Table 8. Cypermethrin Surface Water, Pore Water and Sediment EECs Obtained From PRZM/ EXAMS Georgia PECANS Crop Use ( Ground Application, Airblast). a Source Peak 21 day 60 day 90 day Surface Water ( ug/ L) 0.953 0.086 0.049 0.038 Pore Water ( ug/ L) 0.017 0.013 0.008 0.007 Sediment ( ug/ kg) 93.7 72.3 46.6 41.8 a 1 in 10 year probability Lettuce There is only one QCed PRZM scenario currently for lettuce ( California). The representative soil type is a Placentia sandy loam ( hydrologic Group D). Lettuce is a year round crop in California, so the application timing of cypermethrin can vary ( Jackson et al. 1996). Lettuce is usually planted at depths of approximately 1/ 8 to 1/ 4 inches primarily on 40 inch raised beds with 2 seed lines per bed. For a midsummer planting, the harvest usually begins 70 80 days later and cypermethrin is typically foliar applied as needed following emergence. The surface water, pore water and sediment EECs for the lettuce scenario are provided in Table 9.  41 Table 9a. Cypermethrin Surface Water, Pore Water and Sediment EECs Obtained From PRZM/ EXAMS California LETTUCE Crop Use with One Crop per Year. a Source Peak 21 day 60 day 90 day Surface Water ( ug/ L) 0.29 0.034 0.025 0.020 Pore Water ( ug/ L) 0.005 0.005 0.004 0.003 Sediment ( ug/ kg) 30.5 27.8 23.7 21.0 a 1 in 10 year probability Multiple Applications There is a possible uncertainty related to the exposure levels estimated to the lettuce scenario. In coastal southern California, lettuce is a year round crop so the application of cypermethrin may vary. According to the label, the maximum application rate is 0.6 lb a. i./ A/ season. The exposure scenarios modeled in this assessment assumed only one season per year. However, the exposure may be considerably higher if more than one season occurs. For this reason, the EFED conducted a special run with the California lettuce scenario, with applications corresponding to crops occurring in May and August ( first applications on 05/ 01 and 08/ 01, that is, two applications very close to each other). The input parameters were the same as those indicated in Tables 6a and 6b, except that the applications started on 05/ 01, and the application intervals were arranged so that the second set of applications started on 08/ 01. Results were as follows:

Table 9b. Cypermethrin Surface Water, Pore Water and Sediment EECs Obtained From PRZM/ EXAMS California LETTUCE Crop Use with Two Crops Per Year. a Source Peak 21 day 60 day 90 day Surface Water ( ug/ L) 0.40 0.042 0.029 0.023 Pore Water ( ug/ L) 0.007 0.007 0.006 0.005 Sediment ( ug/ kg) 42.4 38.8 33.0 29.2 a 1 in 10 year probability It appears that the peak concentrations are the most affected. The peak surface water EEC is higher for the run with two crops by about 38%, while the peak sediment EEC is higher for the run with two crops by a similar percentage. This run was performed assuming that the two crops were in May and August, that is, they were very close to each other. In the field, there is uncertainty as to the proximity of the crops during the year, or the number of crops per year.  42 Spray Drift/ Buffer Zone Analysis: The extent to which spray drift may be an important component of the concentrations of cypermethrin after applications of final products, reaching bodies of water adjacent to treated areas was investigated. The proposed cypermethrin label [ Ammo 2.5 Insecticide, EPA Reg. No. 279 3027] has specific restrictions for aerial applications related to the imposition of buffer zones between the treated areas and bodies of water in order to minimize the level of spray drift. The imposed buffer zone is 150 ft. The label has some additional directions related to the minimum volume of finished spray in gallons per acre for both aerial and ground applications. For the aerial applications, the minimum volume of finished spray is 1 gallon per acre if the chemical is applied in water or 1 quart per acre if the chemical is applied in refined vegetable oil; however, if the chemical is applied in water, it can be emulsified with 1 quart of oil to add a total of 1 gallon. For ground applications, it should be applied in a minimum of 5 gallons of finished spray. The label does not establish a range of droplet sizes, but it makes certain recommendations about the boom height, and limits the wind speed. These are variables that play a critical role in defining the level of spray drift. It is noted that the label has other language related to spray drift and buffer zones:

C Do not apply by ground equipment within 25 feet, or by air within 150 feet of lakes; reservoirs, rivers, permanent streams, marshes or natural ponds, estuaries, and commercial fish farm ponds. Increase the buffer zone to 450 feet when ultra low volume ( ULV) application is made.

C For aerial applications, the spray boom should be mounted on the aircraft so as to minimize drift caused by wingtip or rotor vortices. The minimum practical boom length should be used and must not exceed 75% of wing span or rotor diameter.

C Use the largest droplet size consistent with good pest control. Formation of very small droplets may be minimized by appropriate nozzle selection, by orienting nozzle away from the air stream as much as possible, and by avoiding excessive spray boom pressure.

C Spray should be released at the lowest height consistent with pest control and flight safety. Applications more than 10 feet above the crop canopy should be avoided.

C Make aerial or ground applications when the wind velocity favors on target product deposition ( approximately 3 to 10 mph). Do not apply when wind velocity exceeds 10 mph. Avoid applications when wind gusts approach 15 mph.

C Risk of exposure to sensitive aquatic areas can be reduced by avoiding applications when wind direction is toward the aquatic area.

C Do not cultivate within 10' of the aquatic area so as to allow growth of a vegetative filter strip.

C Low humidity and high temperatures increase the evaporation rate of spray droplets and therefore, the likelihood of increased spray drift to aquatic areas. Avoid spraying during conditions of low humidity and/ or high temperature.

C Do not make aerial or ground applications during temperature inversions, inversions are characterized by stable air and increasing temperatures with height above the ground. Mist or fog may indicate the presence of an inversion in humid areas. The applicator may detect the presence of an inversion by producing smoke and observing a smoke layer near the ground surface. 1 AgDRIFT ® is a computer program provided by the Agency's OPP, as a product of the Cooperative Research and Development Agreement ( CRADA), between the EPA's Office of Research and Development, and the Spray Drift Task Force ( SDTF, a coalition of pesticide registrants formed to develop a comprehensive database of off target drift information in support of pesticide registration requirements).

2 American Society for Agricultural Engineers 3 DV0.5 half of the volume is contained in droplets smaller than this value and half of the volume is contained in droplets larger than this value.

 43 Traditionally, the EFED uses a default level of spray drift for aerial applications of 5%. It is beneficial to compare this value to the data from AgDRIFT ® 1. A cursory review of the AgDRIFT ® data indicates that the " standard" level of 5% spray drift is adequate for ASAE2 Coarse to Very Coarse and ASAE Medium to Coarse droplet size sprays, but the level of spray drift may be underestimated for ASAE Fine to Medium and ASAE Very Fine to Fine droplet size sprays.

EFED used the NC cotton crop scenario to represent the crops assessed in this document in a buffer zone/ spray drift analysis. First, EFED ran PRZM/ EXAMS with the same input parameters as the standard run, except that the spray drift level was set to 0% and 5%. These are representative runs of no drift and no buffer zone runs. When the results of the run with spray drift of 5% were compared with the special run with spray drift of 0%, the results indicated that the percent of the peak EEC that was attributable to spray drift was 9.6% for NC cotton ( Supplementary Table D). This scenario has a relatively small component of drift. Some scenarios will be driven by runoff, while others will be driven by spray drift, depending on the properties of the chemical and the PRZM scenario, the weather, soil type and porosity, site slope, interception, irrigation, and other factors.

As a second step, a number of PRZM/ EXAMS were run, to anticipate the possible effect of buffer zones of up to 200 ft. The level of spray drift was determined with the help of AgDRIFT ® . Since the label for Ammo 2EC Insecticide provided some limitations and recommendations for the aerial applications, EFED bracketed the options by running a " low end drift," a " typical drift," and a " high end drift" ( most conservative) scenarios. These scenarios are summarized in Supplementary Table A.

Supplementary Table A. Spray drift scenarios Low End Spray Drift Scenario ( not conservative) Typical Spray Drift Scenario High End Spray Drift Scenario ( conservative)

release height, 8 ft release height, 10 ft release height, 15 ft wind speed, 3 mph wind speed, 10 mph wind speed, 15 mph large droplets, ASAE Medium to Coarse droplets ( DV0.5 = 340.86 : m) 3 ASAE Fine to Medium droplets ( DV0.5 = 254.72 : m) small droplets, ASAE Very Fine droplets ( DV0.5 = 81.52 : m)  44 In AgDRIFT ® , this is considered a Tier 2 calculation; nevertheless, all parameters were maintained at the AgDRIFT ® default value, except for the ones mentioned above, the spray volume, which is set to 1 gal/ A in water or 1 quart/ A in oil, as per label recommendations ( minimum volume recommended), and the boom length, which was set to 75% of wing span, as per label recommendations. Two quick representative calculations with 1 gallon of water and 1 quart of oil yielded higher percentage of drift with water; therefore, all the study was conducted with the more conservative 1 gal water/ A.

Once the AgDRIFT ® calculations were done, the levels of spray drift at various buffer zones were obtained with the help of the " toolbox" ` Aquatic Assessment'. This level of spray drift was used as the input value in PRZM/ EXAMS, modeled accordingly. The results are summarized in Supplementary Table B and D F for NC cotton; the raw data ( input and output files) from the PRZM/ EXAMS and AgDRIFT ® models appear in the Appendix O.

Supplementary Table B. Levels of Spray Drift Predicted by AgDRIFT ® for Buffer Zones from 0 to 200 ft. with the Low, Typical, and High End Spray Drift Scenarios.

Buffer Zone ( feet) Low End Drift ( Not conservative) Scenario (%) Typical Drift Scenario (%) High End Drift ( Very conservative) Scenario (%)

0 2.8 13.0 35.6 100 0.9 5.5 21.9 150 0.6 4.3 18.9 200 0.5 3.6 16.1 One PRZM field scenario was modeled, the North Carolina cotton, for agricultural crops. This scenario was selected to represent the crops for which the registrant is requesting reregistration for aerial applications. EECs for ecological risk assessment were determined using the farm pond scenario. The specified input parameters used for the PRZM/ EXAMS modeling are shown in Supplementary Table C. All the input parameters are similar to those used in the risk assessment, except for the spray drift, which is as indicated in the Supplementary Table B. With the exception of the special run that simulates a ground application, the singular parameter that differs in this particular study is the level of spray drift.

Supplementary Table C. PRZM/ EXAMS Inputs for Cypermethrin Runs With NC Cotton.

PARAMETER VALUE SOURCE Application date Cotton July 1st Crop specific a Supplementary Table C. PRZM/ EXAMS Inputs for Cypermethrin Runs With NC Cotton.

PARAMETER VALUE SOURCE  45 Application rate 0.1 lb a. i./ A = 0.112 Kg a. i./ ha Product label Maximum number of applications 6 Product label Incorporation depth 0.0 Aerial Application Aerobic soil metabolism half life 62 days MRID 42156601 ( 90% C. L. on the mean, n = 2 observations)

Koc 141,700 MRID 42129003 ( mean value, n= 4)

Henry's Law Constant 3.4x10 7 atm m3/ mol Laskowski ( 2002)

Aerobic aquatic metabolism 11.3 days MRID 45920801 ( 90% C. L. on the mean, n = 2 observations)

Anaerobic aquatic metabolism 19.3 days MRID 44876105 ( 90% C. L. on the mean, n = 2 observations)

Aqueous photolysis half life 36.2 days MRID 42395701 Hydrolysis half life ( days) pH 7 stable MRID 42620501 Molecular weight 416.3 Laskowski ( 2002)

Solubility ( WSOL) 0.04 ppm Laskowski ( 2002) ( solubility x 10)

Vapor pressure ( VP) 2.5x10 9 Laskowski ( 2002)

PLDKRT ( foliage pesticide rate constant) 0 EFED Model Input Guidance, Version II ( 2002)

FEXTRC ( foliar extraction) 0.5 EFED Model Input Guidance, Version II ( 2002)

FILTRA ( filtration parameter; required if CAM set to 3) NA

CAM ( chemical application method) 2 Reflects foliar application IPSCND 1 Surface Applied Application efficiency ( fraction) 0.99 for ground application 0.95 for aerial applications EFED Model Input Guidance, Version II ( 2002) Supplementary Table C. PRZM/ EXAMS Inputs for Cypermethrin Runs With NC Cotton.

PARAMETER VALUE SOURCE  46 Spray drift ( fraction) 0.01 for ground application 0.05 for standard run with no buffer 0.00 for special run with no drift refer to Supplementary Table B for other runs Calculated with AgDRIFT ® ( Tier 1): pecans is applied by ground ( airblast) with a buffer zone of 25 ft, other crops aerially with a buffer zone of 150 ft a See overview of pesticide use section for more information PRZM/ EXAMS modeling was conducted with all the parameters as discussed above. The results are summarized in the following tables for NC cotton:

Supplementary Table D. Surface Water Concentrations, EECs ( ppb) for ecological risk assessment, based on North Carolina cotton ( Special Runs)

ID % drift peak 21 day 60 day reference run 0 2.155 0.253 0.122 std. ground applic. 1, 99% applic. efficiency 2.292 0.265 0.129 std. aerial applic. 5 2.385 0.260 0.142 Three significant figures after the decimal were provided for illustration purposes.

Supplementary Table E. Surface Water Concentrations, EECs ( ppb) for ecological risk assessment, based on North Carolina cotton ( Buffer Zone Analysis).

Buffer Zone ( ft) Low end drift scenario, release height 8 ft, wind speed 3 mph, ASAE medium to coarse droplets ( EECs) Typical drift scenario, release height 10 ft, wind speed 10 mph, ASAE fine to medium droplets ( EECs) High end ( very conservative) drift scenario, release height 15 ft, wind speed 15 mph, ASAE very fine droplets ( EECs)

% drift peak 21 day 60 day % drift peak 21 day 60 day % drift peak 21 day 60 day 0 2.8 2.284 0.256 0.131 13.0 2.737 0.342 0.188 35.6 3.676 0.663 0.319 100 0.9 2.196 0.254 0.124 5.5 2.408 0.260 0.145 21.9 3.104 0.468 0.239 150 0.6 2.183 0.254 0.123 4.3 2.352 0.258 0.138 18.9 2.980 0.426 0.222 200 0.5 2.178 0.254 0.123 3.6 2.320 0.257 0.134 16.1 2.865 0.386 0.206  47 Pore water concentrations were obtained for all runs, but results are shown only for the typical drift scenario, with the buffer zone of 150 ft ( refer to Supplementary Table F).

Supplementary Table F. Pore Water Concentrations EECs ( ppb) for ecological risk assessment, based on North Carolina in North Carolina cotton.

