Freshwater Fish Figure 10 shows acute risk quotients for freshwater fish based on maximum label rates; the acute risk LOC ( RQ $ 0.5) is exceeded on citrus alone. Endangered species LOC is met or exceeded on all of the crops modeled. RQ's based on QUA average and reported average rates ( APPENDIX F Table 12) exceeded the acute risk LOC for citrus while the endangered species was exceeded on all crops for both use rates except on sugar beets; at average and maximum reported rates, sugar beets did not exceed any acute LOC. 41 0 0.2 0.4 0.6 0.8 1 Sweet Corn Fi e l d C o rn Apples S ugar B e e ts Citrus Crop C ategory Acute RQ Acute Risk Quotients at Maximum Label Rates for Freshwater Fish Acute Risk LOC Acute Restricted Use LOC Acute Endangered Species LOC Figure 10. Acute risk quotients ( RQ) in selected crop categories for freshwater fish at maximum label application rates. Acute risk level of concern ( LOC) is exceeded at RQ $ 0.5; acute restricted use LOC is exceeded at RQ $ 0.1 and acute endangered species LOC is exceeded at RQ $ 0.05 . 42 0 10 20 30 40 Sweet C orn Fi e l d C o rn A ppl e s S ugar B e e ts Citrus Crop C ategory Acute RQ Acute Risk Quotients at Maximum Label Rates for Freshwater Invertebrates Acute Risk LOC Figure 11. Acute risk quotients ( RQ) in selected crop categories for freshwater invertebrates at maximum label application rates. Acute risk level of concern ( LOC) is exceeded at RQ $ 0.5; acute restricted use LOC is exceeded at RQ $ 0.1 and acute endangered species LOC is exceeded at RQ $ 0.05 . Freshwater Invertebrates Acute risk quotients ( RQ range: 4.5  30) for freshwater invertebrates at maximum label rates ( Figure 11), QUA average rates ( RQ range: 1.4  20) and Doane maximum reported rates ( RQ range: 1.0  26) all exceed acute risk levels of concern ( APPENDIX F Table 13).

Chronic risk quotients for freshwater invertebrates exceed the chronic LOC for maximum label rates ( RQ range: 8.7  55), QUA average rates ( RQ range: 2  34) and Doane maximum reported rates ( RQ range: 2  45) ( APPENDIX F Table 13). 43 0 10 20 30 40 Sweet Corn Fi e l d C o rn Apple s Sugar Beets Citrus Crop C ategory Acute RQ Acute Risk Quotients at Maximum Label Rates for Estuarine/ Marine Invertebrates Acute Risk LOC Figure 12. Acute risk quotients ( RQ) in selected crop categories for estuarine/ marine invertebrates at maximum label application rates. Acute risk level of concern ( LOC) is exceeded at RQ $ 0.5; acute restricted use LOC is exceeded at RQ $ 0.1 and acute endangered species LOC is exceeded at RQ $ 0.05 . Estuarine/ Maine Fish None of the uses modeled exceeded acute risk or restricted use LOCs at maximum label rates, QUA average rates or maximum ( Doane) reported rates ( APPENDIX F Table 14). The endangered species LOC was minimally exceeded for maximum label and maximum reported rate rates on citrus ( RQ = 0.06).

Estuarine/ Marine Invertebrates The acute risk LOC for estuarine/ marine invertebrates is exceeded for all five carbaryl uses modeled at maximum label rates ( Figure 12) ( RQ range: 4  27), QUA average rates ( RQ range: 1.2  18) and Doane maximum reported rates ( RQ range: 0.9  23) ( APPENDIX F Table 15). 44 Aquatic Plants Based on a single core aquatic plant toxicity study available, neither the acute risk nor the endangered species LOC ( RQ $ 1) is exceeded for any of the five use scenarios modeled, at maximum label ( RQ range: 0.11  0.66), QUA average ( RQ range: 0.05  0.43), and maximum reported use rates ( RQ range: 0.01  0.56) ( APPENDIX F Table 16). However, to fully assess carbaryl risk to aquatic plants, it is recommended that toxicity studies with Lemna gibba, Anabaena flos aquae, Skeletonema costatum, and a freshwater diatom be submitted. 45 ECOLOGICAL RISK CHARACTERIZATION Carbaryl is a carbamate insecticide registered for control of a wide range of insect and other arthropod pests on over 100 crop and noncrop use sites, including home and garden uses. The pesticide is a cholinesterase inhibitor that acts on contact or ingestion by competing for binding sites on the enzyme acetyl cholinesterase, thus preventing the breakdown of acetyl choline.

Carbaryl is not very persistent and dissipates in the soil environment by abiotic and microbially mediated degradation and is not likely to persist. The major degradation products are CO2 and 1 naphthol, which is further degraded to CO2. Carbaryl is stable to hydrolysis in acidic conditions, but hydrolyzes rapidly in alkaline environments. The compound is degraded by photolysis in water, with a half life of 21 days. Under aerobic conditions the compound degrades rapidly by microbial metabolism with half lives of 4 to 5 days in soil and aquatic environments. In anaerobic environments metabolism is much slower with half lives on the order of two to three months. Carbaryl is mobile in the environment ( Kf = 1.7 to 3.5) and has been detected in all environmental compartments; it dissipates rapidly from foliage with a mean half life of 3.2 d, but is easily washed off leaf surfaces, with 91% removal with 1 cm of rain. Sorption onto soils is positively correlated with soil organic content, increasing with higher soil organic content ( R2 = 0.94.) Carbaryl is not expected to bioaccumulate ( BCF = 45X).

In field studies, carbaryl dissipated from terrestrial field dissipation studies with DT50 of 4 ( California) and 7 ( North Carolina) days. No leaching was observed in either study. but recharge may not have been sufficient to cause downward movement. In a forestry dissipation study, time to fifty percent removal was 21 days on foliage, 75 days on leaf litter, and 65 days on soil. In two aquatic ( rice paddy) dissipation studies in Texas and Mississippi, DT50' s at both sites were less than two days.

Fate data on the primary degradate, is limited; however, 1 naphthol appears to be somewhat mobile but is not likely to persist due to fairly rapid degradation. Since 1 naphthol can occur from a variety of natural and anthropogenic processes, its presence cannot be considered indicative of carbaryl use.

Carbaryl is widely detected in non targeted and targeted monitoring studies. Observed concentrations are generally low with fifty percent of the samples below minimum detection limits and ninety five percent of the samples less than 0.065 : g/ L. Carbaryl is not very persistent in most surface water conditions suggesting that the wide spread occurrence is a result of its extensive use in a variety of applications.

As noted above, carbaryl is expected to be mobile, but degrade rapidly in the environment in most cases. However, there are circumstances, i. e., under acidic conditions with low biological activity and/ or in reducing ( anaerobic) conditions, where carbaryl is likely to persist. Available field data are in general agreement with the laboratory data, with the forestry dissipation study indicates somewhat longer persistence than the other studies, but not so far as to be an outlier. The fate and transport data has a relatively complete coverage of the expected routes of fate and transport, but is limited in the amount of data for any particular study. In particular, there is only one available 46 guideline metabolism study for each route of metabolism. Given the high variability typically associated with these studies, there is some uncertainty in these rates. Since this uncertainty is factored into the aquatic and drinking water exposure estimates, an increase in the number of metabolism studies could potentially decrease current exposure estimates.

Additionally, there are a number of factors inherent in the modeling that can affect the accuracy and precision of this analysis including the selection of the high exposure scenarios, the quality of the input data, the ability of the models to represent the real world, and the number of years that were modeled. The EEC's in this analysis are accurate only to the extent that the site represents this hypothetical high exposure site.

Although carbaryl is not expected to be persistent, on low organic carbon content soils and following high rain events the pesticide is likely to be mobile. Laboratory studies of terrestrial and aquatic animals indicates that carbaryl is practically nontoxic to birds, moderately toxic to mammals and fish, and very highly toxic to bees and aquatic invertebrates on an acute exposure basis. Additionally, data indicate that the carbaryl hydrolysis degradate 1 naphthol ranges in toxicity from moderately to highly toxic to aquatic organisms.

Risk to Terrestrial Animals Given that carbaryl is practically nontoxic to birds on both an acute oral exposure and a subacute dietary exposure basis, the threat of adverse effects to birds resulting from acute exposure to carbaryl is considered low. On an chronic exposure basis however, the chronic risk level of concern ( RQ = 1) is exceeded on over 50% of the crops modeled for birds feeding on short grasses ( 100%), tall grasses ( 55%) and broadleaf plants/ small insects ( 66%) for nongranular product at maximum label rates. In general, crops receiving multiple applications of nongranular products greater than 3 lbs a. i./ acre with short (# 7 day) reapplication intervals were likely to represent a risk of chronic effects in birds. At " average" application rates modeled for short grasses the number of exceedances was reduced from 100% to 49% of the crops.

Although bird incidents ( 5) have been reported for carbaryl, only two could be clearly attributed to the chemical and only one could be linked to a specific registered use. The one incident reported a single morning dove ( Zenaida macroura) dying following application to a homeowner's lawn in the vicinity of a bird feeder.

Even though carbaryl has been classified as practically nontoxic to birds on an acute exposure basis, there is uncertainty regarding the sensitivity of smaller, passerine birds. Open literature on smaller birds and incidents involving blackbirds and starlings suggest that perching birds may be more sensitive.

Consistent with carbaryl's moderate acute toxicity to mammals, the acute risk level of concern ( RQ $ 0.5), acute restricted use ( RQ $ 0.2) and acute endangered species ( RQ $ 0.1) are exceeded for majority (> 75%) of the uses modeled for small ( 15 g) and intermediate sized ( 35 g) animals feeding on short grasses and broadleaf/ forage plants. For large sized mammals ( 1000 g), acute risk LOCs are exceeded on 40% of the uses modeled for animals feeding on short grasses and 47 for over 50% of the uses modeled for large animals feeding on broadleaf/ forage plants. For mammals feeding on fruits/ pods/ seeds/ large insects, the acute risk LOC is exceeded for small sized animals and the acute endangered species LOC is exceeded for large sized mammals following application to citrus. For granivores, acute endangered species LOCs are minimally exceeded for small ( RQ = 0.17) and intermediate sized mammals ( RQ = 0.12) following application to citrus and for small sized mammals alone ( RQ = 0.11) following application to turfgrass. The mammalian chronic risk LOC is exceeded for all registered uses for animals feeding on short grasses, forage/ small insects, and fruits/ large insects ( RQ range: 1.1  31). For mammals feeding on seed fruit, the chronic LOC is exceeded on citrus, olives, stone fruit, tree nuts and turf ( RQ range: 1.1  3.2). Even when looking at average application rates, acute risk LOCs are exceeded on 89% of the uses while the chronic risk LOC is exceeded on all uses except Chinese cabbage.

Mammals may also be exposed to granular/ bait formulations of carbaryl through ingestion and/ or walking on exposed granules. The acute risk LOC for small and intermediate sized mammals is exceeded ( RQ range: 0.99  21) for all 40 registered granular uses. For large sized mammals, acute restricted use and endangered species LOCs are exceeded following application for trees and ornamentals, turfgrass, and tick control.

Although 2 incidents have attributed to carbaryl, one involving a gray squirrel ( Sciurus carolinensin) and the second involving a hairytail mole ( Parascalops breweri), neither could be associated with a specific use of carbaryl. However, based on the risk quotients for small and intermediate sized animals, estimated acute environmental concentrations are sufficiently high to result in mortality.

Carbaryl is highly toxic to beneficial insects on an acute exposure basis. Bee kill incidents have been reported; however, all but one involving the use of carbaryl on asparagus in Washington, contained sufficient information to implicate a specific use of carbaryl. Although the bee industry has expressed its concerns regarding the toxicity of carbaryl to bees, it has not provided sufficient data to support its concerns.

The risk to bees from the use of carbaryl to thin orchard fruit has recently been evaluated. Under the conditions tested in the German apple orchards, carbaryl SC applications to thin fruit did not have a significant ( P > 0.05) effect on bee mortality and/ or behavior.

