APTER 6 Analysis of Key Topics-Environmental Significance 6.1 IMPLICATIONS FOR HUMAN HEALTH Under provisions of the Safe Drinking Water Act (SDWA), the U.S. Environmental Protection Agency (USEPA) has established an enforceable maximum contaminant level (MCL) allowed in drinking water for certain pesticides with past or present use in the United States (Table 6.1). The MCLs are health-based standards and are results of chronic toxicity tests conducted with animals. The MCLs are derived from the highest concentration at which no adverse health effects were observed in the test animals, multiplied by a safety factor of 100, or 1,000 in the case of suspected or probable carcinogens. Considerations of treatment feasibility, cost of treatment, and analytical detection limits also were included in the derivation of the MCLs. The USEPA also has established a maximum contaminant level goal (MCLG) for all chemicals with an established MCL. The MCLG is a nonenforceable concentration of a drinking-water contaminant that is protective of human health and allows an adequate margin of safety (Nowell and Resek, 1994), without regard for economic or analytical constraints. The MCLG is set at zero for known or probable human carcinogens. Pesticides with an MCLG of zero include alachlor, chlordane, dibromochloropropane (DBCP), EDB, heptachlor, heptachlor epoxide, pentachloro- phenol (PCP), hexachlorobenzene (HCB), and toxaphene. Of these, alachlor is the only one with significant current use in the United States. These standards apply to finished (treated) drinking water supplied by a community water supply, and require that the annual average concentration of the specific contaminant be below the MCL. As of 1994, the SDWA requires most suppliers of drinking water to monitor for 39 pesticides or pesticide transformation products in finished water, 14 of which are no longer registered for use in the United States. Pesticides with current agricultural use, for which MCLs have been established and monitoring is required, include seven herbicides (alachlor, atrazine, 2,4-D, diquat, glyphosate, picloram, and simazine), four insecticides (carbofuran, lindane, methoxychlor, and oxamyl), and one fungicide (PCP). In addition, monitoring is required for 13 pesticide-related compounds for which MCLs have not been established (U.S. Environmental Protection Agency, 1994b). From a compliance standpoint, the standards (MCLs) do not apply to most water bodies reported on in this book, since most of the studies reviewed were not analyzing finished drinking water. For many of the pesticides with no established MCL, other (nonregulatory) criteria have been established. The USEPA has issued drinking-water health advisory (HA) levels for adults and children for various exposure periods. The National Academy of Sciences has issued a Suggested No-Adverse-Response Level (SNARL) for many pesticides. Both the HA and SNARL values represent estimates of the maximum level of a contaminant in drinking water at which no adverse effects would be expected. The lifetime HA and the SNARL are derived in the same © 1998 by CRC Press, LLC Table 6.1. Standards and criteria for protection of human and aquatic organism health for pesticides targeted in surface waters a N P [All standards and criteria values are from Nowell and Resek (1994). Concentrations are in microgram(s) per liter. Human Health: MCL, Maximum contaminant level for drinking water established by the U.S. Environmental Protection Agency (USEPA); MCLG, Maximum contaminant level goal for - drinking water established by the USEPA (equal to zero for known or probable human carcinogens); HA (child, long term), Health advisory level for drinking water established by the USEPA (for a 10-kilogram child over a 7-year exposure period and for a 70-kilogram individual over a 70-year exposure period). 