Crop Scenario Typical drift scenario, release height 10 ft, wind speed 10 mph, ASAE fine to medium droplets, buffer zone 150 ft ( ppb)

% drift peak 21 day 60 day NC cotton 4.3 0.046 0.039 0.025 The low end drift scenario resulted in percentages of spray drift ranging from 0.5 2.8% for buffer zones of 0 200 ft. The high end drift scenario resulted in percentages of spray drift ranging from 16.1 35.6%, using buffer zones of 0 200 ft. The typical drift scenario resulted in percentages of spray drift ranging from 3.6 13.0% for buffer zones of 0 to 200 ft. The level of spray drift for the buffer zone imposed by the registrant of 150 ft using the typical drift scenario is 4.3%. This value may be compared to the default level of 5% that is the standard input value for aerial applications without a buffer zone. The high end scenario levels of spray drift were approximately 13 32 times higher than the corresponding low end scenario spray drift levels. It is expected, that the low end drift scenario will result in lower EEC's. This effect will be more substantial for scenarios that have large components of spray drift. The typical drift scenario levels of spray drift were approximately 5 7 times higher than the corresponding low end scenario spray drift levels. It is also noted that the levels of spray drift of the low end scenario with buffer zones ( 0.5 0.9% with buffer zones of 100 to 200 ft.) were of similar order of magnitude than the level of spray drift assigned to standard ground applications ( 1%). For an aerial application, a low wind speed, low boom height, large droplets, and a buffer zone of 100 ft or more, are necessary to achieve a level of spray drift of less than 1%.

Supplementary Table G. Percent reduction of the NC cotton peak EECs for the buffer zones of 150 and 200 ft, to observe if substantial additional reduction is obtained by increasing the buffer zone imposed by the registrants in the label.

ID Low end drift scenario Typical drift scenario High end drift scenario Peak EECs for Buffer Zone of 0 ft ( ppb) 2.284 2.737 3.676 Peak EECs for Buffer Zone of 150 ft ( ppb) 2.183 2.352 2.980 Percent reduction with buffer zone of 150 ft 4.4 14.1 18.9 Peak EECs for Buffer Zone of 200 ft ( ppb) 2.178 2.320 2.865 Percent reduction with buffer zone of 200 ft 4.6 15.2 22.1 Supplementary Table G. Percent reduction of the NC cotton peak EECs for the buffer zones of 150 and 200 ft, to observe if substantial additional reduction is obtained by increasing the buffer zone imposed by the registrants in the label.

ID Low end drift scenario Typical drift scenario High end drift scenario  48 Additional reduction with buffer zone of 200 ft in percentage 0.2 1.1 3.2 With respect to the EECs, the discussion is more meaningful in relationship to the peak EECs because they are the most sensitive to the levels of spray drift. Supplementary Table G shows the percent reduction of the peak EECs for the runs corresponding to buffer zones of 150 ft and 200 ft, compared to the respective runs with no buffer zone. For the NC cotton scenario, the peak EECs for the runs related to the no buffer zone ( 0 ft.) were 2.284, 2.737 and 3.676 ppb for the low end, typical drift, and high end drift scenarios, respectively, compared to the EECs for the runs related to the 150 ft. buffer zone, they were, 2.183, 2.352 and 2.980 ppb, respectively. This corresponds to a 4.4, 14.1 and 18.9% reduction, respectively. The EECs for the 200 ft buffer zone runs were 2.178, 2.320 and 2.865 ppb for the low end, typical drift, and high end drift scenarios, respectively, corresponding to a 4.6, 15.2 and 22.1% reduction, respectively. For the low end and typical drift scenario, the additional reduction was relatively little; however, for the high end drift scenario, the additional reduction was more meaningful.

This limited analysis has specific uncertainties.

C It is assumed that the level of runoff is similar in all PRZM/ EXAMS runs. The current version of PRZM/ EXAMS cannot take into consideration the fact that there are buffer zones ranging from 0 to 200 ft, that might mitigate the level of runoff ( particularly for the peak values), or the mandatory vegetative strip included in the label.

C Only one scenario was explored and was considered representative for all the areas where aerial applications of cypermethrin occur. It was found that this scenario has a relatively small component of spray drift. Ideally various scenarios would be explored, and data compared among each other.

C The scope of this analysis is limited. It constitutes only an overview, with calculations performed with NC cotton only.

b. Aquatic Exposure Monitoring and Field Data A variety of sources were searched for surface and groundwater monitoring data on cypermethrin, including registrant submitted studies, and federal, state and local agencies. An internet search was conducted for ground and/ or surface water monitoring data on cypermethrin. The following websites were searched: USGS National Water Quality Assessment ( NAWQA) Program, EPA STORET, and the NCOD. Among these sites, no data were located related to ground or surface water detections of cypermethrin. It cannot be expected that the temporal or spatial design of these studies would necessarily have taken place in vulnerable portions of the cypermethrin use area. In addition, some monitoring data may be collected from areas that are not  49 representative of potential susceptible surface water or drinking water sources. Therefore, although no monitoring data were located, this lack of data does not conclusively indicate that cypermethrin concentrations do not exist in surface and ground water bodies. Moreover, cypermethrin is very hydrophobic and rapidly partitions to the sediment compartment when released to water bodies. Monitoring studies that include analysis of the surface sediments of water bodies would be beneficial when analyzing for hydrophobic pyrethroid pesticides such as cypermethrin.

3. Measures of Terrestrial Exposure a. Terrestrial Exposure Modeling The EFED terrestrial exposure model T REX ( T REX, Version 1.12, dated December 7, 2004) is used to estimate exposures and risks to avian and mammalian species. Input values for avian and mammalian toxicity as well as chemical application and foliar dissipation half life data are required to run the model. The model provides estimates of exposure concentrations and risk quotients ( RQs). Specifically, the model provides estimates of concentrations ( maximum, or upper bound, and average, or mean) of chemical residues on the surface of different types of foliage and insects that may be dietary sources of exposure to avian, mammalian, reptilian, or terrestrial phase amphibian receptors. The surface residue concentration ( ppm) is estimated by multiplying the application rate ( pounds active ingredient per acre) by a value specific to each food item. These values ( termed the Hoerger Kenaga estimates) along with a more detailed discussion of the methodology implemented by T REX, are presented in Appendix D ( T REX Model). T REX was run for four crop uses ( cotton, lettuce, pecans, and canola), using the input values provided in Table 10.

Table 10. Input Parameters Used in T REX v1.12 to Determine Terrestrial EECs for Cypermethrin.

Input Variable Parameter Value Source Maximum single application rate Cotton: 0.1 lb a. i./ A Pecans: 0.1 lb a. i./ A Canola: 0.1 lb a. i./ A Lettuce: 0.1 lb a. i./ A Product Label Maximum number of applications per year Cotton: 6 Pecans: 6 Canola: 4 Lettuce: 6 Product Label Minimum application interval Cotton: 3 days Pecans: 5 days Canola: 7 days Lettuce: 7 days Product Label Table 10. Input Parameters Used in T REX v1.12 to Determine Terrestrial EECs for Cypermethrin.

Input Variable Parameter Value Source  50 Foliar dissipation half life 5.3 days Willis and McDowell 1987 A summary of the terrestrial EECs generated by T REX for the four crop uses is presented in Table 11. More detailed summaries of the T REX output are presented in Appendix D. Cypermethrin residues ranged from 66.93 ppm ( cotton, short grass) to 2.44 ppm ( canola, fruits/ pods/ large insects) for maximum residues, and from 23.70 ( cotton, short grass) to 1.14 ppm ( canola, fruits/ pods/ large insects) for mean residues.

Table 11. Peak Terrestrial EECs Estimated for Cypermethrin Using Kenaga Values.

Crop Use Forage Type Maximum Residues ( ppm) Mean Residues ( ppm)

Cotton short grass 66.93 23.70 tall grass 30.68 10.04 broadleaf plants and small insects 37.65 12.55 fruits/ pods/ large insects 4.18 1.95 Lettuce short grass 39.86 14.12 tall grass 18.27 5.98 broadleaf plants and small insects 22.42 7.47 fruits/ pods/ large insects 2.49 1.16 Pecans short grass. 49.01 17.36 tall grass 22.46 7.35 broadleaf plants and small insects 27.57 9.19 fruits/ pods/ large insects 3.06 1.43 Canola short grass 38.99 13.81 tall grass 17.87 5.85 broadleaf plants and small insects 21.93 7.31 fruits/ pods/ large insects 2.44 1.14  51 b. Residue Studies No terrestrial residue studies were located for cypermethrin.

C. Ecological Effects Characterization In screening level ecological risk assessments, effects characterization describes the types of effects a pesticide can have on aquatic or terrestrial organisms. This characterization is based on registrant submitted studies that describe information regarding acute and chronic effects toxicity for various aquatic and terrestrial animals. Appendix E summarizes the results of the registrant submitted toxicity studies used to characterize effects for this risk assessment. Toxicity testing reported in this section does not represent all species of birds, mammals, or aquatic organisms. Only a few surrogate species for both freshwater fish and birds are used to represent all freshwater fish ( 2000+) and bird ( 680+) species in the United States. For mammals, acute studies are usually limited to the Norway rat or the house mouse. Estuarine/ marine testing is usually limited to a crustacean, a mollusk, and a fish. Also, testing for reptiles and amphibians are not required. The risk assessment assumes that avian and reptilian toxicities are similar. The same assumption is used for fish and amphibians.

In general, categories of acute toxicity ranging from " practically nontoxic" to " very highly toxic" have been established for aquatic organisms ( based on LC 50 values), terrestrial mammals ( based on LD 50 values), avian species ( based on LC 50 values), and non target insects ( based on LD 50 values for honey bees) ( U. S. EPA 2001). These categories are presented in Appendix E.

1. Aquatic Effects Characterization The most sensitive acute and chronic toxicity reference values associated with cypermethrin exposure to freshwater and estuarine/ marine species are summarized in Table 12. All toxicity reference values used to assess the potential risks of cypermethrin exposure are obtained from studies using technical grade cypermethrin, rather than from studies using cypermethrin metabolites or formulated product. A more detailed summary of the aquatic toxicity data available to characterize risks associated with cypermethrin applications is given in Appendix E.

Results of acute toxicity studies in freshwater fish, freshwater invertebrates, estuarine/ marine fish, estuarine/ marine invertebrates ( shrimp and crustaceans), and benthic organisms indicate that cypermethrin TGAI is very highly toxic on an acute basis. The lowest acute LC 50 values reported for freshwater fish, freshwater invertebrates and estuarine/ marine fish range from 0.39 : g a. i./ L in freshwater fish to 0.95 : g a. i./ L in sheepshead minnow. These results suggest that freshwater fish, freshwater invertebrates, and estuarine/ marine fish have a similar susceptibility to cypermethrin toxicity. For estuarine/ marine invertebrates, the lowest acute LC 50 value reported is 0.00475 : g a. i./ L, approximately 100 times lower than the LC 50 values reported for other aquatic animals, indicating that estuarine/ marine invertebrates are more sensitive to cypermethrin toxicity than other types of aquatic animals. Thus, estuarine/ marine  52 invertebrates are expected to be the species at greatest risk for acute effects ( lethality). Cypermethrin is categorized very highly toxic to estuarine/ marine shrimp and crustaceans and highly toxic in oysters. Results of acute toxicity studies on cypermethrin formulations in freshwater fish and invertebrates indicate that cypermethrin formulations are also very highly toxic, with LC 50 values that are similar to those reported for cypermethrin TGAI. Acute toxicity studies on the cypermethrin degradate 3 phenoxybenzoic acid in freshwater fish and invertebrates show that the degradate is much less toxic than cypermethrin TGAI.

In addition to lethality data, several acute toxicity studies provide information regarding sublethal effects of cypermethrin. For fish, sublethal effects include rapid and erratic swimming, partial/ complete loss of equilibrium, jaw spasms, gulping respiration, lethargy, and darkened pigmentation. In aquatic invertebrates, sublethal effects include lethargy, erratic swimming behavior, loss of equilibrium, surfacing, immobilization, and decreased movement in response to stimulation. In most studies, the acute NOAEC values for sublethal effects are approximately 2 to 3 fold lower than the corresponding LC 50 values. However, in rainbow trout and bluegill sunfish, the acute NOAEC values for sublethal effects are several orders of magnitude lower than the corresponding LC 50 values, indicating that sublethal effects can occur at exposure levels far below the concentrations that cause lethality.

Chronic toxicity studies are available for freshwater fish and estuarine/ marine invertebrates. Results in freshwater fish show that neonate survival is adversely affected by cypermethrin exposure. For estuarine/ marine invertebrates, chronic exposure to cypermethrin produced adverse effects on reproductive and growth parameters.

Results of aquatic field studies conducted with cypermethrin formulations yield a wide range of results, from no observable effects to catastrophic drift and profound decreases in population diversity and abundance. While results of these studies show that cypermethrin can have profound effects on aquatic populations, particularly freshwater invertebrates and benthic organisms, due to the variability in experimental methodologies and the lack of rigorous monitoring of water and sediment concentrations of cypermethrin, results of these studies are not sufficient for use in quantitative assessments. However, the observations made in field studies using cypermethrin demonstrate that the laboratory studies are predictive of the types of toxicity that can result from environmental exposure to cypermethrin.

Calculations for sediment and pore water exposure to benthic organisms followed the equilibrium partitioning model as noted previously and in Appendix M. The LC 50 value of 0.00257 : g a. i./ L pore water ( Table 12) was calculated as follows: The LC 50 value from whole sediment [ 3.6 µ g a. i./ kg sediment] is divided by the proportion of organic carbon in the sediment [ 0.0099 kg OC / kg whole sediment]. Thus, the LC 50 value in units of OC is 364 µ g a. i./ kg OC [ 3.6 µ g a. i./ kg sediment ÷ 0.0099 kg OC / kg sediment]. The equivalent concentration in pore water is based on the definition of the K oc ,

K oc ( L/ kg OC ) = Sediment Conc in OC ( mg/ kg OC ) ÷ Conc in pore water ( mg/ L).

By rearrangement,  53 Conc in water = Sediment Conc in units of OC ÷ K oc .

For cypermethrin, the K oc is taken as 141,700 [ L/ kg OC ]. Thus, the calculated concentration in pore water corresponding to the LC 50 value of 364 µ g a. i./ kg OC is 0.00257 µ g a. i./ L [ 364 µ g a. i./ kg OC ÷ 141,700 L/ kg OC ].  54 Table 12. Cypermethrin Toxicity Reference Values ( TRVs) (: g of active ingredient/ L) for Aquatic Organisms.

Exposure Scenario Species Exposure Duration Toxicity Reference Value (: g a. i./ L) Effects Reference Freshwater Fish Acute rainbow trout 96 hours LC50 = 0.39 : g a. i./ L Morbidity MRID 44546027 Chronic fathead minnow 30 days NOAEC = 0.14 : g a. i./ L LOAEC = 0.33 ug ai/ L Growth and morbidity MRID 89039 Freshwater Invertebrates Acute waterflea 48 hours EC50 = 0.42 : g a. i./ L Lethargy MRID 44546031 Chronic No adequate data submitted; to assess chronic risk to freshwater invertebrates, a surrogate NOAEC value of 0.069 : g a. i./ L was derived based on the acute: chronic ratio method using acute and chronic data for estuarine/ marine invertebrates. a Benthic Organisms Acute amphipod 10 days sediment value ( experimental data): LC50 = 3.6 : g a. i./ kg sediment pore water value ( derived data) b: LC50 = 0.00257 : g a. i./ L pore water Morbidity and Growth MRID 44074406 Chronic No chronic data submitted; to assess chronic risk to benthic organisms, surrogate chronic NOAEC toxicity values for sediment of 0.59 : g a. i./ kg sediment c and for pore water of 0.00042 : g a. i./ L pore water d were derived based on the acute: chronic ratio method using acute and chronic data for estuarine/ marine invertebrates.

