD50) was >5000 mg/kg bw for both 

mallard duck and bobwhite quail (practically non-toxic). 

o Since cyfluthrin shows low toxicity towards bobwhite quail and mallard 

species, EFED is not requiring the data for beta-cyfluthrin at this time. 

 Guideline 850.2300 - Avian Reproduction - required if birds are more sensitive 

than mammals. 

o Preliminary inspection of available data for cyfluthrin indicates that birds 

are less sensitive to the chemical compared to mammals. Studies 

examining beta-cyfluthrin reproductive effects to mammals have been 

submitted. Therefore, at this time, no additional data are required for betacyfluthrin. 

Aquatic 

 Guideline 850.1075 or 850.1010 – Acute Freshwater Fish Toxicity or Acute 

Freshwater Invertebrate Toxicity - Several tests with beta-cyfluthrin technical 

were submitted for freshwater fish, freshwater invertebrates and estuarine/marine 

invertebrates. Two studies with mysids were determined to be acceptable. All 

other aquatic studies with beta-cyfluthrin were deemed supplemental. 

o The most sensitive species based on registrant-submitted data is

Mysidopsis bahia. At this time, no additional data are required for betacyfluthrin effects on mysids. 

 Guideline 850.1400 or 850.1300/ 850.1350 - Fish Early Life Stage or 

Invertebrate Life Cycle - test most sensitive species from previous studies with 

cyfluthrin. 

o Required for beta-cyfluthrin. Preliminary inspection of the results 

indicates that the most sensitive species is Mysidopsis bahia. 

Nontarget Plant 

 Guideline 850.4100 or 850.4150 - Seedling Emergence or Vegetative Vigor

Test most sensitive monocotyledon and dicotyledon based on results of cyfluthrin 

terrestrial plant toxicity tests. No data is available for cyfluthrin. 

o Required for beta-cyfluthrin. 

 Guideline 850.4400 - Aquatic Plant Growth, Lemna gibba 

No data is available for cyfluthrin. 

o Required for beta-cyfluthrin. 

 Guideline 850.5400 - Aquatic Plant Growth, algae –The available acceptable 

study conducted on cyfluthrin shows that the EC50 was non-definitive (>181 μg 

a.i./L). 

o Since the highest level tested is much greater than the preliminary peak 

aquatic estimated exposure concentration (EEC) (1.62 μg a.i./L based on 

the PRZM/ EXAMS MS cotton scenario), no additional nonvascular 

aquatic plant data are required at this time for beta-cyfluthrin. 
 75

Table 7.2 lists the status of the ecological effects data requirements for cyfluthrin and 

beta-cyfluthrin. All additional data requests are for cyfluthrin only, with the exception of 

invertebrate life cycle, seedling emergence, vegetative vigor and vascular aquatic plant 

growth studies required for beta-cyfluthrin (see footnote section of table for each of these 

data requests). 

Table 7.2. Ecological Effects Data Requirements for Cyfluthrin and Beta-cyfluthrin

Data Requirement 

Use 

Pattern1

Does EPA Have 

Data To Satisfy 

This 

Requirement? 

(Yes, No, or 

Partially) 

Bibliographic 

Citation (MRID) 

Must 

Additional 

Data Be 

Submitted 

Under FIFRA 

3(c)(2)(B)? 

§158.490 WILDLIFE AND AQUATIC ORGANISMS

71-1(a) Acute Avian Oral, 

Quail/Duck/Passerine 

1, 2 Partially 00073629 Yes, passerine 

study 

71-2(a) Acute Avian Diet, Quail 1, 2 Yes 00131500 No2

71-2(b) Acute Avian Diet, Duck 1, 2 Yes 00131501 No2

71-3 Wild Mammal Toxicity 1, 2 NA 

71-4(a) Avian Reproduction Quail 1, 2 Yes 00152829, 00152830 No 

71-4(b) Avian Reproduction Duck 1, 2 No 00015782, 00014533 Yes3 

71-5(a) Simulated Terrestrial Field Study 1, 2 NA 

71-5(b) Actual Terrestrial Field Study 1, 2 NA 

72-1(a) Acute Fish Toxicity Bluegill 1, 2 Yes 00131503, 45426707 No 

72-1(b) Acute Fish Toxicity Bluegill 

(TEP) 

1, 2 Yes 41558001 No4

72-1(c) Acute Fish Toxicity Rainbow 

Trout 

1, 2 Yes 00131502, 45426705 No 

72-1(d) Acute Fish Toxicity Rainbow 

Trout (TEP) 

1, 2 Yes 41558002 No 

72-2(a) Acute Aquatic Invertebrate 1, 2 Yes 00131504, 45426701, 

42605801 

No

72-2(b) Acute Aquatic Invertebrate (TEP) 1, 2 Yes 41558003 No 

72-3(a) Acute Est/Mar Toxicity Fish 1, 2 Yes 00146485 No 

72-3(b) Acute Est/Mar Toxicity Mollusk 1, 2 Yes 00158783 No 

72-3(c) Acute Est/Mar Toxicity Shrimp 1, 2 Yes 00149598, 40069501, 

45426704, 45426709 

No 

72-3(d) Acute Est/Mar Toxicity Fish 

(TEP) 

1, 2 No NA No5
 76

Table 7.2. Ecological Effects Data Requirements for Cyfluthrin and Beta-cyfluthrin

Data Requirement 

Use 

Pattern1

Does EPA Have 

Data To Satisfy 

This 

Requirement? 

(Yes, No, or 

Partially) 

Bibliographic 

Citation (MRID) 

Must 

Additional 

Data Be 

Submitted 

Under FIFRA 

3(c)(2)(B)? 

72-3(e) Acute Est/Mar Toxicity Mollusk 

(TEP) 

1, 2 No NA Yes5 

72-3(f) Acute Est/Mar Toxicity Shrimp 

(TEP) 

1, 2 No NA Yes5 

72-4(a) Early Life Stage Fish 1, 2 Yes 41450401 No

72-4(b) Life Cycle Aquatic Invertebrate 1, 2 Yes 00132761, 00162969 Yes6

72-5 Life Cycle Fish 1, 2 Yes 00151442 No

72-6 Aquatic Organism Accumulation 1, 2 No NA No 

72-7(1) Simulated Aquatic Field Study 1, 2 No NA No 

72-7(b) Actual Aquatic Field Study 1, 2 No NA No 

Whole sediment: acute freshwater 

invertebrates 

1, 2 Yes 46591507 No7

Whole sediment: acute marine invertebrates 1, 2 Yes 46591506 No7

Whole sediment: chronic invertebrates 

freshwater & marine 

1, 2 No NA Yes8 

Non-guideline Aquatic Invertebrate Acute 

Toxicity (Hyalella) 1, 2 No NA Yes 

§158.540 PLANT PROTECTION

122-1(a) Seed Germ, Seedling Emergence 1,2 No NA Yes9

122-1(b) Vegetative Vigor 1, 2 No NA Yes9

122-2 Aquatic Plant Growth 1, 2 No 43984901 Yes10

124-1 Terrestrial Field Study 1, 2 No NA No 

124-2 Aquatic Field Study 1, 2 No NA No 

§158.490 NONTARGET INSECT TESTING

141-1 Honey Bee Acute Contact 1, 2 Yes 00153638 No 

141-2 Honey Bee Residue on Foliage 1, 2 No NA No 

141-5 Field Test for Pollinators 1, 2 No NA No 

§158.630 AQUATIC ORGANISMS TESTING

 850.1730 Bioaccumulation in Fish 1, 2 Yes 00143143 No 
 77

Table 7.2. Ecological Effects Data Requirements for Cyfluthrin and Beta-cyfluthrin

Data Requirement 

Use 

Pattern1

Does EPA Have 

Data To Satisfy 

This 

Requirement? 

(Yes, No, or 

Partially) 

Bibliographic 

Citation (MRID) 

Must 

Additional 

Data Be 

Submitted 

Under FIFRA 

3(c)(2)(B)? 1

 Use Patterns: (1=Terrestrial/Food; 2=Terrestrial/Feed). 2 Original review classified the study as acceptable, completed in 1983 by W. Faatz. Study not required at this time as the 

study is acceptable based on a cursory review, but may be required pending additional evaluation of the data. 3

 A bluegill toxicity test with an end-use product has been submitted for cyfluthrin, but the study was classified as 

supplemental. However, TEP data has been submitted for the most acutely sensitive fish species, rainbow trout so the data 

requirement is waived. 

3

 Both submitted chronic studies for mallard duck are classified as supplemental. Therefore, a new study is requested. 

4

 Based on preliminary calculations (see Appendix D), the peak aquatic EEC is 1.62 μg a.i./L using the PRZM/ EXAMS 

MS cotton scenario. In estuarine/marine tests conducted with cyfluthrin technical, the lowest 96-hour LC50 was 4.05 μg/L 

for sheepshead minnow, 0.0022 μg/L for mysid shrimp and 2.69 μg/L for the eastern oyster. Therefore, cyfluthrin fulfills 

the requirements for requesting TEP studies with all tested estuarine/marine invertebrate species, but not estuarine/marine 

fish (According to Part 158, for TEP data requests, the maximum expected environmental concentration or estimated 

environmental concentration in the aquatic environment is greater than or equal to one-half the LC50 or EC50 of the TGAI). 5

 Data are required for beta-cyfluthrin. 6

 Data in review. According to current Part 158 guidelines, only chronic sediment studies would be requested for cyfluthrin. 

7

 Data required for chironomids, Hyalella azteca and Leptocheirus plumulosus. 8

 Studies are required for cyfluthrin and beta-cyfluthrin. For beta-cyfluthrin, the most sensitive monocotyledon and 

dicotyledon should be tested from tests with cyfluthrin.

9

 Aquatic toxicity tests are required for aquatic vascular plant species. A test has been submitted for green algae 

(acceptable), but the EC50 was non-definitive (>181 μg a.i./L). Because the highest level tested is much greater than the 

preliminary peak aquatic estimated exposure concentration (EEC) (1.62 μg ai/L based on the PRZM/EXAMS MS cotton 

scenario), no additional nonvascular aquatic plant data is requested at this time. A study should be conducted on betacyfluthrin (vascular aquatic plant study only). 
 78

8. References 

Amweg, E.L., D.P.Weston, and N.M. Ureda. 2005. Use and Toxicity of Pyrethroid 

Pesticides in the Central Valley, California, USA. Environmental Toxicology and 

Chemistry, Vol. 24, No. 4, pp. 966–972 

Amweg, E.L., D.P. Weston, C.S. Johnson, J. You and M.J. Lydy. 2006a. Effect of 

Piperonyl Butoxide on Permethrin Toxicity in the Amphipod Hyalella azteca. Environ. 

Tox. & Chem. 25(7), pp. 1817-1825. 

Amweg, E.L. D.P. Weston, J. You and M.J. Lydy. 2006b. Pyrethroid Insecticides and 

Sediment Toxicity in Urban Creeks from California and Tennessee. Environ. Sci. 

Technol., 2006, 40 (5), pp 1700–1706. 

Amweg, E.L. and D.P. Weston. 2007. Whole-Sediment Toxicity Identification 

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9. Fate and Eco-Toxicity Bibliography 

Environmental Fate Cyfluthrin

161-1 Hydrolysis 

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131492 Mobay Chemical Corp. (1983) Synopsis of Baythroid: The Effects on the 

Environment--Environmental Chemistry: ?Summary|. (Unpub- lished study 

received Oct 12, 1983 under 3125-EX-188; CDL: 072003-A) 

131493 Sandie, F.; Thornton, J. (1983) Hydrolysis of Baythroid in Sterile, Aqueous 

Buffered Solutions: 86051. (Unpublished study received Oct 12, 1983 under 

3125-EX-188; submitted by Mobay Chemical Corp., Kansas City, MO; 

CDL:072003-B) 

137539 Sandie, F.; Thornton, J. (1983) Hydrolysis of Baythroid in Sterile, Aqueous 

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3125-351; submitted by Mobay Chemical Corp., Kansas City, MO; 

CDL:072361-B) 

137543 Puhl, R.; Hurley, J.; Dime, R. (1983) Photodecomposition of Bayth- roid-14C in 

Aqueous Solution and on Soil: 86182. (Unpublished study received Feb 13, 

1984 under 3125-351; submitted by Mobay Chemical Corp., Kansas City, MO; 

CDL:072362-B) 

161-2 Photodegradation-water 

MRID Citation Reference 

149596 Mobay Chemical Corp. (1984) Baythroid: Addition No. 1, January 6, 1984, 

Brochure No. 1239 to Brochure Entitled: Baythroid: The Effects on the 

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45022101 Anderson, C. (1986) Degradation Behavior of (carbon-14)-Cyfluthrin in Natural 

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45022102 Gronberg, R. (1984) Photodecomposition of (Phenyl-UL-(carbon-14))-Baythroid 

in Aqueous Solution by Sunlight: Lab Project Number: 83R-195: 88598. 

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161-3 Photodegradation-soil 

MRID Citation Reference 

137543 Puhl, R.; Hurley, J.; Dime, R. (1983) Photodecomposition of Baythroid-14C in 

Aqueous Solution and on Soil: 86182. (Unpublished study received Feb 13, 
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1984 under 3125-351; submitted by Mobay Chemical Corp., Kansas City, MO; 

CDL:072362-B) 

157043 Chopade, H. (1986) Photodecomposition of [Carbon 14] Baythroid on Soil: 

88981. Unpublished study prepared by Mobay Chemical Corp. 25 p. 

162-1 Aerobic soil metabolism 

MRID Citation Reference 

131492 Mobay Chemical Corp. (1983) Synopsis of Baythroid: The Effects on the 

Environment--Environmental Chemistry: ?Summary|. (Unpub- lished study 

received Oct 12, 1983 under 3125-EX-188; CDL: 072003-A) 

131494 Wagner, K.; Neitzel, H.; Oehlmann, L. (1983) Decomposition of Baythroid in 

Soil under Aerobic and Anaerobic Conditions: ?Sub- mitter| 86052. 

(Unpublished study received Oct 12, 1983 under 3125-EX-188; prepared by 

Bayer AG, W. Ger., submitted by Mobay Chemical Corp., Kansas City, MO; 

CDL:072003-C) 

162-4 Aerobic aquatic metab. 

MRID Citation Reference 

46824101 Dyer, D.; Sabbagh, G. (2006) Cyfluthrin - Aerobic Aquatic Metabolism 

Overview. Project Number: MEBDP001, M/151/0985/9, SVJ/002. Unpublished 

study prepared by Bayer Corp. 143 p. 

163-1 Leach/adsorp/desorption 

MRID Citation Reference 

131492 Mobay Chemical Corp. (1983) Synopsis of Baythroid: The Effects on the 

Environment--Environmental Chemistry: ?Summary|. (Unpub- lished study 

received Oct 12, 1983 under 3125-EX-188; CDL: 072003-A) 

131495 Obrist, J.; Thornton, J. (1982) Soil Thin-layer Mobility of Bay FCR 1272, Bay 

SIR 8514, and Bay SSH 0860: 82232. (Unpublished study received Oct 12, 

1983 under 3125-EX-188; submitted by Mobay Chemical Corp., Kansas City, 

MO; CDL:072003-D) 

137540 Obrist, J.; Thorton, J. (1982) Soil Thin-layer Mobility of Bay FCR 1272, Bay Sir 

8514, and Bay SSH 0860: 82232. (Unpublished study received Feb 13, 1984 

under 3125-351; submitted by Mobay Chemi- cal Corp., Kansas City, MO; 

CDL:072361-D) 

137544 Whitfield, S.; Obrist, J. (1983) Soil Thin-layer Mobility of Aged Extracts of Soil 

Treated with Amethydione, Baythroid, Alsystin, and BAY SLJ 0312: 86158. 

(Unpublished study received Feb 13, 1984 under 3125-351; submitted by 

Mobay Chemical Corp., Kansas City, MO; CDL:072362-C) 

149596 Mobay Chemical Corp. (1984) Baythroid: Addition No. 1, January 6, 1984, 

Brochure No. 1239 to Brochure Entitled: Baythroid: The Effects on the 

Environment (Dated September 16, 1983):[Attached: 1. Studies on 
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Environmental Fate in Soil; 2. Accumulation Study in Bluegill Sunfish]. 

Unpublished study. 171 p. 

40223402 Gronberg, R. (1987) Adsorption of Baythroid to Sandy Loam: Report No. 

94541. Unpublished study prepared by Mobay Corp. 13 p. 

45022103 Burhenne, J. (1996) Adsorption/Desorption of Cyfluthrin on Soils: Lab Project 

Number: 1310003-8: 107397. Unpublished study prepared by Bayer 

Corporation. 34 p. 

