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c-, Federal Agencies U.S. ENVIRONMENTAL PROTECTION AGENCY Environmental Fate Data As part of its pesticide registration responsibili- ties, the EPA's OPP is requesting environmental fate data on selected pesticides with the potential to contaminate groundwater. Some 84 pesticides were the subject of an expanded data call-in program (Table 5-1), which is authorized by section 3(c) (2) (B) of the Federal Insecti- cide, Fungicide, and Rodenticide ACt (FIFRA) . The test data requested include vapor pressure, octanol-water coefficient, water Volubility hydrolysis, photodegra- dation, soil metabolism, mobility, and field dissipation. The EPA requires submission of some data within 6 months and field dissipation study results within 2 years after receipt of the request. This data call-in is in addition to requests for environmental fate data for 51 pesticides undergoing active development of standards or having Completed registration standards (Table 5-2). During the summer of 1984, Holden visited a number of federal agencies in Washington, D.C. The people with whom he discussed groundwater quality and/or pesticide issues included staff from the U.S. Enviro D ental Protection Agency's Office of Pesticide Programs (OPP) ! Office of Groundwater Protection (OGWP), and Office of Drinking Water (ODE). He also visited a national program leader in water resources, Extension Service, U.S. Department of Agriculture. 98
99 TABLE 5-1 Pesticides for Which Data on the Potential for Groundwater Contamination Are Being Called in by the EPA Ametryn tEvik) Aminocarb (Metacil) Asulam Azinphos-methyl (Guthion) Bendiocarb (Ficam) aromoxynil Bufencarb 1 suspended] Cacodylic acid Calcium arsenate CDAA (Randox) Chlormequat chloride (Cycocel) 4-Chloropyridine N-oxide Chloropropham Crotoxyphos (Ciodrin) Cychloate (Ro-Neet) Dalapon Dazomet DCPA (Dacthal) Demeton (Systox) Desm~dipham (Bentanex) Diazinon Dicholbenil DiChofop methyl (Boelon) 1,3-Dichloropropene (Telone II) Difenzoguat methyl sulfate (Avenge Diflubensuron (Di-lin) Dinocap (Rarathane) Dinoseb and salts (DNBP) Diphenamid Dipropetryn (Sancap) Diquat 2,2-Dithiobisbenzthiazole DSMA EBDCs Endothall Ethiofencarb (Croneton) Fenamiphos (Nemacur) Ferbam Fluameturon Fosamine ammonium (DPX 1108) Fosthietan Idiscontinued Iso penfos (Oftanol) Lead arsenate Maleic hydrazide (ME) Mecoprop (MCPP) Mefluidide Mercaptodimethur (Mesurol) Metam-sodium (Vapam) Methyl bromide Methy, isothiocyanate Metribuzin Mobam Mevinphos (Phosdrin) Molinate Monocrotophos (Azodin) M - A Napropamide (Devrinol) Naptalam (Alanap) Neburon Oxamyl (Vydate) Oxydeme ton-methyl (He tasystox-R) Paraguat Pebulate ($illam) Phenmedipham Pho~met (Imidan) Phosphamidon Prometon (Pramitol) Proateryn (Caparol) Pronamide (Kerb) Propachlor Propam Propanil Siduron Tebuthiuron Terbutol, terbu"-rc IAzak) Terbutryn Thiabendazole Thidiazuron (Dropp) Triallate (Far Go) Triadimefon (Bayleton) 2,3,6-TBA (2,3,6-Trichlorobenzoic acid). Vernolate (Surpass, Vern Ziram SOURCE: Adapted from ~Potential for Groundwater Con~=mination Data Asked on 84 Pest~cides,. Pesticide ~ Toxic Chemical News! May 2, 19~4, p. 37. National Groundwater Monitoring Program The EPA's OPP and ODW are currently in the design phase of a national monitoring plan for pesticides in groundwater. According to ~National Pesticides Ground-Water Survey Overview, n April 23, 1985, an EPA memorandum, the survey will focus on pesticides in groundwater as a result of agr~cultural practice. Both
100 TABLE 5-2 Pesticides with Active or Completed Registration Standards for Which Environmental Fate Data Have Been Requested by the EPA Acephate (Or thene) Alachlor Aldicarb (Temik) Amitrole Ammonium sulfate (Agate) Anilazine tDyrene) Aspon Bentazon (Basagran ) Bromacil Butylate (Susan. ) Carbofuran (FuradLan) Carbophenothion (Tr ithion ) Carboxin (Vitavax) Chloramhen (and salts ) Ch lor dime form Chlordimeform hydrochloride Chloropyr if as Chloropicr in Chlorothalon il Cryolite Cyanazine (Bladex) Daminoz ide (Alar ) DCNA Dialifor (Torak ) [discontinued! Diallate (Avadex) Dicta Diclone Dicrotophos Dimethoate Disulfoton Diuron EPTC Ethoprop (Mocap ) Fenaminosulf (Lesan) Fensulfothion (Dasanit ) Fonofos (donate) Formetanate tCarZol ) Bexazinone Linuron MCPA Methidathion (Supracide ) Methomyl Metolachlor Monuron Phorate Phosalone Picloram S'ma~-ine Terbacil Tr ichlorfon SOURCE: Adapted from Potential for Groundwater Contamination, ~ p. 38. private and public drinking-water wells will be sampled and analyzed for approximately four dozen pesticides and a nether of transformation products. Roughly 1,500 wells will be sampled once. These wells will be chosen in a three-stage process. In the first stage, counties will be ranked according to (1) their estimated pesticide usage (computed by using Doane Marketing data on pesti- cide usage and county-level crop acreage data from the U.S. Department of Commerce, Census of Agriculture) and (2) their groundwater vulnerability (estimated by using the National Well Association's recently published DRASTIC ranking scheme). In the second stage, the counties will be segmented, and in the third stage, the wells to be sampled will be chosen. The second- and third-stage operations are not yet settled. Each of the three stages will be designed to ensure statistical validity. The final list of pesticides will be selected