Estuarine/ Marine Fish Acute sheepshead minnow 96 hours LC50 = 0.95 : g a. i./ L Morbidity MRID 90075 Chronic No data submitted; to assess chronic risk to estuarine/ marine fish, a surrogate NOAEC value of 0.34 : g a. i./ L for sheepshead minnow was derived based on the acute: chronic ratio method using acute and chronic data for freshwater fish. e Table 12. Cypermethrin Toxicity Reference Values ( TRVs) (: g of active ingredient/ L) for Aquatic Organisms.

Exposure Scenario Species Exposure Duration Toxicity Reference Value (: g a. i./ L) Effects Reference  55 Estuarine/ Marine Invertebrates Acute mysid shrimp 96 hours f LC50 = 0.00475 : g a. i./ L Morbidity Acc. No. 42444601 Chronic mysid shrimp 28 days g NOAEC = 0.000781 : g a. i./ L LOAEC = 0.00197 ug/ L NOAEC = 0.0015 ug/ L LOAEC = 0.0028 ug/ L Weight of Females reduced Number of offspring MRID 42725301 Table 12. Cypermethrin Toxicity Reference Values ( TRVs) (: g of active ingredient/ L) for Aquatic Organisms.

Exposure Scenario Species Exposure Duration Toxicity Reference Value (: g a. i./ L) Effects Reference  56 a The chronic NOAEC estimated for waterflea is based on the acute to chronic ratio method, determined by the following mathematical relationship: Estuarine/ marine invertebrate LC50 ( 0.00475: g a. i./ L) / Estuarine/ marine invertebrate NOAEC ( 0.000781: g a. i./ L) = Freshwater invertebrate LC50 ( 0.42 : g a. i./ L)/ X ( estimated value for Freshwater invertebrate NOAEC), where X = 0.069 : g a. i./ L b For benthic organisms, the LC50 value of 0.00257 : g a. i./ L pore water was calculated as follows. The LC50 value in whole sediment [ 3.6 µ g a. i./ kg sediment] is divided by the proportion of organic carbon in the sediment [ 0.0099 kg OC/ kg whole sediment]. Thus, the LC50 value in units of OC is 364 µ g a. i./ kg OC [ 3.6 µ g a. i./ kg sediment ÷ 0.0099 kg OC/ kg sediment]. The equivalent concentration in pore water is based on the definition of the Koc, Koc ( L/ kg OC) = Sediment Conc in OC ( mg/ kg OC) ÷ Conc in pore water ( mg/ L).

By rearrangement, Conc in water = Sediment Conc in units of OC ÷ Koc.

For cypermethrin, the Koc is taken as 141,700 [ L/ kg OC]. Thus, the calculated concentration in pore water corresponding to the LC50 value of 364 µ g a. i./ kg OC is 0.00257 µ g a. i./ L [ 364 µ g a. i./ kg OC ÷ 141,700 L/ kg OC]. c The chronic NOAEC estimated for benthic organisms in terms of µ g a. i./ kg sediment is based on the acute tochronic ratio method, determined by the following mathematical relationship: Estuarine/ marine invertebrate LC50 ( 0.00475: g a. i./ L) / Estuarine/ marine invertebrate NOAEC ( 0.000781: g a. i./ L) = Benthic LC50 in sediment 3.6 µ g a. i./ kg sediment / X ( estimated benthic NOAEC value in sediment), where X = 0.59 : g a. i./ kg sediment. d The chronic NOAEC estimated for benthic organisms in units of µ g a. i./ kg pore water is based on the acuteto chronic ratio method, determined by the following mathematical relationship: Estuarine/ marine invertebrate LC50 ( 0.00475: g a. i./ L) / Estuarine/ marine invertebrate NOAEC ( 0.000781: g a. i./ L) = Benthic LC50 in pore water ( 0.00257 µ g a. i./ L / X ( estimated benthic NOAEC value in pore water ), where X = 0.00042 : g a. i./ L pore water. e The chronic NOAEC estimated for the sheepshead minnow is based on the acute to chronic ratio method, determined by the following mathematical relationship: Freshwater LC50 ( 0.39 : g a. i./ L) / Freshwater NOAEC ( 0.14: g a. i./ L) = Estuarine/ Marine LC50 ( 0.95 : g a. i./ L)/ X ( estimated value for Estuarine/ Marine NOAEC), where X = 0.34 : g a. i./ L. f The acute toxicity reference value identified to calculate acute RQs for estuarine/ marine invertebrates is for a 96 hour exposure duration, rather than the guideline recommended 48 hour exposure duration. Although 48 hour LC50 value have been reported in other studies ( see Appendix E), these values are higher than the 96 hour LC50 of 0.005 : g a. i./ L. Taking the most conservative approach, EFED will use the lowest LC50 value reported for estuarine/ marine invertebrates. g The exposure duration of 28 days was not reported in the DER for this study. Since this study was classified as " Acceptable" by EFED, an exposure duration of 28 days is assumed.  57 a. Aquatic Animals ( 1). Acute Effects Freshwater Fish The acute toxicity of technical grade cypermethrin to freshwater fish was evaluated in several species, with 96 hour LC 50 values ranging from 0.39 : g a. i./ L in rainbow trout ( MRID 44546027) to 4.5 : g a. i./ L in bluegill sunfish ( MRID 44546030). Details of these studies are provided in Appendix E, Table E 1a. Based on these results, cypermethrin is categorized as very highly toxic to freshwater fish on an acute basis. Taking the most conservative approach, the lowest 96 hour LC 50 of 0.39 : g a. i./ L in rainbow trout is used to evaluate acute toxic exposure to freshwater fish.

Studies assessing the acute toxicity of three cypermethrin formulations in rainbow trout were submitted; results are summarized in Table E 1b. The formulations tested were WL 43467 40% EC ( 40% a. i.), and GFU 070 ( 25.1% a. i.). The 96 hour LC 50 values reported for GFU 061 and GFU 070 are 4.7 : g formulation/ L ( MRID 65813) and 13.0 : g formulation/ L ( MRID 88947), respectively, indicating that these cypermethrin formulations are very highly toxic to freshwater fish. Comparison of the 96 hour LC 50 values for cypermethrin TGAI ( 0.39 to 3.3 : g a. i./ L) and cypermethrin formulations ( 4.7 to 13.0 : g formulation/ L; equivalent to approximately 1.2 to 5.2 : g a. i./ L) indicates that the formulated products have a similar order of toxicity to technical grade cypermethrin.

Acute toxicity studies in freshwater fish were also submitted for the cypermethrin degradate 3 phenoxybenzoic acid in rainbow trout ( MRID 89037) and bluegill sunfish ( MRID 89038). Results yield 96 hour LC 50 values of 13.3 and 36.3 mg degradate/ L in rainbow trout and bluegill sunfish, respectively ( details provided in Appendix E, Table E 1c). Based on these 96 hour LC 50 values, 3 phenoxy benzoic acid is categorized as slightly toxic to freshwater fish on an acute basis and is much less toxic than cypermethrin TGAI to freshwater fish.

Freshwater Invertebrates Acute toxicity studies of technical grade cypermethrin to daphnids yield toxicity values ranging from a 48 hour LC 50 value of 0.42 : g a. i./ L ( MRID 44546031) to a 24 hour EC 50 value ( for immobility) of 2.0 : g a. i./ L ( Acc. No. 42444601). Study details are provided in Appendix E, Table E 2a. Based on these results, cypermethrin TGAI is categorized as very highly toxic on an acute basis. Taking the most conservative approach, the lowest LC 50 values reported ( 48 hour LC 50 value of 0.42 : g a. i./ L) is used to assess acute risk to freshwater invertebrates.

Studies assessing the acute toxicity of three cypermethrin formulations to daphnids were submitted; results are summarized in Appendix E, Table E 3b. The formulations tested were GFU 034/ A ( 36% a. i.), GFU 061 ( 36% a. i.), and GFU 070 ( 24% a. i.). Results of these studies were reported as EC 50 values ( for immobility), rather than LC 50 values. The 48 hour EC 50 values ranged from 1.56 : g a. i./ L ( MRID 62793) to 21.6 : g a. i./ L ( MRID 89040), indicating that these cypermethrin formulations are very highly toxic to freshwater invertebrates on an acute basis.  58 Comparison of the 48 hour LC 50 / EC 50 values for cypermethrin TGAI ( 0.42 to 2.0 : g a. i./ L) and cypermethrin formulations ( 1.56 to 21.6 : g a. i./ L) indicates that the formulated products have a similar order of toxicity to technical grade cypermethrin.

Acute toxicity tests in freshwater invertebrates using the cypermethrin degradate 3 phenoxybenzoic acid to daphnids were also submitted. Results yield 48 hour EC 50 values of 89.0 mg degradate/ L ( MRID 152739) and 111 mg degradate/ L ( Acc. No. 42444601). Based on these acute toxicity values, 3 phenoxy benzoic acid is categorized as practically non toxic to slightly toxic to freshwater invertebrates on an acute basis. Thus, the 3 phenoxy benzoic acid degradate is much less toxic than cypermethrin TGAI to freshwater invertebrates.

Estuarine/ Marine Fish The acute toxicity of technical grade cypermethrin to estuarine/ marine fish was evaluated in sheepshead minnow and Atlantic salmon, with 96 hour LC 50 values of 0.95 : g a. i./ L ( MRID 41068003) and 4.3 : g a. i./ L ( MRID 41968212), respectively, indicating that cypermethrin TGAI is very highly toxic to estuarine/ marine fish on an acute basis. Study details are provided in Appendix E, Table E 5. Taking the most conservative approach, the lowest 96 hour LC 50 value of 0.95 : g a. i./ L in sheepshead minnow will be used to evaluate acute toxic exposure to estuarine/ marine fish. No acute toxicity studies of cypermethrin formulations or cypermethrin degradates in estuarine/ marine fish were submitted.

Estuarine/ Marine Invertebrates Acute toxicity tests with estuarine/ marine invertebrates using the cypermethrin TGAI were conducted in shrimp, molluscs, and crustaceans. Study details are provided in Appendix E, Table E 6. Toxicity values ( EC 50 and LC 50 ) reported for shrimp range from the 96 hour LC 50 value of 0.00475 : g a. i./ L ( Acc. No. 42444601) to the 96 hour LC 50 value of 0.01 : g a. i./ L ( MRID 41068003). Similar results were observed in lobster ( 96 hour LC 50 = 0.04 : g a. i./ L; MRID 41068003) and fiddler crab ( 96 hour LC 50 = 0.197 : g a. i./ L; MRID 89045). Based on these results, cypermethrin TGAI is categorized as very highly toxic to estuarine/ marine shrimp and crustaceans. Results of acute toxicity tests in molluscs show that cypermethrin TGAI is moderately to highly toxic in oysters, with a 96 hour EC 50 value of 0.37 mg a. i./ L in Eastern oyster ( MRID 89049) and a 48 hour LC 50 value of > 2.27 mg a. i./ L in Pacific oyster ( Acc. No. 42444601). Results of these studies indicate that molluscs are less susceptible than shrimp and crustaceans to cypermethrin toxicity on an acute basis. Taking the most conservative approach, the 96 hour LC 50 value of 0.00475 : g a. i./ L in mysid shrimp will be used to categorize acute risk to estuarine/ marine invertebrates. No acute toxicity studies of cypermethrin formulations or cypermethrin degradates in estuarine/ marine invertebrates were submitted.

Benthic Organisms Several studies on the toxicity of cypermethrin TGAI to benthic organisms have been submitted; details are summarized in Appendix E, Table E 4. Studies were conducted using two types of experimental protocols, exposure in a water only system and exposure in a watersediment system. In the water system studies, organisms were exposed to cypermethrin in overlying ( surface) water; no sediment was present in the test chamber. For studies conducted  59 using the water sediment system protocol, cypermethrin was applied to water sediment systems and allowed to settle for 2 days; organisms were introduced to the above water sediment systems, and toxicity was assessed after a 10 day exposure period. However, these studies present a degree of uncertainty because of the lack of equilibration of spiked sediments with the pore water ( e. g., equilibration should have occurred for at least one month). While compounds bound to the sediment present potential toxicity concerns, those residues that have reached equilibrium in the pore water are considered a greater source of toxic risk to benthic invertebrates ( Di Toro et al., 1991). Therefore the studies presented in this assessment may underestimate sediment toxicity. The registrant is currently conducting new sediment studies in order to address this uncertainty.

Two studies on cypermethrin TGAI were conducted using a water sediment system, one study with midge ( MRID 44074402) and one study with amphipod ( MRID 44074406). Both studies were conducted using the same protocol, as described above, using sediments from three sources ( Florissant, Mississippi, and Duluth). All toxicity values for these studies are expressed in terms of the concentration of cypermethrin in sediment (: g a. i./ kg) on Day 0. Measurement of cypermethrin in sediment and surface water on Days 0 and 10 of exposure indicates that the water sediment system was not at equilibrium, thus adding uncertainty to the results of these studies. Results yield 10 day LC 50 values ranging from 3.6 : g a. i./ kg sediment ( Florrisant sediment) in amphipods to 67 : g a. i./ kg sediment in midge ( Mississippi sediment). In general, toxicity decreased ( as reflected by higher LC 50 values), with increasing organic carbon content of the sediment. Taking the most conservative approach, the lowest 10 day LC 50 value of 3.6 : g a. i./ kg sediment in amphipods will be used to characterize the risk of acute exposure of benthic organisms to cypermethrin TGAI in sediment.

In order to assess the risk of acute exposure to benthic organisms to cypermethrin TGAI based on pore water concentrations, the equivalent toxicity value in pore water is derived using the lowest 10 day LC 50 value of 3.6 : g a. i./ kg sediment in amphipods as follows. The LC 50 value in whole sediment [ 3.6 µ g a. i./ kg sediment] is divided by the proportion of organic carbon ( OC) in the sediment [ 0.0099 kg OC/ kg whole sediment]. Thus, the LC 50 value in units of OC is 364 µ g a. i./ kg OC [ 3.6 µ g a. i./ kg sediment ÷ 0.0099 kg OC/ kg sediment]. The equivalent concentration in pore water is based on the definition of the K oc ,

K oc ( L/ kg OC) = Sediment Conc in OC ( mg/ kg OC) ÷ Conc in pore water ( mg/ L).

By rearrangement,

Conc in water = Sediment Conc in units of OC ÷ K oc .

For cypermethrin, the K oc is taken as 141,700 [ L/ kg OC] ( MRID 42129003). Thus, the calculated concentration in pore water corresponding to the LC 50 value of 364 µ g a. i./ kg OC is 0.00257 µ g a. i./ L pore water [ 364 µ g a. i./ kg OC ÷ 141,700 L/ kg OC]. To assess risk of acute exposure to benthic organisms to cypermethrin TGAI in terms of pore water concentrations, the derived LC 50 value of 0.00257 µ g a. i./ L pore water is used.