163-3 Volatility - field 

MRID Citation Reference 

149596 Mobay Chemical Corp. (1984) Baythroid: Addition No. 1, January 6, 1984, 

Brochure No. 1239 to Brochure Entitled: Baythroid: The Effects on the 

Environment (Dated September 16, 1983):[Attached: 1. Studies on 

Environmental Fate in Soil; 2. Accumulation Study in Bluegill Sunfish]. 

Unpublished study. 171 p. 

164-1 Terrestrial field dissipation 

MRID Citation Reference 

42794801 Grace, T.; Cain, K. (1990) Dissipation of Cyfluthrin in California Soils: Lab 

Project Number: BD830089R01: 100152: ML022101. Unpublished study 

prepared by Siemer and Associates, Inc. and Net Atlantic, Inc. 389 p. 

44822901 Lam, C.; Dehart, B.; Barney, W. (1995) Terrestrial Field Dissipation of Cyfluthrin 

on North Carolina Soil, 1992: Lab Project Number: 106949: BD022101. 

Unpublished study prepared by Bayer Corporation and ABC Laboratories, Inc. 

247 p. 

42752901 Lin, J. (1993) Field Measurement of Cyfluthrin Fate and Runoff from a Cotton 

Field in Southern Georgia: Lab Project Number: 103919: BD882303. 

Unpublished study prepared by Miles Inc. 61 p. 

42752902 Lin, J. (1992) Field Measurement of Cyfluthrin Fate and Runoff from a Cotton 

Field in Benoit, Mississippi: Lab Project Number: 103918. Unpublished study 

prepared by Miles Inc. 66 p. 

ACC 259111 Ash, C.R. 1983 Residues in Arizona soil 

ACC 259111 McMullen, P.W. 1983 Residues in Ontario Soil 

ACC 259111 Warren, J.W. 1983 Residues in Oregon soil 

Acc 259111 Meriweather, B.K. 1983 Residues in Mississppi soil 

ACC 259111 Robertson, R.E., 1983 Residues in Kansas soil 

ACC 259111 Rogers, W.D. 1983 Residues in Georgia soil 

ACC 259111 Fleming, M.O. 1983 Residues in Florida soil 

ACC 259111 Price, D.A. 1983 Residues in Florida soil 
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165-2 Field rotational crop 

MRID Citation Reference 

40942701 Leslie, W. (1988) Baythroid--Residues in Field Rotational Cereal Crops: Project 

ID; BD850086R01: Mobay Project ID: Objective No. 8500. Unpublished study 

prepared by Cambridge Analytical Assoc- iates, Inc. 136 p. 

41190202 Leslie, W. (1989) Baythroid--Residues in Field Rotational Cereal Crops--

Addendum No. 1: Mobay Project ID: Baythroid Objective No. 8500: Report No. 

98429-1. Unpublished study prepared by Mobay Corp. 20 p. 

165-4 Bioaccumulation in fish 

MRID Citation Reference 

143143 Carlisle, J.; Roney, D. (1984) Bioconcentration of Cyfluthrin (Baythroid) by 

Bluegill Sunfish: Study Number 83-766-01. Unpub- lished study prepared by 

Mobay Chemical Corp. 14 p. 

149596 Mobay Chemical Corp. (1984) Baythroid: Addition No. 1, January 6, 1984, 

Brochure No. 1239 to Brochure Entitled: Baythroid: The Effects on the 

Environment (Dated September 16, 1983):[Attached: 1. Studies on 

Environmental Fate in Soil; 2. Accumulation Study in Bluegill Sunfish]. 

Unpublished study. 171 p. 

202-1 Drift field evaluation 

MRID Citation Reference 

143144 Olson, T. (1984) Evaluation of Spray Drift Following Aerial ULV Applications of 

Baythroid 2. Unpublished study prepared by Mobay Chemical Corp. in 

cooperation with Chemonics Industries. 147 p. 

Not Available McDaniel, S.G. 

850.7100 Data reporting for environmental chemistry 

methods 

MRID Citation Reference 

47053001 Robinson, N. (2007) Residue Analytical Method for the Determination of 

Residues of Bifenthrin, Cypermethrin, Cyfluthrin, Deltamethrin, Esfenvalerate, 

Fenpropathrin, Lambda-cyhalothrin and Permethrin in Sediment. Unpublished 

study prepared by Syngenta Jealotts Hill International. 185 p. 

47053002 Reed, R. (2006) Laboratory Validation: Validation of the Residue Analytical 

Method: Residue Analytical Method for the Determination of Residues of 

Bifenthrin, Cypermethrin, Cyfluthrin, Deltamethrin, Esfenvalerate, 

Fenpropathrin, Lambda-Cyhalothrin and Permethrin in Sediment: Final Report. 

Project Number: MLI/06/02, ML06/1286/PWG. Unpublished study prepared by 
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Morse Laboratories Inc. 418 p. 

Environmental Fate Beta-Cyfluthrin

162-4 Aerobic aquatic metabolism 

MRID Citation Reference 

46824101 Dyer, D.; Sabbagh, G. (2006) Cyfluthrin - Aerobic Aquatic Metabolism 

Overview. Project Number: MEBDP001, M/151/0985/9, SVJ/002. Unpublished 

study prepared by Bayer Corp. 143 p. 

 

Non Guideline Selections 

47647801 Hanzas, J.; Stone, C.; Toth, B.; et al. (2008) Bifenthrin and Beta-Cyfluthrin: 

Quantification of Pyrethroid Runoff Losses from Treated Turfgrass Under OverIrrigation Conditions and Simulated Rainfall: Final Report. Project Number: 

082018, SEI001. Unpublished study prepared by Stone Environmental, Inc., CRG 

Marine Laboratories, Inc. and Agvise Laboratories. 280 p. 

Ecological Effects Cyfluthrin

71-1 Avian Single Dose Oral Toxicity 

MRID Citation Reference 

131498 Carlisle, J.; Carsel, M.; Lamb, D. (1983) Acute Oral LD50 of Tech- nical 

Cyfluthrin to Bobwhite Quail: Study No. 83-015-02; 85941. (Unpublished study 

received Oct 12, 1983 under 3125-EX-188; submitted by Mobay Chemical 

Corp., Kansas City, MO; CDL: 072004-B) 

143142 Thyssen, J. (1980) Acute Oral Toxicity to Quails: FCR 1272: Study No. 

1272/048. Unpublished Mobay study no. 82347 prepared by Bayer Institute of 

Toxicology. 6 p. 

42005407 Toll, P. (1991) Aztec 2.1 percent Granular: An Acute Oral LD50 with Bobwhite 

Quail (Colinus virginianus): Lab Project No: M4711701: 101219. Unpublished 

study prepared by Mobay Corp. 33 p. 

42005408 Toll, P. (1990) Aztec 2.1 (percent) Granular: An Acute Oral LD50 with House 

Sparrows (Passer domesticus): Lab Project Number: M4711401: 100346. 

Unpublished study prepared by Mobay Corp. 2 p. 

71-2 Avian Dietary Toxicity 
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MRID Citation Reference 

131497 Mobay Chemical Corp. (1983) Synopsis of Environmental Toxicology of FCR 

1272 (Cyfluthrin): (Summary). (Unpublished study re- ceived Oct 12, 1983 

under 3125-EX-188; CDL:072004-A) 

131500 Carlisle, J.; Toll, P.; Lamb, D.; et al. (1983) Acute Dietary LC50 of Cyfluthrin 

Technical to Mallard Ducks: Study No. 83-175-02; 85937. (Unpublished study 

received Oct 12, 1983 under 3125-EX- 188; submitted by Mobay Chemical 

Corp., Kansas City, MO; CDL: 072004-D) 

131501 Carlisle, J.; Carsel, M.; Lamb, D.; et al. (1983) Acute Dietary LC50 of Cyfluthrin 

Technical to Bobwhite Quail: Study No. 83- 175-05; 85943. (Unpublished study 

received Oct 12, 1983 under 3125-EX-188; submitted by Mobay Chemical 

Corp., Kansas City, MO; CDL:072004-E) 

71-4 Avian Reproduction 

MRID Citation Reference 

145330 Carlisle, J. (1984) Effect of Cyfluthrin (Baythroid Technical) on Bobwhite Quail 

Reproduction: Study Number 83-675-08. Unpub- lished study prepared by Mobay 

Chemical Corp. 94 p. 

145331 Carlisle, J. (1984) Effect of Cyfluthrin (Technical Baythroid) on Mallard Duck 

Reproduction: Study Number 83-675-06. Unpublished study prepared by Mobay 

Chemical Corp. 85 p. 

152829 Carlisle, J. (1985) Effects of Cyfluthrin (Baythroid Technical) on Bobwhite Quail 

Eggshells: Study No. 85-675-04: Mobay Report No. 90275. Unpublished study 

prepared by Mobay Chemical Corp. 52 p. 

158782 Beavers, J. (1986) Baythroid Technical: A One-generation Reproduc- tion Study 

with the Mallard (Anas platyrhynchos): Final Report: Project No.: 149-117. 

Unpublished Mobay Report No. 91888 pre- pared by Wildlife International Ltd. 

118 p. 

71-5 Simulated or Actual Field Testing 

MRID Citation Reference 

42005415 Fischer, D. (1991) Simulated Field Study of Acute Hazard to House Sparrows 

and Juvenile Northern Bobwhite Posed by Applications of Aztec 2. 1%

Granular Insecticide to Cornfields: Lab Project Num- ber: M4752302: 101313. 

Unpublished study prepared by Mobay Corp. 78 p. 

42752601 Idema, P.; Kolaszar, T.; Perritt, J.; et al. (1993) Aztec 2.1% Granular 

Insecticide: An Evaluation of its Effects Upon Avian Species in and around 

Corn Fields in Central Iowa: Lab Project Number: M4752303: 105013: 149-170. 

Unpublished study prepared by Wildlife International Ltd. 534 p. Mixture 

Phostebuprim/Cyfluthrin 

72-1 Acute Toxicity to Freshwater Fish 
 90

MRID Citation Reference 

131497 Mobay Chemical Corp. (1983) Synopsis of Environmental Toxicology of FCR 

1272 (Cyfluthrin): (Summary). (Unpublished study re- ceived Oct 12, 1983 

under 3125-EX-188; CDL:072004-A) 

131502 Carlisle, J.; Carsel, M.; Lamb, D. (1983) Acute Toxicity of Cyflu- thrin Technical 

to Rainbow Trout: Study No. 83-066-02; 85701. (Unpublished study received 

Oct 12, 1983 under 3125-EX-188; submitted by Mobay Chemical Corp., 

Kansas City, MO; CDL: 072004-F) 

131503 Carlisle, J.; Roney, D.; Lamb, D. (1983) Acute Toxicity of Cyflu- thrin Technical 

to Bluegill Sunfish: Study No. 83-066-05; 85809. (Unpublished study received 

Oct 12, 1983 under 3125-EX-188; submitted by Mobay Chemical Corp., 

Kansas City, MO; CDL: 072004-G) 

145332 

ACC 72004 

Carlisle, J. (1984) Acute Toxicity of Cyfluthrin to Rainbow Trout: Study No. 84-

066-05. Unpublished study prepared by Mobay Chem- ical Corp. 10 p. 

158554 Carlisle, J. (1984) Acute Toxicity of Fluorphenoxybenzaldehyde to Rainbow 

Trout: 86696: Study No. 84-066-07. Unpublished study prepared by Mobay 

Chemical Corp. 11 p. 

158557 Carlisle, J. (1984) Acute Toxicity of Dichlorvinylcarboxylic Acid to Rainbow 

Trout: 87452: Study No. 84-066-08. Unpublished study prepared by Mobay 

Chemical Corp. 11 p. 

41558001 Bowman, J. (1989) Acute Flow-through Toxicity of Tempo 2 EC to Blue gill 

(Lepomis macrochirus): Lab Project Number: 38341: 99787. Un published 

study prepared by Analytical Bio-Chemistry Labora- tories, Inc. 30 p. 

42005425 Bowman, J.; Leak, T. (1991) Acute Flow-through Toxicity of (Carbon 14) Aztec 

to Bluegill (Lepomis macrochirus): Lab Project Num- ber: 38624: 101217. 

Unpublished study prepared by Analytical Bio-Chemistry Labs, Inc. 39 p. 

45375001 

Beta-Cyfluthrin 

PC Code 

118831 

Bowers, L. (1994) Acute Toxicity of (carbon 14)-FCR 4545 to the Rainbow 

Trout (Oncorhynchus mykiss) Under Flow-Through Conditions: Lab Project 

Number: F5812202: 106656. Unpublished study prepared by Miles Inc. 34 p. 

45375002 

Beta-Cyfluthrin 

PC Code 

118831 

Surprenant, D. (1991) Acute Toxicity of FCR 4545 Technical to Rainbow Trout 

(Oncorhynchus mykiss) Under Flow-Through Conditions: Lab Project Number: 

103231: 274.0387.6121.108: 89-6-2998. Unpublished study prepared by 

Springborn Labs., Inc. 58 p. 

45375003 

Beta-Cyfluthrin 

PC Code 

118831 

Surprenant, D. (1991) Acute Toxicity of FCR 4545 Technical to Bluegill 

(Lepomis macrochirus) Under Flow-Through Conditions: Lab Project Number: 

103232: 274.0387.6121.105: 89-5-2985. Unpublished study prepared by 

Springborn Labs., Inc. 57 p. 

45426703 

Beta-Cyfluthrin 

PC Code 

118831 

Grau, R.; Kollbach, R.; Kohler, J. (1988) The Acute Toxicity of FCR 4545 

(Techn.) to Rainbow Trout (Salmo gairdneri) in a Flow-Through Test: Lab 

Project Number: E 2810061-8: 99197. Unpublished study prepared by Bayer 

AG. 19 p. 

41558002 Bowman, J. (1989) Acute Flow-through Toxicity of ?carbon 14|-Tempo 2 EC 

To Rainbow Trout (Oncorhynchus mykiss): Lab Project Number: 38342: 

99843. Unpublished study prepared by Analytical Bio- Chemistry Laboratories. 
 91

31 p. 

45426707 

Beta-Cyfluthrin 

Gagliano, G. (1994) Acute Toxicity of (Carbon 14)-Cyfluthrin to the Bluegill 

(Lepomis macrochirus) Under Flow-Through Conditions: Lab Project Number: 

BD810301: 106774. Unpublished study prepared by Miles Incorporated. 34 p. 

45426706 

Beta-Cyfluthrin 

Bowers, L. (1994) Acute Toxicity of (Carbon 14)-FCR 4545 to the Bluegill 

(Lepomis macrochirus) Under Flow-Through Conditions: Lab Project Number: 

F5810302: 106655. Unpublished study prepared by Miles Incorporated. 34 p. 

45426705 

Beta-Cyfluthrin 

Bowers, L. (1994) Acute Toxicity of (Carbon 14)-Cyfluthrin to the Rainbow 

Trout (Oncorhynchus mykiss) Under Flow-Through Conditions: Lab Project 

Number: BD812202: 106652. Unpublished study prepared by Miles 

Incorporated. 35 p 

45426708 

Beta-Cyfluthrin 

Gagliano, G.; Bowers, L. (1994) Acute Toxicity of (Carbon 14)-Cyfluthrin to the 

Rainbow trout (Oncorhynchus mykiss) Under Flow-Through Conditions: Lab 

Project Number: BD812201: 106778. Unpublished study prepared by Miles 

Incorporated. 33 p. 

 72-2 Acute Toxicity to Freshwater Invertebrates 

MRID Citation Reference 

131497 Mobay Chemical Corp. (1983) Synopsis of Environmental Toxicology of FCR 

1272 (Cyfluthrin): (Summary). (Unpublished study re- ceived Oct 12, 1983 

under 3125-EX-188; CDL:072004-A) 

131504 Carlisle, J.; Carsel, M.; Lamb, D. (1983) Acute Toxicity of Techni- cal Cyfluthrin 

(Baythroid) to Daphnia magna: Study No. 83-067- 05; 85944. (Unpublished 

study received Oct 12, 1983 under 3125-EX-188; submitted by Mobay 

Chemical Corp., Kansas City, MO; CDL:072004-H) 

158555 Forbis, A.; Burgess, D. (1984) Acute Toxicity of FPB ALD to Daphnia magna: 

Report 31761. Unpublished study prepared by Analytical Bio-Chemistry Labs, 

Inc. 35 p. 

158556 Forbis, A.; Burgess, D. (1984) Acute Toxicity of DCVA to Daphnia magna: 

Report 31762. Unpublished study prepared by Analytical Bio-Chemistry Labs, 

Inc. 35 p. 