Risks to Aquatic Animals In general, carbaryl is moderately toxic to freshwater fish and the acute risk LOC is exceeded for citrus alone ( RQ = 0.61); acute endangered species LOCs are exceeded ( RQ range: 0.06  0.61) on all crops modeled except sugar beets. None of the uses modeled exceeded the chronic risk LOC. Although three fish kill incidents hare been reported for carbaryl, there appears to be only one credible report where carbaryl used to control gypsy moth ( Lymantria dispar) could be directly associated with a fish kill.

Carbaryl ranged from being slightly to moderately toxic to amphibians on an acute exposure basis. Intra and inter species variability contributed to the range of responses to carbaryl. While 48 much of the current research focuses on direct acute effects of carbaryl on tadpoles/ frogs, the indirect effects of carbaryl on impairing predator avoidance is frequently raised as a concern. Additionally, carbaryl exposure has been associated with skeletal deformities in frogs.

Consistent with carbaryl's classification as being very highly toxic to freshwater invertebrates, acute risk LOCs are exceeded ( RQ range 1  30) for all uses modeled at maximum label rates, average rates and maximum reported rates. Similarly, the chronic risk LOC is exceeded ( RQ range: 2  55) for all uses at all rates. Interestingly, carbaryl's toxicity to aquatic macroinvertebrates has been associated with phytoplankton blooms where it is hypothesized that selective mortality on zooplankton reduced grazing on phytoplankton to a sufficient extent to favor/ promote phytoplankton abundance. Increased growth rates in tadpoles exposed to carbaryl has been theorized as a response of the amphibians to increased phytoplankton food supplies.

Similar to freshwater fish, carbaryl is moderately toxic to estuarine/ marine fish; however, none of the estimated environmental concentrations exceeded acute risk LOCs. The acute endangered species LOC was minimally exceeded ( RQ = 0.06) for citrus.

Carbaryl is very highly toxic to estuarine/ marine invertebrates and the acute risk LOC is exceeded on all uses modeled at maximum label, average and maximum reported application rates ( RQ range: 0.9  27).

Risks to Plants For both aquatic and terrestrial plants, the likelihood of adverse effects from maximum label use rates appears to be low; however, there were limited data on which to evaluate the effects of carbaryl on a range of plants. Studies over a broader range of terrestrial and aquatic plants should be submitted to address this uncertainty. Although, toxicity data suggest that carbaryl is relatively innocuous to plants, the greatest number of incidents ( 11) for carbaryl have involved terrestrial plants ( APPENDIX D1). While the majority of these reports have been associated with homeowner use of the product, some agricultural crops, e. g., quince and olive, have reported losses resulting from spotting, low fruit set and malformations in fruit shape. Reconciling the phytotoxicity reported in field incidents with the laboratory data represents an uncertainty.

Additional Concerns Grasshopper and Mormon Cricket Control on Rangeland With respect to U. S. Department of Agriculture's Animal and Plant Health Inspection Service ( USDA APHIS) Grasshopper and Mormon Cricket Suppression Program use of carbaryl to control grasshoppers and Mormon crickets, acute and chronic risk LOCs are exceeded for smaller sized mammals when 0.5 lbs/ Acre is applied; however, at 0.25 lbs/ A the acute endangered species LOC alone is exceeded for smaller animals ( APPENDIX G). Additionally, assuming 5% spray drift, acute restricted use and endangered species LOCs are exceeded for freshwater invertebrates. If 95% spraydrift ( direct overflight of aquatic habitat), then acute endangered species LOC is exceeded for fish and acute and chronic risk LOCs are exceeded for aquatic invertebrates. 49 Based on the potential for both acute and chronic effects to terrestrial ( primarily mammals) and aquatic animals ( primarily invertebrates), plans are underway for USDA APHIS to consult with the U. S. Fish and Wildlife Service and the National Marine Fisheries Service to assure that endangered species are protected to the extent possible. Section 7 consultations on the use of carbaryl on rangelands to control grasshoppers/ crickets are ongoing.

Section 24c Use of Carbaryl to Control Burrowing Shrimp For several decades, carbaryl has been used to control burrowing shrimp on tidal mudflats in Willapa Bay and Grays Harbor, Washington ( APPENDICES E1 to E3) . Although concern has been raised regarding this use and its potential impact to nontarget animals outside of treated areas, very little data have been provided to substantiate these concerns. The available data indicate that acute mortality will likely be near 100% for animals trapped on mudflats in the immediate application area and that carbaryl will likely drift off site with the tide. However, a combination of the rapid degradation of carbaryl due to both biotic and abiotic factors and dilution by a relatively large influx of water together render potential acute and chronic effects remote. Additionally, as part of a memorandum of agreement between the Washington Stage government representatives and various stakeholders, the oystergrowers have agreed to developed an integrated pest management program to look at alternatives to carbaryl and to conduct studies to determine the extent to which carbaryl impacts areas adjacent to treated sites. Through this cooperative approach it may be possible to better document by monitoring of surface waters and sediments the extent to which carbaryl drifts. Studies are also planned to determine to what extent salmonids may be impacted. However, at this time, given the limited number of acres treated and the combination of chemical degradation and potential dilution by successive tides, there is insufficient data to warrant concern that nontarget animals are at risk throughout the Willapa Bay/ Grays Harbor area.

Endocrine Disruption Concerns There are data indicating that carbaryl exposure may impact endocrine mediated processes in both aquatic and terrestrial animals. Serum and pituitary levels of gonadotropic hormone and gonadotropin releasing hormone ( GnRH) in the freshwater snakehead fish ( Channa punctatus) are reduced by exposure to 1.66  3.73 ppm of carbaryl in laboratory and paddy field tests ( Ghosh et al., 1990). The decrease in GnRH levels could be explained by exposure to high estrogen levels, acting through a negative feedback pathway to inhibit GnRH release, and thus the release of gonadotropins ( Klotz et al., 1997). Plasma and ovarian estrogen levels in freshwater perch ( Anabas testudineus) exposed to 1.66 ppm of carbaryl for 90 days increase until day 15 and then decline, relative to control fish, indicating that long term exposure to this chemical may cause an inhibitory effect on fish reproduction ( Choudhury et al., 1993).

In addition, chronic exposure of fathead minnows ( Pimephales promelas) to carbaryl resulted in reduced survival and reproductive effects ( LOEC = 0.680 ppm) including reduced number of eggs per female and reduced number of eggs spawned. Chronic studies with aquatic macroinvertebrates resulted in reduced emergence and developmental rates in midges, Chironomous riparius, and reproductive effects in Daphnia magna. In avian reproduction studies of the mallard duck ( Anas 50 platyrhynchos) carbaryl exposure resulted in reduced number of eggs produced and increased number of eggs cracked.

These chronic toxicity measurement endpoints are considered consistent with a chemical that acts on endocrine medicated pathways. When considered in concert with open literature, there is uncertainty regarding the endocrine disrupting potential of carbaryl and its 1 naphthol degradate.

EPA is required under the Federal Food, Drugs, and Cosmetics Act ( FFDCA), as amended by Food Quality Protection Act ( FQPA), to develop a screening program to determine whether certain substances ( including all pesticide active and other ingredients) " may have an effect in humans that is similar to an effect produced by a naturally occurring estrogen, or other such endocrine effects as the Administrator may designate." Following the recommendations of its Endocrine Disruptor Screening and Testing Advisory Committee ( EDSTAC), EPA determined that there was scientific basis for including, as part of the program, the androgen and thyroid hormone systems, in addition to the estrogen hormone system. EPA also adopted EDSTAC's recommendation that the Program include evaluations of potential effects in wildlife. For pesticide chemicals, EPA will use FIFRA and, to the extent that effects in wildlife may help determine whether a substance may have an effect in humans, FFDCA authority to require the wildlife evaluations. As the science develops and resources allow, screening of additional hormone systems may be added to the Endocrine Disruptor Screening Program ( EDSP).

When the appropriate screening and or testing protocols being considered under the Agency's Endocrine Disruptor Screening Program have been developed, it is recommended that carbaryl be subjected to additional screening and or testing to better characterize effects related to endocrine disruption.

Endangered Species Avian Chronic LOCs are exceeded for birds feeding on short grasses for all uses modeled except rangeland. For birds feeding on tall grasses, the avian chronic LOC is exceeded for 55% of the modeled uses and for birds feeding on broadleaf/ forage plants and small insects, the chronic LOC is exceeded for 60% of the uses modeled. When RQs were based on average use rates, 49% of the uses exceeded chronic LOCs. When RQs were based on maximum reported use rates, 81% of the uses exceeded the chronic LOC.

Mammals For mammals, all uses modeled exceeded the acute endangered species LOC for herbivores. For mammals foraging on broadleaf plants and small insects, the endangered species LOC is exceeded for all uses except cucurbits, trees, ornamentals, rangeland and forested areas. For mammals feeding on large insects, roughly 70% and 45% of the use categories modeled exceeded the acute endangered species LOC small ( 15 g) and intermediate sized ( 35 g) mammals, 51 respectively. Only one use, i. e., citrus, exceeded the LOC for large sized animals ( 1,000 g). For granivores, the acute endangered species LOC is exceeded for small sized animals feeding in citrus and turfgrass areas and for intermediate sized mammals feeding in citrus areas. Chronic LOCs are exceeded for all modeled uses for mammals feeding on all food items except seeds/ fruits and large insects. For granivores, the chronic LOC is exceeded for citrus, olives, stone fruits, tree nuts and turf grass. When RQ were based on average rates or maximum reported rates, acute and chronic endangered species LOCs are exceeded for all of the modeled uses. Additionally, granular products represented an acute risk to both small and intermediate sized mammals all on of the uses modeled. Granules were only a risk to large sized mammals for trees, ornamental, turfgrass and tick control uses.

Aquatic Animals For freshwater fish the endangered species LOC is exceeded for all of the crops modeled for all three use rates except for sugar beets. The LOC for endangered species was not exceeded on for sugar beets at the maximum reported use rate. For freshwater invertebrates, the both acute and chronic endangered species LOCs are exceeded for all of the uses modeled. For estuarine/ marine fish, only use on citrus exceeded the acute LOC for all three use rates. For estuarine/ marine invertebrates, the acute endangered species LOC is exceeded for all of the use and rates modeled; however, there currently are no federally listed estuarine invertebrates. At the current application rates, carbaryl use is likely to result in both acute and chronic risks to endangered/ threatened species of animals.

In 1989 the U. S. Fish and Wildlife Service ( USFWS) issued a biological opinion ( USFWS 1989) on carbaryl in response to the U. S. Environmental Protection Agency's request for consultation. In issuing its opinion the USFWS considered the following factors: ( 1) potential for exposure of the listed species to the pesticide; ( 2) information on the chemical toxicity relative to estimated environmental concentrations; ( 3) potential for secondary impacts; and ( 4) special concerns not specifically addressed in the preceding factors or unique to the situation being evaluated. Given the evaluation criteria, a total 127 species ( 6 amphibians, 77 fish, 32 mussels, 9 crustaceans, 1 insect, and 2 bird species) were considered potentially affected by the use of carbaryl. Of those organisms potentially affected, the USFWS listed 85 aquatic species as jeopardized, of which the majority ( 51%) were endangered/ threatened species of freshwater fish. One terrestrial ( avian) species was also classified as being in jeopardy. The remaining potentially affected organisms were listed either as having no potential for exposure or as not being in jeopardy. For all of the species listed as jeopardized the USFWS lists reasonable and prudent alternatives ( RPA) to mitigate the effects of carbaryl use. For some of the species listed as not jeopardized, the USFWS lists reasonable and prudent measures ( RPM) and incidental take ( IT) to mitigate effects. For details on the RPA and RPM recommendations, the reader is referred to USFWS 1989 publication. Many additional species, especially aquatic species, have been federally listed as endangered/ threatened since the biological opinion of 1989 was written, and determination of jeopardy to these species has not been assessed for carbaryl.