No toxicity tests on cypermethrin formulations or cypermethrin degradates in freshwater  60 benthic organisms were submitted.

( 2). Chronic Effects Freshwater Fish An early life stage study in fathead minnow was submitted by the registrant to establish the chronic toxicity of cypermethrin to freshwater fish ( MRID 89039); data are summarized in Appendix E, Table E 2. Results of this 30 day exposure study show that survival was significantly reduced compared to controls at 0.33 : g a. i./ L, yielding a 30 day NOAEC value for survival of 0.14 : g a. i./ L. No treatment related effects were observed for hatchability or growth. The NOAEC value for survival of 0.14 : g a. i./ L will be used to assess the risk of chronic exposure of freshwater fish to cypermethrin TGAI. No chronic toxicity studies of cypermethrin formulations or cypermethrin degradates in freshwater fish were submitted.

Freshwater Invertebrates No valid chronic toxicity studies on technical grade cypermethrin in freshwater invertebrates were submitted. The chronic NOAEC estimated for waterflea is based on the acuteto chronic ratio method, determined by the following mathematical relationship:

Estuarine/ marine invertebrate LC 50 ( 0.00475: g a. i./ L) / Estuarine/ marine invertebrate NOAEC ( 0.000781: g a. i./ L) = Freshwater invertebrate LC 50 ( 0.42 : g a. i./ L)/ X ( estimated value for Freshwater invertebrate NOAEC), where X = 0.069 : g a. i./ L.

To assess the risk of chronic exposure of freshwater invertebrates to cypermethrin TGAI, the estimated NOAEC for waterflea of 0.069 : g a. i./ L is used. No chronic toxicity studies of cypermethrin formulations or cypermethrin degradates in freshwater invertebrates were submitted.  61 Estuarine/ Marine Fish No valid chronic toxicity studies on technical grade cypermethrin in estuarine/ marine fish were submitted. The chronic NOAEC estimated for the sheepshead minnow is based on the acute to chronic ratio method, determined by the following mathematical relationship:

Freshwater LC 50 ( 0.39 : g a. i./ L) / Freshwater NOAEC ( 0.14: g a. i./ L) = Estuarine/ Marine LC 50 ( 0.95 : g a. i./ L)/ X ( estimated value for Estuarine/ Marine NOAEC), where X = 0.34 : g a. i./ L.

To assess the risk of chronic exposure of estuarine/ marine fish to cypermethrin TGAI, the estimated NOAEC for sheepshead minnow of 0.34 : g a. i./ L is used. No chronic toxicity studies of cypermethrin formulations or cypermethrin degradates in estuarine/ marine fish were submitted.

Estuarine/ Marine Invertebrates Three studies involving life cycle tests in mysid shrimp were submitted by the registrant to establish the chronic toxicity of cypermethrin to estuarine/ marine invertebrates; data are summarized in Appendix E, Table E 7. The NOAEC values reported in these studies range from 0.781 ng a. i./ L for effects on first generation mortality, male length and weight and female weight ( MRID 42725301), to 1.5 ng a. i./ L for number of offspring ( MRID 42444601) and survival and reproduction ( MRID 44546035). Taking the most conservative approach, the lowest NOAEC value of 0.781 ng a. i./ L will be used to characterize chronic risk to estuarine/ marine invertebrates. No chronic toxicity studies of cypermethrin formulations or cypermethrin degradates in estuarine/ marine invertebrates were submitted.

Benthic Organisms Chronic toxicity studies in benthic organisms were not submitted. To assess chronic risk to benthic organisms, chronic toxicity values were derived for both sediment and pore water. The chronic NOAEC estimated for benthic organisms in terms of µ g a. i./ kg sediment is based on the acute to chronic ratio method, determined by the following mathematical relationship:

Estuarine/ marine invertebrate LC 50 ( 0.00475: g a. i./ L) / Estuarine/ marine invertebrate NOAEC ( 0.000781: g a. i./ L) = Benthic LC 50 in sediment 3.6 µ g a. i./ kg sediment / X ( estimated benthic NOAEC value in sediment), where X = 0.59 : g a. i./ kg sediment.  62 The chronic NOAEC estimated for benthic organisms in units of µ g a. i./ kg pore water is based on the acute to chronic ratio method, determined by the following mathematical relationship:

Estuarine/ marine invertebrate LC 50 ( 0.00475: g a. i./ L) / Estuarine/ marine invertebrate NOAEC ( 0.000781: g a. i./ L) = Benthic LC 50 in pore water ( 0.00257 µ g a. i./ L / X ( estimated benthic NOAEC value in pore water ), where X = 0.00042 : g a. i./ L pore water. To assess chronic risk to benthic organisms, the estimated NOAEC values of 0.59 : g a. i./ kg sediment and 0.00042 : g a. i./ L pore water are used.

No chronic toxicity tests on cypermethrin formulations or cypermethrin degradates in freshwater benthic organisms were submitted.

( 3). Sublethal Effects Freshwater Fish In addition to lethality endpoints, sublethal effects of acute cypermethrin ( TGAI) exposure were assessed in studies in rainbow trout and bluegill sunfish. Study details are provided in Appendix E, Table E 1a. The sublethal signs of toxicity include rapid and erratic swimming, partial/ complete loss of equilibrium, jaw spasms, gulping respiration, lethargy, and darkened pigmentation. The acute NOAEC values for sublethal effects ranged from < 0.00068 : g a. i./ L in rainbow trout ( Acc. No. 241598) to 2.1 : g a. i./ L in bluegill sunfish ( MRID 44546030). For two studies, the acute NOAEC value for sublethal effects was several orders of magnitude lower than the LC 50 value; in rainbow trout, the acute NOAEC and LC 50 values were 0.00068 : g a. i./ L and 0.8 : g a. i./ L, respectively ( Acc. No. 241598), and in bluegill sunfish, the acute NOAEC and LC 50 values were < 0.0022 : g a. i./ L and 2.2 : g a. i./ L, respectively ( Acc. No. 241598). Thus, sublethal effects can occur at exposure levels far below the concentrations that cause lethality.

Similar sublethal effects were reported in an acute toxicity study in rainbow tout using the cypermethrin formulation GFU 070 ( 25.1% a. i.), with an acute NOAEC value of 1.15 : g formulation/ L ( MRID 88947). Acute toxicity studies on the cypermethrin degradate 3 phenoxybenzoic acid did not report sublethal effects.

Results of a chronic toxicity study in fathead minnow report that no significant treatmentrelated effects on hatchability or growth were observed during a 30 day exposure to technical grade cypermethrin ( MRID 89039). Thus, no sublethal effects were observed at concentrations up to 0.33 : g a. i./ L, the highest dose tested.

Freshwater Invertebrates The sublethal effects of acute cypermethrin ( TGAI) exposure were assessed in studies in waterflea. Study details are provided in Appendix E, Table E 3a. The sublethal signs of toxicity include immobilization and decreased movement in response to stimulation. Acute NOAEC values for sublethal effects range from 0.085 : g a. i./ L ( MRID 44546032) to 0.14 : g a. i./ L ( MRID 44546031).  63 Similar sublethal effects were reported following acute exposure to cypermethrin formulations ( Appendix E, Table E 3b), however, acute NOAEC values were not reported. Acute toxicity studies on the cypermethrin degradate 3 phenoxy benzoic acid did not report sublethal effects ( Appendix E, Table E 3c). No valid chronic toxicity studies in freshwater invertebrates were submitted. Thus, no information is available regarding the sublethal effects of chronic exposure.

Estuarine/ Marine Fish Sublethal effects of acute cypermethrin exposure in estuarine/ marine fish ( loss of equilibrium and lethargy) were reported in two studies of sheepshead minnow ( Appendix E, Table E 5). Acute NOAEC values for sublethal effects ranged from 0.84 : g a. i./ L ( MRID 44546034) to 1.4 : g a. i./ L ( MRID 44546034) and are approximately 2 to 3 fold lower than the corresponding LC 50 values of 2.7 and 2.4 : g a. i./ L, respectively. No valid chronic toxicity studies on technical grade cypermethrin, cypermethrin formulations, or cypermethrin degradates in estuarine/ marine fish were submitted. Thus, no information is available regarding the sublethal effects of chronic exposure.

Estuarine/ Marine Invertebrates Sublethal effects ( lethargy, erratic swimming behavior, loss of equilibrium, and surfacing) of cypermethrin TGAI in estuarine/ marine invertebrates were reported in two studies of mysid shrimp ( Appendix E, Table E 6). Acute NOAEC values for sublethal effects range from 1.7 ng a. i./ L ( MRID 44561210) to 2.3 ng a. i./ L ( MRID 44561209) and are approximately 2 to 3 fold lower than the corresponding LC 50 values of 5.5 and 5.9 ng a. i./ L, respectively.

Results of chronic toxicity studies in mysid shrimp show that exposure to technical grade cypermethrin had adverse effects on reproductive and growth parameters; study details are provided in Appendix E, Table E 7. For decreased number of young, a chronic NOAEC value of 1.5 ng a. i./ L was reported in two studies ( Acc. No. 42444601, MRID 44546035). For decreased growth and length, the chronic NOAEC value reported is 0.781 ng a. i./ L ( MRID 42725301). No chronic toxicity studies of cypermethrin formulations or cypermethrin degradates in estuarine/ marine invertebrates were submitted.

Benthic Organisms Acute toxicity tests using the water sediment system ( Appendix E, Table E 5) report decreased growth ( length and dry weight) in both amphipod ( MRID 44074406) and midge ( MRID 44074402). Acute NOAEC values range from < 1.8 : g a. i./ kg sediment in amphipod ( Florrisant sediment) and 25 : g a. i./ kg sediment in midge ( Mississippi sediment). Acute toxicity studies in benthic organisms using the water only system did not specifically report sublethal effects resulting from cypermethrin exposure. No valid chronic toxicity studies on technical grade cypermethrin, cypermethrin formulations, or cypermethrin degradates in benthic organisms were submitted. Thus, no information is available regarding the sublethal effects of chronic exposure.

( 4). Field Studies Several aquatic field studies on the effects of cypermethrin formulations have been  64 reviewed for this risk assessment. Results are summarized in Appendix E, Table E 8. Data from field studies were obtained from studies submitted by the registrant and from open literature studies identified from searches of the ECOTOX database. Results of these studies provide information on the effects of cypermethrin on fish and invertebrates ( including benthic organisms) in freshwater aquatic environments. However, due to the variability in experimental techniques and methodologies and the lack of rigorous monitoring of water and sediment concentrations of cypermethrin, results of these studies are not sufficient for use in quantitative assessments. Thus, information provided in these studies will be used qualitatively for this assessment.

Freshwater Fish Data from field studies on the effects of cypermethrin on fish were obtained from three registrant submitted studies ( MRID 155770, MRID 155772, MRID 152737,) and two openliterature studies ( Crossland et al., 1982; Davies and Cook, 1993). Results of the registrantsubmitted studies using single applications of cypermethrin at rates ranging from 0.0012 lb a. i/ A ( MRID 152737) to 0.089 lb a. i./ A ( MRID 155770) show no lethal or sublethal effects on fish populations. In the open literature studies, application rates ranged from 0.011 lb a. i./ A ( Davies and Cook, 1993) to 0.0623 lb a. i./ A ( Crossland et al., 1982). Although no adverse effects were observed on fish populations at the higher application rate of 0.0623 lb a. i./ A, sublethal effects ( including loss of equilibrium, lethargy, and muscle tetany) were reported following single application of 0.011 lb a. i./ A ( Davies and Cook, 1993). In this study, sublethal effects were observed for 8 days following application and were attributed, in part, to exposure to cypermethrin from ingestion of dead and dying invertebrates.

Freshwater Invertebrates and Benthic Organisms In field studies assessing the effects of cypermethrin on aquatic invertebrates and benthic populations, results range from no observable effects to catastrophic drift and profound decreases in population diversity and abundance. For studies reporting no adverse effects on macroinvertebrate populations ( Acc. No. 250506, Supplemental; MRID 155772, application rates range from a single application of 0.0623 lb a. i./ A ( MRID 155772) to repeated applications of 0.126 lb a. i./ A ( 6 applications at 5 day intervals to cotton fields) ( Acc. No. 250506). However, results of several field studies show that exposure to cypermethrin at application rates ranging from 0.00025 lb a. i./ A ( Mulla et al. 1978) to 0.125 lb a. i./ A ( Acc. No. 250506; Supplemental) causes significant decreases is abundance and diversity of aquatic invertebrate populations. Effects include catastrophic drift within 0 90 minutes after application of cypermethrin ( Crossland et al., 1982; Farmer et. al., 1995; Moshen and Mulla, 1982), and decreased abundance and diversity of macroinvertebrates over a longer time period ( several weeks to several months ( MRID 155770; MRID 152737; Farmer et al., 1995; Kedwards et al., 1999a, b; Mulla et al., 1978; Mulla et al., 1982). In some cases, recovery of individual species was rapid ( MRID 155770; Kedwards et al., 1999a, b); however, for other species, recovery did not occur for several months ( Kedwards et al., 1999b; Davies and Cook, 1993).

a. Residue Monitoring ( non agricultural)  65 Weston et al., ( 2005) recently completed monitoring of water courses draining residential areas ( Roseville, Placer County, Califorinia) for pyrethroid residues and effects. The suburban development is situated adjacent to several creeks that drain the sudivisions. Weston's findings showed that nearly all creek sediments collected caused toxicity to the amphipod Hyallella azteca with about half of these samples causing complete mortality to the test organisms. Although the pyrethroid bifenthrin was implicated as the prime cause of toxicity, additional contributions to toxicity also occurred from cypermethrin and cyfluthrin. All of these pyrethroids are used in lawn care ( bifenthrin, cyfluthrin) and structural pest control ( cypermethrin, cyfluthrin, bifenthrin) which can account for residue runoff to these adjacent water bodies. In 2003 information from professional applicators in Placer County show that cypermethrin accounted for about 75% of the structural pest control which include below ground use as termidicides. Although this type of application lessens the likelihood of runoff, the product is also registered for above ground application which may account for cypermethrin residues in the samples. The uncertainty brought out by this study presents the question of whether this situation is unique to Roseville, California or possible representative of suburban systems in general.

b. Plants Inhabiting Aquatic Areas No data were submitted to evaluate the effects of cypermethrin exposure to non target plants inhabiting aquatic areas. However the Agency does not consider cypermethrin or the other pyrethroids as being phytotoxic for the following reasons: 1) the compound is used as a spray on agricultural crops with no phytotoxic effects; 2) the neural toxic mode of action precludes phytotoxic concerns; 3) the Agency is not aware of any incidents involving plants and cypermethrin alone.