41494001 Suprenant, D. (1990) Acute Toxicity of (Carbon 14)-Baythroid to Crayfish 

(Procambus clarkii) under Flow-through Conditions: Lab Project I.D. 87-7-

2434: Mobay Report No. 100108. Unpublished study prepared by Mobay 

Corp., Agricultural Chemicals Div. 58 p. 

 

41558003 Burgess, D. (1989) Acute Flow-through Toxicity of ?carbon 14|-Tempo 

(Cyfluthrin) to Daphnia magna: Lab Project Number: 37593: 99848. 

Unpublished study prepared by Analytical Bio-Chemistry Labora- tories, Inc. 

30 p. 

42005429 Blakemore, G.; Hicks, S.; Burgess, D. (1991) Acute Toxicity of ?carbon 14| 

Aztec to Daphnia magna under Flow-through Conditions :Lab Project Number: 

38625: 101218. Unpublished study prepared by Analytical Bio-Chemistry 

Labs, Inc. 34 p. 
 92

42705801 Burgess, D. (1990) Acute Flow-through Toxicity of (carbon 14)-Cyfluthrin to 

Daphnia magna: Lab Project Number: 37684: 100321. Unpublished study 

prepared by ABC Labs, Inc. 29 p. 

45426701 

Beta-Cyfluthrin 

118831 

Forbis, A. (1988) Acute Toxicity of FCR 4545-1 Technical to Daphnia Magna 

under Flow-Through Conditions: Lab Project Number: 34561: 98515. 

Unpublished study prepared by ABC Laboratories, Inc. 30 p. 

45426702 

Beta-Cyfluthrin 

Heimbach, F. (1988) Acute Toxicity of FCR 4545 (Techn.) to Water Fleas: Lab 

Project Number: 98561. Unpublished study prepared by Bayer AG. 13 p. 

45375003 

Beta-cyfluthrin 

PC Code 

118831 

Surprenant, D. (1991) Acute Toxicity of FCR 4545 Technical to Bluegill 

(Lepomis macrochirus) Under Flow-Through Conditions: Lab Project Number: 

103232: 274.0387.6121.105: 89-5-2985. Unpublished study prepared by 

Springborn Labs., Inc. 57 p. 

42605801 

Wrong MRID May be same study as 41558003 

72-3 Acute Toxicity to Estuarine/Marine Organisms 

MRID Citation Reference 

146118 Barrows, B. (1984) Shell Deposition in Eastern Oyster (Crassostrea virginica) 

Exposed to Cyfluthrin Technical in a Static Test System: Project No. 84E060CV. Unpublished study prepared by Biospherics, Inc. 10 p. 

146485 Barrows, B. (1984) The Static Acute Toxicity of Cyfluthrin Technical to the 

Sheepshead Minnow, Cyprinodon varieqatus: Project No. 84E-060SHM: 

Report No. 88914. Unpublished study prepared by Biospherics Incorporated. 

14 p. 

149598 Ward, G. (1985) Toxicity Test Report: Acute Toxicity of Cyfluthrin to the 

Saltwater Mysid, Mysidopsis bahia: ESE No. 85-317-0200- 2130: Mobay 

Report No. 90274. Unpublished study prepared by Environmental Science and 

Engineering, Inc. 19 p. 

158783 Carr, R. (1986) The Oyster Shell Deposition Test To Assess the Acute Effects 

of Baythroid on the Eastern Oyster, (Crassostrea virginica): Final Report: 

Project No. N 07780100. Unpublished Mobay Report No. 91889 prepared by 

Battelle New England Marine Research Laboratory. 95 p. 

40069501 Surprenant, D. (1987) Acute Toxicity of Baythroid to Mysid Shrimp (Mysidopsis 

bahia) under Flow-through Conditions: Bionomics Report #BW-87-1-2277: 

Bionomics Study #274.1286.6115.515. Un- published Mobay report 94220 

prepared by Springborn Bionomics, Inc. 218 p. 

44815301 Cunningham, F. (1996) MAT 7484: Acute Effect on New Shell Growth of the 

Eastern Oyster (Crassostrea virginica): Lab Project Number: J9604005D: 

107660: 107370. Unpublished study prepared by Toxikon Environmental 

Sciences. 64 p. 

44815302 Cunningham, F. (1996) MAT 7484: Acute Toxicity to Mysid Shrimp 

(Mysidopsis bahia) Under Flow-Through Conditions: Lab Project Number: 

J9604005C: 107524: 107527. Unpublished study prepared by Toxikon 

Environmental Sciences. 74 p. 

44815303 Cunningham, F. (1996) MAT 7484: Acute Toxicity to the Sheepshead Minnow 
 93

(Cyprinodon variegatus) Under Flow-Through Conditions: Lab Project Number: 

J9608008: 107666: 107527. Unpublished study prepared by Toxikon 

Environmental Sciences. 73 p. 

46591506 Putt, A. (2005) Cyfluthrin - Toxicity to Estuarine Amphipods (Leptocheirus 

plumulosus) During a 28-Day Sediment Exposure. Project Number: 

13656/6116. Unpublished study prepared by Springborn Smithers 

Laboratories. 85 p. 

45426704 

Beta-cyfluthrin 

= PC Code 

118831 

Machado, M. (1994) Acute Toxicity of FCR 4545 to Mysid Shrimp (Mysidopsis 

bahia) Under Flow-Through Conditions: Lab Project Number: 

13507.1293.6105.515: 106588. Unpublished study prepared by Springborn 

Laboratories Incorporated. 72 p. 

45426709 

Beta-cyfluthrin 

= PC Code 

118831 

Machado, M. (1994) Acute Toxicity of FCR 4545 to the Mysid Shrimp 

(Mysidopsis bahia) Under Flow-Through Conditions: Lab Project Number: 

106797: 13507.0894.6108.515. Unpublished study prepared by Springborn 

Laboratories Incorporated. 72 p. 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle 

Study 

MRID Citation Reference 

145333 Carlisle, J. (1984) Toxicity of Cyfluthrin (Baythroid) to Rainbow Trout Early Life 

Stages: Study No. 83-666-05. Unpublished study prepared by Mobay 

Chemical Corp. 13 p. 

151442 Forbis, A.; Burgess, D.; Franklin, L.; et al. (1984) Chronic Toxi- city of [Carbon 

14]-Cyfluthrin to Daphnia magna under Flow- through Test Conditions: Final 

Report #31763. Unpublished Mobay Report No. 88690 and Toxicology Report 

No. 557 prepared by Ana- lytical Bio-Chemistry Laboratories, Inc. 255 p. 

155898 Carlisle, J. (1985) Toxicity of Cyfluthrin (Baythroid) Technical to Early Life 

Stages of Rainbow Trout: Study No. 85-666-01. Unpub- lished study prepared 

by Mobay Chemical Corp. 20 p. 

158781 Ward, G. (1986) Effects of Cyfluthrin on Survival, Growth, and Development of 

Sheepshead Minnow (Cyprinodon variegatus): ESE No. 85-317-0830-2130. 

Unpublished Mobay Report No. 91887 prepared by Environmental Science 

and Engineering, Inc. 29 p. 

158784 Carr, R. (1986) Chronic Toxicity of Baythroid to the Sheepshead Minnow, 

Cyprinodon variegatus: Final Report: Project No. N 0778-0100. Unpublished 

Mobay Report No. 91890 prepared by Battelle New England Marine Research 

Lab. 115 p. 

158785 Hoberg, J.; Breteler, R. (1986) Chronic Toxicity of Baythroid to Opossum 

Shrimp (Mysidopsis bahia): Report #BW-86-3-1964; Study #274-0286-6106-

530. Unpublished Mobay Report No. 91891 prepared by Springborn 

Bionomics, Inc. 59 p. 

164499 Brussell, G. (1986) Letter sent to G. LaRocca dated Oct 29, 1986: Baythroid 2 

on cotton: [Including Page 9 of Mobay report no. 91890 and supporting raw 

data for Mobay report no. 91890, 91887 and 91891]. Prepared by Mobay 

Chemical Corp. 2307 p. 
 94

40047301 Breteler, R. (1987) Chronic Toxicity of Baythroid to Opossum Shrimp 

(Mysidopsis bahia): Report #BW-86-3-1964: Study #274-0286-6106- 530. 

Unpublished Mobay report #91891 prepared by Springborn Bionomics, Inc. 

148 p. 

41450401 Rhodes, J.; McAllister, W.; Leak, T.; et al. (1990) Full Life-cycle Toxicity of 

?Carbon 14|-Cyfluthrin (Baythroid) to the Fathead Minnow (Pimephales 

promelas) under Flow-through Conditions: Final Report #33821: Mobay Report 

No. 100097. Unpublished study prepared by Analytical Bio-Chemistry 

Laboratories, Inc. 905 p. 

40359001 Breteler, R. (1986) Chronic Toxicity of Baythroid to Opussum Shrimp 

(Mysidopsis bahia): Supplemental Submission to Mrid No. 158785: 

Addendum to Mobay Report No. 91891: Study No.: 274-0286-6106- 530. 

Unpublished study prepared by Springborn Bionomics, Inc. 12 p. 

40359002 Carlisle, J. (1985) Toxicity of Cyfluthrin (Baythroid) Technical to Early Life 

Stages of Rainbow Trout: Supplemental Submission to Mrid No. 155898:

Addendum to Mobay Report No. 90801: Study No.: 85-66601. Unpublished 

study prepared by Mobay Corp. 22 p. 

72-5 Fish Full Lifecycle Study 

41450401 Rhodes, J.; McAllister, W.; Leak, T.; et al. (1990) Full Life-cycle Toxicity of 

?Carbon 14|-Cyfluthrin (Baythroid) to the Fathead Minnow (Pimephales 

promelas) under Flow-through Conditions: Final Report #33821: Mobay Report 

No. 100097. Unpublished study prepared by Analytical Bio-Chemistry 

Laboratories, Inc. 905 p. 

72-7 Simulated or Actual Field Testing 

MRID Citation Reference 

41511301 Kennedy, J.; Johnson, P.; Montandon, R. (1990) Assessment of the Potential 

Ecological/Biological Effects of BAYTHROID (Cyfluthrin) utilizing Artificial Pond 

Systems: Lab Project Number: 100147. Unpublished study prepared by 

University of North Texas. 1600 p. 

42005434 Graney, R.; Giddings, J. (1991) Aztec: Aquatic Microcosm Test for 

Environmental Fate and Ecological Effects: Lab Project Number: M4882401: 

101293. Unpublished study prepared by ABC Labs, Inc. in coop. with Mobay 

Corp. and Springborn Labs. 321 p. Mixture 2 ais

42734801 Graney, R.; Gagliano, G. (1993) Response to EPA Review of: Assessment of 

the Potential Ecological / Biological Effects of BAYTHROID (Cyfluthrin) 

Utilizing Artificial Pond Systems: Supplemental Report: Lab Project Number: 

100147-1. Unpublished study prepared by University of North Texas. 632 p. 

123-2 Aquatic plant growth 

MRID Citation Reference 

41450402 or 

158558 

Heimbach, F. (1984) Growth Inhibition of Green Algae (Scenedesmus 

subspicatus) caused by FCR 1272 (Technical): Report No. 99836. 

Unpublished study prepared by Bayer AG, Institute for Environmental Biology. 
 95

14 p. 

43984901 Dobbs, M. (1996) Toxicity of Cyfluthrin to the Green Alga, Selenastrum 

capricornutum: Lab Project Number: 107333: BD883501. Unpublished study 

prepared by Bayer Corp. 36 p. 

158558 Heimbach, F. (1984) Growth Inhibition of Green Algae (Scenedesmus 

subspicatus) by FCR 1272 (Technical): Report HBF/A102: Study No. A1 

04/84. Unpublished study prepared by Bayer AG. 15 p. 

141-1 Honey bee acute contact 

MRID Citation Reference 

153638 Atkins, E. (1984) Letter sent to C. Engle dated Nov 21, 1984: Honey bee adult 

worker (BATDT) laboratory LD/50 toxicity study with cyfluthrin, Bathroid] (sic). 

Prepared by Univ. of California, Riverside, Dept. of Entomology. 32 p. 

47775501 Chauzat, M.; Carpentier, P.; Martel, A.; et al. (2009) Influence of Pesticide 

Residues on Honey Bee (Hymenoptera: Apidae) Colony Health in France. 

Environmental Entomology 38(3): 514-523.

47796306 Marletto, F.; Patetta, A.; Manino, A. (2003) Laboratory Assessment of 

Pesticide Toxicity to Bumblebees. Bulletin of Insectology 56(1): 155-158.

162586 Schmidt, H. (1985) [Bee Toxicity of Baythroid Sprayed on Alfalfa]: Report No. 

VAZ 16/85. Unpublished study prepared by Bayer AG. 18 p. 

141-2 Honey bee residue on foliage 

MRID Citation Reference 

158786 Bayer AG (1986) Letter sent to Mobay Chemical Corp. dated March 10, 1986: 

Honey bee residue testing/Baythroid: [Foliar residues in Alfalfa]: Mobay Report 

No. 91915. 39 p. 

47800530 Chauzat, M.; Carpentier, P.; Martel, A.; et al. (2009) Influence of Pesticide 

Residues on Honey Bee (Hymenoptera: Apidae) Colony Health in France. 

Environ. Entomol. 38(3):514-523.

47796308 Gels, J.; Held, D.; Potter, D. (2002) Hazards of Insecticides of the Bumble 

Bees Bombus impatiens (Hymenoptera: Apidae) Foraging on Flowering White 

Clover in Turf. J. Econ. Entomol. 95(4): 722-728.

850.1790 Chironomid Sediment Toxicity Test 

MRID Citation Reference 

46871501 Giddings, J. (2006) Overview of Sediment Toxicity Studies with Synthetic 

Pyrethroids. Project Number: 06723, 06273. Unpublished study prepared by 

Compliance Services International. 62 p. 

46591507 Putt, A. (2005) Cyfluthrin - Toxicity to Midge (Chironomus tentans) During a 

10-Day Sediment Exposure. Project Number: 13656/6115. Unpublished study 
 96

prepared by Springborn Smithers Laboratories. 89 p. 

Non Guideline Selections 

157786 Machemer, L.; Eben, A.; Thyssen, J. (1983) Toxicity of Pyrethroids in 

Warmblooded Animals with Special Reference to Cyfluthrin. Unpublished paper 

presented at the International Conference on Environmental Hazards of 

Agrochemicals in Developing Countries; Vol. 1; Nov 8-12, 1983, Alexandria, 

Egypt. 20 p. 

42005416 

Aztec = 

129086 + 

128831 

mixture 

Fischer, D. ; Toll, P. (1991) Measurement of Whole Blood and Brain 

Cholinesterase Activity in House Sparrows Given a Sub-lethal Dose of Aztec 

2.1% Granular Insecticide: Lab Project Number: M4761401: 101312. 

Unpublished study prepared by Mobay Corp. 21 p. 

42005418 Fischer, D.; Best, L. (1991) Oral Exposure of Birds to Silica Gran- ules Applied 

at-Planting to Cornfields: Lab Project Number: GE761402: 101315. Unpublished 

study prepared by Mobay Corp. 32 p. 

42005419 Best, L.; Gionfriddo, J. (1990) Literature Review of Grit Use by Birds: Lab Project 

Number: 99846. Unpublished study prepared by Iowa State Univ., Dept. of 

Animal Ecology and Agrobirds. 69 p. 

42005420 Best, L.; Gionfriddo, J. (1990) Characterization of Natural Grit Use in House 

Sparrows: Lab Project Number: 99847. Unpublished study prepared by Iowa 

State Univ., Dept. of Animal Ecology and Agrobirds. 29 p. 

42005421 Best, L.; Gionfriddo, J. (1990) Characterization of Grit Use by 22 Species of 

Birds Using Cornfields During the Breeding Season: Lab Project Number: 

100129. Unpublished study prepared by Iowa State University, Dept. of Animal 

Ecology and Mobay Corp. 31 p. 

42005422 Best, L.; Gionfriddo. J. (1991) Integrity of Five Granular Insecti- cide Carriers in 

the Gizzards and Intestines of House Sparrows: Lab Project Number: 1000130. 

Unpublished study prepared by Iowa State Univ., Dept. of Ecology and 

Agrobirds. 29 p. 

42385001 Morris, R. (1991) Pyrethroid Insecticide Effects on Bluegill Sunfish (Lepomis 

Macrochirus) and the Impacts of Bluegill Predation on Invertebrates in 

Microcosms: Lab Project Number: 101953. Unpublished study prepared by 

Mobay Corp. 111 p. 