101 primarily on leaching potential, with previous detection in groundwater and toxicity being considered. Groundwater samples will be analyzed by multiresidue methods whenever possible. All positives will be confirmed by at least a second analysis. A}1 samples will be analyzed for all pesticides. The primary analyses will be done under contract, with some in-house quality control work. Sampling and analysis are tentatively scheduled to begin in spring 1986 and to be completed by fall 1987, with a final report due in spring 1988. Before the first sample is taken, some sort of health guidelines will be established. Residue levels exceeding those guidelines will be reported to appro- priate state agencies. The form of the health guidance remains undetermined, but may be a shortened version of a typical ODW Health Advisory. T}le total cost of this project is estimated to be S5-$6 million. (As of April 1985, the funding for fiscal year 1986 was not certain.) The overall goals of the survey are to · Characterize the occurrence of selected pesticides in groundwater; · Determine the relationship between pesticide uses, pesticide characteristics, and field conditions (e.g., soil types) to groundwater and drinking-water contamin- ation; · Estimate human exposure to these chemicals via drinking water contaminated by normal use. The OPP believes the development of these data can provide a basis for drinking-water standards and health advisories, label restrictions, regulatory decisions to restrict or ban the use of specific pesticides, and the assessment of the environmental impacts of innovative agricultural practices such as no-till farming and chemigation. Bealth Advisories The need to establish health advisor ies for pesticides in water was recognized by most of the people interviewed at the EPA. The National Agricultural Chemicals ASSO- ciation (NACA) has taken a strong position encouraging the EPA to establish federal drinking-water health advisories for pesticides. Health advisories provide
102 information on the health effects of unregulated con- taminants so that users of the water in question can he assisted in making decisions regarding what action to take if contaminants are detected. Health advisories are developed for various lengths of exposure from 1 day to 2 years, depending on the availability of data. The development of health advisories involves intensive scientific and technical evaluation of available data coupled with peer review by leading toxicologists. Officials of the ODW indicated that the NACA approach (which is based on acceptable daily intake data and sum- marized in Chapter 6) makes sense for acute toxicity but may not be appropriate when considering chronic health impacts and multiple exposures. In May 1984 the EPA's OPP and ODW signed an interoffice memorandum of under- standing on pesticides in drinking water. One provision of the memorandum establishes procedures for the OPP to supply scientific data for the ODW'S use in setting standards for residues in drinking water. A health advisory does not have the same level of regulation as the primary drinking-water standards established under the Safe Drinking Water Act. Primary drinking-water standards have been established for just six pesticides (endrin, lindane, methoxychlor, toxaphene, 2,4-D, and 2,4,5-TP). Approximately 20 additional pesticides are being considered for inclusion in the National Primary Drinking Water Regulations (Federal Register, October 5, 1983, National Revised Primary Drinking Water Regulations, n p. 45518. ) Multiresidue Analytic Techniques The OPP staff discussed the need for multiresidue analytic methods to screen water samples for pesticides. The advantages of such screening techniques include the more rapid development of a broad data base, less exposure in sample acquisition and sample analysis, and more comprehensive water quality assessments. Such techniques involve tradeoffs, however, including more tome required for sample preparation before analysis, greater expense associated with increased laboratory preparation, and less sensitivity of the analysis. The use of a multiresidue analytic technique would depend on the goals of the sampling program. A number of multiresidue methods have been developed by the FDA and the USDA. These include a chlorinated
103 hydrocarbon method, an organophosphate method, a phenoxy herbicide method, the Luke method, a carbonate method, and the Pesticide Analytical Method (PAM). Some of the screening techniques are generally sensitive only to the parts-per-million level and perhaps would not be adequately sensitive for water samples where accuracy in the parts-per-billion range is often desired. However, there seems to be no technical reason why multi- residue screens for pesticides in water with sensitivity to the parts-per-billion level cannot be developed. Groundwater Protection rebels for Pesticides m e EPA announced in 1984 that it would contract with the Conservation Foundation (CF) to develop pesticide labels that indicate the potential for a specif ic pesticide to leach to groundwater. The OF was to develop pesticide labeling that would be relevant to growers, indicate potential impacts on groundwater quality, and somehow factor in local soil and hydrologic conditions (see Pesticide and Toxic Chemical News, November 21, 1984, p. 7). However, the project has apparently been canceled by the EPA, illustrating the unsettled nature of pesticide/groundwater policies. Other EPA Activities During 1985 the OPP and the OGWP began prepar ing a strategy statement on pesticides and groundwater. In January 1986, however, this project was combined with a broader effort by the EPA's Office of Pesticides and Toxic Substances to write a strategy on agrichemical management. EXTENSION SERVTCE--U.S. DEPARTMENT OF AGRICULTURE The National Program Leader in Water Resources of the USDA Extension Service (ES) is organizing an ES response to groundwater contamination caused by agricultural practices. The efforts include the assessment and characterization of the nature of groundwater problems caused by agriculture, definition of the ES's role in the protection of groundwater resources, and mobilization of the ES's resources in addressing the issue.
104 The ES has recently organized a Groundwater Task Force that includes eight people, two each from four major regions encompassing the entire United States. This task force is now engaged in a national survey of current ES activity in individual states related to groundwater and is also assessing what specific needs should be addressed by the ES. In addition to contamination of groundwater caused by pesticides, the task force will consider questions about groundwater quantity (amount available as a resource) and salinity. This work is just beginning, so little substantive information has been produced.