2. Terrestrial Effects Characterization The most sensitive acute and chronic toxicity reference values associated with cypermethrin exposure to mammals and birds are summarized in Table 13. A more detailed summary of the terrestrial toxicity data available to characterize risks associated with cypermethrin applications is given in Appendix E. Based on the results of acute oral and acute dietary toxicity studies in birds, cypermethrin is categorized as practically non toxic and slightly toxic, respectively. In mammals, results of acute exposure studies indicate that cypermethrin is moderately toxic. Results of available toxicity studies indicate that cypermethrin is highly toxic to honey bees and very toxic to earthworms on an acute contact basis. Thus, honey bees and nontarget insects are expected to be the species at risk for acute effects ( lethality). Although cypermethrin exposure does not appear to cause chronic toxicity to birds, there is uncertainty regarding levels above 50 ppm. There is a concern for chronic risk to mammals, based on parental toxicity and toxicity to offspring ( decreased body weight and body weight gain).  66 Table 13. Cypermethrin Toxicity Reference Values ( TRVs) for Terrestrial Organisms.

Exposure Scenario Species Exposure Duration Toxicity Reference Value Reference Mammals Acute ( Dose based) rat single oral dose LD50 ( M): 247 mg/ kg MRID 00056800 Chronic ( Dietary based and Dose based) rat 3 generation reproduction study NOAEL ( toxicity to parents and offspring) = 5 mg/ kg/ day [ equivalent to dietary concentration of 100 ppm diet] MRID 00090040 Birds Acute ( Dose based) bobwhite quail single oral dose LD50 > 2,000 mg a. i./ kg body wt MRID 44546024 Acute ( Dietary based) mallard duck 5 day dietary LC50 > 20,000 mg a. i./ kg diet MRID 90071 Chronic ( Dietary based) mallard duck and bobwhite quail Avian reproduction study ( dietary exposure) NOAEC > 50 mg a. i./ kg diet MRID 90072 MRID 90074 a. Terrestrial Animals ( 1). Acute Effects Birds Acute toxicity studies on technical grade cypermethrin have been conducted with bobwhite quail and mallard ducks; results are summarized in Appendix E, Tables E 9 and E 10. Results of acute oral toxicity studies in mallard ducks ( Acc. No. 241598 ) and bobwhite quail ( MRID 44546024) yield LD 50 values of > 9,520 and > 2,000 mg a. i./ kg body weight, respectively, indicating that cypermethrin is practically non toxic to birds on an acute oral basis. Results of acute dietary toxicity studies in mallard ducks and bobwhite quail yield LC 50 values ranging from> 20,000 mg a. i./ kg diet in mallard ducks ( MRID 90071) to > 5,290 mg a. i./ kg diet in mallard ducks ( MRID 44546025) and bobwhite quail ( MRID 44546026), indicating that cypermethrin is categorized as practically non toxic to slightly toxic on an acute dietary basis. To assess acute risk of cypermethrin to birds, the lowest acute oral LD 50 value of > 2,000 mg a. i./ kg body weight and the lowest acute dietary LC 50 value of > 20,000 mg a. i./ kg diet are used.  67 No acute toxicity studies of cypermethrin formulations or cypermethrin degradates in avian species were submitted.

Mammals Results of an acute oral toxicity study in rats administered single doses of cypermethrin TGAI yield LD 50 values of 247 mg a. i./ kg body wt in males and 309 mg a. i./ kg body weight in females ( MRID 00056800). Results are summarized in Appendix E, Table E 12. Based on these results, cypermethrin TGAI is classified as moderately toxic to mammals. The lowest oral LD 50 of 247 mg a. i./ kg body weight is used to assess acute risk in mammals.

No acute toxicity studies of cypermethrin formulations or cypermethrin degradates in mammals were submitted.

Terrestrial Invertebrates Results of an acute contact study in honey bees using technical grade cypermethrin yield a 48 hour LD 50 value of 0.023 : g a. i./ bee, categorizing cypermethrin as highly toxic to honey bees ( Acc. No. 260647). Results are summarized in Appendix E, Table E 13a. In an oral exposure study in honey bees, a LD 50 value of 0.172 : g a. i./ bee was reported ( Acc. No. 260647). Similar results were obtained from acute contact studies using cypermethrin formulations, with LD 50 values ranging from 0.088 : g a. i./ bee ( Acc. No. 260647) for the cypermethrin formulation GFU 061 to 0.13 : g formulation/ bee for a formulation containing betacypermethrin (% a. i. not specified) ( MRID 44544208; Appendix E, Table E 13b).

An acute contact study in earthworms was identified from an open literature study ( Roberts and Dorough 1984; Appendix E, Table E 14). Results of this study yield a 48 hour contact LC 50 value of 26.09 : g a. i./ cm2 for cypermethrin applied to filter paper, categorizing cypermethrin as very toxic to earthworms.

No acute toxicity studies of cypermethrin degradates in terrestrial invertebrates were submitted.  68 ( 2). Chronic Effects Birds One generation reproductive studies were submitted for mallard ducks ( MRID 90073) and bobwhite quail ( MRID 90074). Results of both studies show no treatment related effects on adults, reproductive parameters, or offspring, as a result of cypermethrin exposure at dietary concentrations up to 50 mg a. i./ kg diet ( the highest dose tested). Since a LOAEC was not established there is uncertainty regarding the NOAEC especially for exposure levels above 50 ppm. As a comparison, the Agency evaluated another pyrethroid, permethrin, for chronic avian toxicity and noted that the NOAEC/ LOAEC were 125/ 500 ppm.

No chronic toxicity studies of cypermethrin formulations or cypermethrin degradates in avian species were submitted.

Mammals Results of 3 generation reproduction studies in rats show that exposure to technical grade cypermethrin results in decreased body weight and decreased body weight gain in both adults and offspring, with NOAELs ranging from 100 mg a. i./ kg diet ( equivalent to 5 mg a. i./ kg body weight/ day) ( MRID 00090040) to 150 mg a. i./ kg diet ( equivalent to 7.5 mg a. i./ kg body weight/ day) ( MRIDs 00112912, 42068504, 9202704). No other treatment related effects on reproductive parameters were reported in these studies. To assess chronic risk to mammalian species, the lowest NOAEL value of 150 mg a. i./ kg diet ( equivalent to 7.5 mg a. i./ kg body weight/ day) is used. Details are summarized in Appendix E, Table E 12.

No chronic toxicity studies of cypermethrin formulations or cypermethrin degradates in mammalian species were submitted.

Terrestrial Invertebrates No chronic toxicity studies of technical grade cypermethrin, cypermethrin formulations or cypermethrin degradates in terrestrial invertebrates were submitted.

( 3). Sublethal Effects Birds Acute toxicity studies in birds report aversion to feed containing cypermethrin at concentrations greater than approximately 2,000 mg a. i./ kg diet ( MRID 44546025, MRID 44546026). In addition, reductions in body weight, which may have been caused by aversion to feed, were reported, with NOAEC values ranging from 1290 to 2550 mg a. i./ kg diet. No other gross pathological findings, clinical signs of toxicity, or adverse effects on reproductive parameters or offspring were reported in the submitted acute and chronic toxicity studies in avian species.  69 Mammals Exposure of rats to a single dose of cypermethrin produced clinical signs of neurotoxicity and abnormal gait. Results of chronic toxicity studies show that exposure to technical grade cypermethrin results in decreased body weight and decreased body weight gain in both adults and offspring, with NOAELs ranging from 100 mg a. i./ kg diet ( equivalent to 5 mg a. i./ kg body weight/ day) ( MRID 00090040) to 150 mg a. i./ kg diet ( equivalent to 7.5 mg a. i./ kg body weight/ day) ( MRIDs 00112912, 42068504, 9202704). No treatment related effects on reproductive parameters were reported in these studies.

Terrestrial Invertebrates No information on sublethal effects of cypermethrin on terrestrial invertebrates was reported in the available studies in honey bees and earthworms.

( 4). Field Studies No field studies on the effects of cypermethrin on terrestrial organisms were submitted.

b. Terrestrial Plants No data were submitted to evaluate the effects of cypermethrin exposure to non target terrestrial plants or terrestrial plants inhabiting semi aquatic areas. However, cypermethrin as well as other pyrethroids have been used on agricultural crops without any phytotoxic effects. The neural effects caused by pyrethroids appears to be a mode of action that does not trigger a toxic response in plants.

IV. Risk Characterization Risk characterization is the integration of exposure and effects characterization to determine the ecological risk from the use of cypermethrin and the likelihood of effects on aquatic life and wildlife based on varying pesticide use scenarios. The risk characterization provides an estimation and a description of the risk; articulates risk assessment assumptions, limitations, and uncertainties; synthesizes an overall conclusion; and provides the risk managers with information to make regulatory decisions.

A. Risk Estimation  Integration of Exposure and Effects Data Results of the exposure and toxicity effects data are used to evaluate the likelihood of adverse ecological effects on non target species. For the assessment of cypermethrin risks, the risk quotient ( RQ) method is used to compare exposure and measured toxicity values ( see Appendix F). Estimated environmental concentrations ( EECs) are divided by acute and chronic toxicity values. The resulting RQs are then compared to the Agency's levels of concern ( LOCs). These LOCs, summarized in Appendix F, are the Agency's interpretive policy used to analyze potential risk to non target organisms and the need to consider regulatory action. For non target aquatic animals ( i. e., fish and invertebrates), surface water, pore water, and sediment EECs were  70 obtained from the Tier 2 model PRZM/ EXAMS ( see Tables 7 9). For non target terrestrial animals ( i. e., birds and mammals), EECs and RQs were obtained from T REX ( see Appendix D). Toxicity reference values for aquatic and terrestrial organisms exposed to cypermethrin are summarized in Table 12 and Table 13, respectively. Details of all RQs are provided in Appendix G.

1. Non Target Aquatic Animals and Plants To assess risks of cypermethrin to non target aquatic animals ( i. e., fish and invertebrates), surface water, pore water, and sediment EECs were obtained from the Tier II model PRZM/ EXAMS ( see Tables 7 9). The PRZM/ EXAMS model was run using the following six scenarios: California cotton, Mississippi cotton, North Carolina cotton, Texas cotton, Georgia pecans, and California lettuce ( head). EFED uses the peak concentration to derive RQs for acute exposure and the 21 day average concentration to derive RQs for chronic exposure. Since results of acute toxicity studies in freshwater fish and invertebrates ( See Appendix E, Tables E 1c and E 3c) indicate that the major cypermethrin degradate ( 3 phenoxy benzoic acid) is much less toxic than the parent compound, EECs and RQs were derived only for the parent compound, not for total residue ( parent plus degradates). The major biodegradation degradates: 3 PBA, cis and trans DCVA and 3 phenoxybenzaldehyde, are the result of the cleavage of the ester moiety of the parent compound.

a. Water Column Exposure  Acute and Chronic Risk Acute RQs for aquatic animals are summarized in Table 14. The LOC for acute risk ( LOC 0.5) is exceeded for all aquatic animals and modeled crop scenarios, except CA cotton for freshwater invertebrates and estuarine/ marine fish, and CA lettuce for estuarine/ marine fish. LOCs for acute restricted use ( LOC 0.1) and acute listed risk ( LOC 0.05) are exceeded for freshwater and estuarine/ marine fish and invertebrates for all six crop scenarios considered in this assessment, The highest acute RQs are observed for estuarine/ marine invertebrates, ranging from 37 ( CA cotton) to 423 ( NC cotton), greatly exceeding all acute LOCs. As discussed previously ( Section III. C), based on comparison of acute LC 50 values, estuarine/ marine invertebrates appear to be the most sensitive aquatic animal. Thus, acute RQ values derived for estuarine/ marine invertebrates are much higher than those derived for the other aquatic animals. Because acute toxicity values for freshwater fish, freshwater invertebrates, and estuarine/ marine invertebrates are similar in magnitude, the ranges of acute RQs for these species are also similar ( 0.5 to 5.2 for freshwater fish, 0.4 to 4.8 for freshwater invertebrates, and 0.2 to 2.1 for estuarine/ marine fish). For all aquatic animal species, the highest acute RQs are observed for the NC cotton scenario, and the lowest acute RQs are observed for the CA lettuce scenario. This trend reflects the same trend of the values of the EECs, which are used in the calculation of the RQs ( see Tables 7 to 9).  71 Table 14. Acute RQs for Freshwater Fish, Freshwater Invertebrates, Estuarine/ Marine Fish and Estuarine/ Marine Invertebrates Exposed to Cypermethrin. a Crop Use PRZM/ EXAMS Scenario Freshwater Fish Acute RQ Freshwater Invertebrate Acute RQ Estuarine/ Marine Fish Acute RQ Estuarine/ Marine Invertebrate Acute RQ Cotton California 0.5 b, c, d 0.4 c, d 0.2 c, d 37 b, c, d Mississippi 3.3 b, c, d 3.0 b, c, d 1.3 b, c, d 269 b, c, d North Carolina 5.2 b, c, d 4.8 b, c, d 2.1 b, c, d 423 b, c Texas 1.3 b, c, d 1.2 b, c, d 0.5 b, c, d 104 b, c, d Pecans Georgia 2.4 b, c, d 2.3 b, c, d 1.0 b, c, d 201 b, c, d Lettuce ( Head) California 0.7 b, c, d 0.69 b, c, d 0.3 c, d 61 b, c, d a RQs = EEC/ LC50, where EECs are the peak concentrations in surface water generated from PRZM/ EXAMS, and acute toxicity reference values are as follows: freshwater fish, rainbow trout 96 hr LC50 = 0.39 : g a. i./ L; freshwater invertebrates, Daphnia 48 hr EC50 = 0.42 : g a. i./ L; estuarine/ marine fish, sheepshead minnow 96 hour LC50 = 0.95 : g a. i./ L; and estuarine/ marine invertebrates mysid shrimp 96 hour LC50 = 0.00475 : g a. i./ L. b RQs meet or exceed LOC for acute risk ( LOC 0.5). c RQs meet or exceed LOC for acute restricted use ( LOC 0.1). d RQs meet or exceed LOC for acute listed species ( LOC 0.05).