42725601 Johnson, P. (1992) Impacts of the Pyrethroid Insecticide Cyfluthrin on Aquatic 

Invertebrate Populations in Outdoor Experimental Tanks: Lab Project Number: 

105036. Unpublished study prepared by University of North Texas. 5 p. 

45245501 Soderlund, D.; Clark, J.; Mullin, L. et al. (2000) Pyrethroid Insecticides: Is there a 

Common Mechanism of Mammalian Toxicity?: Lab Project Number: PWG FQPA 

2000-01. Unpublished study prepared by Pyrethroid Working Group. 144 p. 

47506603 Hall, L.; Killen, W.; Anderson, R.; et. al. (2008) An Assessment of Benthic 

Communities with Concurrent Physical Habitat, Pyrethroid, and Metals Analysis 

in an Urban and Residential Stream in California in 2006 and 2007-Pyrethroid: 

Assessment. Project Number: T001523/08. Unpublished study prepared by Wye 

Research and Education Center and Northern Illinois University. 229 p. 
 97

Appendix A. PRD data request justification tables 

The following proposed Data Call-in tables include rationales for requiring the data 

requested in this problem formulation, explanations of the utility of the data, and 

explanations for how the data might impact risk assessment, following the format 

provided by PRD. 

Guideline Number: 835.4100 

Study Title: Aerobic Soil Metabolism 

Guideline Number: 835.4200 

Study Title: Anaerobic Soil Metabolism

Rationale for Requiring the Data 

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300 

(Environmental fate data requirements table), these data are required for all terrestrial use 

patterns. 

The Agency has aerobic soil metabolism studies performed in two soils, with flurophenyl 

labeled cyfluthrin; no data are available with cyclopropyl-labeled cyfluthrin. A study 

performed in two soils should be submitted for cyfluthrin (at least one of which should be 

conducted with cyclopropyl-labeled cyfluthrin, for the identification of possible 

cyclopropyl labeled metabolites, such as DCVA). In addition, a study should be 

performed in four soils for beta-cyfluthrin. The data requirement is being required for 

beta-cyfluthrin too as per current draft guidance provided in the EFED Interim Policy for 

Stereoisomeric Pesticides, that indicates that “...an aerobic soil metabolism study (GLN 

162-1/835.3300) is required as part of the minimal data set for enantiomeric enriched 

mixtures.” (Current guideline 835.4100) Furthermore, there is evidence in the literature 

that the degradation of cyfluthrin and beta-cyfluthrin may be enantioselective (Qin et al.

2006, Li et al. 2008). Aerobic soil metabolism studies with one soil type are generally 

sufficient for the evaluation of transformation pathways. Rates of transformation should 

be determined in at least three additional soils (from Fate, Transport and Transformation 

Test Guidelines – OCSPP Guideline 835.4100 & 835.4200). 

The available supplemental anaerobic soil metabolism study, conducted on cyfluthrin, 

was performed with only one soil, for a period of only one month of anaerobic 

incubation, and sampling was insufficient to determine a suitable half-life. A new study 

is required. Anaerobic studies with one soil type are generally sufficient for the 

evaluation of transformation pathways, but for cyfluthrin, cyclopropyl and phenyl-labeled 

studies are needed. Rates of transformation should be determined in at least three 

additional soils (from Fate, Transport and Transformation Test Guidelines – OCSPP 

Guideline 835.4100 & 835.4200). 

Practical Utility of the Data 

How will the data be used? 

Cyfluthrin and beta-cyfluthrin are synthetic pyrethroids with high toxicity towards 

aquatic organisms, including those living in the benthos. Knowledge of their persistence 

in terrestrial and aquatic environments is important. The results of this study will be used 
 98

in the environmental fate assessment, and later on, in the ecological risk characterization. 

In addition, the data will be used to derive the rate of reaction input parameter to be used 

in the aquatic models GENEEC2, PRZM/ EXAMS, FIRST and SCI-GROW. The results 

from these models are used to determine exposure concentrations, for ecological risk 

estimation, and to determine surface drinking water concentrations, for drinking water 

exposure assessments. 

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

Without these data, the Agency would have to make certain conservative assumptions 

(e.g. calculate the upperbound value derived from only two soils, for the aerobic soil 

metabolism input value). These conservative assumptions could lead to higher predicted 

concentrations (EECs or EDWCs), according to the models, and consequently, higher 

risk quotients or drinking water exposures. Also, there would be a higher degree of 

uncertainty in the environmental fate assessment. Knowledge of these dissipation 

pathways in detail is essential to perform a better and accurate environmental fate 

assessment and risk assessment. 

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 

cyfluthrin and beta-cyfluthrin that may be unnecessary. 
 99

Guideline Number: 835.4300 

Study Title: Aerobic Aquatic Metabolism 

Guideline Number: 835.4400 

Study Title: Anaerobic Aquatic Metabolism

Rationale for Requiring the Data 

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300 

(Environmental fate data requirements table), these data are required for all terrestrial use 

patterns. 

Two aerobic aquatic metabolism studies (soil/ sediment systems) are available that were 

conducted with cyclopropyl-labeled beta-cyfluthrin. The studies available that were 

conducted with fluorophenyl-labeled beta-cyfluthrin were considered of low quality 

because major deficiencies were detected. A study should be conducted utilizing 

fluorophenyl-labeled beta-cyfluthrin on one sediment system of marine origin. 

According to the OCSPP Fate, Transport and Transformation Test Guidelines (835.4300 

& 835.4400)...“At least two sediments and their associated waters are used for both the 

aerobic and the anaerobic studies respectively...However, there may be cases where 

more than two aquatic sediments should be used, for example, for a chemical that may be 

present in freshwater and/or marine environments. Sediments should be representative of 

intended use sites.” Since both cyfluthrin and beta-cyfluthrin have the potential for use 

near estuarine/ marine areas, the required sediment system should be from estuarine/ 

marine environment. 

There is no anaerobic aquatic metabolism study available for review. It should be 

conducted on beta-cyfluthrin. Three sediment systems are required, one of which should 

be of marine origin (see above). 

Practical Utility of the Data 

How will the data be used? 

Cyfluthrin and beta-cyfluthrin are synthetic pyrethroids with high toxicity towards 

aquatic organisms, including those living in the benthos. Knowledge of their persistence 

in soil and aquatic environments is important. The results of this study will be used in the 

environmental fate assessment, and later on, in the ecological risk characterization. 

In addition, the data will be used to derive the rate of reaction input parameter to be used 

in the aquatic models GENEEC2, PRZM/ EXAMS and FIRST. The results from these 

models are used for ecological risk estimation and in drinking water exposure 

assessments. 

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

Without these data, the Agency would have to make certain conservative assumptions 

(e.g. use the upperboud value derived from only two supplemental values for the aerobic 

aquatic metabolism or two times the aerobic aquatic metabolism half-life input for the 

anaerobic aquatic metabolism). These conservative assumptions could lead to higher 

predicted concentrations (EECs), according to the models, and consequently, higher risk 
 100

quotients. Also, there would be a higher degree of uncertainty in the environmental fate 

assessment. At this time, the anaerobic aquatic metabolism of cyfluthrin and betacyfluthrin is uncertain. Knowledge of these dissipation pathways in detail is essential to 

perform a better and accurate environmental fate assessment and risk assessment. 

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 

cyfluthrin and beta-cyfluthrin that may be unnecessary. 
 101

Guideline Number: 835.1230 

Study Title: Mobility – Adsorption/ Desorption 

Rationale for Requiring the Data 

According to 40 CFR Part 158, Subpart N (Environmental Fate) §158.1300 

(Environmental fate data requirements table), this data is required for all terrestrial use 

patterns. 

The available study was performed at a single concentration and no Freundlich 

correlations or isotherms are available. According to OCSPP Fate, Transport and 

Transformation Test Guideline (835.1230), the purpose of the main part of the study in 

Batch Equilibrium studies is the “Determination of Freundlich adsorption isotherms to 

determine the influence of concentration on the extent of adsorption on soils.” The 

available study indicated that cyfluthrin is relatively immobile in the various soils tested 

(KOC ≥ 73,500). The mobility of this chemical may be greatly under or overestimated 

and is uncertain. A new study is required. 

Practical Utility of the Data 

How will the data be used? 

Cyfluthrin and beta-cyfluthrin are synthetic pyrethroids with high toxicity towards 

aquatic organisms, including those living in the benthos. Knowledge of their mobility in 

soil environments and its organic carbon normalized Freundlich adsorption coefficient is 

important. The results of this study will be used in the environmental fate assessment, 

and later on, in the ecological risk characterization. 

In addition, the data will be used to derive the mobility input parameter to be used in the 

aquatic models GENEEC2, PRZM/ EXAMS, FIRST and SCI-GROW. The results from 

these models are used for ecological risk estimation and in drinking water exposure 

assessments. 

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

Without these data, the Agency would have to make certain uncertain assumptions (e.g.

use the adsorption constants derived at the highest concentration for the mobility input 

parameter in the aquatic models). These uncertain assumptions could lead to higher or 

lower predicted concentrations (EECs), according to the models, and consequently, 

higher or lower risk quotients. The KOC input parameter has a major effect in the 

determination of the EECs for benthic organisms. Also, there would be a higher degree 

of uncertainty in the environmental fate assessment. Knowledge of the mobility of this 

chemical in detail is essential to perform a better and accurate environmental fate and risk 

assessment. 

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 

these chemicals that may be unnecessary. 
 102

Guideline Number: Non-guideline 

Study Title: Wood Leachability 

Rationale for Requiring the Data 

A study is required. It should be conducted according to the American Wood Preservers 

Association Standard Method of Determining the Leachability of Wood Preservatives 

(E11-06). It is strongly suggested that the registrant provide a protocol to be evaluated by 

the Agency prior to performing the study. 

Practical Utility of the Data 

How will the data be used? 

Cyfluthrin and beta-cyfluthrin are synthetic pyrethroids with high toxicity towards 

aquatic organisms, including those living in the benthos. They are used for wood 

protection treatment to buildings/products indoor and outdoor and wood protection 

treatment to forest products (unseasoned). The results of this study will be used in the 

ecological risk characterization, and in particular, for aquatic assessments. At the present 

time, the EFED believes that cyfluthrin and beta-cyfluthrin bind strongly to the wood 

material, but there are uncertainties as to the degree to which this occurs. Knowledge of 

the leachability from treated wood for these chemicals is important. 

In addition, the data will be used to derive the application rate to be used in the aquatic 

models GENEEC2 and PRZM/ EXAMS. The results from these models are used for 

exposure assessment and ecological risk estimation. 

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

Without these data, the Agency would have to make certain uncertain assumptions (e.g.

assume that 100% of the cyfluthrin and/ or the beta-cyfluthrin leaches instantaneously 

from the wood, to estimate the application rate in GENEEC and PRZM/ EXAMS). 

These uncertain assumptions could lead to higher predicted concentrations (EECs), 

according to the models, and consequently, higher risk quotients. The application rate 

input parameter has a major effect in the determination of the aquatic EECs. Also, there 

would be a higher degree of uncertainty in the overall transport assessment for ecological 

effects. Knowledge of the leachability from treated wood of this chemical in detail is 

essential to perform a better and accurate environmental fate/ transport and risk 

assessment. 

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 

this chemical that may be unnecessary. 
 103

 

Guideline Number: None 

Study Title: Environmental Chemistry Methods (ECM) and Independent 

Laboratory Validation (ILV) for Soil, Water and Sediment

Rationale for Requiring the Data 

According to the data requirements in 40 CFR Part 158, ECMs are currently required 

along with successful confirmatory method trials (validation) by an independent 

laboratory (i.e. ILVs). The registrant submitted two methods and one independent 

laboratory validation (MRID 41511301, 47053001 and 47053002), that could quantify 

cyfluthrin in water and sediment. The Agency will verify the suitability of these methods 

and the appropriateness of their levels of quantization. At this time, no methods have 

been identified for the analysis of beta-cyfluthrin. In addition to the method for soil, at 

this time, methods are required for water and sediment. The results of previous 

assessments indicate that there is risk for freshwater and estuarine/ marine fish, 

invertebrates and benthic organisms. Therefore, ECMs for water and sediment are 

required in addition to the ECM for soil. The ECMs should include parent and those 

residues found in the laboratory studies that exceed 10% of the applied. Acceptable 

ECMs for the residues of concern (parent and its transformation products, DCVA, FPBacid and FPB-ald) should have levels of quantization that are adequate to address risk 

concerns or that are at levels below the toxicological endpoints for the relevant aquatic 

organisms. The registrant is encouraged to submit state-of-the-art environmental 

chemistry methods; further, multi-residue methods (MRMs) for soil, water and sediment 

are preferred. 

Practical Utility of the Data 

How will the data be used? 

The data will be used to verify the suitability of the methods. Subsequently the methods 

could be used by states or other enforcement agencies, departments or entities, to monitor 

concentrations of the residues of concern. Validated analytical methods in environmental 

media (a.k.a., ECMs) are useful for conducting and evaluating submitted environmental 

fate and toxicity field and monitoring studies and for addressing potential risks to the 

environment posed by the use and/or accidental release of pesticides. 

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

If monitoring of the chemical is required or performed, the Agency could be able to 

determine if the chemical is present in the environment at concentrations that are 

threatening to wildlife (or to humans, in the case of drinking waters), according to the 

levels of concern (LOCs). If that is the case, measures to prevent these concentrations to 

occur could be taken. The data could also be used by enforcement entities like the states 

or government agencies or departments. Without these data, the potential for the 

determination of residues of cyfluthrin, beta-cyfluthrin and transformation products 

(DCVA, FPB-acid and FPB-ald) in soil, water and sediment is restricted. 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 

cyfluthrin and beta-cyfluthrin which may otherwise be avoided, or which are 

unnecessarily severe. 
 104

Guideline Number: None 

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, to assess the percentage removed in the biosolids by 

the treatment, the amount that would degrade during treatment, and the amount that 

would remain in the waste water. 

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 cyfluthrin and beta-cyfluthrin (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 

cyfluthrin and beta-cyfluthrin which may otherwise be avoided, or which are 

unnecessarily severe. 
 105

Guideline Number: 850.2100 

Study Title: Passerine Acute Avian Oral 

Rationale for Requiring the Data 

An acute avian oral study was received for bobwhite quail. The Agency updated its data 

requirements in 40 CFR Part 158 (October 26, 2007) to include an acute oral toxicity 

study for both a passerine species and either a waterfowl or an upland game species. 

Prior to starting toxicity testing, a protocol will need to be provided for review. Many 

passerine species utilize agricultural fields, forests, residential areas and surrounding 

areas, and, therefore, have the potential to be exposed to pesticides used in agricultural, 

forest, and residential settings. It is likely that, for most pesticide use patterns, passerines 

are more likely to be exposed to pesticides than upland game species and waterfowl. 

Passerines are smaller in size and generally have faster metabolisms than the waterfowl 

and upland game bird species traditionally used in avian toxicity tests which could impact 

their sensitivity to chemicals. 

Practical Utility of the Data 

How will the data be used? 

Data from passerine toxicity studies will be used to estimate potential risks to birds 

associated with uses of cyfluthrin. The data will reduce uncertainties associated with the 

current risk assessment for passerine species and will improve our understanding of the 

potential effects of cyfluthrin. 

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

Because birds significantly contribute to overall environmental quality, a solid 

understanding of the potential risks to birds, including passerine species, is essential for 

sound environmental management. Without acceptable data for cyfluthrin, the Agency 

cannot determine the level of exposure that result in effects to passerine species. If the 

data indicates that registered usage may pose a risk of adverse effects to non-target birds 

above the Agency Level of Concern, the Agency may explore decision options to 

mitigate this risk. 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 cyfluthrin which may otherwise be avoided, or which are 

unnecessarily severe. 
 106

Guideline Number: 850.2300 Chronic Toxicity for Avian Species

Study Title: Avian Reproduction Study (Waterfowl with cyfluthrin TGAI) 

Rationale for Requiring the Data 

No acceptable data on reproductive toxicity to the most sensitive bird species has been 

submitted (mallard duck). A chronic risk assessment for birds is needed based on 

cyfluthrin’s use patterns and potential impact on birds. The avian reproduction toxicity 

study is justified for cyfluthrin because 1) the avian reproduction studies for both 

waterfowl and upland game bird species are standard data requirements for all outdoor 

terrestrial use patterns, 2) evidence of chronic toxicity to mammals indicates possible 

chronic toxicity in birds, and 3) cyfluthrin use pattern indicates that chronic exposure is 

likely. 

Practical Utility of the Data 

How will the data be used? 