EPA's current assessment of ecological risks uses both more refined methods to define ecological risks of pesticides and new data, such as that for spray drift. Therefore, the Reasonable 52 and Prudent Alternatives and Reasonable and Prudent Measures in the Biological Opinion may need to be reassessed and modified based on these new approaches.

The Agency is currently engaged in developing a consultation package for transmittal to National Marine Fisheries Service ( NMFS) on April 1, 2003, to address listed Pacific salmon and steelhead. EPA is committed to look at other species beyond those discussed in this consultation package; additional consultations with both USFWS and NMFS are expected to cover other terrestrial and aquatic species.

The Agency is also engaged in a Proactive Conservation Review with USFWS and the National Marine Fisheries Service under section 7( a)( 1) of the Endangered Species Act. The objective of this review is to clarify and develop consistent processes for endangered species risk assessments and consultations. Subsequent to the completion of this process, the Agency will reassess the potential effects of carbaryl use to federally listed threatened and endangered species. At that time the Agency will also consider any regulatory changes recommended in the IRED that are being implemented. Until such time as this analysis is completed, the overall environmental effects mitigation strategy articulated in this document and any County Specific Pamphlets described in Section IV which address carbaryl, will serve as interim protection measures to reduce the likelihood that endangered and threatened species may be exposed to carbaryl at levels of concern.

The Agency has developed the Endangered Species Protection Program to identify pesticides whose use may cause adverse impacts on endangered and threatened species, and to implement mitigation measures that address these impacts. The Endangered Species Act requires federal agencies to ensure that their actions are not likely to jeopardize listed species or adversely modify designated critical habitat. To analyze the potential of registered pesticide uses to affect any particular species, EPA puts basic toxicity and exposure data developed for REDs into context for individual listed species and their locations by evaluating important ecological parameters, pesticide use information, the geographic relationship between specific pesticide uses and species locations, and biological requirements and behavioral aspects of the particular species. This analysis will take into consideration any regulatory changes recommended in this RED that are being implemented at this time. A determination that there is a likelihood of potential impact to a listed species may result in limitations on use of the pesticide, other measures to mitigate any potential impact, or consultations with the Fish and Wildlife Service and/ or the National Marine Fisheries Service as necessary.

The Endangered Species Protection Program as described in a Federal Register notice ( 54 FR 27984 28008, July 3, 1989) is currently being implemented on an interim basis. As part of the interim program, the Agency has developed County Specific Pamphlets that articulate many of the specific measures outlined in the Biological Opinions issued to date. The Pamphlets are available for voluntary use by pesticide applicators on EPA's website at www. epa. gov/ espp. A final Endangered Species Protection Program, which may be altered from the interim program, was proposed for public comment in the Federal Register in December 2, 2002. 53 REFERENCES ( Excluding MRID Studies)

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Wolfe, N. L., R. G. Zepp and D. F. Paris, 1978. Carbaryl, Propham and Chlorpropham: A Comparison of the Rates of Hydrolysis and Photolysis with the Rate of Biolysis. Water Research, 12: 565 571. 58 APPENDIX A1. DRINKING WATER MEMO UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D. C. 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES MEMORANDUM March 12, 2003 SUBJECT: Final Report of Carbaryl EEC's for Drinking Water DB Barcode: D288455 PC Code: 056801 TO: Anthony Britten, Chemical Review Manager, Reregistration Branch 3 Special Review and Reregistration Division FROM: R. David Jones, Ph. D., Senior Agronomist Environmental Risk Branch 4 THROUGH: Elizabeth Behl, Chief Environmental Risk Branch 4 Environmental Fate and Effects Division This is the final report for revised estimated environmental concentrations ( EEC's) in surface water for the use of carbaryl on selected crops. These EEC's are intended to replace those in the Environmental Fate and Ecological Risk Assessment for the Reregistration of Carbaryl ( Libelo et al., 2002). Since the issuance of that document, new information has been received by the Agency in response to a request for public comments on the draft assessment ( particularly on foliar degradation rates) that warranted a re evaluation of the aquatic exposure. We have also taken the opportunity to make some other changes that improve the general quality and reliability of the estimates.

The EEC's in Table 1 represent the 90 percentile exposure value for carbaryl use on representative crops. These EEC's are based on the maximum use patterns allowed on each label as described below. Because we estimate that the highest carbaryl concentrations will 59 result from the use of carbaryl on citrus, those values are used as a screen in estimating potential drinking water exposure nationally. It should be noted that concentrations estimated to result from carbaryl use on other crops are substantially lower than for the citrus use( see table 1). In addition to the point estimates, we have also provided the time series of carbaryl concentrations for the entire duration of the simulation for the different citrus scenarios. These estimates are intended for use in a more refined estimate of dietary exposure for carbaryl and are being combined with carbaryl residues in food using the DEEM model.

The following changes were made in the selection of input parameters used in this assessment relative to those used in the original set of estimates:

C The foliar half life was changed from 35 to 3.71 days, to reflect relevant data submitted by the registrant. C The foliar washoff coefficient was also changed from a default value of 0.5 to 0.91 based on estimates made from two literature studies submitted by the registrant. C The site for used to represent a vulnerable site for apples was changed from Oregon to Pennsylvania, which better reflects a vulnerable use site for apples across the whole country and is more consistent with EFED's policy on Tier 2 site selection. C In the original assessment, measured soil water partition coefficient's ( Kd's) were used based on the texture of a measured soil. This was changed to using a single Koc of 196 L kg 1 based on the texture in the soil represented in the model scenario, which better reflects current policy. C The value used to represent microbial degradation in the pond sediment was changed from 72.2 to 216 days in keeping with current policy of parameter selection which indicates single metabolism values should be multiplied by three.

Table 1. EEC's for the ` maximum' use patterns for carbaryl on selected agricultural crops Crop Acute EEC Chronic EEC  : g L 1 carbaryl equivalents

Apples 62.9 2.20 Citrus 316 14.2 Field Corn 51.3 2.72 Sweet Corn 57.3 5.53 Sugar Beets 48.2 2.16 C The value originally used for aerobic aquatic metabolism, 12 days, unintentionally resulted in double counting of hydrolysis. A revised value of 29.6 days avoids doubling the hydrolysis rate. C The application date on some sites was changed to better reflect the actual use practice. 60 A more complete description of rationale and effects of these changes is provided below. The revised EEC's for the maximum use pattern are in Table 1. A complete list of EEC's for all use patterns is in Table 6.

Models These estimates were calculated using PRZM version 3.12 dated May 24, 2001 and EXAMS version 2.98.04 dated July 18, 2002. These models were run in the EFED PRZM EXAMS shell, PE3 version 1.2, dated October 15, 2002. The shell also processed the output from EXAMS to estimate the 1 in 10 year return values reported here. In addition, time series of daily values for thirty years were output and have been provided for use in more refined dietary exposure assessment. A list of the input files used to generate these EEC's is in the APPENDIX A2.

It is worth noting that the Office of Pesticide Programs is aware of an error in the current modeling system that results in the " peak" EEC's reported actually representing not instantaneous peak concentrations, but 24 hour mean concentrations on the day the peak occurs. The OPP is currently taking corrective action, but revisions had not completed QA review prior to initiation of this analysis. For the case of carbaryl, this likely results in an approximately five percent underestimation of the peak. However, this error is certainly covered by other substantial conservatisms which are inherent in these estimates.

Scenarios EEC's were calculated for 5 crops which include those which are the major use sites for carbaryl. These sites are: apples, citrus, field corn, sweet corn, and sugar beets. The scenario for apples is in Lancaster County, Pennsylvania and represents a Elioak silt loam soil, Hydrologic Group C soil. The scenario for citrus is in Collier and Hendry Counties Florida and represents a Wabasso sand soil. The scenario for field corn and sweet corn is in Darke and Rickaway Counties, Ohio and represents a Cardington silt loam soil which is Hydrologic Group C. The scenario for sugar beets is in Polk County, Minnesota. The soil there is an Adair clay loam in Hydrologic Group C.

The apple scenario used in previous modeling was set in Oregon rather than Pennsylvania. The site was switched to Pennsylvania as this site is thought to better represent a vulnerable site among all apple orchards across the United States. The Oregon site may not be protective of drinking water facilities downstream from apple orchards in the eastern United States as that geographic region receives lower rainfall and runoff during the growing season than the site in the East. 61 Use Patterns The use patterns for each crop were adapted from the carbaryl labels to represent the maximum use patterns. The input parameters used to represent these use patterns are in Table 2. These values are essentially the same as in for the previous set of EEC's except that the date of first application was changed for some crops to better represent the use pattern. For citrus, simulations for two different initial application dates were done, April 1 and August 31. The April 1 date appears to be plausible for Florida given the pests carbaryl is intended to control, but monitoring data in Florida citrus watersheds indicate that there is use during August and September ( D285826). The results for the citrus scenario are discussed in the characterization section below. In cases where a minimum re application interval was specified on the label this value was used in the maximum application pattern. In cases when no minimum interval is specified, a interval of 3 days was used. The OPP current has no written guidance for this subject. However, three days is a reasonable minimum retreatment interval, given that scouting and evaluation of efficacy would have to occur before another treatment is undertaken. This minimum value has been used by OPP for Tier 2 modeling in the absence of guidance for 10 years. Metadata for each scenario is described in EFED, 2002b.

Table 2. Maximum use patterns for carbaryl application on selected crops based on the EPA label.

Crop Single app. Rate ( lb acre 1) Number of Applications Applicatio n Interval Application Method Date of First Application Apples 2 5 3 days aerial June 1 Citrus 5 4 14 days aerial April 1 Field Corn 2 4 14 days aerial June 1 Sweet Corn 2 8 14 days aerial May 1 Sugar Beets 1.5 2 14 days aerial June 1 62 Table 3. Maximum reported use patterns for carbaryl application on selected crops Crop Single app. Rate ( lb acre 1) Number of Applications Application Interval Application Method Date of First Application Apples 1.6 2 14 days aerial June 1 Citrus 4.26 3 14 days aerial April 30 Field Corn 1.5 2 14 days aerial June 1 Sweet Corn 3* 1  aerial June 1 Sugar Beets 1.2 1  aerial June 1 * The maximum reported rate is greater than the maximum label rate. The seasonal maximum rate is not exceeded, however.

Table 3 contains maximum reported use patterns ( application rate and number of applications), and represents the high end of actual carbaryl use patterns for these crops as determined from survey usage data available from the Doane's Agricultural Services. Table 4 contains " average" use patterns, developed from estimates of the mean ( 50 percentile??) number of applications application rate, the total number of acres receiving an application and total applied to each acre for each crop. ( Hernandez, 2002). For the " average" use pattern, the number of applications more closely reflects those that are reported by BEAD in the QUA ( Hernandez, 2002).

Table 3. ` Average' use patterns for carbaryl application on selected crops Crop Single app. Rate ( lb acre 1) Number of Applications Application Interval Application Method Date of First Application Apples 1.2 2 14 days air blast June 1 Citrus 3.4 2 14 days aerial April 30 Field Corn 1 2 14 days aerial June 1 Sweet Corn 3.4 2 14 days aerial June 1 Sugar Beets 1.5 1  aerial June 1 * The maximum reported rate is greater than the maximum label rate. The seasonal maximum rate is not exceeded, however. ** The ` average' rate is greater than maximum reported rate. The reason for this discrepancy is not known.

In all cases, an aerial application was used for the maximum use pattern and the maximum reported use pattern as this is the application practice on the label which results in 63 the most drift. In practice, the orchard crops would most often receive an application by air blast equipment, therefore air blast was simulated for average uses. Aerial application is represented by using a spray drift efficiency of 0.16 and an application efficiency of 0.95 while air blast is represented by values of 0.064 and 0.99 for these parameters respectively.