Chronic RQs for aquatic animals are summarized in Table 15. For estuarine/ marine invertebrates, chronic RQs exceed the chronic LOC ( LOC 1) by factors ranging from 44 to 246. As discussed earlier ( Section III. C), results from chronic toxicity studies indicate that estuarine/ marine invertebrates are far more sensitive to chronic cypermethrin exposure than other species of aquatic animals. Thus, as anticipated, chronic RQs derived for estuarine/ marine invertebrates are much higher than those derived for other aquatic animals. For freshwater fish, RQs range from 0.1 to 0.7. Due to data gaps for chronic toxicity studies for freshwater invertebrates and estuarine/ marine fish, chronic RQs are based on estimated chronic toxicity values ( detailed description provided in Section III. C), adding considerable uncertainty to chronic risk estimates. For freshwater invertebrates, chronic RQs range from 0.5 to 2.8, exceeding the chronic LOC for four of the six crop scenarios. For freshwater and estuarine/ marine fish, all chronic RQs are below the chronic LOC.  72 Table 15. Chronic RQs for Freshwater Fish, Freshwater Invertebrates, Estuarine/ Marine Fish and Estuarine/ Marine Invertebrates Exposed to Cypermethrin. a Crop Use PRZM/ EXAMS Scenario Freshwater Fish Chronic RQ Freshwater Invertebrate Chronic RQ Estuarine/ Marine Fish Chronic RQ Estuarine/ Marine Invertebrate Chronic RQ Cotton California 0.2 0.8 0.1 70 b Mississippi 0.7 2.7 b 0.3 241 b North Carolina 0.7 2.8 b 0.3 246 b Texas 0.2 0.9 b 0.1 77 b Pecans Georgia 0.3 1.2b 0.1 110b Lettuce ( Head) California 0.1 0.5 0.1 44 b a RQs = EEC/ NOAEC, where EECs are the 21 day average concentration in surface water generated from PRZM/ EXAMS is used to calculate chronic RQs for invertebrates. The 60 day PRZM/ EXAMS output was used to calculate potential chronic RQs for fish. TRVe values are as follows: freshwater fish, fathead minnow 28 day NOAEC = 0.14 : g a. i./ L; freshwater invertebrates, estimated chronic NOAEC = 0.069 : g a. i./ L; estuarine/ marine fish, estimated chronic NOAEC = 0.34 : g a. i./ L; and estuarine/ marine invertebrates, mysid shrimp 28 day NOAEC = 0.0.000781 : g a. i./ L. Details for all estimated chronic toxicity values are provided in Section III. C. b RQs exceed LOCs for chronic risk ( LOC 1).

b. Sediment Exposure  Acute and Chronic Risk Acute and chronic RQs have been derived for exposure of benthic organisms via sediment and pore water ( Table 16). All acute and chronic RQs for benthic organisms exceed the LOCs for acute risk ( LOC 0.5), acute restricted use ( LOC 0.1), acute listed risk ( LOC 0.05) and chronic risk ( LOC 1) for all modeled crop uses. There are several uncertainties regarding both acute and chronic RQs. Due to data gaps, acute RQs for pore water and chronic RQs for sediment and pore water were derived from estimated toxicity values based on the acute sediment toxicity value ( details provided in Section III. C). However, there is considerable uncertainty surrounding the acute sediment toxicity value, since this value was obtained from a study using a water sediment system that was not at equilibrium ( sediment concentrations decreased throughout the exposure period).  73 Table 16. Acute and Chronic RQs for Benthic Organisms Exposed to Cypermethrin.

Crop Use PRZM/ EXAMS Scenario Sediment Acute RQ a, e Pore Water Acute RQ b, e Sediment Chronic RQ c, e Pore Water Chronic RQ d, e Cotton California 7 2 35 9 Mississippi 44 11 228 57 North Carolina 48 12 244 60 Texas 13 3 52 13 Pecans Georgia 26 7 123 31 Lettuce ( Head) California 8 2 47 12 a Sediment acute RQs = EEC/ LC50, where EECs are the peak concentration in sediment generated from PRZM/ EXAMS and acute toxicity reference value is the amphipod 10 day LC50 = 3.6 : g a. i./ kg sediment b Pore water acute RQs = EEC/ LC50, where EECs are the peak concentration in pore water from PRZM/ EXAMS and estimated acuteLC50 = 0.00257 : g a. i./ L pore water ( details for estimated toxicity value are provided in Section III. C). c Sediment chronic RQs = EEC/ NOAEC, where EECs are the 21 day average concentration in sediment from PRZM/ EXAMS and estimated chronic NOAEC = 0.59 : g a. i./ kg sediment ( details for estimated toxicity value are provided in Section III. C). d Pore water chronic RQs = EEC/ NOAEC, where EECs are the 21 day average concentration in pore water from PRZM/ EXAMS and estimated chronic NOAEC = 0.00042 : g a. i./ L pore water ( details for estimated toxicity value are provided in Section III. C). e All RQs exceed LOCs for acute risk ( LOC 0.5), acute restricted use ( LOC 0.1), acute listed species ( LOC 0.05), and chronic risk ( LOC 1).

c. Use of Buffer Zones For the Spray Drift/ Buffer Zone Analysis, risk quotients were calculated for the most sensitive species on an acute basis. The peak EEC is the EEC most sensitive to the changes to the values of spray drift.  74 Supplementary Table H. Acute Risk Quotients for Estuarine/ Marine Invertebrates Using Different Buffer Zones and Levels of Spray Drift. Peak Surface Water Concentrations, EECs ( ppb) for Ecological Risk Assessment, Based on NC cotton ( surrogate scenario for estuarine/ marine environments). Use of Most Sensitive Species, Estuarine/ Marine Invertebrate ( Mysid Shrimp) LC50 = 0.00475 ppb ( special runs).

Buffer Zone ( ft) Typical drift scenario, release height 10 ft, wind speed 10 mph, ASAE fine to medium droplets ( EECs)

% drift peak ( ppb) RQ reference run 0 std. ground applic 1, 99% app. effic. 2.292 483 ( 1,2,3)

std. aerial applic. 5 2.385 502 ( 1,2,3)

For run with 0% drift, an RQ is not calculated because it is only a hypothetical run, not likely to happen in the field. Risk Presumption 1. Acute High Risk $ 0.5 2. Acute Restricted Use $ 0.1 3. Acute Endangered Species $ 0.01 Supplementary Table I. Acute Risk Quotients for Estuarine/ Marine Invertebrates Using Different Buffer Zones and Levels of Spray Drift. Peak Surface Water Concentrations, EECs ( ppb) for Ecological Risk Assessment, Based on NC cotton ( surrogate scenario for estuarine/ marine environments). Use of Most Sensitive Species, Estuarine/ Marine Invertebrate ( Mysid Shrimp) LC50 = 0.00475 ppb ( Buffer Zone Runs).

Buffer Zone ( ft) Low end drift scenario, release height 8 ft, wind speed 3 mph, ASAE medium to coarse droplets ( EECs) Typical drift scenario, release height 10 ft, wind speed 10 mph, ASAE fine to medium droplets ( EECs) High end ( very conservative) drift scenario, release height 15 ft, wind speed 15 mph, ASAE very fine droplets ( EECs)

% drift peak ( ppb) RQ( 1,2,3) % drift peak ( ppb) RQ( 1,2,3) % drift peak ( ppb) RQ( 1,2,3)

0 2.8 2.284 481 13.0 2.737 575 35.9 3.676 774 100 0.9 2.196 462 5.5 2.408 506 21.9 3.104 653 1504 0.6 2.183 459 4.3 2.352 495 18.9 2.980 627 200 0.5 2.178 459 3.6 2.320 488 16.1 2.865 603 Risk Presumption 1. Acute High Risk $ 0.5 2. Acute Restricted Use $ 0.1 3. Acute Endangered Species $ 0.01 4. 150 ft is the current buffer zone imposed in the label for aerial applications.

Using the NC cotton scenario as a surrogate for estuarine/ marine scenario and using the most sensitive species of estuarine/ marine invertebrates ( Mysid Shrimp), all the acute RQs exceed all the LOCs ( acute high risk, acute restricted use and acute endangered species). The trends in the  75 RQs are the same described earlier for the EECs because the RQs are directly proportional to the EECs. The RQs were higher for the high end drift scenario and for the smaller buffer zones. It is noted that even using a ground application, the corresponding RQ is about 966X the LOC for the acute high risk. Using the 150 ft. buffer zone imposed in the label, with the typical drift scenario, the RQ ( 495) is around 990X the LOC for the acute high risk. With the more conservative scenario, the RQ can increase to 627 ( or around 1254X the LOC for the acute high risk). If stringent measures of caution are taken, and the low end drift scenario is used, the RQ decreases only to 459 ( or around 918X the LOC for the acute high risk). For the typical drift scenario, if the buffer zone is increased from 150 ft to 200 ft, the RQ decreases from 495 to 488 ( only about 1%). The NC cotton scenario has a relatively small component of drift; however, other PRZM scenarios may have larger components of drift and the effect of the buffer zones may be more important.

d. Aquatic Plants No toxicity data in the effects of cypermethrin on aquatic plants are available; thus RQs cannot be derived.

2. Non Target Terrestrial Animals To assess risks of cypermethrin to non target birds and mammals, EECs and acute and chronic RQs for residues on various forage categories ( short grass, tall grass. broadleaf plants/ small insects, fruits/ pods/ large insects, and seeds) were obtained from the Tier I model TREX for four crop uses: cotton, lettuce, pecans, and canola.

For birds, acute RQs are derived using dose based and dietary based acute toxicity values, and chronic RQs are derived using a dietary based chronic toxicity value. For mammals, acute RQs are derived using a dose based acute toxicity value, and chronic RQs are derived using a dietary based chronic toxicity value and a calculated dose based chronic toxicity value ( the dietary based chronic toxicity value is converted to a dose based chronic toxicity value using the standard FDA lab rat conversion by T REX).

Dietary based RQs are calculated using EECs expressed in terms of residue concentration for the various forage categories, and toxicity values ( LC 50 or NOAEC) are expressed in units of dietary concentration. Dose based RQs are calculated using a body weight adjusted LD 50 and consumption weighted equivalent dose sorted by food source and body size. For both birds and mammals, three weight categories ( or sizes) are considered.

a. Acute Risk to Mammals and Birds Dose based and dietary based acute RQs for birds are summarized in Table 17. All dosebased and dietary based avian acute RQs are below the LOCs for acute risk ( LOC 0.5), acute restricted use ( LOC 0.2), and acute listed risk ( LOC 0.1). The highest acute RQs are associated with application of cypermethrin to cotton, with RQs ranging from 0.001 ( a 1000 g bird feeding on fruits/ pods/ large insects) to 0.05 ( 20 g bird feeding on short grass). For birds, acute RQs are  76 less than the reported value, since the available acute toxicity studies did not establish acute LC 50 and LC 50 values ( toxicity values are reported as " greater than" the highest dose/ concentration tested). However, since all avian acute RQs are well below LOCs for acute risks, this uncertainty does not affect the acute avian risk characterization.

Dose based acute RQs for mammals are summarized in Table 18. All acute RQs are below the LOC for acute risk ( LOC 0.5) and acute restricted use ( LOC 0.2) for all crop uses. However, the acute listed LOC ( 0.1) is exceeded by two RQs associated with use of cypermethrin on cotton: 15 gram mammals feeding on short grass ( RQ 0.12) and 35 gram mammals feeding on short grass ( RQ 0.10).  77 Table 17. Dose based Acute RQs a and Dietary based Acute RQs b for Birds Exposed to Cypermethrin Based on Upper Bound Residues as Calculated by T REX.

Crop Use Body Weight ( g) Avian Risk Quotients c Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/ Pods/ Large Insects Dose based Acute Avian RQs Cotton 20 < 0.02 < 0.01 < 0.01 0.000 100 < 0.01 0.00 0.00 0.000 1000 0.00 0.00 0.00 0.000 Lettuce 20 < 0.02 < 0.01 < 0.01 0.000 100 < 0.01 0.00 0.00 0.000 1000 0.00 0.00 0.00 0.000 Pecans 20 < 0.02 < 0.01 < 0.01 0.000 100 < 0.01 0.00 0.00 0.000 1000 0.00 0.00 0.00 0.000 Canola 20 < 0.02 < 0.01 < 0.01 0.000 100 < 0.01 0.00 0.00 0.000 1000 0.00 0.00 0.00 0.000 Dietary based Acute Avian RQs Cotton 0.0 0.0 0.00 0.000 Lettuce 0.0 0.0 0.00 0.000 Pecans 0.0 0.0 0.00 0.000 Canola 0.0 0.0 0.00 0.000 a Acute dose based RQ = EEC/ LD50, where EEC values are upper bound residues expressed as equivalent dose ( mg a. i./ kg body weight) generated from T REX and the toxicity value is the acute dose based LD50 > 2,000 mg a. i./ kg diet in bobwhite quail. See Appendix D for full T REX output. b Acute dietary based RQ = EEC/ LC50, where EEC values are upper bound residues expressed as dietary concentrations ( mg a. i./ kg diet) generated from T REX and the toxicity value is the acute dietary based LC50 > 20,000 mg a. i./ kg diet in mallard ducks. See Appendix D for full T REX output. c All RQs are below the LOC for acute risk ( LOC 0.5), acute restricted use ( LOC 0.2), and acute listed species ( LOC 0.1).  78 Table 18. Dose based Acute RQs a for Mammals Exposed to Cypermethrin Based on Upper Bound Residues as Calculated by T REX.

Crop Use Body Weight ( g) Mammalian Acute Risk Quotients Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/ Pods/ Large Insects Seeds Cotton 15 0.23c, d 0.11d 0.13d 0.01 0.000 35 0.20cd 0.09 0.11d 0.01 0.000 1000 0.1d 0.05 0.06 0.010 0.000 Lettuce 15 0.04 0.02 0.02 0.00 0.000 35 0.04 0.02 0.02 0.00 0.000 1000 0.02 0.01 0.01 0.000 0.000 Pecans 15 0.04 0.02 0.02 0.00 0.000 35 0.04 0.02 0.02 0.00 0.000 1000 0.02 0.01 0.01 0.000 0.000 Canola 15 0.04 0.02 0.02 0.00 0.000 35 0.04 0.02 0.02 0.00 0.000 1000 0.02 0.01 0.01 0.000 0.000 a Acute dose based RQ = EEC/ LD50, where EEC values are upper bound residues expressed as equivalent dose ( mg a. i./ kg body weight) generated from T REX and the toxicity value is the acute dose based LD50 = 247 mg a. i./ kg body weight in rats. See Appendix D for full T REX output. b RQs meet or exceed the LOCs for acute risk ( LOC 0.5) c RQs meet or exceed acute restricted use ( LOC 0.2) d RQs meet or exceed the LOC for acute listed species ( LOC 0.1).

b. Chronic Risk to Mammals and Birds Dietary based chronic RQs for birds are summarized in Table 19. Chronic RQs for birds are below the LOC for chronic risk ( LOC 1), except for one exposure scenario ( birds feeding on short grass for application of cypermethrin to cotton, RQ < 2.65). Chronic RQs for birds range from 0.03 to< 2.65. However, since the chronic toxicity value used to derive chronic avian RQs was reported as " greater than" the highest dietary concentration tested ( i. e., a true chronic NOAEC was not established), chronic RQs are actually lower than those reported. Thus, this assessment may overestimate chronic risks to birds.  79 Table 19. Dietary based Chronic RQs for Birds Exposed to Cypermethrin Based on Upper Bound Residues as Calculated by T REX.

Crop Use Avian Chronic Risk Quotients ( all RQs are < the reported value) a Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/ Pods/ Large Insects Cotton < 2.65 b < 1.21 b < 1.49 b 0.17 Lettuce 0.80 0.37 0.45 0.05 Pecans 0.48 0.22 0.27 0.03 Canola 0.48 0.22 0.27 0.03 a Chronic dietary based RQ = EEC/ NOAEC, where EECs values are upper bound residues expressed as dietary concentrations ( mg a. i./ kg diet) generated from T REX and the toxicity value is the chronic dietary NOAEC value of > 50 mg a. i./ kg diet in bobwhite quail and mallard ducks. See Appendix D for full T REX output. b RQ is above the LOC for chronic risk ( LOC 1).