The avian reproduction studies are needed for future regulatory decisions and for an 

endangered species assessment in particular. The data would allow the Agency to 

quantify the potential for chronic risk, as measured by effects on reproduction and 

hatchling survival, from the use of cyfluthrin. Results of this study would be used to 

calculate risks to avian reproduction from dietary exposure to cyfluthrin at labeled use 

rates and to identify what, if any, label language is needed to mitigate identified risks. 

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

If future endangered species risk assessments are performed without these data, the 

Agency would have to assume that cyfluthrin "may affect" birds directly (and endangered 

species from other taxa indirectly), and use of cyfluthrin might need to be restricted in 

areas where endangered species could be exposed. 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 cyfluthrin which are 

unnecessarily severe. 
 107

Guideline Number: 850.1075

Study Title: Fish Acute Toxicity (saltwater, cyfluthrin TEP only) 

Guideline Number: 850.1025 

Study Title: Oyster Acute Toxicity (saltwater, cyfluthrin TEP only) 

Guideline Number: 850.1035

Study Title: Mysid Acute Toxicity (saltwater, cyfluthrin TEP only) 

Rationale for Requiring the Data 

Cyfluthrin and beta-cyfluthrin have the potential to enter estuarine/marine water bodies based on 

current usage patterns that include coastal areas (see Fig. 3.1). Cyfluthrin technical is very highly 

toxic to estuarine/marine fish and invertebrates on an acute basis, but no information is available 

for cyfluthrin TEP effects on estuarine/marine species. 

According to the Part 158 data requirements, testing on the typical end-use product may be 

required for aquatic toxicity tests when any of the following conditions exist: 

 1. The end-use product will be introduced directly into the aquatic environment. 

2. The maximum expected environmental concentration or estimated environmental 

concentration in the aquatic environment is greater than or equal to one-half the LC50 or 

EC50 of the TGAI. 

3. An ingredient in the end-use formulation other than the active ingredient is expected to 

enhance the toxicity of the active ingredient or cause toxicity to aquatic organisms. 

Previous assessments on cyfluthrin indicate that the expected environmental concentrations in 

aquatic environments are well above acute 50% mortality levels for all species tested. For 

example, the maximum peak aquatic EEC was 2.67 μg ai/L based on the PRZM/EXAMS MS 

cotton scenario in the cyfluthrin new use 2004 assessment for a variety of crops, including tree 

nuts, grapes and leafy vegetables (DP 274813, 290926, 290922, 291313, 291923, 294835 and 

294488). In estuarine/marine tests conducted with cyfluthrin technical, the lowest 96-hour LC50

was 4.05 μg/L for sheepshead minnow, 0.0022 μg/L for mysid shrimp and 2.69 μg/L for the 

eastern oyster. Therefore, cyfluthrin fulfills the second requirement (above) for TEP studies with 

all tested estuarine/marine species. 

Practical Utility of the Data 

How will the data be used? 

These data are needed for a registration review decision and for an endangered species 

assessment, which will be conducted as part of that decision. The data would allow the Agency 

to determine acute and chronic risk to estuarine/marine organisms from exposure to cyfluthrin. 

The effects data would be used to determine the likelihood that exposure to cyfluthrin can 

potentially impact aquatic communities, either by direct effects or by indirect effects on other 

organisms by reducing their food sources. 

How could the data impact the Agency’s future decision-making? 
 108

If future endangered species risk assessments are performed without these data, the Agency 

would have to assume that cyfluthrin “may affect" endangered invertebrates directly (and 

endangered species from other taxa indirectly), and use of cyfluthrin might need to be restricted 

in areas where endangered species could be exposed. 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 cyfluthrin which are unnecessarily severe. 
 109

Guideline Number: 850.1010 and 850.1300 

Study Title: Aquatic Invertebrate Acute and Life Cycle studies (Beta-cyfluthrin only)

Rationale for Requiring the Data 

Required for beta-cyfluthrin as per the EFED Interim Policy for Stereoisomeric Pesticides. 

According to the interim policy, certain studies are required for stereoisomeric pesticides to 

identify the possibility that the chemical may be more, equally or less toxic than the previously 

assessed chemical (in this case, cyfluthrin). 

Practical Utility of the Data 

How will the data be used? 

The aquatic invertebrate chronic toxicity study would allow the Agency to analyze chronic toxic 

effects to one of the most sensitive species of freshwater and marine aquatic invertebrates. The 

effects data would be used to determine the likelihood that chronic 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 beta-cyfluthrin. 

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 water flea and mysid to beta-cyfluthrin, as compared to 

cyfluthrin, using other means which may include using an extrapolation factor based on 

sensitivity differences with cyfluthrin. 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 beta-cyfluthrin which are unnecessarily severe. 
 110

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 cyfluthrin 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 cyfluthrin. 

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 cyfluthrin 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 cyfluthrin which are 

unnecessarily severe. 
 111

Guideline Numbers: 850.1735 & 850.1740 

Study Title: Whole sediment: Freshwater and marine invertebrates 

Rationale for Requiring the Data 

No chronic sediment toxicity tests for freshwater or marine invertebrates have been 

submitted to satisfy the Agency’s updated data requirements for outdoor uses in 40 CFR 

Part 158 (October 26, 2007). For cyfluthrin, available information indicates that benthic 

organisms may be exposed via run-off or spray drift applications used in agricultural, 

forest, and residential settings. Specifically, 

o Based on preliminary calcutions, the peak sediment porewater EECs predicted for 

cyfluthrin (0.048 μg ai/L) exceeds 0.1 of the most sensitive acute LC/EC50

(0.0022 μg ai/L for mysid shrimp), which satisfies one of the criteria for requiring 

chronic whole sediment toxicity testing under 40 CFR Part 158. 

o The expected half-life of cyfluthrin in sediment (73.5-94.8 for aerobic soil 

metabolism and 32.9-42 days for aerobic aquatic metabolism) is substantially 

greater than 40 CFR Part 158 criterion of 10 days. 

o The third set of trigger criteria for requiring chronic testing (Kd > 50, or log Kow 

>3 or Koc > 1000) is also met for cyfluthrin (e.g., Kd values are 974-1793, log 

Kow is 6, and KOC values are 69900-180300). 

o Chronic effects were also seen in all aquatic taxa tested at levels ranging from 

0.00040 – 0.63 μg a.i./L. 

o There is a potential for persistent exposure from cyfluthrin in sediment is also 

indicated by open literature studies on pyrethroids (Weston et al. 2005, Amweg et 

al. 2006 and Ding et al. 2009). 

For sediment studies involving pyrethroids, chronic tests on Hyalella azteca, Chironomus 

tentans, and Leptocheirus plumulosus are requested. Although both are freshwater 

species, Hyalella and Chironomus differ substantially in their ecological niche (i.e., 

epibenthic vs. infaunal species), physiology, and potential sensitivities to pyrethroid 

exposure (e.g., Anderson et al. 2006; Maund et al., 2002). Cyfluthrin has the potential to 

enter estuarine/marine water bodies based on current usuage patterns that include coastal 

areas. Therefore, testing is required for Leptocheirus plumulosus, an estuarine/marine 

sediment-dwelling invertebrate species.

Practical Utility of the Data 

How will the data be used? 

Data from sediment toxicity studies will be used to estimate potential risks to benthic 

organisms associated with uses of cyfluthrin. The data will reduce uncertainties 

associated with the current risk assessment for benthic species and will improve our 

understanding of the potential effects of cyfluthrin. 

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

Although there was uncertainty in estimating the effect of cyfluthrin on benthic 

organisms in previous assessments, there was a potential risk associated with adverse 

effects identified for other aquatic organisms. Acceptable data for benthic organisms will 

reduce the uncertainty from the previous assessment If the data indicates that registered 
 112

cyfluthrin usage may pose a risk of adverse effects to non-target benthic organisms above 

the Agency Level of Concern, the Agency may explore decision options to mitigate this 

risk. 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 cyfluthrin which may otherwise be avoided, or which are unnecessarily 

severe. 
 113

Guideline Numbers: 850.4100 and 850.4150 

Study Title: Vegetative vigor and Seedling emergence, Tier I/ Tier II (Cyfluthrin and 

Beta-cyfluthrin) 

Rationale for Requiring the Data 

No acceptable toxicity data are currently available to assess the risk of cyfluthrin to nontarget terrestrial plants. Since cyfluthrin has residential outdoor uses, vegetative vigor and 

seedling emergence studies are required. Additionally, three incidents have been reported 

to the Agency where cyfluthrin was identified as the possible – highly probable cause of 

phytotoxic damage. Phytotoxicity data are needed to evaluate the level of pesticide 

exposure to non-target terrestrial and aquatic plants and to assess the impact of pesticides 

on endangered and threatened plants. In addition to the studies required for cyfluthrin, 

tests conducted on beta-cyfluthrin are required for the most sensitive monocotyledon and 

dicotyledon as per requirements of the EFED Interim Policy for Stereoisomeric Pesticides. 

 

Practical Utility of the Data 

How will the data be used? 

Data from terrestrial plant toxicity studies will be used to estimate potential risks to plants 

associated with uses of cyfluthrin and beta-cyfluthrin. The data will reduce uncertainties 

associated with the current risk assessment for terrestrial plants and will improve our 

understanding of the potential effects of cyfluthrin on plants. 

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

Because plants form the basis of most habitats and significantly contribute to overall 

environmental quality, a solid understanding of the potential risks to terrestrial plants is 

essential for sound environmental management. Without acceptable plant growth data for 

cyfluthrin and beta-cyfluthrin, the Agency cannot determine the levels of cyfluthrin that 

result in effects to terrestrial plants. If the data indicates that registered usage may pose a 

risk of adverse effects to non-target terrestrial plants plants above the Agency Level of 

Concern, the Agency may explore decision options to mitigate this risk. 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 cyfluthrin which 

may otherwise be avoided, or which are unnecessarily severe. 
 114

Guideline Number: 850.4400 

Study Title: Aquatic Vascular Plant Growth-Lemna spp. Tiers I/II (Cyfluthrin and 

Beta-cyfluthrin) 

Rationale for Requiring the Data 

No studies for cyfluthrin have been submitted for vascular aquatic plants. The Agency 

has finalized its update to the data requirements in 40 CFR Part 158, which were 

promulgated on October 26, 2007. In these updated data requirements, vascular plant 

testing is required for pesticides with outdoor uses, such as cyfluthrin. In addition to the 

study on cyfluthrin, a study is required for beta-cyfluthrin, as per the EFED Interim 

Policy for Stereisomeric Pesticides. 

Practical Utility of the Data 

How will the data be used? 

Data from aquatic plant toxicity studies will be used to estimate potential risks to plants 

associated with uses of cyfluthrin and beta-cyfluthrin. The data will reduce 

uncertainties associated with the current risk assessment for aquatic plants and will 

improve our understanding of the potential effects on vascular aquatic plants. 

How could the data change the Agency’s decision, or impact the Agency’s future 

decision-making? 

Because plants form the basis of most habitats and significantly contribute to overall 

environmental quality, a solid understanding of the potential risks to aquatic plants is 

essential for sound environmental management. Without plant growth data for 

cyfluthrin, the Agency cannot determine the levels of cyfluthrin that result in effects to 

vascular aquatic plants. If the data indicates that registered usage may pose a risk of 

adverse effects to non-target aquatic vascular plants above the Agency Level of 

Concern, the Agency may explore decision options to mitigate this risk. 

If future endangered species risk assessments are performed without these data, the 

Agency would have to assume that cyfluthrin and beta-cyfluthrin "may affect" 

endangered plants and use might need to be restricted in areas where endangered species 

could be exposed. 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 cyfluthrin that may be unnecessarily severe.
 115

Appendix B. Summary of registrant-submitted aquatic toxicity studies 

for cyfluthrin and beta-cyfluthrin

Species 

(common name) 

Test 

Substance % a.i. Endpoint 

Duration 

(hours) 

 Mean 

concentration 

(μg a.i./L) 

MRID and 

study 

classification 

Oncorhynchus 

mykiss 

(Rainbow trout) 

 87% LC50 96 0.68 00131502 

Acceptable 

Lepomis 

Macrochirus 

(Bluegill sunfish) 

 87% LC50 96 1.50 00131503 

Acceptable 

Lepomis 

Macrochirus 

(Bluegill sunfish) 

Cyfluthrin 

(TEMPO 

2EC) 

2% LC50 96 0.647 41558001 

Supplemental 

Oncorhynchus 

mykiss 

(Rainbow trout) 

Cyfluthrin 

(TEMPO 

2EC) 

2% LC50 96 0.295 41558002 

Acceptable 

Oncorhynchus 

mykiss 

(Rainbow trout) 

Betacyfluthrin, 

FCR-4545 

98% LC50 96 0.111 45375001 

Supplemental 

Oncorhynchus 

mykiss 

(Rainbow trout) 

Betacyfluthrin, 

FCR-4545 

99.4% LC50 96 0.068 45375002 

Supplemental 

Lepomis 

Macrochirus 

(Bluegill sunfish) 

Betacyfluthrin, 

FCR-4545 

99.4% LC50 96 0.28 45375003 

Supplemental 

Oncorhynchus 

mykiss 

(Rainbow trout) 

Betacyfluthrin, 

FCR-4545 

98.1% LC50 96 0.085 45426703 

Supplemental 

Oncorhynchus 

mykiss 

(Rainbow trout) 

Cyfluthrin 97.6% LC50 96 0.302 45426705 

Acceptable 

Lepomis 

Macrochirus 

(Bluegill sunfish)

Betacyfluthrin, 

FCR-4545 

98% LC50 96 0.566 45426706 

Supplemental 

Lepomis 

Macrochirus 

(Bluegill sunfish)

Cyfluthrin 97.6% LC50 96 0.998 45426707 

Acceptable 

Oncorhynchus 

mykiss 

(Rainbow trout) 

Cyfluthrin 97.6% LC50 96 0.209 45426708 

Supplemental 
 116

Species 

(common name) 

Test 

Substance % a.i. Endpoint 

Duration 

(hours) 

 Mean 

concentration 

(μg a.i./L) 

MRID and 

study 

classification 

Oncorhynchus 

mykiss 

(Rainbow trout)

 96% 

NOAEC 

LOAEC 

58 (days) 

0.010 

0.018 

00155898 

Supplemental 

Pimephales 

promelas 

(Fathead 

Minnow)

Cyfluthrin 99% 

NOAEC 

LOAEC 

60 (days) 

0.14 

0.25 

41450401 

Acceptable 

Daphnia magna 

(Water Flea)

 Tech LC50 48 0.141 

00131504 

Acceptable 

Daphnia magna 

(Water Flea)

Betacyfluthrin, 

FCR-4545 

Tech EC50 48 0.29 

45426701 

Supplemental 

Daphnia magna 

(Water Flea)

Cyfluthrin 98.6% LC50 48 0.16 

42705801 

Unreviewed 

Daphnia magna 

(Water Flea)

Cyfluthrin 

(TEMPO 

2EC) 

2% EC50 48 0.025 

41558003 

Acceptable 

Daphnia magna 

(Water Flea)

 94.7% 

NOAEC 

LOAEC 

 21 (days) 

0.0074 

0.0157 

00151442 

Acceptable 

Chironomus 

tentans 

(Midge)

Cyfluthrin 99% LC50 10 (days) 

0.44 (pore 

water) 

290 μg a.i./kg 

sediment 

(bulk sediment) 

46591507 

In review 

Cyprinodon 

variegatus

(Sheepshead 

minnow) 

 87% LC50 96 4.05 

00146485 

Acceptable 
 117

Species 

(common name) 

Test 

Substance % a.i. Endpoint 

Duration 

(hours) 

 Mean 

concentration 

(μg a.i./L) 

MRID and 

study 

classification 

Cyprinodon 

variegatus

(Sheepshead 

minnow)

 90.5% 

NOAEC 

LOAEC 

39 (days) 

0.025 

0.084 

00158781 

Supplemental 

Cyprinodon 

variegatus

(Sheepshead 

minnow)

 90.5% 

NOAEC 

LOAEC 

28 (days) 

0.27 

0.63 

00158784 

Not reviewed 

Mysidopsis bahia 

(Mysid shrimp)

 90.5% LC50 96 0.0064 

00149598 

Acceptable 

Mysidopsis bahia 

(Mysid shrimp)

 92% LC50 96 0.0024 

40069501 

Acceptable 

Mysidopsis bahia 

(Mysid shrimp)

Betacyfluthrin, 

FCR-4545 

>98% LC50 96 0.0023 

45426704 

Acceptable 

Mysidopsis bahia 

(Mysid shrimp)

Betacyfluthrin, 

FCR-4545 

>98% LC50 96 0.0022 

45426709 

Acceptable 

Crassostrea 

virginica 

(Eastern oyster) 

 93% EC50 96 2.69 

00158783 

Acceptable 

Leptocheirus 

plumulosus 

(Amphipod) 

 99% 

LC50

(survival) 

EC50

(growth) 

28 (days) 

35 

36 

46591506 

In review 

Mysidopsis bahia 

(Mysid shrimp)

 97% 

NOAEC 

LOAEC 

28 (days) 

0.00017 

0.00040 

00158785 

Supplemental 
 118

Appendix C. Open Literature Information 

The following is a cursory search of the available literature on cyfluthrin, beta-cyfluthrin 

and synthetic pyrethroids in general, mostly about their prevalence/ occurrence, and 

about their toxicity to aquatic invertebrates and sediment dwelling organisms (which also 

pertains to Section 4.1). It is not intended to be exhaustive. In the relatively recent past 

there has been an increased awareness of the prevalence and toxicity of cyfluthrin, and 

other synthetic pyrethroids, in sediment environments of urban and agricultural sites, 

particularly in California. 