Chemical Parameters The input parameters used to describe the chemical properties of carbaryl are in Table 5. In most cases these parameters were selected in accordance with guidance ( Environmental Fate and Effects Division, 2002). Data quality descriptions for each parameter were derived as follows. ` Excellent' was used to describe parameters which very well know and had little or no error associated with them ( e. g. molecular weight) or when there is an abundance of high quality data available. ` Very good' is used to describe parameters from high quality studies and the study is generally reproducible ( e. g. hydrolysis) , or when there is substantial background variability ( e. g. aerobic soil metabolism) there are multiple high quality studies used to develop the input parameter. Good is used to describe abiotic process data where there the data is expected to be reproducible, but is more uncertain than normal, or metabolism parameters base on two high quality, or multiple studies which are usable but not high quality. Fair is used to describe metabolism parameters based on a single study, or significantly flawed by usable data for describing abiotic processes. Poor is used describe input parameters based on surrogate data . In the previous drinking water modeling, soil water partitioning was represented by Kd values which were keyed to the soil texture in studies where Kd's were measured. Since texture is usually only a factor of secondary importance, this does not always result in great accuracy. In this assessment, a Koc was estimated by regressing the Kd's values against the organic carbon content. The Koc value estimated using a regression model with both a slope and an intercept is significant at p = 0.05. However, the Koc model used in both PRZM and EXAMS assumes that the binding at zero organic carbon content is zero ( no y intercept). The regression to this model is significant at p = 0.1 but not 0.05 and results in a Koc estimate of 196 kg L 1. This will result in some underestimation of the binding ( and overestimation of carbaryl mobility) in soils with low organic carbon content, but greater accuracy over all scenarios.

Metabolism half lives were estimated from single studies available for each of the following three studies: aerobic soil metabolism, aerobic aquatic metabolism, and anaerobic aquatic metabolism. The aerobic soil and anaerobic aquatic metabolism half lives were consequently multiplied by three in keeping with current policy to account for the uncertainty caused by the high background variability in these parameters. The anaerobic aquatic metabolism values in the previous modeling assessment was not adjusted by three. In the previous assessment, the aerobic aquatic metabolism half life input parameter was 14.7 days, or three times the single estimate. However, this value was not adjusted to account for hydrolysis, resulting in the effect of hydrolysis being double counted in the previous assessment. This assessment corrected that error; the expected hydrolysis rate ( 9.3 days) at the study pH ( 7.1) was subtracted from the rate constant for the measurement from the aerobic aquatic metabolism 64 study. The resulting value, 9.87 days, which is the half life in the aerobic aquatic metabolism study due to metabolism alone, was multiplied by three for an input parameter of 29.6 days.

In the original assessment, the foliar degradation rate was set to 35 days, the default value based on current OPP policy for terrestrial exposure assessments which is not the same as the current guidance for aquatic modeling. Current guidance for setting the foliar degradation rate for PRZM ( the PLDKRT parameter) recommends, in the absence of data to set the parameter to zero ( no degradation) or no degradation is this correct. The primary registrant, Bayer CropScience, provided data ( MRID 45860501) in their comments on the draft Carbaryl EFED chapter ( Libelo et al, 2002) demonstrating that carbaryl degrades on foliage at a substantially faster rate than 35 days. The data submitted with the report was reviewed and analyzed ( D288376). Based on this assessment, a new value of 3.71 days was used as the foliar degradation half life. This represents an upper 90% confidence bound on the mean from 30 studies from which foliar dissipation of carbaryl could be estimated.

Table 5. Chemical input parameters for carbaryl.

Parameter Value Quality Molecular weight 201.22 g mol 1 excellent Solubility 32 mg L 1 good Henry's Law Constant 1.28 x 10  8 atm m 3 mol 1 fair Koc 196 L kg 1 good Aerobic soil metabolism half life 12 d fair Aerobic aquatic metabolism half life 29.6 d fair Anaerobic aquatic metabolism half life 216.6 d fair Hydrolysis half life pH 5  assumed stable pH 7  12 d pH 9  0.133 d very good Aqueous photolysis 21 d very good Foliar Degradation Rate 3.71 d excellent Foliar Washoff Coefficient 0.91 fair As part of the data submitted for consideration in estimating the foliar degradation rate, the registrant also submitted data which supported a revised estimate of the foliar washoff coefficient. In the absence of data, current EFED policy recommends value of 0.5 which represents the fraction of chemical that washes off with each 1 cm of rainfall. An analysis of two relevant studies indicates that carbaryl washoff is greater; a washoff coefficient of 0.91 is more appropriate based on the data reviewed. However, the estimates for both studies were based on two data point, so no error term or determination of variability in the data could be made. A more complete description of how the studies were assessed is in OPP review D288376. 65 Effects of Drinking Water Treatment There is some evidence that conventional drinking water treatment, that is coagulation, flocculation and settling, is expected to reduce carbaryl concentration by 43% of the concentration prior to treatment ( US EPA, 1989). This is based on a study of wastewater containing carbaryl treated with alum at 100 mg L 1 and 1 mg L 1 of anionic polymer ( Whittaker et al. 1982). In addition, ozone has been shown to be 99% effective at removing carbaryl from water ( Shevchenko et al., 1982) and removes it from water at a rate too fast to measure ( Mason et al. 1990). Evidence suggests that chlorine and hypochlorite may be ineffective at degrading carbaryl ( ibid.). At this point in time, ozonation is only infrequently used for disinfection of public drinking water in the United States. Based on the hydrolysis data, softening would be expected to substantially reduce carbaryl concentrations ( via alkaline hydrolysis) as softening raises the pH of the water as high as 11. Softening is used on ` hard' water that is high in calcium and magnesium and decreases the concentrations of these cations. The Office of Pesticide Programs currently does not have sufficient information to account for locations where water softening processes are utilized at public drinking water treatment facilities, and thus cannot systematically use this information in estimating EEC's.

Results and Characterization EEC's were calculated as described above and then adjusted for percent cropped area ( PCA), based on OPP guidance ( OPP, 2000). For apples, citrus, and sugar beets, the default PCA for all agricultural land of 0.87 was used. The individual PCA for corn of 0.46 was used for field corn and sweet corn. These adjusted EEC's were reported in Table 1 at the front of the document, and the full distribution of EEC's were made available for use in dietary exposure estimation. The citrus scenario is recommended in estimating EEC's for Tier II drinking water assessment. A Tier II EEC uses a single site which represents a high exposure scenario for the use of the pesticide on a particular crop or non crop use site. The weather and agricultural practice are simulated at the site over multiple ( in this case, 30) years so that the probability of an EEC occurring at that site can be estimated. Sites are selected to represent a site which is more vulnerable than 90% of the sites which are used for growing the crop on a nationwide basis. Sites are currently selected to meet this standard by best professional judgement. For each simulation, the exposure of interest, either the annual peak or mean, is identified for each year. These 30 values are sorted and the single point estimate is selected by identifying the value that would be expected to recur once every 10 years. For these simulations, this specific value is linearly interpolated from between the third and fourth highest annual values.

These values are greater than those that would be expected to be found in the environment primarily for three reasons. First, we have used the default PCA of 0.87, as the PCA for citrus in Florida. The default PCA is the maximum proportion of agricultural land found in any basin in the country, In fact, the actual PCA in Florida is probably closer to one third this value, although a precise estimate is not available at this time. Secondly, the percent crop treated has been assumed to be 100%. In fact, according to BEAD ( Hernandez, 2002), the percent crop treated for different citrus crops ranges for 1.5 to 6%, depending on the crop. Thirdly, since the 66 labels have not specified maximum number of applications, the maximum practice modeled is substantially greater than that which is usually used in practice.

Table 6. Drinking Water EEC's for carbaryl based maximum, `' average'' and maximum reported use patterns.

Crop Number of Applications per Year Pounds A. I. per application Surface Water Acute ( ppb) ( 1 in 10 year peak single day concentration) Surface Water Chronic ( ppb) ( 1 in 10 year annual average concentration)

Sweet Corn ( OH) ( PCA = 0.46) Maximum1 8 2 57.3 5.53 Average2 2 3.4 49.8 2.31 Maximum3 Reported 3 1 25.6 1.26 Field Corn ( OH) ( PCA = 0.46) Maximum1 4 2 51.3 2.72 Average2 2 1 14.6 0.68 Maximum3 Reported 2 1.5 21.9 1.02 Apples ( PA) ( PCA = 0.87) Maximum1 5 2 62.9 2.20 Average2 2 1.2 23.4 0.63 Maximum3 Reported 2 1.6 34.4 1.04 Sugar Beats ( MN) ( PCA = 0.87) Maximum1 2 1.5 48.2 2.16 Average2 1 1.5 13.6 0.73 Maximum3 Reported 1 1.2 10.8 0.58 Citrus ( FL) ( PCA = 0.87) Maximum1 4 5 316 14.2 Average2 2 3.4 203 7.33 Maximum3 Reported 3 4.26 272 10.0 1 Maximum application rate on label 2 Average application rate from Quantitative Usage Analysis for Carbaryl, prepared July 21, 1998 by Frank Hernandez, OPP/ BEAD 3 Maximum rate of application reported in Doanes survey data In particular, the rate per acre, and the number of treatments per season is often less than that allowed on the label. In addition, the interval between applications, when there is more than one is usually longer than has been simulated for the maximum use pattern. This third factor has been addressed in this assessment, and is reflected in the EEC's from the ` average' and maximum reported use patterns from Table 3 and 4.

Three additional simulations were done for citrus in order to better characterize the exposure in this scenario. In the first simulation, the application date for the first application was changed from April 30 to August 31, otherwise using the maximum application practice. The second simulation also changed the first application date but with ` average' application practice. While there are pests which could be of concern on citrus as early as April, monitoring data from 67 the area indicates that most of the usage actually occurs in the late summer. The 1 in 10 year peak EEC for the April application and maximum label practice is 316 while for September the value is 220 : g L 1. For ` average' application practice, the respective EEC's are 203 and 125 : g L 1. Another run was done where best estimates for all the metabolism values were used as inputs ( 4 day half life for aerobic soil metabolism, a 9.6 day half life for aerobic aquatic metabolism, 72.2 days for anaerobic aquatic metabolism, and 3.2 days for foliar degradation) combined with `' average'' application practice in September to give a ` best' estimate of the EEC for this site. The 1 in 10 year peak in this case was 78.9 : g L 1.

In addition to the point estimate EEC's for drinking water exposure described above. We have provided the time series of concentrations for the entire duration of the simulation for the different citrus scenarios. These series of estimates are intended for use in a more full of the whole range dietary exposure for carbaryl and are being combined with pesticide residues in food using the DEEM model. While making fuller use of the whole time series for drinking water exposure is expected to improve the description of the dietary risk, using the time series for water in combination with the distribution of food residues and consumption patterns normally used in DEEM substantially alters the interpretation of the risk represented by the output of the model because the drinking water component introduces a time component which is not present in the food and consumption data  any time component in the data is ignored by DEEM. Technically, the food and consumption distributions are assumed to be ` stationary' with respect to time and location, that is the distributions are always the same at any point in time and any location in the United States. This is a reasonable assumption for food residues and consumption, but not a reasonable one for pesticide residues in drinking water which are expected to vary by orders of magnitude with both time and location. The difference in interpretation can be best illustrated by describing how the interpretation differs when the different exposure components dominate the exposure profile. When food ( other than water dominates the exposure and the drinking water contribution is negligible, an exceedance of the 99.9% threshold implies that one person in 1000 across the whole U. S. population is above the threshold each day. If drinking water dominates and food contributions are negligible, an exceedance of the 99.9% means that the entire population provided drinking water from a facility represented by scenario, are expected to exceed the risk once every 1000 days, a little less that once every three years. When both water and food sources make significant contributions to exposure, a more detailed analysis of the structure of the data is necessary to determine the nature of the risk. Depending on the structure of the risk, regulating on the 99.9 percentile in a manner similar to that used previously may not provide a intended level of safety similar to that which is provided by using DEEM with food only and the DWLOC approach with water.

Beyond the three major factors which are described above, there are a number of other factors inherent in the modeling can affect the accuracy and precision of this analysis including the selection of the high exposure scenarios, the quality of the input data, the ability of the models to represent the real world, and the number of years that were modeled.