Dose based chronic RQs and dietary based chronic RQs for mammals are summarized in Table 20. Dose based chronic RQs exceed the LOC for chronic risk ( LOC 1) for nearly all modeled crop uses and mammalian weight classes for exposure via short grass, tall grass, and broadleaf plants/ small insects. Chronic dose based RQs for mammals feeding on short grass generally exceed the LOC for chronic risk ( LOC 1), ranging from1.19 to 7.62) for all crops. Cotton produced the highest risk to all size groups ( 15, 35, and 100 g) with chronic RQ exceedances for short grass, tall grass and broadleaf plants/ small insects. The other crops, lettuce, pecans, and canola showed potential chronic risk to the 15 and 35 g size groups that might feed on short grass. Dietary based chronic RQs range from 0.01 ( mammals feeding on fruits/ pods/ large insects for cypermethrin use on canola and lettuce) to 0.88 ( mammals feeding on short grass for cypermethrin use on cotton), with no RQs exceeding the chronic LOC.  80 Table 20. Dose based Chronic RQs a and Dietary based Chronic RQs b for Mammals Based on Maximum Residues as Calculated by T REX.

Crop Use Body Weight ( g) Mammalian Chronic Risk Quotients Short Grass Tall Grass Broadleaf Plants/ Small Insects Fruits/ Pods/ Large Insects Seeds Dose based Chronic RQs for Mammals Cotton 15 7.62 c 3.49 c 4.29 c 0.48 0.11 35 6.55 c 3.0 c 3.68 c 0.41 0.09 1000 3.44 c 1.58 c 1.93 c 0.21 0.04 Lettuce 15 1.38 c 0.6 0.8 0.09 0.02 35 1.19 c 0.5 0.7 0.07 0.02 1000 0.6 0.29 0.35 0.04 0.01 Pecans 15 1.38 c 0.6 0.8 0.90 0.02 35 1.19 c 0.5 0.7 0.07 0.02 1000 0.6 0.29 0.4 0.04 0.01 Canola 15 1.38 c 0.6 0.8 0.90 0.02 35 1.19 c 0.5 0.7 0.07 0.02 1000 0.6 0.29 0.4 0.04 0.01 Dietary based Chronic RQs for Mammals Cotton 0.88 0.40 0.50 0.06

Lettuce 0.16 0.07 0.09 0.01

Pecans 0.16 0.07 0.09 0.01

Canola 0.16 0.07 0.09 0.01

a Dose base chronic RQ = EEC/ NOAEL, where EECs values are upper bound residues expressed as equivalent dose ( mg a. i./ kg body weight) generated from T REX and the chronic toxicity value is the chronic NOAEL = 5 mg a. i./ kg body weight in rats, converted from the NOAEC of 100 mg a. i./ kg diet in the rat using the standard FDA lab rat conversion by T REX. See Appendix D for full T REX output. b Dietary based RQs = EEC/ NOAEC, where EECs values are upper bound residues expressed as dietary concentrations ( mg a. i./ kg diet) generated from T REX and the toxicity value is the chronic dietary NOAEC value of 100 mg a. i./ kg diet in rats. See Appendix D for full T REX output. c RQs exceed the LOC for chronic risk ( LOC 1).  81 c. Risk to Terrestrial Invertebrates Although EFED does not assess risks to non target terrestrial invertebrates, cypermethrin toxicity data show that technical grade cypermethrin is very toxic to honey bees and earthworms. As reviewed in the Ecological Effects Characterization ( Section III. C), cypermethrin exposure can result in acute toxicity to honey bees, and is considered to be very highly toxic on both an acute contact and an acute oral basis ( contact 48 hour LD 50 = 0.023 : g a. i./ bee; oral 48 hour LD 50 = 0.13 : g a. i./ bee). Similar results were observed for acute contact and oral toxicity studies using formulations containing cypermethrin ( beta cypermethrin 10 EC and Cypermethrin Emulsifiable Concentrate GFU 061). Cypermethrin ( Cymbush 3E) was also found to be highly toxic on an acute basis to honey bees exposed to oilseed rape seed foliage at application rates of approximately 0.06 to 0.13 lb a. i./ A. Exposure of earthworms to cypermethrin deposits on filter paper show that cypermethrin is highly toxic to earthworms.

3. Non target Plants Inhabiting Terrestrial and Semi Aquatic Areas No toxicity data on the effects of cypermethrin on terrestrial plants and terrestrial plants in semi aquatic areas plants are available; thus RQs cannot be derived.

B. Risk Description The Agency has identified acute and chronic risk concerns to aquatic systems for cypermethrin uses ( especially for cotton, pecans, lettuce). This concern includes risk to listed and non listed fish, aquatic crustaceans, snails, clams, and amphibians. Although this compound binds readily to particulate and organic carbon in the water column, possibly limiting bioavailability in this media after 24 to 48 hours, the bound residues settle onto the benthos, increasing their concentrations in the sediment. Therefore this media can serve as a repository of pesticide residues that can result in a direct toxic risk concern for benthic and epibenthic aquatic organisms ( e. g. early life stage of many invertebrates and fish, as well as crabs and shrimp). The data pertaining to sediment toxicity shows that cypermethrin is still potentially very highly toxic and biologically available. Therefore, coupled with cypermethrins persistence and toxicity profile, sediment bound cypermethrin presents a potential for direct acute and chronic toxic risk to aquatic life in the water column and the benthos ( e. g. invertebrates), as well as potential indirect sublethal risk to fish through food chain alterations that can affect freshwater and estuarine fish year classes. Relative to the use patterns identified in this RED, cypermethrin exposure to terrestrial organisms is not expected to result in acute risk to birds or mammals ( listed or nonlisted Although, there does not appear to be the potential for chronic risk to birds, there is uncertainty regarding chronic risk from residues > 50 ppm ( e. g., especially to birds consuming short grass or young plants). This assessment also suggests that there can be chronic risk to mammals feeding on short grass, tall grass and broadleaf plants/ large insects which also raises concerns for listed mammals ( 15g to 35g).. EFED is also concerned with the potential for risk to terrestrial invertebrates such as non target insects ( i. e., non listed and listed species), including honey bees and other insect pollinators, as well as earthworms.  82 Cypermethrin is a third generation synthetic pyrethroid that is moderately persistent in the environment, and readily binds to soils ( average K oc = 141,700 L/ Kg). It is relatively stable to breakdown from sunlight, with an aqueous photolysis half life of approximately 36 days and a dark control corrected soil photolysis half life of over 100 days), and biodegrades slowly with a half life of about 2 months in aerobic and anaerobic soils. If released to water, cypermethrin will rapidly partition to the sediment compartment which acts as an environmental sink for this compound. Hydrolysis occurs slowly, except under alkaline conditions. The degradation products of cypermethrin occur as a result of cleavage of ester bond moiety of the parent structure, resulting in cis and trans DCVA and 3 phenoxybenzaldehyde, which is subsequently oxidized to 3 phenoxybenzoic acid ( 3 PBA) However, based on results of toxicity studies on 3 PBA in freshwater fish and invertebrates, effective toxicities of the cypermethrin degradates are assumed to be low relative to toxicity of the parent compound.

1. Risks to Aquatic Organisms This risk assessment of cypermethrin shows that aquatic systems are potentially at risk from acute and chronic toxic exposure to this chemical. Evaluation of this risk to aquatic organisms was approached by dividing the aquatic system into two general compartments, water column and the benthos.

The first compartment, the water column, which is defined as the aquatic area between surface and the benthos ( approximately 6 inches above the bottom) represents an area where organisms are free swimming and can feed and breed at the surface, mid water and/ or on the benthos ( sediment). Direct pesticidal contact ( e. g., gill lamella, ingestion, and integument) to these organisms is assumed to be from the surface water via drift and/ or runoff. The toxicity assessment points are the acute LC 50 and chronic NOAEC that are generated through standard water column toxicity tests.

The second aquatic compartment to be considered is the benthos, which is composed of sediments and an area 6 inches above the sediment ( epibenthos). The benthos is composed of a diversity of aquatic invertebrates ( e. g., insect larvae, crustaceans, mollusks) and species of fish ( e. g., catfish, loachs), as well as certain critical life stages of organisms that reside in the water column; the benthos is also the initial breeding strata and nursery area for several species of fish, especially commercial species such as salmonides. The benthos can also be a source of food items for several species of fish that are actively feeding on the organisms in the sediment and/ or capturing organisms that are emerging from this area. The Agency is concerned with the toxic exposure of these organisms to compounds in the sediment is a result of chemical binding to particulate and organic carbon in the water column and the eventual settling out and accumulation of these compounds in the benthos.  83 a. Estimating Risk to Aquatic Systems To evaluate the potential for toxic risk from cypermethrin exposure in the water column, EFED uses a model generated estimated environmental concentration ( EEC) divided by an effects endpoint ( LC 50 , EC 50 , or NOAEC) to generate acute and chronic RQ values. The evaluation of toxic risk to the benthic organisms was approached by assuming equilibrium partitioning of a high K oc compound like cypermethrin between the sediment and the pore water ( i. e., the water found between particulates in the sediment). Risk to the benthos was assessed using two approaches: ( 1) EECs for sediment were model generated ( PRZM/ EXAMS) and compared to the toxicity value as reported for sediment exposure ( LC 50 ); and ( 2) EECs for pore water were modelgenerated ( PRZM/ EXAMS) and compared to a derived toxicity value for pore water ( based on the sediment exposure toxicity value). The Agency is also concerned with possible risk from urban use of cypermethrin and is exploring potential modeling that can best address this issue.

Chronic exposure of a pesticide at low levels is likely to cause toxic responses distinct from those observed after acute exposure at higher concentrations. Although the ratio between acute and chronic toxicity values can vary depending upon the pesticide, a median ratio range of acute and chronic values is expected to be about 5  25 as noted by scientists in EFED ( Brian Montegue, personal communication).

Since it can be assumed that there is a correlation between acute and chronic toxicity values, extrapolations can sometimes be conducted if components of the registrant submitted data package are missing. This extrapolation method consists of applying the lowest observed similar species acute and chronic effects values as a ratio ( e. g., LC 50 / NOAEC) to a similar relationship in another aquatic group ( e. g., freshwater fish vs. estuarine/ marine fish and freshwater invertebrates vs. estuarine/ marine invertebrates).

In the absence of data on the chronic effects of cypermethrin on freshwater invertebrates, estuarine/ marine fish, and benthic organisms, EFED assumes that there are physiological similarities ( e. g., developmental, reproduction, etc.) between freshwater invertebrates and estuarine/ marine invertebrates; freshwater fish and estuarine/ marine fish, and estuarine/ marine invertebrates and benthic organisms. Using these assumptions to estimate a chronic value, EFED has extrapolated NOAEC values for freshwater invertebrates, estuarine/ marine fish, and benthic organisms by using the acute to chronic ratio method as follows:

° Chronic NOAEC for Freshwater Invertebrates ( X) = Estuarine/ Marine Invertebrates LC 50 / Estuarine/ Marine NOAEC × Freshwater Invertebrate LC 50 / X.

° Chronic NOAEC for Estuarine/ Marine Fish ( X) = Freshwater Fish LC 50 / Freshwater Fish NOAEC × Estuarine/ Marine Fish LC 50 / X.  84 ° Chronic NOAEC for Benthic Organisms ( X) = Estuarine/ Marine Invertebrates LC 50 / Estuarine/ Marine NOAEC × Benthic Organisms LC 50 / X.

b. Aquatic Animals ( Water Column Exposure)

In evaluating possible cypermethrin risk to aquatic systems from use on agricultural crops, EFED is focusing on use patterns that appear to have the greatest potential for toxicity exposure to non target aquatic wildlife. These agricultural uses include application to cotton, pecans and lettuce, as these crops have the highest use. Since results of toxicity studies show that cypermethrin is very highly toxic to aquatic animals, the potential for risk to aquatic systems is anticipated. Results of this assessment show that PRZM/ EXAMS modeled surface water concentrations resulting from drift and runoff from agricultural areas pose acute and chronic risk to listed and non listed fish and invertebrates ( freshwater and estuarine/ marine). As shown in Table 14, almost all acute RQs exceed the LOC for acute risk, and all RQs exceed the LOC for acute restricted risk and acute listed risk. The risk to estuarine/ marine invertebrates appears to be several orders of magnitude greater that the potential risk to freshwater fish and invertebrates, and to estuarine/ marine fish. This was an expected outcome of this risk analysis, based on comparison of toxicity values for aquatic animals. As shown in Table 15, results of this analysis show that the chronic LOC is exceeded for some crop uses for freshwater fish ( cotton) and invertebrates ( cotton and pecans), and for all crop uses for estuarine/ marine invertebrates, and cypermethrin does not pose a chronic risk concern for estuarine/ marine fish. The potential for chronic risk reflects exposure from large acreage crops, such as cotton.

Results of this risk analysis identify the potential for acute risks to aquatic animals based on measures of acute lethality, and indicate that cypermethrin exposure has the potential to reduce survival of aquatic animal populations. However, in addition to acute lethality, results of acute toxicity studies in freshwater fish and invertebrates show that sublethal effects can occur at cypermethrin concentrations ranging from slightly lower to several orders of magnitude lower than corresponding acute LC 50 values. Development of these sublethal effects, which include erratic swimming, partial/ complete loss of equilibrium, immobility, lethargy, and darkened pigmentation, is likely to leave fish and invertebrates more vulnerable to predation pressure, resulting in indirect effects on survival of aquatic populations ( Sousa, 1998; Dionne, 1998) Sublethal effects and subsequent indirect effects on population survival are anticipated to occur at concentrations lower than those triggering acute risks to aquatic animals.

The potential for cypermethrin to pose acute and chronic risks to freshwater fish and invertebrates is further supported by results of field studies in freshwater aquatic systems. Results of these studies show sublethal effects in fish following application of cypermethrin at rates ranging from 0.0012 lb a. i/ A to 0.089 lb a. i./ A, and significant lethality of aquatic invertebrates at 4 Drift is the the dislodgement of macroinvertebrates from the substrata with entry into the water column. Catastrophic drift includes those organisms that are forced to enter the water column by disturbances ( e. g., exposure to pesticides).

 85 application rates ranging from 0.00025 to 0.125 lb a. i/ A. Since rigorous monitoring of surface water concentrations was not conducted in these studies, comparison of the exposure levels in field studies to the modeled water column concentrations is not possible. However, results of field studies show that use of cypermethrin at application rates lower than those modeled for this risk assessment can produce sublethal and lethal effects to aquatic species.

c. Aquatic Animals ( Sediment Exposure)

Risk estimates for benthic organisms show that cypermethrin poses acute and chronic risks to benthic organisms, based on acute and chronic RQs calculated using both sediment and pore water EECs ( Table 16). However, as discussed in Section III. C, there is considerable uncertainty surrounding the acute toxicity value obtained from the available sediment toxicity study. In this study, the concentration of cypermethrin in sediment decreased over time, indicating that the water sediment system had not reached equilibrium. If the exposure system had been at equilibrium, it is likely that the toxicity reference value would be lower, resulting in RQs that are higher than those derived in this assessment. This uncertainty is also introduced to pore water acute RQs and sediment and pore water chronic RQs, as these RQs are based on toxicity values derived from the same uncertain acute sediment toxicity value. Even with this uncertainty, acute and chronic RQs for benthic organisms exceed the chronic LOC for all modeled crop uses.