In a 3-year field test studying honey bee (Apis mellifera) colony health, Chauzat et al. 

(2009) found no residues of cyfluthrin at levels of 0.7 μg/bee (MRID 47775501) (Note 

that the acute contact LD50 for honeybees is 0.037 μg/bee according to registrantsubmitted studies). Although no statistical significant relationships were found between 

colony mortality and the presence of pesticides overall, the authors state that “more work 

is needed to determine the role these residues play in affecting colony health”. In another 

study, Dai et al. (2010) examined the sublethal effects of two pyrethroids, deltamethrin 

and bifenthrin, on bee colony health. The authors concluded that both chemicals 

adversely impacted bees by reducing bee fecundity and decreasing the rate of bee 

development into adulthood. 

Ureda (2004) determined the LC50s for deltamethrin, lambda-cyhalothrin and cyfluthrin, 

using the test species Hyalella azteca. Also, sediment samples from two locations in 

Central Valley, California were tested. They found that there was a linear relationship 

between the LC50 and the total organic carbon for cyfluthrin, but not for lambdacyhalothrin or for deltamethrin. They found that for cyfluthrin, the LC50s ranged from 

0.34 to 1.07 μg/gOC. The LOEC for cyfluthrin were 0.17-0.77 μg/gOC. In addition, 

Amweg, et al., 2005 determined the toxicity of six pyrethroids in three Central Valley, 

CA sediments towards Hyalella azteca. They found that of all the synthetic pyrethroids 

tested, bifenthrin exhibited the highest toxicity, while for cyfluthrin the average sediment 

10-day median LC50 was roughly an order of magnitude higher (or less toxic) than for 

bifenthrin. The actual value was 1.08 μg/gOC, which is of the same order of magnitude 

reported in the Ureda 2004 study. 

Two major factors that affect the toxicity of the pyrethroids include the presence of a 

synergist, such as piperonyl butoxide (PBO) and the temperature. Amweg et al. 2006a 

documented the effect of PBO on the pyrethroid permethrin’s toxicity towards Hyalella 

azteca in sediment samples. It was found that PBO could increase the toxicity of 

permethrin in sediment up to seven-fold. Also, Amweg and Weston 2007, documented 

the effects of the presence of PBO in sediments containing the synthetic pyrethroid 

bifenthrin and other representative chemicals, which included cadmium (a metal), 

chlorpyrifos (an organophosphate), DDT (an organochlorine), and flouranthene (a 

polycyclic aromatic hydrocarbon). The presence of PBO was considered as a Toxicity 

Identification Evaluation (TIE) tool. The 10-day Hyalella azteca LC50 was 0.26 μg/gOC, 

compared to 0.12 μg/gOC in the presence of PBO in the overlying water, at 25 μg/L 

(increased toxicity by a factor of 2.2). For the other chemicals, the factor was around or 
 119

less than 1 with no statistical difference in toxicity for all but chlorpyrifos. Eight field 

collected sediments, containing a variety of synthetic pyrethroids, or synthetic 

pyrethroids and chlorpyrifos (except for one sediment that contained only chlorpyrifos), 

that were previously tested and found to be toxic to Hyalella azteca, were examined with 

and without the presence of PBO. All the sediments exhibited higher toxicity in the 

presence of PBO except for the sediment that contained only chlorpyrifos. 

The effect of temperature was documented by Weston et al., 2009a. In an effort to 

identify factors affecting the toxicity identification evaluation (TIE) of the synthetic 

pyrethroids (TIE refers to “manipulating a sample in a manner that alters the toxicity of 

some toxicants but not others”), they performed sediment toxicity tests at various 

temperatures (13, 18, 23 and 28oC). 10-day LC50’s to Hyalella azteca were determined 

for four pyrethroids, (permethrin, bifenthrin, esfenvalerate and cyhalothrin), also for 

chlorpyrifos, cadmium and DDT (which were representative of other classes of 

chemicals). For the four pyrethroids, the toxicity approximately doubled when the 

temperature was decreased from 23 to 18oC, and approximately tripled when the 

temperature was further decreased to 13oC. The results at 28oC were mixed, but for some 

of the control samples, survival was low, which could indicate that the test species was 

not tolerant of the change to high temperature. For DDT, there was a similar response 

profile with temperature, but not as pronounced as for the synthetic pyrethroids. For 

chlorpyrifos and cadmium, the responses with temperature were either nearly 

independent of temperature or opposite to the one for the pyrethroids (increasing toxicity 

with increasing temperature), respectively. Various field samples with known amounts 

of pyrethroids (some of which contained cyfluthrin), also showed similar responses to 

those of the tested pyrethroids (as indicated above), with a few exceptions. The authors 

discussed the possible repercussions of the temperature dependence of the synthetic 

pyrethroids during the winter season, when the temperatures of the waters and sediments 

are lower. 

Yang et al. 2007 observed the effect of dissolved organic matter (DOM) on the 

bioavailability of the pyrethroids cyfluthrin and permethrin, and their toxicity towards 

Daphnia magna and Ceriodaphnia dubia. A total of 15 surface water samples from 

southern California were utilized. The dissolved organic content (DOC) ranged from 3.3-

20.2% and the pH ranged from 6.67-7.76. Various indicators were also characterized in 

the waters like an indicator of the level of aromaticity, the carboxyl group capacity and 

the phenol group capacity. They also obtained bioconcentration factors (BCFs) for D. 

magna. Using polydimethylsiloxane (PDMS) activated fiber, a measure of the freely 

dissolved pesticide concentration was obtained (the PDMS fibers were placed in 

scintillation vials and measured via LSC). Based on their low absortivity at 254 nm, it 

was suggested that the water samples had low DOM aromaticity. The E4/E6 (a ratio of 

absorbance at two specified wavelengths) of <5 suggested humic acid dominated 

composition and lesser fulvic acids. Finally, the molar content of carboxylic acid and 

phenolic acid, normalized for DOC varied widely. The DOM did not affect the freely 

available permethrin, but for cyfluthrin, the freely available cyfluthrin was less than for 

the control samples in all instances. The KDOC were less for cyfluthrin than for 

permethrin by about twice, suggesting affinity of cyfluthrin towards the DOM. 
 120

KDOC = (Cw – Cfree) / (DOC x Cfree) 

The cyfluthrin D. magna body residues were lower than in the control in 14 of the 15 

samples (for 9 samples, the difference was significant). There was a significant 

correlation between the cyfluthrin body residue and Cfree, but not for permethrin. In 96-

hour static exposure tests with C. dubia neonates, the cyfluthrin LC50s were greater than 

the controls in every case (for 7 samples, the difference was significant). These findings 

suggest high affinity of cyfluthrin with organic carbon and organic matter, and lower 

bioavailability in natural waters than in control waters. 

In a recent study (Stout II, et al. 2009), conducted by the US Department of Housing and 

Urban Development, in collaboration with the Agency, several chemicals were surveyed 

on floors of occupied homes. The survey included several synthetic pyrethroids like 

cyfluthrin. The most frequently detected pesticide was permethrin (89% of the samples). 

Cyfluthrin was detected with a frequency of 17% (n = 480 samples; mean not reported 

for chemicals with detection frequency below 30%; maximum value = 129 ng/cm2), 

illustrating that this chemical is commonly applied, detected and present in homes.

Cyfluthrin is among the constituents monitored by the National Water Quality 

Assessment (NAWQA), maintained by the U.S. Geological Survey. Two kinds of 

parameters (types of samples) are reported. One is “Cyfluthrin_ water_ filtered_ 

recoverable_ micrograms per liter,” with a reported percent of samples with this 

parameter of 9.7 (report units of μg/L). The other is “Cyfluthrin_ solids_ recoverable_ 

dry weight_ micrograms per kilogram,” with a reported percent of samples with this 

parameter of 0.1 (report units of μg/Kg). 

Multiple articles from the literature document the presence of synthetic pyrethroids, 

including cyfluthrin, in both urban and agricultural sediments. Weston et al. 2005, 

studied the presence of synthetic pyrethroids in Roseville, CA, selected as a typical 

suburban development. Sediments from creeks that drain subdivisions of single-family 

homes were found to be toxic to Hyalella azteca. The sediments were tested for several 

pesticides, including 7 pyrethroids. Bifenthrin was present in all the sediment samples. 

It was considered to be the primary cause of the toxicity towards the organism, with 

additional contributions of the pyrethroids cyfluthrin and cypermethrin. The maximum 

concentration of cyfluthrin was found to be 169 ng/g dry weight, for a tributary of 

Kaseberg Creek, in sampling site 11. It was detected in 12 out of 24 sediment samples. 

The authors indicate that the presence of synthetic pyrethroids was not likely to be due to 

agricultural uses. In Placer County, the use of synthetic pyrethroids for agricultural 

purposes was reported to amount to around 1%. 

Amweg et al. 2006b also studied synthetic pyrethroids in urban areas of California and 

Tennessee. Bifenthrin was found to be the major contributor to the toxicity of sediments 

sampled in California to Hyalella azteca, due to its high reported concentrations and 

toxicity. Cypermethrin, cyfluthrin, deltamethrin and lambda-cyhalothrin may have 

contributed to the toxicity in some of the sites. The concentrations of cypermethrin and 

cyfluthrin were typically higher than for other synthetic pyrethroids (usually 2-30 ng/g), 

but the bifenthrin and permethrin concentrations were the highest. On the other hand, in 

Tennessee only a few samples contained synthetic pyrethroids and none of the samples 
 121

were toxic to Hyalella azteca. The differences between the two sites were attributed to 

different climate, types of residential development and pesticide use practices. 

Holmes et al. 2008 presented the occurrence and toxicity of the synthetic pyrethroids 

throughout the state of California’s urban creek sediment samples. First, 90 samples 

were screened for toxicity to Hyalella azteca, of which around one third caused 

significant toxicity to the organism. Later, 30 sample locations were selected for the final 

study. Of the 30 samples, 25 were toxic to Hyalella azteca at 23oC and all 30 samples 

were toxic at 15oC (the synthetic pyrethroids often show higher toxicity at lower 

temperatures, as indicated above). Seven of eight pyrethroids were detected in the 

sediment samples. Fenpropathrin was not detected in any of the samples, and 

deltamethrin and esfenvalerate were detected infrequently; but bifenthrin was present in 

all the 30 samples (2.19 to 219 ng/g dry weight). Permethrin was the second most 

detected pyrethroid and cyfluthrin was detected in 16 samples, with a highest 

concentration of 127 ng/g dry weight. The results suggested an important role of the 

synthetic pyrethroids in California’s urban creeks sediment toxicity. Bifenthrin 

accounted for around two thirds of the toxicity on an average basis, with cyfluthrin and 

cypermethrin also playing an important role in the pyrethroid toxicity statewide. 

Trimble et al. 2009 screened a previously referenced database of 24 pesticides and 94 

urban sediment samples, with minimal agricultural or industrial contribution, collected 

from creeks and streams throughout central and northern California. The seven synthetic 

pyrethroids tested and chlorpyrifos were the pesticides most commonly occurring in 

toxicologically significant mixtures. Bifenthrin, permethrin and DDT were observed in 

greater than 90% of the samples. After normalizing the chemical concentrations for 

organic carbon “to provide better estimates of the biologically available chemical 

fractions,” all the seven pyrethroids monitored had levels exceeding the established level 

of interest, LOI (defined as 0.005 toxic units, 0.005 TU) for at least one sample. 

Cyfluthrin was detected in around 70% of the samples (Fig. 1 of the report). Bifenthrin, 

cypermethrin and cyfluthrin exceeded 0.5 TU (100x the initially established LOI) in 

greater than 30% of the samples. It was stated that... “The three pesticides with the 

highest average TU values were bifenthrin (2.4 TU), cypermethrin (1.2 TU), and 

cyfluthrin (0.5 TU).” These are just a few examples that illustrate the high use of 

synthetic pyrethroids in urban settings and potential ecological ramifications. 

Budd et al. 2007 sampled sediments in mixed land (urban and agricultural) in the San 

Diego Creek in Newport Bay Watershed in southern California. Bifenthrin and 

fenpropathrin were among the most frequently detected synthetic pyrethroids, with 

bifenthrin found in 95-100% of the samples. Cyfluthrin was observed less frequently, at 

a highest concentration of 2.48 ug/kg. The highest concentrations were associated with 

commercial nurseries. The authors found in this case that the concentration of synthetic 

pyrethroids was generally lower in residential or commercial areas as opposed to 

agricultural sites. Also, the frequency of detections of pyrethroids was higher during the 

wet season (e.g., cyfluthrin 33% vs. 5%), but the total concentration was not statistically 

different between the wet and dry seasons. 
 122

Weston et al. 2004 studied the presence of 26 pesticides, including five pyrethroids, in 70 

sediment samples taken from the agriculture dominated Central Valley in California. 

Ten-day sediment tests were conducted for Hyalella azteca and Chironomus dilutus 

(formerly known as Chironomus tentans), for some of the samples. Synthetic pyrethroids 

were found in 75% of the sediment samples; also they were found, based on a toxicity 

unit basis, to be sufficiently high to cause toxicity in 40% of the samples toxic to C. 

dilutus and around 70% of the samples toxic to H. azteca. The most commonly found 

pyrethroids were permethrin > esfenvalerate > bifenthrin > lambda-cyhalothrin. Even 

though this study did not include cyfluthrin or beta-cyfluthrin, the presence of several 

synthetic pyrethroids illustrated the possibility of high levels of several synthetic 

pyrethroids in agricultural zones. 

In a study, Gan et al. 2005 monitored the spatial distribution and enrichment (enrichment 

ratio, ER, or ratio of the concentration of a substance in eroded sediment to that of the 

source matrix) of the synthetic pyrethroids permethrin and bifenthrin, along a 260 meters 

runoff path. A sedimentation pond was used as the source point for the study (permethrin 

and bifenthrin had been used extensively at the site, for ant control, in a nursery 

environment). It was observed that, in general, the sediment concentration of permethrin 

and bifenthrin increased with distance (downstream from the source). Using the source 

as the reference value, ERs were calculated for these chemicals. The ERs reached 25.7-

32.2 for bifenthrin at 145 m and beyond, and they were lower for permethrin. Also, the 

persistence of the test substances was assessed, both, in aerobic and anaerobic 

environments. Despite the fact that this study was not conducted with cyfluthrin or betacyfluthrin, this study illustrated the possibility of enrichment through a runoff path for the 

synthetic pyrethroids. 

Woudneh & Oros 2006 presented a multi-chemical analytical method that included 

among others cyfluthrin and piperonyl butoxide (PBO). Analysis of the San Francisco 

Bay tributary sediment samples (six samples from five sites) revealed that cyfluthrin was 

detected in one of the sediments, at 17.6 ng/g and was less than the detection limit in the 

other samples. PBO was detected in all the samples at 0.010-0.215 ng/g. 

Weston et al.2009b, found that bifenthrin was the most frequently detected pyrethroid 

from runoff waters from Roseville and Elk Grove urban sites. Cyfluthrin, cypermethrin 

and permethrin were also detected frequently. During the dry season, cyfluthrin was 

detected with a frequency of 50%, while during the wet season, it was found with a 

frequency of detection of 100% (maximum concentration 26.6 ng/L). It was noted that 

stormwater runoff (which occurs mostly around the winter) was responsible for more 

transport than irrigation runoff (which occurs mostly around the summer), towards 

surface waters. It was suggested that mitigation of the effects of the synthetic pyrethroids 

would need to target both sources of runoff. It was reported that the use of bifenthrin (for 

retail and for professional use) was higher approximately in the months around the 

summer. 