Scenarios that are selected for use in Tier 2 EEC calculations are ones that are likely to produce large concentrations in the aquatic environment. It should represent a site that really exists and would be likely to have the pesticide in question applied to it. It should be extreme 68 enough to provide conservative estimates of the EEC, but not so extreme that the model cannot properly simulate the fate and transport processes at the site. Currently, sites are chosen by best professional judgement to represent sites which generally produce EEC's larger than 90% of all sites use for that crop. The EEC's in this analysis are accurate only to the extent that the site represents this hypothetical high exposure site.

The quality of the analysis is directly related to the quality of the input parameters. In general, the fate data for carbaryl are good. The paucity of soil and aquatic metabolism data is the main limitation of the data set. Because metabolism values are set to the upper 90% confidence limit of the mean, the EEC's will be conservative to the extent we are uncertain of the true central tendency of the metabolism data. Additional metabolism data would greatly increase our confidence, and likely reduce our EEC estimates. As noted above, using best estimates for " average" application practice rather than the standard upper bound estimates reduced the EEC from 125 : g L 1 to 78.9 : g L 1. This indicates that the quantity and quality of the metabolism data can substantially effect the estimates.

The models themselves represent a limitation on the analysis quality. While the models are some of the best environmental fate estimation tools available, they have significant limitations in their ability to represent some processes. Spray drift is estimated as a straight 16% of the application rate reaching the reservoir for each application. In actuality, this value should vary with each application from zero when the wind blows away from the reservoir to perhaps as high as 20%. A second major limitation of the models is the lack of validation at the field level for pesticide runoff. While several of the algorithms ( volume of runoff water, eroded sediment mass) are well validated and well understood, there is less confidence that PRZM 3.12 well represents the amount of pesticide transported in runoff events. Some validation efforts undertaken by the pesticide industry and under review by the Agency indicate that PRZM gives reasonable estimates of pesticide extraction into runoff, but validation of the runoff portion of PRZM is not extensive. Another limitation of the models used is their inability to handle withinsite variation ( spatial variability), lack of crop growth algorithms, and an overly simple soil water transport algorithm ( the " tipping bucket" method). A final limitation is that only thirty years of weather data were available for modeling at each site. Consequently there is approximately a 1 in 20 chance that the true 10% exceedance EEC's are larger than the maximum EEC in the calculated in the analysis. If the number of years of weather data could be increased it would increase the confidence that the estimated value for the 1 in 10 year exceedance EEC was close to the true value.

Literature Citations D285826. Behl, Elizabeth. 2003. Review of " Surface Water Monitoring for Residues of Carbaryl in High Use Areas in the United States." EPA Internal Memorandum to Tony Britten.

D288376. Jones. R. David. 2003. Review of " Estimation of the Foliar Dissipation Half life of Carbaryl" and Re analysis of the Foliar Degradation Rate. EPA Internal Memorandum to Tony Britten. 69 MRID 45860501. Holmsen, Jeffrey D. Estimation of the Foliar Dissipation Half life of Carbaryl. Bayer CropScience Research Triangle Park, NC Study ID 606YS. Report No. B003798.

Environmental Fate and Effects Division. 2002. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides, Version II. U. S. Environmental Protection Agency. Washington, D. C. http:// www. epa. gov/ oppefed1/ models water/ input_ guidance2_ 28_ 02. htm/

Environmental Fate and Effects Division. 2002b. Pesticide Root Zone Model ( PRZM) Field and Orchard Crop Scenarios: Standard Procedures for Conducting Quality Control and Quality Assurance. http:// www. epa. gov/ oppefed1/ models/ water/ qa_ qc_ documentation_ ver2. htm/

Hernandez, Frank. March 18, 2002. Quantitative Usage Analysis for Carbaryl. Internal EPA Memorandum.

Libelo, E. Laurence, Angel Chiri, and Thomas Steeger. 2001. Environmental Fate and Ecological Risk Assessment for the Reregistration of Carbaryl. Unites States Environmental Protection Agency/ Office of Pesticide Programs. http:// cascade. epa. gov/ RightSite/ getcontent/ Tempfile. pdf? DMW_ OBJECTID= 090007d4800cd83d& DMW_ FORMAT= pdf Office of Pesticide Programs. 2000. Part A. Guidance for Use of the Index Reservoir in Drinking Water Assessments. http:// www. epa. gov/ oppfead1/ trac/ science/ reservoir. pdf Shevchenko, M. A., P. N. Taran, and P. V. Marchenko., 1982. Modern methods for purifying water from pesticides. Soviet Journal of Water Chemistry and Technology. 4( 4): 53 71.

United States Environmental Protection Agency. 1989. Lewis Publishers. Drinking Water Health Advisory: Pesticides. Lewis Publishers. Chelsea, Michigan.

Whittaker, K. F., J. C. Nye, R. F. Wukasch, R. J. Squires, A. C. York, H. A. Kazimier. 1982. Collection and treatment of wastewater generated by pesticide application. EPA Report No. 600/ 2 82 028 70 APPENDIX A2. INPUT FILES FOR ESTIMATING DRINKING WATER EXPOSURE FOR TOTAL CARBARYL RESIDUES.

Table C 1. Input files archived for azinphos methyl applied to pome fruits.

File Name Date Description W12842. dvf July 3, 2002 weather data for Florida citrus scenario W14637. dvf July 3, 2002 weather data for Pennsylvania apple scenario W14914. dvf November 20, 2002 weather data for Minnesota sugar beet scenario.

W93815. dvf July 3, 2002 weather data for Ohio corn scenario Flcitrus. txt October 12, 2002 Florida citrus scenario parameters for PRZM & EXAMS MNsugarbeet. txt October 12, 2002 Minnesota scenario parameters for PRZM & EXAMS OHcorn. txt October 12, 2002 Ohio corn scenario parameters for PRZM & EXAMS PAapple. txt October 12, 2002 Pennsylvania apple scenario parameters for PRZM & EXAMS Input Data Files for specific simulations (. PZR extension)

FLCits00 February 13, 2003 citrus, maximum use pattern, index reservoir FLCits01 February 13, 2003 citrus, maximum use pattern, Sept application, index reservoir FLCits02 February 13, 2003 citrus, ` average' use pattern, index reservoir FLCits03 February 13, 2003 citrus, maximum reported use pattern, index reservoir FLCits04 February 13, 2003 citrus, ` average' use pattern, air blast, September application, best estimate metabolism parameters.

FLCits10 March 7, 2003 citrus, ` average' use pattern, air blast, September application OHCorn00 February 13, 2003 field corn, maximum use pattern, index reservoir OHCorn01 February 13, 2003 field corn, ` average' use pattern, index reservoir OHCorn02 February 13, 2003 field corn, maximum reported use pattern, index reservoir OHCorn03 February 13, 2003 sweet corn, maximum use pattern, index reservoir OHCorn04 February 13, 2003 sweet corn, ` average' use pattern, index reservoir OHCorn05 February 13, 2003 sweet corn, maximum reported use pattern, index reservoir PAAppl00 February 13, 2003 apples, maximum use , index reservoir PAAppl01 February 13, 2003 apples, ` average' use, index reservoir PAAppl02 February 13, 2003 apples, maximum reported use, index reservoir MNSbet00 February 13, 2003 sugar beets, maximum use pattern, index reservoir MNSbet01 February 13, 2003 sugar beets, ` average' use pattern, index reservoir MNSbet02 February 13, 2003 sugar beets, maximum reported use pattern, index reservoir cc: Jeff Dawson Felicia Fort chemical actions 71 APPENDIX B1. REVIEW OF DRINKING WATER MONITORING STUDY.

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D. C. 20460 PC Code: 056801 DP Bar Code D285826 DATE: March 13, 2003 MEMORANDUM SUBJECT: Review of " Surface Water Monitoring for Residue of Carbaryl in High Use Areas in the United States: Final Report"

FROM: Elizabeth Behl, Chief Environmental Risk Branch IV Environmental Fate and Effects Division ( 7507C)

THROUGH: R. David Jones, Sr. Agronomist, ERB4 Environmental Fate and Effects Division ( 7507C)

TO: Anthony Britten, PM Team Reviewer Branch X Michael Goodis, Acting Chief Special Review and Reregistration Division ( 7508C)

This memo presents EFED's review of the final report from a study voluntarily conducted by Aventis for carbaryl. Interim results from this study were reviewed previously by the Agency ( DP Bar Code D274824; 8/ 7/ 2001), and a preliminary review of the study and data from the interim report were included in the EFED Risk Assessment of Carbaryl ( USEPA, 2002). Aventis provided feedback to the Agency on our review of that study, which the Agency responded to ( USEPA 2002a). Aventis provided further comment ( largely a repetition of their original comments) on the Agency's review of this monitoring study in public comments submitted to the electronic docket in October 2002.

Conclusions This study provides useful information on measured concentrations of carbaryl in selected surface waters of the United States. Based on our analysis of sites selected, we do not concur that these results can be used directly in the dietary risk assessment to represent exposure to carbaryl in surface water source drinking water. The information from this study does provide some good quality data that can be used in association with other monitoring data sets to characterize carbaryl exposure. 72 These data will be used in conjunction with other monitoring data, to characterize surface water modeling estimates of carbaryl exposure from surface water source drinking water.

Involving EFED/ OPP in the scoping and planning of this study, developing the protocol design, and during site selection is necessary to ensure that the data collection effort is focused on adequately addressing the specific risk assessment questions. The main study goal is in line with data needed by the Agency to refine the drinking water risk. However, the implementation of the study ( especially site selection) was not consistent with the study goal and the data can be used only qualitatively.

A detailed critique of the monitoring data are presented in the body of this review. Several major drawbacks to the quantitative use of these data to represent drinking water exposure are:

° With only 16 sites to represent vulnerable surface water bodies for selected agricultural uses ( really 15, as the LA site was selected to represent population exposure not because source waters were vulnerable) and four suburban sites, this study is not likely to provide comprehensive coverage of all carbaryl usage sites, given the great geographic diversity of carbaryl use areas and carbaryl uses.

° We do not concur that sites sampled represent the " the highest probable risk of human exposure to carbaryl in surface water in each state". A majority of the agricultural sites monitored do not have " high" carbaryl usage in the county, based on registrant criteria. The size of watersheds ( another measure of site vulnerability) exceeded the 70th percentile nationally ( about 1000 aquare kilometers) for all but five agricultural CWSs. Overall, the majority of monitoring sites are located in areas where carbaryl usage is not the highest nationally, on water bodies draining large watersheds, or on systems which derive their water from large lakes or rivers. Although there is some carbaryl usage in the watersheds of these CWS, a minority of monitoring locations appear to represent CWS which are most vulnerability to contamination.

° Because little supporting data were provided on non agricultural sales and national scale nonagricultural carbaryl usage, the relative vulnerability of the systems selected to represent " home and garden" useage effects could not be determined. The majority of those systems were located on smaller sized waterbodies, and from that perspective are vulnerable to contamination. Only one system had watershed which exceeded the 70th percentile CWS watershed size nationally ( Blomquist, 2003).

° The monitoring interval ( one week to two weeks) is unlikely to capture peak concentrations necessary for estimating acute dietary risk, given the variable nature of the exposure.

° The finished water data are difficult to interpret. According to the study design finished water samples were collected before raw samples, complicating the temporal pairing of samples. Also, to collect temporally paired raw and finished samples ( and to interpret the resulting data) there must be data on temporally relevent treatment processes in place at each sampling point during the sampling period. These data were not provided or discussed. 73 Despite these drawbacks, the study design was one of the better surface water monitoring studies submitted to the Agency over the past several years. The analytical methodology and method sensitivity, quality assurance procedures, study duration, and aspects of their approach to site selection were sound.

Results of this study indicate that carbaryl was found in source drinking water ( raw water) at low concentrations in the majority of sites ( 13 of 16 sites) selected to represent impacts from agricultural uses, despite the relative lack of vulnerability of these sites. Concentrations measured at these sites were low ( roughly 2 to 31 ppt) in raw water and generally lower in treated drinking water; however, the highest concentrations were found in finished, not raw, drinking water ( 181 ppt). Where residues were detected, frequency of detection in raw water samples ranged from a few percent of total samples ( 1 6 %) at 9 of the 13 sites to about 20% of total samples ( 14  21%) at 4 sites. Two of these higher detection frequency sites are on the Sacramento River, one site in Florida, and one site in Massachusetts representing impacts from use on cranberries. There is some correspondence annually with the timing of detections at each site, but it is not uniformly strong. At several sites, low level concentrations were measured over 3 4 week periods in weekly samples. Given the environmental fate characteristics of this compound, this is most likely the result of the volume of usage rather than the persistence of the compound.