2 SNARL, Suggested No-Adverse-Response Level for drinking water established by the National Academy of Sciences (NAS). Exceeded Values, Number of - studies in which a criteria value was exceeded / Number of studies in which an analyte was targeted. All studies from Tables 2.1 and 2.2 that targeted the # compound are included in the denominator, regardless of whether a maximum concentration was reported. The number of studies with exceeded values may be V, an underestimate, because some studies did not report a maximum concentration. Aquatic Organism Health: USEPA, Acute and Chronic, Established 2 concentration below which adverse effects on aquatic organisms are not expected for acute or chronic exposure. National Academy of Sciences and the National Academy of Engineering (NASDJAE), Concentration established in 1973 below which adverse effects are not expected. Exceeded Values, as defined above. nsg, no standards given] $ 0 Aldrin Chlordane DDT Dieldrin Human Health Endosulfan Endrin HCH (all isomer^)^ n INSECTICIDES V, MCL Aquatic Organism Health rn nsg 2 nsg nsg USEPA nsg 2 0.2 Exceeded nsg 0 nsg nsg MCLG nsg 2 0.2 SNARL z 0.3 0.5 nsg 0.5 HA nsg 4.5 33 Exceeded values Child Acute nsg nsg nsg nsg Studies in which MCL or HA exceeded NAS/NAE Adult Chronic nsg 1.6 2 3 values rn nsg nsg nsg nsg nsg nsg nsg 2/57 2/50 nsg 4/72 I nsg 0160 6/65 Bradshaw and others, 1972 Page, 1981 Warry and Chan, 1981 Kuntz and Warry, 1983 Klaasen and Kadoum, 1975 Wany and Chan, 1981 Leung and others, 1982 Kuntz and Warrv. 1983 None None Nicholson and others, 1964 Bradshaw and others, 1972 Page, 198 1 Warry and Chan, 1981 Kuntz and Warry, 1983 Takita, 1984 3 2.4 1.1 2.5 0.22 0.19 2 nsg 0.0043 0.001 0.0019 0.056 0.0023 0.08 0.01 nsg nsg nsg 13/57 17/50 38/74 37/72 nsg nsg nsg 4/45 16/60 14/65 © 1998 by CRC Press, LLC Table 6.1. Standards and criteria for orotection of human and aauatic oraanism health for ~esticides targeted in surface waters Continued I Human Health I Aauatic Oreanism Health MCL - MCLG USEPA Acute 1 Chronic HA Child I Adult NAS/NAE Exceeded values SNARL Exceeded values Studies in which MCL or HA exceeded © 1998 by CRC Press, LLC Table 6.1. Standards and criteria for protection of human and aquatic organism health for pesticides targeted in surface waters Continued IV Q) Q) Human Health -0 rn Y - G 0 m cn - z cn C 13 3 0 rn Other ~nsecticides:~ s 3 rn n cn HERBICIDES lkiazine and Acetanilide: Aquatic Organism Health Alachlor 2 0 100 nsg 700 10115 , Takita, 1984 Yorke and others, 1985 Wnuk and others, 1987 Baker, 1985, 1988b Squillace and Engberg, 1988 Moyer and Cross, 1990 Lewis and others, 1992 Goolsby and Battaglin, 1993 Goolsby and others, 1993 , nsg nsg nsg nsg © 1998 by CRC Press, LLC Table 6.1. Standards and criteria for protection of human and aauatic oraanism health for pesticides taraeted in surface waters Continued I Human Health I Aauatic Oreanism Health Ametryn Atratone Atrazine MCL nsg nsg 3 10 nsg 4/23 Baker, 1985, 1988b Wnuk and others, 1987 Propachlor Propazine Mas nsg nsg 3 - USEF'A NAS/NAE 3~.~l nsg 31.~ Acute nsg nsg nsg i? 3 8 nsg nsg Exceeded values 1/11 nsg 21/41 nr 2. 