The potential for cypermethrin to pose acute and chronic risk to sediment dwelling organisms is further supported by results of field studies in freshwater aquatic systems ( Table E 8). Results of these studies show variable immediate and longer term effects on freshwater invertebrates and benthic organisms exposed to cypermethrin, ranging from no observable effects to catastrophic drift4 and profound decreases in population diversity and abundance. Application rates for cypermethrin in these studies varied greatly, from 0.00025 to 0.125 lb a. i./ A. However, results of the available field studies show that adverse effects on sediment dwelling populations can occur under conditions of recommended cypermethrin label use. For field studies assessing the effects of cypermethrin on aquatic invertebrate populations, results range from no observable effects on aquatic invertebrate and benthic populations to catastrophic drift and profound decreases in population diversity and abundance. For studies reporting no adverse effects on macroinvertebrate populations ( Acc No 250506, Supplemental; MRID 155772, Supplemental), application rates range from a single application of 0.0623 lb a. i./ A ( MRID 155772) to repeated applications of 0.126 lb a. i./ A, ( 6 applications at 5 day intervals to cotton fields) ( Acc. No. 250506, Supplemental). However, results of several other field studies show that exposure to cypermethrin at application rates ranging from 0.00025 lb a. i./ A ( Mulla et al. 1978) to 0.125 lb a. i./ A ( Acc. No. 250506; Supplemental) causes significant decreases in abundance and diversity of aquatic invertebrate populations over a longer time period ( several weeks to several months)  86 ( MRID 155770), and catastrophic drift within 0 90 minutes after application of cypermethrin ( Crossland et al, 1982; Farmer et al. 1995; Moshen and Mulla 1982), and decreased abundance and diversity of macroinvertebrates over 2737, Supplemental; Farmer et al. 1995; Kedwards et al., 1999a, b; Mulla et al., 1978; Mulla et al., 1982). In some cases, recovery of individual species was rapid ( MRID 155770, Supplemental; Kedwards et al., 1999a, b; ); however, for other species, recovery did not occur for several months ( Kedwards et al;. 1999b; Davies and Cook 1993).

In addition to potential acute and chronic risk from cypermethrin exposure in sediments to sensitive macroinvertebrates and fish, from agricultural uses, this risk concern should be extended to include non agricultural uses. Although the Agency does not usually model urban pesticide uses for possible risk to aquatic and terrestrial organisms, monitoring information is used when it is available. Recently the Agency received information of a monitoring project in California that was used to evaluate pyrethroid residues in stream sediments adjacent to an urban subdivision. The findings show that toxic residue levels of cypermethrin and other pyrethroids have been found in sediments near storm drains inputs to streams that possible received runoff from the subdivisions ( Weston, et al., 2005). Although bifenthrin was the major pyrethroid residue found, cypermethrin levels were also of toxic significance to aquatic invertebrates. Weston's work is significant because it documents the presence of pyrethroids in the sediments of creeks within residential areas and with additional research it is possible to better identify their likely sources. Since a large amount of pyrethroids are being used in non agricultural urbane settings the Agency has a concern for the possible additional risk to aquatic systems that this implies. Currently the Agency is evaluating appropriate modeling that may be useful in assessing this potential risk to the environment.

d. Aquatic Plants Toxicity data are not available for plants inhabiting aquatic environments; thus, risks associated with cypermethrin exposure to plants inhabiting aquatic environments cannot be assessed. However, based on cypermethrin's mode of action, plant toxicity resulting from cypermethrin exposure does not appear to be an issue of concern for this assessment. In addition the Agency is not aware of any cypermethrin plant incidents, or plant incidents from exposure to other pyrethroids.

e. Other Special Considerations for Evaluating Aquatic Risk ( Buffer Zones)

EFED performed a brief buffer zone/ spray drift analysis with various buffer zones and drift scenarios, to evaluate the extent to which the buffer zone imposed by the registrant might mitigate the level of spray drift reaching bodies of water close to treated areas for the NC cotton scenario. For aerial applications, the labeled buffer zone is 150 ft. First, EFED ran PRZM/ EXAMS with the input parameters of a standard run, except that the spray drift level was set to  87 0%. When the standard results with spray drift of 5% were compared with the special run with spray drift of 0%, the results indicated that the percent of the peak EEC that was attributable to spray drift was 9.6% for NC cotton PRZM scenario. This scenario has a relatively small component of drift. Then, the scenario was run with aerial applications and various buffer zones to evaluate the possible effects of buffer zones on spray drift, in reducing potential risk from exposure to aquatic systems. The levels of spray drift simulated a high end drift scenario ( high boom height, high wind speed, small droplet size), a low end drift scenario ( low boom height, low wind speed, large droplet size), and typical drift scenario, to bracket the spectrum of possibilities. Supplementary Tables H and I show the calculated acute risk quotient ( RQ) values for the most sensitive species ( Mysid Shrimp, estuarine/ marine invertebrate), for buffer zones set from 0 to 200 ft and spray drift set at 1 and 5% and the assigned spray drift values for the specific drift scenarios. All scenarios showed that the RQs for estuarine/ marine invertebrates exceeded all the LOCs. However, the low end drift scenario yielded lower levels of drift and consequently lower EECs and RQs. The low end drift scenario, with no buffer zone, yielded an RQ of a similar order of magnitude as the one produced by ground applications.

For the NC cotton scenario a buffer zone of 150 ft reduced the peak EECs ( and consequently the acute RQs) by about 4.4% for the low end drift scenario, 14.1% for the typical drift scenario and 18.9% for the high end drift scenario, compared to the equivalent conditions with no buffer zone.

For the NC cotton scenario, the acute RQ for the most sensitive species ( Mysid shrimp), for the typical drift scenario, with a buffer zone of 150 ft the RQ is approximately 990X the LOC of acute high risk ( 0.5). If the application is made under more stringent measures, and the low end drift scenario is used, the RQ decreases slightly to about 918X the LOC of the acute high risk.

The identified uncertainties of this analysis are as follows: It is assumed that the level of runoff is similar in all PRZM/ EXAMS runs. The current version of PRZM/ EXAMS cannot take into consideration the fact that there are buffer zones ranging from 0 to 200 ft, that might mitigate the level of runoff ( particularly for the peak values), or the mandatory vegetative strip included in the label. The scope of this analysis is limited. It constitutes only an overview, with calculations performed with NC cotton only, it was considered representative for all the areas where aerial applications of cypermethrin occur. Furthermore, it was found that this scenario has a relatively small component of spray drift. Ideally various scenarios would be explored, and data compared among each other.

f. Summary of Risk to Aquatic Systems The complexities of natural aquatic systems forgoes the use of a single factor approach in evaluating even a screening level assessment of risk to fish and aquatic invertebrates from toxic exposure to cypermethrin. Thus, EFED approached the cypermethrin evaluation by assessing the potential toxic impact to the aquatic system from exposure in the water column and in sediment and pore water. As noted earlier, EFED modeled the possible exposure of cypermethrin use from agricultural areas for application to cotton, pecans and lettuce. These agricultural uses were  88 chosen because these crops have the highest cypermethrin use. One of the crops is representative of ground applications ( pecans).

This screening level assessment of cypermethrin shows that the agricultural use of this pyrethroid on crops ( cotton, pecans, and lettuce) can result in potential toxic exposure to aquatic systems. This concern includes organisms that frequent the surface and water column, as well as those that live in/ on the benthos. The risk to water column organisms and to sediment dwelling organisms has the potential for synergy of effects, where the consequences can exceed the sum of the effects caused by each factor separately. As cypermethrin is introduced to surface water via drift or runoff from a crop area, it can disperse down through the water column causing acute toxicity ( sublethal and lethal effects) to sensitive species. In addition to acute risk, chronic effects are a potential concern for aquatic organisms that are exposed to cypermethrin in the water column during critical life stages. Possible chronic effects to aquatic life may also be a concern where an initial cypermethrin exposure may cause embryological effects ( possible neonate mortality and growth effects may reflect toxin exposure at an early embryological stage) or possible reproductive effects 21 days to 60 days following initial exposure. Because cypermethrin has a high affinity to bind to particulate and organic carbon, sediment can act as a sink where cypermethrin can accumulate ( modeled sediment concentrations of cypermethrin exceed those for surface water by approximately 85 to 800 fold Tables 7 9)..

Toxic exposure of cypermethrin in the sediment can present a more far reaching impact on a multitude of organisms than exposure in the water column ( e. g., cypermethrin residues decline in the water column by about 98% after 48 hours). A wide variety of aquatic organisms depend upon the benthos for food ( e. g., fish feeding on invertebrates), reproduction ( e. g., salmonid and other species using the benthic substrate for breeding), and shelter ( e. g., bottom dwelling fish, mollusks, aquatic invertebrates, etc.); the benthos is a dynamic system that interacts directly or indirectly with most, if not all aquatic species at some point in their development or life stages. Because of their influence on various functional parameters in streams, such as primary productivity, detritus processing, and energy flow, changes in abundances and distributions of benthic macroinvertebrates have the potential to reflect changes in stream ecosystems. In addition, because benthic macroinvertebrates are the major prey of many species of fish ( freshwater and estuarine/ marine), they also have societal relevance in terms of recreation and ecological biodiversity. As food resources decline or widely fluctuate, fish communities often display increased disease, parasitism, and deformities as a result of less than adequate diet.

EFED has a concern for the potential chronic risk that may occur to aquatic organisms from cypermethrin load in sediments. Chronic toxicant loads in sediments may drive populations toward a limited set of tolerant genotypes over time. Such reductions in genetic diversity reduce a population's plasticity to adapt to the new stresses that can arise as anthropogenic stress on aquatic ecosystems increases ( especially in agricultural areas). This impact cumulatively results in structural and functional responses of the aquatic ecosystems and biota. The time required for invertebrate assemblages to return to their natural state, following disturbances such as those of pesticide drift and/ or runoff, can be on the order of many years for streams, and decades for lakes.

In addition to acute and chronic risk of cypermethrin exposure to sensitive macroinvertebrates and fish, from agricultural uses, this risk concern should be extended to  89 include non agricultural uses. Toxic residue levels of cypermethrin have been found in sediments near storm drains inputs to streams that are located adjacent to urban subdivisions in Roseville, California ( Weston, et al., 2005). Although difficult to model and quantify, urban uses of pyrethroids have the potential to impact aquatic systems. The vast majority of insecticides sold for consumer use now contain pyrethroids, and are widely used around homes by consumers and professional pest control applicators. Cypermethrin accounts for a large percentage of this market especially for structural pest control. Since this area is hardly unique from other suburban areas, the Agency is concerned that urban use of cypermethrin can result in sediment contamination and possible toxic impact to aquatic life in some areas of the country.

2. Risks to Terrestrial Organisms a. Terrestrial Animals ( Mammals and Birds)

Pesticide exposure can vary substantially in space, mostly because of use patterns. However, terrestrial exposure tends to localize near the application site, extended somewhat by spray drift down wind. In some cases, long range aerial transport can extend this range for a volatile compound. However, in the case of cypermethrin, volatility is not an issue of concern. Therefore, to assess risks to terrestrial organisms ( e. g., birds and mammals), this assessment focuses on the potential for toxic exposure cypermethrin residues on food items. An evaluation of potential risks was conducted using the T REX model, which provides estimates of concentrations of chemical residues on different types of food items that may be sources of dietary exposure to avian, mammalian, reptilian, or terrestrial phase amphibian receptors. The four crop uses were evaluated for the terrestrial assessment ( cotton, lettuce, pecans, and canola) were chosen since they represent over 90% of cypermethrin's agricultural use.

Cypermethrin does not appear to pose an acute risk concern for birds ( Table 17) or mammals ( Table 18), except for acute listed risk to small mammals feeding primarily on short grass ( cotton use only). Given the low order of toxicity observed in acute toxicity studies in mammals and birds, acute risks to terrestrial animals resulting in decreased survival were not expected. For chronic risk for birds, the LOC is exceeded only for birds feeding primarily on short grass for applications of cypermethrin to cotton ( Table 19). However, since the chronic toxicity value used to derive chronic avian RQs is reported as " greater than" the highest dietary concentration tested ( i. e., a chronic LOAEC or NOAEC were not established), chronic RQs may be lower than those reported. Thus, this assessment may overestimate chronic risks to birds. For mammals, the potential for chronic risk was identified for mammals feeding on short grass, tall grass, and broadleaf plants and insects for all modeled crop uses ( Table 20). However, since an expected EEC for cotton is greater than 50 ppm ( NOAEC presented for avian reproduction studies) there is an uncertainty that must be addressed regarding an accurate avian chronic NOAEC, as well as LOAEC. This assessment also suggests that cypermethrin exposure has the potential for chronic effects to mammals that include decreased body weight and decreased body weight gain in adults and offspring.  90 b. Non Target Terrestrial Insects Although EFED does not derive RQ values for non target insects, risks can be assessed qualitatively. Cypermethrin toxicity data show that the compound is very highly toxic to honey bees. This hazard assessment shows that cypermethrin exposure can result in acute toxicity to honey bees and is considered to be highly toxic on both a contact and an oral basis. Cypermethrin was also found to be highly toxic to honey bees exposed to foliage that had been sprayed with a cypermethrin formulation ( Cymbush 3E). In addition, cypermethrin has also been shown to be highly toxic to earthworms. Based on these results, acute risks to non target insects and terrestrial invertebrates are anticipated for the uses considered in this assessment.

c. Terrestrial Plants Toxicity data are not available for terrestrial plants; thus, risks associated with cypermethrin exposure to terrestrial plants cannot be assessed. However, relative to cypermethrin mode of action, plant toxicity resulting from cypermethrin exposure does not appear to be an issue of concern for this assessment.

3. Review of Incident Data Incident reports submitted to EPA since approximately 1994 have been tracked by assignment of " incident numbers" in an Incident Data System ( IDS), microfiched, and then entered to a second database, the Ecological Incident Information System ( EIIS). An effort has also been made to enter information to EIIS on incident reports received prior to establishment of current databases. Incident reports are not received in a consistent format ( e. g., states and various labs usually have their own formats), may involve multiple incidents involving multiple chemicals in one report, and may report on only part of a given incident investigation ( e. g., residues). While some progress has been made in recent years in getting incident reports submitted and entered, there has never been the level of resources assigned to incidents that there has been to the tracking and review of laboratory toxicity studies, for example.

Incidents entered into EIIS are categorized into one of several certainty levels: highly probable, probable, possible, unlikely, or unrelated. In brief, " highly probable" incidents usually require carcass residues, substantial ChE inhibition in avian and/ or mammalian species, and/ or clear circumstances regarding the exposure. " Probable" incidents include those where residues were not available and/ or circumstances were less clear than for " highly probable." " Possible" incidents include those where multiple chemicals may have been involved and it is not clear what the contribution was of a given chemical. The " unlikely" category is used, for example, where a given chemical is practically nontoxic to the category of organism killed and/ or the chemical was tested for but not detected in samples. " Unrelated" incidents are those that have been confirmed  91 to be not pesticide related.