Carbaryl was reported in raw water of all four CWS selected to represent impacts from home and garden uses. Concentrations measured in raw water at these sites were low ( roughly 2 to 44 ppt) and detection frequencies ranged from approximately 1 to 20 %. How representative these systems are of the home and garden use of carbaryl cannot be determined from the data provided. However, the lowest detection frequency occurred at the CWS with the largest watershed size ( exceeding the 70th percentile nationally). At one site, concentrations were reported in sequential weekly samples for a period of several months, likely due to the volume of usage.

Because raw and finished samples were not temporally paired, we cannot make quantitative statements about the impact of treatment processes in removing carbaryl from source water. In fact, in several instances the treated water concentrations were higher than the raw water concentration in the " pair", including the highest reported concentrations Background:

This study was voluntarily conducted by the registrant of carbaryl, and no protocol was submitted for review by the Agency prior to it's initiation. Interim results from this study, containing data covering the period February 19, 1999 through December 31, 2000, were reviewed previously by the Agency ( USEPA, 2001). At the time the Agency concluded that:

" The results of this study may provide useful, though limited, information on the level of carbaryl contamination in raw surface water used for drinking water. It may also provides limited information on concentrations present in finished water. It is hoped that the results of this study, in combination with data from other sources, will increase our understanding of exposure to carbaryl in drinking water. Information 74 on site selection, source water, carbaryl use and how the sampled water supplies relate to population distribution are required to fully evaluate the data collected in this study.

The site selection was subsequently submitted to the Agency ( 10/ 1/ 2002) as an appendix to the final report.

OPP uses the models PRZM and EXAMS to estimate concentrations of pesticides that can occur in surface water, and evaluates available monitoring data in developing pesticide exposure assessments. For chemicals with relatively short half lives and when acute exposure is of key concern, model estimates provide a more realistic estimate of upper end exposure than most monitoring data, largely due to the prohibitive costs associated with very frequent sample collection and analysis of large numbers of samples.

Monitoring data do provide a valuable check on model values, which are intended to represent the upper end of potential exposure. Comparison of model and monitoring results are most relevant when monitoring sites are selected to be similarly representative of the upper end of potential exposure. In general, review of a monitoring study will focus first on the overall design of the monitoring study to determine if the study design is consistent with the study purpose. Second, the review should determine if the implementation of the study is consistent with the study design ( and the study purpose). Finally, the results of the study are evaluated in terms of data quality and in the context of the study design.

Problem Formulation Problem formulation should occur prior to initiation of a monitoring program and should involve interaction between risk assessors, risk managers and other interested parties. The interactive nature of this activity is critical to ensure that the data will address regulatory questions. Problem formulation prior to initiation of this study appears to have been done primarily by Rhone Poulenc.

Study Purpose In their final report, Aventis states the purpose of the study as follows:

" This study was conducted to determine the potential for carbaryl residues to reach public water supplies resulting from the use of SEVIN brand insecticides..... This study was conducted to provide an assessment of the potential of carbaryl residues in surface water to contribute to dietary exposure due to consumption of drinking water."

Assessment Endpoints Bayer does not explicitly identify assessment endpoints for carbaryl. Carbaryl risk from drinking 75 water sources will be determined by the Agency in association with other dietary components, including assessment of both acute and chronic endpoints. Acute endpoints are of particular interest in assessing carbaryl risk, and require an estimate of peak carbaryl concentrations in drinking water. Consideration of this endpoint is not evident in the study design.

Conceptual Model There is no description of the overall system and conceptual model for this monitoring study; however, one can be interpreted from the study design that resulted.

° Monitoring points selected were at community water supply facilities, so drinking water exposure was targeted. All community water supply facilities monitored derived their water from surface water sources and treat the water prior to distribution. This represents the majority of surface water source drinking water consumed by the US population ( there are some surface water source drinking waters that are not treated prior to consumption, but very few). Ground water sources are not included in the study design.

° Sites were selected to represent locations that are " vulnerable" to carbaryl exposure largely on the basis of pesticide sales.

° A secondary study goal is to represent impacts from specific uses in selecting some of the agricultural monitoring sites.

° A third study goal is to incorporate a measure of potential exposure to large human populations ( rather than rather than system vulnerability to contamination)

° Aventis collected both raw and finished drinking water samples, representing the finished drinking water samples collected in this study as more relevant to human exposure than raw water samples.

Study Design ( Analysis Plan)

The following sections describe study design components, study implementation, and results.

Number of sites to monitor. RPAC determined that 16 sites would be monitored in " areas of high agricultural carbaryl use"; and four in " large suburban areas of highest regional carbaryl sales for non crop use". The rationale for the overall number of monitoring sites ( 20 sites) is not provided but was a constraint in the study design, most likely due to cost considerations. Because carbaryl is widely used for both agricultural and home and garden uses, the monitoring sites were apportioned to represent these two major usage categories.

No summary information is provided describing the universe of carbaryl use nationally (" agricultural" and " home and garden") for reference in determining the number of sites which would 76 be adequate to monitor to meet the study goals. Carbaryl is used on a variety of crops in almost every State in the U. S. ( based on Doane usage maps) and is a major insecticide for home and garden use in the U. S. Given the diversity of uses and the hydrologic diversity of the use areas it is difficult to adequately represent overall carbaryl impacts on surface water quality with this small number of monitoring sites.

RPAC also indicated that they tried to meet a secondary study goal, to represent impacts from specific uses ( for example, from cranberries), in selection of some of the 16 agricultural sites. This second goal further complicates the study design adding an additional level of complexity. For example, to represent a range of potential impacts on surface water quality from cranberry uses would require monitoring at several sites where cranberries agriculture dominates water quality impacts or alternatively a description of why only that one site was selected to represent all potential cranberry sites. How crop type would play into site selection decisions is not clear.

Bayer's third study goal, of trying to include sampling of sites which result in high exposure, would result in a very different set of site selection criteria. These criteria are not presented, not is there a description for why the one site selected was chosen over other potential sites.

Site Selection. Aventis characterizes the sites selected for monitoring as:

" The source water for all selected water treatment facilities was surface waters originating in watershed areas with a high carbaryl use on agricultural crops or which drain suburban areas with high sales of carbaryl for home and garden use."

Monitoring sites were all existing Community Water Supply facilities ( CWS), which supply drinking water to the local population. All CWS had to have surface water as their primary exclusive source ( not ground water, not a blend of ground and surface water, not fa surface water source used as a backup to the primary supply).

With the exception of one system, RPAC characterized all CWS as potentially vulnerable to carbaryl contamination, primarily on the basis of " high" carbaryl sales ( or high usage in California) in the counties where the watershed of the CWS is located. The exception was a CWS located in Riverside Co., CA which supplies a very large population ( Los Angeles, CA) and was selected on the basis of potential population exposure rather than vulnerability to contamination. County level sales was stated to be the prime criterion for selection of the other 15 agricultural sites, and high sales in the " sales region" was the prime criterion for selection of the four urban sites. Sales regions typically cover many states; the top distribution city in the sales region was assumed to have the highest sales ( and resulting usage).

Differences between usage and sales are recognized, and " refinements" are described to better represent actual carbaryl usage in a watershed. Use of GIS tools is described for refining the site selection, identifying watersheds boundaries and overlaying sales data. Refinement of crop location was also to be done by consultation with local experts ( RPAC sales personnel and CWS personnel) 77 familiar with the specific sales area. How this will be documented is not clear. Land use data was also to be used in home and garden site selection to screen out agricultural use and identify large suburban areas with CWS using small rivers draining only urban areas. Suburban land use was identified in NLCD data coverages and" low intensity residential". Specific criteria to be used ( what defines a small river; what density of housing defines suburban land; what percentage of the watershed in suburban land use made it qualify) are not provided.

Study design criteria state that:

" CWS using small and medium sized watersheds will be selected, although large watersheds may be selected if the primary carbaryl application area is located near the intake location. This is done to maximize the likelihood of detecting carbaryl residues"

No definitions are provided for the terms " small", " medium", and " large" watersheds and criteria describing the size of the water body being sampled are also not quantified. In identifying vulnerable monitoring sites for the USGS EPA Pilot Reservoir ( Blomquist et al, 2001) monitoring study EPA focused on identifying reservoirs with high potential pesticide use, high intensity agriculture in a watershed, relatively small volume reservoirs ( 120   92,600 acre feet) and relatively small watershed size ( 3.3   784 square miles). These parameters are important in identifying and appropriately characterizing watersheds as vulnerable for site selection.

Several of the rejection criteria identified in the study design are reasonable to use to select CWS as assessment points consistent with the study design goals. In general, for example, the CWS selected must be in a watershed that has significant carbaryl use, derives their water from surface water sources, and represents source waters that are most likely to be contaminated. Consistent with these design goals, CWS were rejected if:

° The CWS watershed was in a non agricultural area of a high carbaryl sales county ° Source waters were either: ground water, mixed surface and ground water, or surface water was only the secondary source. ° Source was a Great Lake ( based on concerns about the size of the watershed and storage) ° Personnel were unwilling to participate ° Source water is pumped from high elevation reservoirs which are outside agricultural areas ( specifically in CA) ° the ratio of county level sales area to non sales area in watershed was " low" ( low is not defined)

Several other criteria are not consistent with the study goal of identifying vulnerable sites for sampling, for example:

° Retaining CWS for county with a low county level sales area to non sales area in watershed when the high sales county was in " proximity" to the CWS intake. The relative influence of the carbaryl use area in comparison to the impact of the rest of the watershed may or may not 78 be significant, and must be documented. If potential carbaryl impacts at the CWS are not likely to occur, these systems should be rejected as measurement locations which are not be consistent with study design goals.

° Retaining CWS for systems with large watersheds or rivers if the " high" sales county was in " proximity" to the CWS intake. Again, the relative influence of the carbaryl use area in comparison to the impact of the rest of the watershed may or may not be significant, and must be documented with all termed defined. If potential carbaryl impacts at the CWS are not likely to occur, these systems should be rejected, as they would not be consistent with study design goals.

° Rejecting CWS in California which draw water from canals or aqueducts ( because of difficulties in accounting for input from flood irrigated fields and " ground water sources"). The rationale for this rejection criterion is unclear, as irrigated fields which may drain into canals ( or for that matter rivers) exist and affect surface water quality in California. Rejection CWS which could have water quality affected by irrigation return flow preferentially removes some of the most potentially vulnerable CWS from consideration. This is not consistent with the study design goal.

Sampling frequency, interval, and study duration. According to the study design, sampling at the agricultural sites begins two weeks prior to the typical carbaryl application period with samples collected weekly during the application period and at least one month afterward. . The timing is based on local expert advice, but how this was determined was not described. Samples are to be collected monthly for the remainder of the year. The exception to this is at the Florida site, as a result of the broad use season, where sampling continued on a weekly basis throughout the year. For the " home and garden" sites, sample is scheduled to begin in March or April, and continued weekly throughout the study. The study protocol was amended to provide a total of three years of sampling, consistent with EFED recommendations.

Targeting sampling frequency to the application period is a reasonable approach. The duration of the study is consistent with EFED study design recommendations, and should be adequate to meet study design goals. Weekly sampling is not likely to provide an adequate estimate of peak concentrations for use in acute exposure assessment, a key design goal.