Most of the studies related to the synthetic pyrethroids were conducted in California, but 

other studies document the presence of synthetic pyrethroids elsewhere. 
 123

Hintzen et al. 2009 monitored for 12 insecticides and degradation products, including 

synthetic pyrethroids and fipronyl in Texas stream sediments from urban sites in 2006, as 

a model to evaluate their potential impact in Southern US. Bifenthrin was the pyrethroid 

found with the highest frequency. Cyfluthrin’s frequency of detection was 9.8% (mean = 

0.27 μg/gOC; maximum = 0.40 μg/gOC; compared to 10-day LC50 to Hyalella azteca of 1.1 

μg/gOC). Lamda-cyhalothrin and permethrin were also frequently detected; the detections 

of lamda-cyhalothrin occurred frequently at concentrations of concern, but the 

concentrations of permethrin were below the LC50 for H. azteca. Bifenthrin was the 

greater contributor to the TUs, followed by lambda-cyhalothrin. The TUs generally 

correlated well with the toxicity of the samples, although some discrepancies between the 

TUs and toxicity were noted (even after normalization for organic carbon). There were 

no seasonal variations of the TUs. 

Ding et al. 2010 conducted monitoring for 29 pesticides, including pyrethroids like 

bifenthrin, fenpropathrin and cyfluthrin, from both urban and agricultural sites in central 

and southern counties in the state of Illinois in 2008. Most of the urban samples were 

from constructed storm drains, while the agricultural samples were from small waterways 

between farmlands in areas where mostly corn and soybeans were grown and the major 

pesticides used were tefluthrin and atrazine. Furthermore, sediment toxicity tests towards 

Hyalella azteca were performed. In the urban samples, the synthetic pyrethroids were 

detected in 95% of the samples. Bifenthrin was detected in 80% of the samples, while 

permethrin, lambda-cyhalothrin and fenpropathrin were also frequently detected; 

cyfluthrin was not detected. In the agricultural samples, bifenthrin, permethrin, 

cypermethrin and tefluthrin were detected (frequency of detection 47%), while cyfluthrin, 

fenpropathrin and lambda-cyhalothrin were not detected. Ten of 17 urban sediment 

samples tested were significantly more toxic to H. azteca than the controls. Only one of 

the agricultural sediment samples was significantly more toxic than the controls. The 

major source of TUs were the pyrethroids (in particular, bifenthrin). It was indicated that 

the detections of fenpropathrin in the urban samples was unexpected because it is a 

pesticide primarily used in agriculture. 

LeBlanc & Perkins, 2009, documented the presence of synthetic pyrethroids in Maine 

sediments. Of five synthetic pyrethroids monitored, only bifenthrin was detected, at 

levels of 1.26 – 16.68 ng/g (means). The other synthetic pyrethroids monitored were 

lambda-cyhalothrin, permethrin, cyfluthrin and cypermethrin. Four sediments were 

monitored: Mill Creek Lower Intertidal, Mill Creek Upper Intertidal, Back Cove and 

Payson Park. 

In an article, Weston & Lydy 2010 studied the possible sources of pyrethroids in 

California’s Sacramento – San Joaquin River Delta, including three types of samples: (a). 

urban runoff, (b). municipal wastewater treatment plants (or Publicly Owned Treatment 

Works, POTWs), and (c). agricultural discharges, in a study that focused on water 

samples (as opposed to most of the studies above that are related to sediments). Samples 

were taken during the wet and dry seasons. First, urban runoff samples were taken from 

concrete sumps, from which pumps lift waters to adjacent rivers over levees. Second, 
 124

POTW effluents with secondary (and in one case, tertiary) treatment were sampled just 

prior to discharge to surface waters. And finally, third, agricultural discharges were 

collected at pump stations, where the runoff is lifted over the levees. Samples were 

tested for 8 pyrethroids and chlorpyrifos (LOQ around 1 ng/L for most samples). Tests to 

Hyalella azteca were also performed on the water samples. Cyfluthrin was found in 55, 6 

and 0% of the samples of urban runoff, POTWs and agricultural drains, respectively. 

Also, 55, 0 and 0% of the samples, respectively, exceeded the EC50 = 1.9 ng/L for H. 

azteca. The maximum measured cyfluthrin concentration was 17.8 ng/L. Through TIE, 

it was found that the toxicity of most samples was increased in the presence of PBO. A 

similar effect was observed when the temperature of the samples was decreased. In the 

presence of the enzyme E3, which is capable to degrade the pyrethroids, the effect was a 

decreased toxicity of the samples towards H. azteca. In the presence of bovine serum 

albumin (BSA), no effect on the toxicity of the samples towards H. azteca, was observed. 

The pyrethroid presence in POTWs was unexpected because the effluents had low 

suspended material and for the possible partitioning with biosolids within the plants. The 

authors indicated that possible sources of pyrethroids are sewer disposal of household 

insecticides, lice control shampoos, pet products and permethrin treated clothing. 

Weston 2007 said that, “Contrary to popular perception, non-agricultural use of 

pyrethroids far exceeds agricultural use, at least in California, one of the few areas where 

data are available. A similar situation is likely elsewhere where there is substantial urban 

development. Whereas agricultural use of pyrethroids in California is about 300,000 

lb/yr, non-agricultural commercial use (mostly applications done by professional pest 

control firms) is currently about 700,000 lb/yr. Retail sales to homeowners are not 

included in this non-agricultural figure, but are probably about another 100,000 lb/yr. 

Some of the major urban uses of pyrethroids include cypermethrin and permethrin for 

termite control, permethrin to maintain landscaping, and bifenthrin and cyfluthrin for a 

variety of pests around homes.” 

Various studies provide additional environmental fate characterization of cyfluthrin and 

beta-cyfluthrin. It appears that cyfluthrin degrades slowly under normal conditions of 

aerobicity and organic matter, but degrades faster under anaerobic environments or in 

soils with higher organic matter. The moisture level does not appear to have a significant 

effect on the rate of degradation (Smith, et.al., 1995). The degradation of cyfluthrin 

appeared to be faster in soils with higher pH’s (Shehata, et.al., 1987), which would be 

expected based upon the results of the available hydrolysis study. In a study performed 

by Fernández-Alvarez et al. 2007, the photolytic behavior of cyfluthrin and various other 

synthetic pyrethroids was studied under artificial and natural light. The detection was 

performed using solid phase micro-extraction (SPME). After 20 minutes of exposure to 

UV light, cyfluthrin was almost completely degraded, with 8 photoproducts tentatively 

identified. However, under natural light for 2 days, there was no decrease in the 

analytical signal of cyfluthrin, indicating that the half-life is much larger than 2 days. 

Additional studies, using SPME were said to be conducted in the future. 

Gupta and Gajbhibe conducted two studies on the fate of beta-cyfluthrin. In a 2002 

study, they determined the persistence and effect of moisture in alluvial soil from India. 
 125

The half-lives ranged from 7.8 to 41.8 days. With an increased application rate, the 

dissipation rate decreased when the soil was at field capacity or flooded, but the effect 

was the opposite (but not pronounced) in air-dried soil. The persistence was greater in 

air-dried soils and lower in flooded soils. In a soil column study, beta-cyfluthrin was 

considered to be “highly immobile” in alluvial soil with greater than 99% of the residues 

in the upper 0-5 cm depth. The soil was classified as a sandy loam and it was an 

inceptisol with a pH of 7.7. In 2005, the same researchers studied the fate of betacyfluthrin in water, and the effect of pH, temperature and presence of sediments 

(approximately 20 mL water plus 1 g of air-dried soil-sediment). They used a 

formulation containing 2.5% a.i. named Bulldock 025 SC. At application rates of 0.01 to 

0.1 μg/mL10 the half-lives in water (pH not specified) were 8.4 – 10.5 days. At pHs 4.0, 

7.0 and 9.2, and 0.1 μg/mL, the half-lives of formulated beta-cyfluthrin were 125.4, 23.9 

and 13.4 days, respectively in studies conducted for a period of 30 days. At 5, 25 and 

40°C, the half-lives were 15.1-16.4, 8.5-10.5 and 5.8-4.7 days respectively. In the 

presence of sediment, the dissipation of beta-cyfluthrin formulation from the water 

followed a biphasic pattern, with initial half-lives in the water of 0.75-0.81 days (initial 0-

5 day period), while the dissipation from the soil-sediment was reported to be slower 

(initial 3.0-4.3 days and 13.5-13.9 during the 10-30 day period). 

Qin et al. 2006 observed enantioselectivity in the degradation of cyfluthrin and other 

selected pyrethroids. No substantive difference was observed in sterile soils, indicating 

preferential biological transformation. One soil (pH 6.7), and one sediment (pH 7.9) 

from California were used for incubation in this study. The incubations were performed 

with viable and sterile soils/ sediments. The incubations were performed with cisbifenthrin, cis-permethrin and cypermethrin (however, they did not use cyfluthrin of 

beta-cyfluthrin in this part of the study). Also, duplicate sediments were collected from 

diverse areas of Orange County, CA and analyzed. Analysis of the field samples 

indicated that for cyfluthrin for the diastereomeric pairs that follow, the stereoisomer 

fraction (SF) were as indicated. 

 1R-trans-αR + 1S-trans-αS, consistently <0.25, and 

 1R-trans-αS + 1S-trans-αR, consistently >0.25. 

They indicated that, “Of the cis enantiomers, the SF remained around 0.125 for some 

samples but clearly increased or decreased in the other samples...When enantioselective 

degradation was observed, the direction of enantioselectivity also appeared to depend on 

the sampling location and environmental conditions.” 

Li et al. 2008 demonstrated that for beta-cyfluthrin, the trans-diastereomer degraded 

faster in a loam Tianjin alkaline soil from North China (pH of 8.2). The half-lives for the 

cis-isomers were 17.16-28.41 days, and for the trans-isomers, they were 8.74-12.67 days. 

A similar enantioselective behavior was observed for beta-cypermethrin, but betacyfluthrin degradation was generally faster. 

Moore et al. 2007 examined the use of constructed wetlands in Leflore County, MS to 

mitigate exposure and ecological impacts in runoff from agricultural fields. The 

synthetic pyrethroids cyfluthrin and lambda-cyhalothrin were used as model 

 

10 It was noted that these concentrations exceed the solubility limit for beta-cyfluthrin of near 2 ppb. 
 126

contaminants. Testing with Hyalella azteca was performed to determine the efficiency of 

the system. There was spatial and temporal variation of the two pyrethroids’ 

concentrations in water, sediment and leaf litter in all three wetland constructed cells. By 

61 days, there were little or no pyrethroids in water or leaf-litter. The concentration of 

the pyrethroids decreased with distance from the application point, but there was no 

decrease in the H. azteca toxicity in water during the 61-day observation period even 

though the pyrethroids’ concentrations decreased significantly. The authors concluded 

that the pyrethroids can move, affecting non-target aquatic organisms for weeks to 

months after entering a constructed wetland. 

In 2009, Moore et al. also used cyfluthrin and lambda-cyhalothrin in constructed 

wetlands (comprised of a sediment retention basin, and two treatment cells) in a study 

lasting 55 days. A high percentage of the measured cyfluthrin was associated with 

vegetation while for lambda-cyhalothrin, it was associated with the sediment. It was 

determined that wetlands lengths of 210-217 m were required to mitigate inflow of both 

chemicals from a 14 ha contributing field. 
 127

Appendix D. Test Run for Cyfluthrin Representing the Cotton Use 

Modeling Results

Table 1. Estimated Environmental Concentrations (EECs) for Cyfluthrin 

MS cottona Peak (ppb) 21-day (ppb) 60-day (ppb) 

Water column 1.62 0.219 0.133 

Pore water 0.0476 0.0442 0.0379 a. A chosen representative scenario for agricultural applications of cyfluthrin. 

Table 2. Previously Generateda EECs for Cyfluthrin 

MS cottonb Peak (ppb) 21-day (ppb) 60-day (ppb) 

Water column 2.67 0.366 0.240 

Sediment 85.7 Not Available Not Available a. At the time there was no aerobic aquatic metabolism study for cyfluthrin and the v. 2 (instead of 2.1) of the input 

parameter guidance was used. Also, the date of application was different. b. A chosen representative scenario for 

agricultural applications of cyfluthrin. 

Table 3. Input Parameters Utilized in Test Run in PRZM/EXAMS for Cyfluthrin1 

Parameter (units) Value(s) Sources Comments 

Output File Name CYFLUTHRIN --- --- 

Chemical Name Cyfluthrin Label e.g., label BAYTHROID® 2 

Emulsifiable Pyrethroid 

Insecticide (Reg. No. 264-745) 

Crop Names MS cotton Label Vulnerable scenario, located in 

Yazoo, MS. 

Application Rate 0.056 Kg a.i./ha Label 0.05 lb a.i./A

Day of Application (daymonth) 

01-07 Label and metadata file --- 

Number of Applications 

Allowed 

10 Label Maximum allowed by the label. 

Interval between 

Applications (days) 

3 Label Minimum allowed by the label. 

KOC (ml/gOC) KOC = 123,950 MRID: 43424901 Mean of 4 values available 

(124000, 180300, 118000, 73500). 

The KOC model was utilized as per 

the 1999 SAP recommendation. 

Aerobic Soil Metabolism 

(days) t t

t s

n input

n

  

1 2

90 1

/

, ( )

tinput = 116.9 days 

MRID: 00131494 Represents the 90th percentile of 

the upper confidence bound on the 

mean of two half-life values: 

[values: 73.5, 94.8 days, mean = 

84.15 days; std. dev. = 15.06 days, 

t90,n-1 = 3.078 for n=2] 

Method of Application Aerial Label --- 

Buffer Zone (ft.) 150 Label --- 

Application Efficiency 

(fraction) 

0.95 Value for aerial 

applications 

--- 

Spray Drift (fraction) 0.039 AgDRIFT, Tier II, default 

values 

Appropriate for a buffer zone of 

150 ft. 

Solubility in Water (ppm) 2.32 x 10-3 Laskowsky 2002 --- 

Aerobic Aquatic 

Metabolism (days) t t

t s

n input

n

  

1 2

90 1

/

, ( )

tinput = 51.5 days 

MRID: 00131494 Represents the 90th percentile of 

the upper confidence bound on the 

mean of two half-life values: 

[values: 32.9, 42.0 days, mean = 

37.45 days; std. dev. = 6.435 days, 

t90,n-1 = 3.078 for n=2]. The value 

available is for beta-cyfluthrin. 
 128

Table 3. Input Parameters Utilized in Test Run in PRZM/EXAMS for Cyfluthrin1 

Parameter (units) Value(s) Sources Comments 

Anaerobic Aquatic 

Metabolism (days) 

60 MRID: 00131494 2x the anaerobic soil metabolism 

input value of ~30 days since 

there are no anaerobic aquatic 

studies 

Hydrolysis at pH 7 0 MRID: 00131493, 

00137539, 45022101 

Relatively stable at pH 7 

Aqueous Photolysis (days) 4.5 MRID: 00149595, 

45022102 

Linear half-life 

Molecular Weight (g/mole) 434.29 TOXNET/ HSDB --- 

Vapor Pressure (torr) 1.5 x 10-8 Laskowsky 2002 --- 

Henry’s Law Constant 

(atm-m3/mol) 

3.7 x 10-6 Laskowsky 2002 --- 

Environment pond298.exv --- 

Field Size EPA Pond --- 

Default for pond scenario, as 

opposed to index reservoir. 

Runoff None --- --- 

PRZM Scenario MScottonSTD.txt --- --- 

Metfile w03940.dvf Meteorological file located 

in Jackson, MS. 

As suggested by the shell (PE5). 

CAM (Chemical 

Application Method) 

2 Foliar applied, linear 

application 

--- 

Incorporation Depth (cm) 0 Label. Appropriate for foliar applications 

IPSCND, Condition for 

disposition of pesticide 

remaining on foliage after 

harvest 

1 Surface applied --- 

FEXTRC, Foliar extraction 0.5 Default value --- 

PLDKRT, Decay rate on 

foliage 

0 --- --- 

PLVKRT, Volatilization 

rate from foliage 

0 --- --- 

UPTKF, Uptake factor 0 --- --- 

Write benthic pore water 

concentrations? 

Yes --- --- 

1

Data were selected according to EFED Guidance on Input Parameters v.2.1, dated October 22, 2009. 