Sample matrix. Samples are to be collected from raw drinking water at the intake and finished water after passing through the treatment plant. Duplicates of both raw and finished are to be collected, with the duplicate available for analysis as needed. All raw water samples are being analyzed. Finished water samples are being analyzed when the paired raw water sample has detectable concentrations of carbaryl. This procedure is consistent with EFED guidance for reactive sampling design, with the stipulation that the drinking water treatment train is well know at each sampling interval so that samples can be considered to be paired. The protocol stipulated that finished samples be collected prior to raw samples, so raw and finished sample " pairs" will not be collected in a time frame relative to the treatment train. 79 Current OPP guidance ( OPP, 2000) for monitoring surface water source drinking water indicates that to represent drinking water exposure, raw water samples should be sampled because of added complexities and uncertainties introduced into estimates. These recommendations were made for two reasons. First, to minimize spatial and temporal variability introduced during treatment. Second, to enable necessary mitigation to be targeted to sources waters of concern. The purpose of collecting temporally paired raw and finished drinking water should be to determine the effect of treatment on exposure. Mixing the raw and finished water results combines two separate sample populations and makes interpretation difficult.

Ancillary data collection. A substantial amount of information is provided for each treatment facility and watershed area including watershed delineation and GIS characterization. Although the information is better than what is presented in the vast majority of monitoring studies, it is difficult to determine a number of important factors about the facilities which control their vulnerability. For example, it is difficult to determine the location of treated areas within the watershed or the location of crops treated, from the information provided. Relatively little information is submitted on the source water ( volume of reservoir or lake, or average monthly flowrate). Information on treatment processes used at each facility is provided, but not in a way that can be used quantitatively to estimate removal or to evaluate the timing required to adequately pair raw and treated samples. The nearest NOAA station is identified as a source of precipitation data. Soils information is also provided for the watershed.

Sample collection and handling: For the most part sample collection and handling procedures as described in the protocol will meet the study design guidelines. Sample collection, handling and shipment procedures according to Stone Environmental SOP's. Samples will be shipped on the day of collection with ice packs ( described in SOP's) and samples frozen upon receipt at the lab until analysis. Samples will be stored for a maximum of 99 days ( from receipt to analysis) Handling procedures will depend on the pH of the water. Since carbaryl is unstable in alkaline water at room temperature, 0.5 ml of formic acid is added to stabilize potential carbaryl residues.

Analytical Method The analytical method described in the protocol, including the method detection limit, are adequate to meet the study goal. LOD is 2 ppt; LOQ is 30 ppt. An independent laboratory validation ( ILV) was submitted for the method. Residues detected between LOD and LOQ were estimated. No degradates of carbaryl will be analyzed. An ILV of the method was completed prior to initiation of the study. Samples are extracted prior to analysis ( SPE using C18 SPE cartridges). Analysis is by reverse phase HPLC, quantified by MS/ MS. The protocol indicates that the control test matrix in quality control samples ( i. e. matrix spikes) uses " Type I" water The source of this water is not clear, and should be described in detail. The effect of this cannot be determined from the data provided.

QA/ QC. Storage stability studies were conducted for field and lab samples. A method blank and a field spike appear to be included with each sample set analysis, but the description is confusing and the overall number is not clear. A sample set appears to consist of: one field spike at 30 ppt, one at 300 ppt in HPLC grade water, one control blank, and some number of field samples. . Clarification is needed to confirm that this is the case. It appears that each sample set included 8 field 80 samples, however this also needs confirmation. Clarification is also needed regarding the use of field blanks.

Storage stability was tested in field recovery studies at 5 locations using field spikes: duplicate samples of raw and finished water ( 200 ml) were spiked at 300 ppt and 30 ppt of carbaryl. Storage stability studies indicated that frozen samples were stable when stored for total of 4 months.

Summary Aspects of the study design are consistent with Agency guidance and the primary study design goals. Useful ancillary data is collected for this study which aids in analysis of the study design and implementation, particularly related to sample QA, analytical results, and collection and handling procedures. Important parameters describing CWS vulnerability ( reservoir volume or stream flowrate) are not taken into consideration in site selection, a significant flaw in the study design. Sampling frequency is not likely to be adequate to meet the primary study design goal. Some important parameters lack adequate definition. Without better more quantitative definition or clear decision criteria important aspects of site selection are subject to interpretation. Adequate information is not provided to determine if the number of sites selected to monitor such a complex and varied use area is adequate. Not enough information is provided to determine if the secondary goal of representing impacts from specific crops could be met by this design. OPP guidance on the use of finished drinking water rather than raw water samples to estimate pesticide exposure is well documented ( OPP, 2000). Because of the protocol for collection of raw and finished samples it will be difficult to draw quantitative conclusions regarding the effect of treatment on carbaryl residues.

Study Implementation Number of sites to monitor It appears that RPAC identified 20 counties in certain states which met their criteria and provided this information to a contractor to finish selection of individual CWS and to implement the study.

According to their contractor:

" The goal for each state [ identified by RPAC] was to establish a monitoring program using the CWSs that represented the highest probable risk of human exposure to carbaryl through surface drinking water. Highest probable risk is assumed to be associated with those watersheds draining the highest sales counties in each state."

RPAC identified 20 municipal water treatment facilities which derive their water from surface water sources. RPAC identified sixteen agricultural sites in: California ( 5 sites); Florida ( 1 site), Michigan ( 2 sites), New York ( 2 sites), Oregon ( 2 sites), Texas ( 2 sites), and Washington ( 2 sites). Sites selected for potential inclusion as " large suburban areas of highest regional carbaryl sales for noncrop use" were: Dallas, TX; Atlanta, GA; Little Rock, AK, and Greensboro, NC Trying to meet a secondary study goal, to represent impacts from specific uses ( for example, from 81 cranberries) played a role in selection of some of the 16 agricultural sites. This second goal complicates the study purpose adding an additional level of complexity to the conceptual model. However, it does not appear that additional monitoring sites were selected to meet these additional criteria. For example, to represent a range of potential impacts on surface water quality from cranberry uses would likely require monitoring at more than one site where cranberry agriculture dominates water quality impacts. At the very least a description of why this one site was selected to represent all potential cranberry sites where carbaryl is used should have been provided.

Bayer's third study goal, of trying to include sampling of sites which result in high exposure, would result in a very different set of site selection criteria. These criteria are not presented, not is there a description for why the one site selected was chosen over other potential sites.

Site Selection The initial scope of the study (" 20 CWS that have potential risk of exposure to carbaryl") was determined by Rhone Poulenc Agricultural Company ( RPAC) based on sales information, location of CWS, and somehow distributed to " encompass different types of agricultural use". Sales data were used as a surrogate for determining actual agricultural usage, except in California where countylevel use data was available. To estimate home and garden use, Aventis relied on regional sales information from " stores such as Walmart, Home Depot, and Sam's Club". Although the site selection report contains a table ( see Table 1 below) of major carbaryl use crops, how this information was used to systematically select sites is not clear.

Table 1 Crop Usage ( as presented in study design) and monitoring locations selected Crop Usage Agricultural Monitoring Site Citrus 17% Riverside, CA, Manatee Co.

Vegetables 14% Manatee Co., Lenawee Co., Marion Co.

Tree nuts 12% W. Sacramento, Lodi, CA Wagoner Co. Calhoun Co Jefferson Co.

Pastures 9% Wagoner Co. Calhoun Co , Jefferson Co.

Stone fruit 8% W. Sacramento, Lodi, CA Pome fruits 7% Lenawee Co. Yates, Co. Chelan Co., Franklin, Co Grains 6%

Grapes 5% Chatauqua Co., Yates, Co.

Roots/ tubers 5% Lenawee Co., Franklin, Co Soybeans 4% 82 Other 7% cranberry  Plymouth, MA rice Calhoun, TX Table 1 represents major use crops and related monitoring sites, according to Aventis. From this table it appears that the effort to distribute sites to represent the variety of carbaryl uses played a relatively major role in site selection efforts. Sites do represent multiple uses; however there is an embedded decision to select sites representing some relatively minor uses rather than to select multiple sites representing major uses. Also, while the stated use may occur in the county, it is not clear how dominant these uses ( or home and garden uses) are in the watersheds.

Agricultural site selection This section describes major factors considered in site selection, and some drawbacks and inconsistencies in applying these factors which resulted in selecting a number of sites for monitoring which were not particularly vulnerable. Information is presented on the agricultural sites selected in Table 2.

Sales. High county level sales, the primary criterion for selection of the agricultural sites, was defined by RPAC as sales greater than 15,000 lb a. i. The intervals used to map county level sales ( in lb. a. i.) were: 0 1,999; " low" 2,000 4,999; " medium" 5,000 14,999; and " high" 15,000 265,000. Using such a large interval to represent the " high sales" of carbaryl masked several of the higher carbaryl sales counties with CWS which should have been considered in site selection. According to the site selection report only 13 candidate systems were found in the high sales category counties, and thus additional systems were selected from " the high end of the medium sales category" ( not defined). Using Doane data ( 1999 2 1) we identified 20 counties nationally with surface water source CWS and carbaryl sales over 15,000 pounds. Five of these counties were represented in the final set of monitoring sites. Several of the CWS selected for monitoring in this study were in counties which would be characterized by RPAC's scale as " low" usage ( less than 5000 pounds), for example: Calhoun Co., 900 pounds; Lenawee Co., 1,500 pounds; Wagoner Co., 1850 pounds; Manatee Co., 3200 pounds; Jefferson Co., 4,300 pounds. Thus, five of the 16 agricultural sites selected did not meet this vulnerability criterion.

Watershed Size and Source Volume.

In selecting sites for the carbaryl monitoring program, information was not gathered on the volume of the reservoir or the flow rate of rivers, and these parameters were not considered in determining the vulnerability of sites. The importance of these factors ( and a third factor, watershed size, which was collected as ancillary data but not used as a vulnerability criterion), on site vulnerability was recognized in study design rejection criterion. CWS which relied on the Great Lakes as their water source were rejected due to the large size of their watersheds and storage of the lakes. Information was not provided to make site selection determinations based on the size or volume of reservoirs and flowrate of rivers. 83 The USGS EPA Pilot reservoir monitoring study targeted reservoirs believed to be vulnerable to pesticide contamination ( but not necessarily the most vulnerable in any given region). Reservoirs selected had a storage capacity of between 120 and 92,600 acre feet and watershed sizes ranging from 3.3 to 784 square miles ( 8.6  2030 square kilometers). Reservoirs vulnerable to pesticide contamination were characterized overall as small reservoirs in high pesticide use areas having high runoff potential.

In an ongoing project, the USGS and EPA have determined the size of watersheds for approximately 7,000 US surface water source CWS ( Blomquist, 2003). The 75 percentile watershed size is approximately 1,000 square kilometers; the 95th percentile value is approximately 40,000 square kilometers. In Table 2 are estimates of watershed size, as described in the final report from this monitoring study, and as determined by the USGS/ EPA effort. Only five of the CWS monitored in this study had watersheds smaller than 1,000 square kilometers. Two of these five watersheds fell into the " low" carbaryl sales category, based on Doane usage estimates. Of the remaining three CWS, one is located on a Keuka Lake, a lake with a large storage capacity. Another, the Minton Reservoir, has the second smallest drinking water watershed in the United States. And the third, Silver Lake, represents a relatively minor use of carbaryl ( cranberries).

In general, CWS with large watersheds are located on very large bodies of water, and are not typically considered as vulnerable. The watersheds of CWS located on the Columbia River, Washington; the Sacramento River, CA, and the California aqueduct intake, which were selected for monitoring are larger than the 95th percentile nationally ( 40,000 square kilometers). The CWS on in Pasco, WA is downstream of the confluence of the Columbia River with the Snake River, where two of the West's largest rivers merge. The CWS site on the Neches River ( Beaumont TX) is also larger than the 90th percentile CWS watershed size nationally.

The practice of inter basin water transfer makes site selection difficult in the West. The Henry J Mills water treatment plant in Riverside, CA is one of five facilities supplying water to the Los Angeles metropolitan area and treats water from multiple sources. The water is derived from a system of rivers and reservoirs located in the high Sierras, flowing through the Feather River, and the Sacramento where it is withdrawn at the Harvey Banks Filtration Plant to the South of San Francisco and transported hundreds of miles to the south to Los Angeles. Riverside County, listed as the intake location, is actually the location of the treatment facility and quality is unaffected by usage there. Lake Mathews, the water source for the City of Corona, is the Western terminus of the Colorado River Aqueduct, whose intake is on the Colorado River at Lake Havasu, Arizona. Therefore, the water in Lake Mathews would not be expected to be affected by carbaryl use in the watershed immediately surrounding the lake.

CWS selected for this study were located on several large lakes, for example Lake Chelan is 55 miles long and is the third deepest lake in the US. A small portion of the watershed of this lake is used in agriculture, however, the majority of the watershed drains pristine forest land. The overall impact of this agriculture on the quality of the drinking water, given it's large storage capacity is difficult to determine, and maybe locally important to determine. However, there are reasonable questions about it's overall vulnerability and selection as one of 16 locations nationally in this monitoring 84 study. Similarly, Keuka Lake is a mid sized Finger Lake in upstate New York. Formed during the last glaciation, the lake has a relatively large storage capacity and an estimated residence time for pollutants of 6 8 years. It is not as vulnerable as smaller sized systems which more rapidly respond to environmental effects. The CWS located on Canyon Lake did not function as a treatment system for the majority of the study due to low reservoir levels calling into question the degree to which runoff and carbaryl usage affected water quality at that location.

It is clear that in most cases there was some degree of carbaryl usage in the watershed and the results of the monitoring are useful; however, the majority of sites selected in implementation of this study are not consistent with the study design purpose as stated.

Watershed sales and usage and crop type. Crop data ( from the 1992 Census of Agriculture and a cranberry bog database) was used by RPAC in 4 states ( New York, Michigan, Washington, and Massachusetts) as a surrogate for carbaryl use to refine watersheds of interest. In other states refinements were made on the basis of discussions with RPAC field personnel or CWS personnel which were largely undocumented. Also, information provided to make determinations about the ratio or cropped versus non cropped area in a watershed is anecdotal at best, derived from observation of CWS and RPAC sales personnel implementation. For example, the CWS on the Neches River in Beaumont Texas is characterized as a high sales site, based on RPAC sales data, but this could not be confirmed using Doane usage data, which indicates usage in Jefferson County is low ( 4300 pounds).

Representing a variety of crops was a secondary criterion in site selection; however, the basis for the carbaryl use within the watershed and the spatial extent of this use within the watershed is not entirely clear. As another example, crops in the watershed of Canyon Lake, the water source for the Elsinore Valley MWD, are identified as citrus, vegetables, and olives. Land Cover information does not include these crops, but does indicate that " orchard/ vineyard/ other" constitute 0.04% of the watershed; " row crops" 14.2%, " residential and commercial" 7.2 %, and " small grains 2.4%. The USGS EPA pilot reservoir monitoring program characterized dominate pesticide usage in this same watershed as urban, with row crops dominated by alfalfa and wheat. Actual crops to which carbaryl is applied and their dominance on water quality in this watershed is unclear.

The rationale for selection of sites representing what appear to be a relatively minor percentage of the overall carbaryl usage ( cranberries) is not clear. The decision to select a monitoring site to characterize exposure from this use appears to be driven more by the desire to represent a broad array of carbaryl uses than the high carbaryl sales county selection criteria. The way in which the study design is implemented calls into question the ability f the results to adequately address the conceptual model. The pasture and pecan use in Wagoner County, OK also appears to have played a dominant role in selecting that site despite the very low sales in that county. The site selection report indicates that a site was sought in Oklahoma after a second site could not be identified in Oregon; however the rationale for focusing on a site in Oklahoma is not provided. There are other geographic locations in the carbaryl use area with higher sales where no monitoring site was selected 85 " Home and Garden" Sites:

No analysis has been done of the relative vulnerability of drinking water systems resulting from the home and garden use of carbaryl, because sales or usage data for these sites is not presented to enable the relative vulnerability of these sites to be determined. Sites were selected in different locations form those originally identified. Characteristics are presented in Table 3. In terms of watershed size, these are roughly the 70th percentile or slightly higher, according to the USGS data ( Blomquist, 2003)

Sampling frequency, interval, and study duration.

Some sampling periods were missed, overall the implementation of this design feature was reasonable. However, the adequacy of weekly sampling in collecting quality data to represent peak exposure values is unlikely and data produced have high uncertainty in representing values useful for acute exposure assessment. The study duration was three years, as indicated in the study design.

Sample matrix Samples are being collected from raw drinking water at the intake and finished water after passing through the treatment plant. All raw water samples are being analyzed. Finished water samples are analyzed when raw water collected at the same time show detectable concentrations of carbaryl. This design component was implemented in reverse. Raw water should have been sampled first and after some time lag linked to the treatment train at each CWS, the finished water sampled. Samples cannot be considered temporally paired and cannot be use quantitatively to assess removal efficiency.

Ancillary data collection Ancillary data was collected as described in the study design. The design provides for the collection of a substantial amount of ancillary data. However, data are not collected on an number of important factors controlling site variability. The treatment train is not described in enough detail to allow quantitative determinations regarding effects on exposure to be made.

Sample Collection Procedure and Handling Procedures are adequate for the most part, with protocol deviations identified. Studies done on unfortified samples from Lake Manattee indicate carbaryl is stable in non acidified water ( pH 6 or higher) under standard sample handling and storage conditions ( freezing conditions).

Fished water collected prior to treated water sample ( backwards). There is no description of the timing of the treatment train. It may still be possible to look in general at the overall data and make observations about trends in levels of carbaryl in finished versus raw water based on these data. 86 Chemical Analysis Samples were analyzed before the maximum allowed time of 99 days with the exception of two samples. Deviations from the protocol were identified; none significantly affected analytical results. When a sample and it's duplicate were analyzed, average values were reported. In some tables, results for finished water samples were substituted for raw samples. Careful interpretation of the results from these two separate water sample populations ( finished and raw) is necessary.

Quality Assurance and Quality Control The laboratory QA samples appear to be adequate for the purposes of the study. Clarification is needed on the size and make up of the sample set. ° method performance indicated recoveries of spiked samples 101+/ 12 %. ° All but one control were negative. ° Field recovery: 72 145 % when analyzed within 6 days of fortification ( field spikes) ° storage stability: non acidified and acidified samples showed no decline in frozen raw or finished water up to 14 weeks ( 98 days).

Summary: Implementation of the study design compromised the study goal. The majority of the agricultural sites monitored do not appear to be vulnerable to carbaryl impacts, based on the sales and watershed characteristics evaluated. Carbaryl usage is likely to occur in the watersheds of most of these systems and results can be evaluated in that context; however, the overall vulnerability of these systems is not as stated in the conceptual model of this study.

Results Monitoring results presented in Table 4 indicate that carbaryl was found in source drinking water ( raw water) at low concentrations in the majority of sites ( 13 of 16 sites) selected to represent impacts from agricultural uses, despite the relative lack of vulnerability of these sites. Concentrations measured at these sites were low ( roughly 2 to 31 ppt) in raw water and generally lower in treated drinking water. However, the highest concentrations were found in finished, not raw, drinking water ( 181 ppt). Only three agricultural sites had quantified detections ( at levels greater than the LOQ): Lodi, CA ( 31 ppt, raw); Brockton, MA ( 31 ppt, raw), and Deerfield, MI ( 160 ppt, finished). These levels were observed in a single sampling interval ( weekly sampling), and concentrations were lower in preceding and succeeding samples collected at those sites.

Where residues were detected, frequency of detection in raw water samples ranged from a few percent of total samples ( 1 6 %) at 9 of the 13 sites to about 20% of total samples ( 14  21%) at 4 sites. Two of these sites are on the Sacramento River, one site in Florida, and one site in Massachusetts representing impacts from use on cranberries. There is some correspondence annually with the timing of detections at each site ( that is they appear to occur in the same season), but it is not strong. At several sites, low level concentrations were measured in weekly samples collected 87 over 3 4 week periods. Measured levels are variable due in part to the nature of the fate and transport of carbaryl and in part to the noise in analytical measurements at these low concentrations. Because treated water sampling was reactive, frequencies of detection were not determined.

No carbaryl residues were detected in raw water at three locations: Corona CA, ( Lake Mathews); Beaumont TX ( Neches River); Manson, WA ( Lake Chelan). Lake Mathews actually derives it's water from inter basin transfer, serving as the western terminus of the Colorado River Aqueduct. Carbaryl usage in the Colorado River watershed and Lake Havasu, AZ area ( the aqueduct withdrawal point) are not described, but expected vulnerability is low. Although carbaryl usage occurs in the other two systems, there are questions about the characterization of the vulnerability of the systems due to watershed size and storage.

Carbaryl was reported in raw water of all four CWS selected to represent impacts from Home and Garden uses. Concentrations measured in raw water at these sites were low ( roughly 2 to 44 ppt) and detection frequencies ranged from 1  about 20 %. In the Birmngham, AL CWS, concentrations were measured at levels greater than the LOQ at four times ( with a raw and finished " pair" both exceeding the LOQ): ( 35 ppt, raw; 38 ppt, raw; 32 ppt, finished; 40 ppt, raw; 40 ppt raw). At this site, concentrations of carbaryl were detected in sequential weekly samples for several months in one year ( out of three years) of monitoring. The pattern of detections was not as strong in other years. How representative these systems are of the home and garden use of carbaryl cannot be determined from the data provided. The lowest detection frequency occurred at the CWS with the largest watershed size ( exceeding the 70th percentile nationally).

The data do not give any indication of the effectiveness of treatment in removing carbaryl. Because the samples were collected at the same time the water exiting the treatment plant was temporally different than the water sampled at the intake. In several cases finished water had higher concentrations then raw water, and finished water had detectable carbaryl when the raw water did not. The highest concentration measured was in finished water ( 0.18 ppb). Raw water sampled at the same time had much lower concentration ( 0.011). This illustrates that carbaryl contamination is transient, and that it is unlikely that weekly or monthly sampling are adequate to capture actual peak concentrations REFERENCES USEPA, 2000, Consultation: National Drinking Water Survey Design for Assessing Chronic Exposure. 6/ 6 9/ 2000, http:// www. epa. gov/ scipoly/ sap/ 2000/ june/ drinkingwatersurvey. pdf USEPA 2002a, " Response to Registrant's 30 day Error Correction Comments on the EFED Risk Assessment Chapter in Support of the Reregistration Eligibility Decision ( RED) on Carbaryl", D276945, dated 4/ 8/ 2002.

USEPA, 2002b, " Revised EFED Risk Assessment of Carbaryl in Support of the Reregistration Eligibility Decision ( RED)" Dated 8/ 17/ 2002. EPA document ID: OPP 2002 0138 0012. 88 http:// www. epa. gov/ oppsrrd1/ reregistration/ carbaryl/, accessed 01/ 03/ 03 Bayer CropScience, 2002, " Review of the Draft Environmental Fate and Ecological Risk Assessment for the Registration of Carbaryl. dated October 2002. Submitted to the docket OPP 2002 0138 during public comment period.

USEPA, 2001, review of: " Surface Water Monitoring for Residue of Carbaryl in High Use Areas in the United States: Interim Study Results", D274824, dated August 7, 2001, Internal Memorandum to Betty Shackleford, SRRD.

Blomquist J. D. et. al., 2001, Pesticides in Selected Water Supply Reservoirs and Finished Drinking Water, 1999 2000: Summary of Results from a Pilot Monitoring Program, USGS Open File Report 01 456, http:// md. water. usgs. gov/ nawqa/ accessed 3/ 1/ 03 J. D. Blomquist, 2003, personal communication regarding national distribution of community water supply system watershed size. 89 APPENDIX B2. SUPPLEMENTAL TABLES IN SUPPORT OF DRINKING WATER MONITORING STUDY ANALYSES.

Table 2: Characteristics of Agricultural Monitoring Sites selected for Carbaryl Monitoring Study.

intake location ( city and state) system name watershed location ( SEI #) carbaryl use crop carbaryl sales ( RPAC) carbaryl use ( lbs per county),

based on Doane source water volume of waterbody watershed size Aventis ( acres) EFED ( square km)

Lake Elsinore,