Output Files

stored as CYFLUTHRIN.out 

Chemical: Cyfluthrin 

PRZM environment: MScottonSTD.txt modified Tueday, 29 May 2007 at 13:57:52 

EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 06:14:07 

Metfile: w03940.dvf modified Tueday, 26 August 2008 at 06:14:14 

Water segment concentrations (ppb) 

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 

1961 0.6178 0.3094 0.162 0.102 0.08218 0.0343 

1962 0.6591 0.2084 0.07601 0.05536 0.05195 0.03778 

1963 0.911 0.3007 0.1155 0.06369 0.04963 0.03501 

1964 0.9171 0.3038 0.1429 0.09722 0.09244 0.0557 

1965 1.632 0.7632 0.22 0.1224 0.1003 0.05414 

1966 1.524 0.4941 0.1858 0.111 0.0928 0.0549 

1967 0.9011 0.2868 0.1062 0.06934 0.06358 0.04478 

1968 0.6025 0.2256 0.07806 0.0558 0.04871 0.04057 

1969 1.259 0.3897 0.1171 0.07503 0.06445 0.04211 

1970 0.9071 0.2927 0.1268 0.09624 0.08772 0.05173 

1971 0.9291 0.4225 0.1755 0.1144 0.09702 0.05525 

1972 0.2607 0.1029 0.07317 0.04625 0.0406 0.03489 

1973 0.5963 0.1876 0.06612 0.0571 0.04712 0.03802 

1974 0.5758 0.253 0.1194 0.08554 0.07335 0.04889 

1975 2.713 0.8339 0.3188 0.1766 0.1442 0.06754 

1976 0.9399 0.3433 0.1508 0.09414 0.08522 0.05163 

1977 0.9897 0.3348 0.1175 0.08002 0.07362 0.05088 
 129

1978 0.5457 0.1733 0.08854 0.05528 0.05214 0.04083 

1979 1.099 0.4613 0.2091 0.1606 0.1375 0.0712 

1980 0.2746 0.1082 0.06339 0.04832 0.04594 0.03503 

1981 0.8641 0.2717 0.08954 0.0681 0.06028 0.04152 

1982 1.34 0.4465 0.224 0.1337 0.1095 0.05912 

1983 1.225 0.3769 0.114 0.06972 0.06131 0.04518 

1984 1.067 0.4438 0.1449 0.09657 0.08231 0.05545 

1985 2.131 0.6539 0.195 0.1105 0.09557 0.05404 

1986 0.8161 0.2788 0.1054 0.06535 0.05894 0.04367 

1987 0.5517 0.178 0.08578 0.05896 0.04898 0.03776 

1988 0.8348 0.2619 0.08565 0.06797 0.06376 0.04412 

1989 0.6678 0.2332 0.0939 0.07086 0.0664 0.04639 

1990 0.7366 0.2281 0.1023 0.05905 0.05797 0.04412 

Sorted results 

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.032258064516129 2.713 0.8339 0.3188 0.1766 0.1442 0.0712 

0.0645161290322581 2.131 0.7632 0.224 0.1606 0.1375 0.06754 

0.0967741935483871 1.632 0.6539 0.22 0.1337 0.1095 0.05912 

0.129032258064516 1.524 0.4941 0.2091 0.1224 0.1003 0.0557 

0.161290322580645 1.34 0.4613 0.195 0.1144 0.09702 0.05545 

0.193548387096774 1.259 0.4465 0.1858 0.111 0.09557 0.05525 

0.225806451612903 1.225 0.4438 0.1755 0.1105 0.0928 0.0549 

0.258064516129032 1.099 0.4225 0.162 0.102 0.09244 0.05414 

0.290322580645161 1.067 0.3897 0.1508 0.09722 0.08772 0.05404 

0.32258064516129 0.9897 0.3769 0.1449 0.09657 0.08522 0.05173 

0.354838709677419 0.9399 0.3433 0.1429 0.09624 0.08231 0.05163 

0.387096774193548 0.9291 0.3348 0.1268 0.09414 0.08218 0.05088 

0.419354838709677 0.9171 0.3094 0.1194 0.08554 0.07362 0.04889 

0.451612903225806 0.911 0.3038 0.1175 0.08002 0.07335 0.04639 

0.483870967741936 0.9071 0.3007 0.1171 0.07503 0.0664 0.04518 

0.516129032258065 0.9011 0.2927 0.1155 0.07086 0.06445 0.04478 

0.548387096774194 0.8641 0.2868 0.114 0.06972 0.06376 0.04412 

0.580645161290323 0.8348 0.2788 0.1062 0.06934 0.06358 0.04412 

0.612903225806452 0.8161 0.2717 0.1054 0.0681 0.06131 0.04367 

0.645161290322581 0.7366 0.2619 0.1023 0.06797 0.06028 0.04211 

0.67741935483871 0.6678 0.253 0.0939 0.06535 0.05894 0.04152 

0.709677419354839 0.6591 0.2332 0.08954 0.06369 0.05797 0.04083 

0.741935483870968 0.6178 0.2281 0.08854 0.05905 0.05214 0.04057 

0.774193548387097 0.6025 0.2256 0.08578 0.05896 0.05195 0.03802 

0.806451612903226 0.5963 0.2084 0.08565 0.0571 0.04963 0.03778 

0.838709677419355 0.5758 0.1876 0.07806 0.0558 0.04898 0.03776 

0.870967741935484 0.5517 0.178 0.07601 0.05536 0.04871 0.03503 

0.903225806451613 0.5457 0.1733 0.07317 0.05528 0.04712 0.03501 

0.935483870967742 0.2746 0.1082 0.06612 0.04832 0.04594 0.03489 

0.967741935483871 0.2607 0.1029 0.06339 0.04625 0.0406 0.0343 

0.1 1.6212 0.63792 0.21891 0.13257 0.10858 0.058778 

 Average of yearly averages: 0.0472183333333333 

Inputs generated by pe5.pl - Novemeber 2006 

Data used for this run: 

Output File: CYFLUTHRIN 

Metfile: w03940.dvf 

PRZM scenario: MScottonSTD.txt 

EXAMS environment file: pond298.exv 

Chemical Name: Cyfluthrin 

Description Variable Name Value Units Comments 

Molecular weight mwt 434.29 g/mol 

Henry's Law Const. henry 3.7e-6 atm-m^3/mol 

Vapor Pressure vapr 1.5e-8 torr 

Solubility sol 2.32e-3 mg/L 

Kd Kd mg/L 

Koc Koc 123950 mg/L 

Photolysis half-life kdp 4.5 days Half-life 

Aerobic Aquatic Metabolism kbacw 51.5 days Halfife 

Anaerobic Aquatic Metabolism kbacs 60 days Halfife 

Aerobic Soil Metabolism asm 116.9 days Halfife 

Hydrolysis: pH 7 0 days Half-life 

Method: CAM 2 integer See PRZM manual 
 130

Incorporation Depth: DEPI 0 cm 

Application Rate: TAPP 0.056 kg/ha 

Application Efficiency: APPEFF 0.95 fraction 

Spray Drift DRFT 0.039 fraction of application rate applied to pond 

Application Date Date 01-07 dd/mm or dd/mmm or dd-mm or dd-mmm 

Interval 1 interval 3 days Set to 0 or delete line for single app. 

app. rate 1 apprate 0.056 kg/ha 

Interval 2 interval 3 days Set to 0 or delete line for single app. 

app. rate 2 apprate 0.056 kg/ha 

Interval 3 interval 3 days Set to 0 or delete line for single app. 

app. rate 3 apprate 0.056 kg/ha 

Interval 4 interval 3 days Set to 0 or delete line for single app. 

app. rate 4 apprate 0.056 kg/ha 

Interval 5 interval 3 days Set to 0 or delete line for single app. 

app. rate 5 apprate 0.056 kg/ha 

Interval 6 interval 3 days Set to 0 or delete line for single app. 

app. rate 6 apprate 0.056 kg/ha 

Interval 7 interval 3 days Set to 0 or delete line for single app. 

app. rate 7 apprate 0.056 kg/ha 

Interval 8 interval 3 days Set to 0 or delete line for single app. 

app. rate 8 apprate 0.056 kg/ha 

Interval 9 interval 3 days Set to 0 or delete line for single app. 

app. rate 9 apprate 0.056 kg/ha 

Record 17: FILTRA 

 IPSCND 1 

 UPTKF 

Record 18: PLVKRT 

 PLDKRT 

 FEXTRC 0.5 

Flag for Index Res. Run IR EPA Pond 

Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run) 

stored as CYFLUTHRINben.out 

Chemical: Cyfluthrin 

PRZM environment: MScottonSTD.txt modified Tueday, 29 May 2007 at 13:57:52 

EXAMS environment: pond298.exv modified Tueday, 26 August 2008 at 06:14:07 

Metfile: w03940.dvf modified Tueday, 26 August 2008 at 06:14:14 

Benthic segment concentrations (ppb) 

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 

1961 0.02832 0.02808 0.02701 0.02551 0.0234 0.01068 

1962 0.02547 0.02532 0.02486 0.02336 0.02192 0.01519 

1963 0.01997 0.01986 0.01957 0.01728 0.01656 0.01296 

1964 0.03422 0.03396 0.03246 0.02953 0.02897 0.02055 

1965 0.04702 0.0467 0.04351 0.03803 0.03485 0.02125 

1966 0.04231 0.04202 0.03923 0.03371 0.03075 0.02171 

1967 0.02597 0.02581 0.02514 0.02282 0.02185 0.01734 

1968 0.02561 0.02556 0.02514 0.02428 0.0233 0.01637 

1969 0.02866 0.02845 0.0262 0.02191 0.01978 0.01568 

1970 0.03352 0.03334 0.03227 0.03062 0.02962 0.01984 

1971 0.03635 0.03606 0.0345 0.03061 0.02967 0.02113 

1972 0.02342 0.02327 0.02281 0.02125 0.02001 0.01347 

1973 0.02372 0.02365 0.02156 0.02087 0.01984 0.01441 

1974 0.02815 0.02798 0.02708 0.02636 0.02508 0.01878 

1975 0.06133 0.06089 0.05683 0.04914 0.04446 0.02577 

1976 0.03603 0.03578 0.03391 0.03084 0.0291 0.02021 

1977 0.02684 0.02663 0.02549 0.02428 0.02319 0.01951 

1978 0.0246 0.0244 0.02382 0.02237 0.0215 0.01576 

1979 0.05109 0.05071 0.04708 0.04272 0.04085 0.02729 

1980 0.0263 0.02611 0.02545 0.02399 0.02275 0.01437 

1981 0.02452 0.02442 0.02343 0.02178 0.02051 0.01534 

1982 0.04762 0.04716 0.04426 0.0366 0.03338 0.02212 

1983 0.02793 0.02788 0.02756 0.02305 0.02068 0.01711 

1984 0.03618 0.03592 0.03307 0.02787 0.02693 0.02169 

1985 0.04408 0.04378 0.0404 0.0344 0.03183 0.02087 

1986 0.02392 0.02383 0.02344 0.02223 0.02061 0.01662 

1987 0.02255 0.02242 0.02202 0.02125 0.02038 0.01492 

1988 0.02533 0.02522 0.02476 0.02377 0.02301 0.01637 
 131

1989 0.02732 0.02723 0.02686 0.02588 0.0241 0.01798 

1990 0.02777 0.02769 0.02723 0.02639 0.0249 0.01726 

Sorted results 

Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 

0.032258064516129 0.06133 0.06089 0.05683 0.04914 0.04446 0.02729 

0.0645161290322581 0.05109 0.05071 0.04708 0.04272 0.04085 0.02577 

0.0967741935483871 0.04762 0.04716 0.04426 0.03803 0.03485 0.02212 

0.129032258064516 0.04702 0.0467 0.04351 0.0366 0.03338 0.02171 

0.161290322580645 0.04408 0.04378 0.0404 0.0344 0.03183 0.02169 

0.193548387096774 0.04231 0.04202 0.03923 0.03371 0.03075 0.02125 

0.225806451612903 0.03635 0.03606 0.0345 0.03084 0.02967 0.02113 

0.258064516129032 0.03618 0.03592 0.03391 0.03062 0.02962 0.02087 

0.290322580645161 0.03603 0.03578 0.03307 0.03061 0.0291 0.02055 

0.32258064516129 0.03422 0.03396 0.03246 0.02953 0.02897 0.02021 

0.354838709677419 0.03352 0.03334 0.03227 0.02787 0.02693 0.01984 

0.387096774193548 0.02866 0.02845 0.02756 0.02639 0.02508 0.01951 

0.419354838709677 0.02832 0.02808 0.02723 0.02636 0.0249 0.01878 

0.451612903225806 0.02815 0.02798 0.02708 0.02588 0.0241 0.01798 

0.483870967741936 0.02793 0.02788 0.02701 0.02551 0.0234 0.01734 

0.516129032258065 0.02777 0.02769 0.02686 0.02428 0.0233 0.01726 

0.548387096774194 0.02732 0.02723 0.0262 0.02428 0.02319 0.01711 

0.580645161290323 0.02684 0.02663 0.02549 0.02399 0.02301 0.01662 

0.612903225806452 0.0263 0.02611 0.02545 0.02377 0.02275 0.01637 

0.645161290322581 0.02597 0.02581 0.02514 0.02336 0.02192 0.01637 

0.67741935483871 0.02561 0.02556 0.02514 0.02305 0.02185 0.01576 

0.709677419354839 0.02547 0.02532 0.02486 0.02282 0.0215 0.01568 

0.741935483870968 0.02533 0.02522 0.02476 0.02237 0.02068 0.01534 

0.774193548387097 0.0246 0.02442 0.02382 0.02223 0.02061 0.01519 

0.806451612903226 0.02452 0.0244 0.02344 0.02191 0.02051 0.01492 

0.838709677419355 0.02392 0.02383 0.02343 0.02178 0.02038 0.01441 

0.870967741935484 0.02372 0.02365 0.02281 0.02125 0.02001 0.01437 

0.903225806451613 0.02342 0.02327 0.02202 0.02125 0.01984 0.01347 

0.935483870967742 0.02255 0.02242 0.02156 0.02087 0.01978 0.01296 

0.967741935483871 0.01997 0.01986 0.01957 0.01728 0.01656 0.01068 

0.1 0.04756 0.047114 0.044185 0.037887 0.034703 0.022079 

 Average of yearly averages: 0.018085 

Inputs generated by pe5.pl - Novemeber 2006 

Data used for this run: 

Output File: CYFLUTHRIN 

Metfile: w03940.dvf 

PRZM scenario: MScottonSTD.txt 

EXAMS environment file: pond298.exv 

Chemical Name: Cyfluthrin 

Description Variable Name Value Units Comments 

Molecular weight mwt 434.29 g/mol 

Henry's Law Const. henry 3.7e-6 atm-m^3/mol 

Vapor Pressure vapr 1.5e-8 torr 

Solubility sol 2.32e-3 mg/L 

Kd Kd mg/L 

Koc Koc 123950 mg/L 

Photolysis half-life kdp 4.5 days Half-life 

Aerobic Aquatic Metabolism kbacw 51.5 days Halfife 

Anaerobic Aquatic Metabolism kbacs 60 days Halfife 

Aerobic Soil Metabolism asm 116.9 days Halfife 

Hydrolysis: pH 7 0 days Half-life 

Method: CAM 2 integer See PRZM manual 

Incorporation Depth: DEPI 0 cm 

Application Rate: TAPP 0.056 kg/ha 

Application Efficiency: APPEFF 0.95 fraction 

Spray Drift DRFT 0.039 fraction of application rate applied to pond 

Application Date Date 01-07 dd/mm or dd/mmm or dd-mm or dd-mmm 

Interval 1 interval 3 days Set to 0 or delete line for single app. 

app. rate 1 apprate 0.056 kg/ha 

Interval 2 interval 3 days Set to 0 or delete line for single app. 

app. rate 2 apprate 0.056 kg/ha 

Interval 3 interval 3 days Set to 0 or delete line for single app. 

app. rate 3 apprate 0.056 kg/ha 
 132

Interval 4 interval 3 days Set to 0 or delete line for single app. 

app. rate 4 apprate 0.056 kg/ha 

Interval 5 interval 3 days Set to 0 or delete line for single app. 

app. rate 5 apprate 0.056 kg/ha 

Interval 6 interval 3 days Set to 0 or delete line for single app. 

app. rate 6 apprate 0.056 kg/ha 

Interval 7 interval 3 days Set to 0 or delete line for single app. 

app. rate 7 apprate 0.056 kg/ha 

Interval 8 interval 3 days Set to 0 or delete line for single app. 

app. rate 8 apprate 0.056 kg/ha 

Interval 9 interval 3 days Set to 0 or delete line for single app. 

app. rate 9 apprate 0.056 kg/ha 

Record 17: FILTRA 

 IPSCND 1 

 UPTKF 

Record 18: PLVKRT 

 PLDKRT 

 FEXTRC 0.5 

Flag for Index Res. Run IR EPA Pond 

Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)