9. Chronic nsg nsg nsg HA nsg nsg nsg nsg 150 Child 900 nsg 50 Adult 60 nsg 3 100 500 Exceeded values 0111 nsg 16/41 Studies in which MCL or HA exceeded None None Wu and others, 1980 Fishel, 1984 Baker, 1985, 1988b Ward, 1987 Wnuk and others, 1987 Fujii, 1988 Squillace and Engberg, 1988 Moyer and Cross, 1990 Lewis and others, 1992 Thurman and others, 1992 Goolsby and Battaglin, 1993 Goolsby and others, 1993 Pereira and Hostettler, 1993 Squillace and others, 1993 90 10 700 325 015 1 None 0113 1 None nsg nsg nsg nsg nsi3 nsg nsg 2 nsg 2. © 1998 by CRC Press, LLC Table 6.1. Standards and criteria for protection of human and aquatic organism health for pesticides targeted in surface waters Continued IU 0-1 Chlorarnben Dacthal Dicarnba Simazine Simetone Simetryn Terbutryn Dinoseb Aquatic Organism Health 03 nsg nsg nsg 7 1 71 101 7 1 39 1 012 1 None I nsg I nsg I nsg I nsg EPTC Fluometuron Linuron Molinate Human Health Phenoxy Acid: $ 0 rn Z 3 m Jl V, Other Herbicides: Diquat 1 20 1 20 1 nsg ( 20 1 nsg I 011 I None I nsg I nsg 1 0.5 1 011 Norflurazon I nsg I nsg I nsg I nsg I nsgl nsg I None I nsg I nsg Paraquat I nsg I nsg 1 50 1 30 1 59.5 1 011 I None I nsg I nsg MCL 4 nsg nsg , nsg USEPA nsg nsg nsg nsg nsg nsg nsg NASfNAE 10 nsg nsg , nsg Acute nsg nsg nsg nsg nsg nsg nsg nsg 35~ Ez:p 3 m 1/18 3 9 0 rn V, nsg - z nsg (I) , nsg MCLG 4 nsg nsg , nsg Chronic nsg nsg nsg , nsg Acrolein Bensulfuron-methyl Butylate 200 5,000 300 nsg nsg nsg nsg nsg 011 nsg nsg On nsg nsg nsg 100 4000 200 nsg 2,000 nsg nsg HA None None None SNARL 1,505 nsg nsg nsg, Child 50 nsg nsg , nsg nsg nsg nsg 1,750 nsg 8.75 nsg 90 nsg nsg Adult 4 nsg nsg , nsg , nsg nsg nsg Exceeded values 3/18 nsg nsg nsg nsg nsg 1,000 011 011 On nsg nsg nsg nsg Studies in which MCL or HA exceeded Ward, 1987 Baker, 1988b Thurman and others, 1992 None None ,None , nsg nsg nsg nsg nsg nsg nsg nsg 700 None None None nsg 011 nsg nsg nsg nsg nsg nsg nsg nsg None None None None nsg nsg nsg nsg nsg nsg nsg 325 nsg 200 nsg nsg nsg nsi2 011 nsg 0n nsg nsg nsg nsg nsg nsg nsg nsg © 1998 by CRC Press, LLC Table 6.1. Standards and criteria for protection of human and aquatic organism health for pesticides targeted in surface waters-Continued Human Health Aauatic Organism Health © 1998 by CRC Press, LLC Table 6.1. Standards and criteria for protection of human and aquatic organism health for pesticides targeted in surface waters Continued rv -J 'DDT totals include five studies in which only "total DDT' (sum of DDT, DDD, and DDE) was reported. 2~~~ data includes studies in which any of four isomers (a, f3.6, and y [lindane]) were targeted. MCL established for lindane only. 3~ecornmended maximum concentration in marine waters (no freshwater value established). 40ther insecticides category includes compounds used as acaricides, miticides, and nematocides, as well as insecticides. Human Health Heptachlor epoxide 2-Hydroxy-2 '6'- diethyl-acetanilide Aquatic Organism Health 0 3 G Z 5 rn ID V) MCL 0.2 nsg MCLG 0 nsg HA SNARL nsg nsg Child 0.1 nsg Adult nsg nsg Exceeded values 4154 nsg Studies in which MCL or HA exceeded Bradshaw and others, 1972 Page, 1981 Warry and Chan, 1981 Kuntz and Warry, 1983 None USEPA NASINAE nsg "st2 Acute 0.52 nsg E.zy -u rn V) 20154 =! s 0 rn V) - z nsg V) ID Chronic 0.0038 nsg © 1998 by CRC Press, LLC Analysis of Key Topics-Environmental Significance 271 manner, so that a lifetime HA value for one compound can be compared with a SNARL value for another. A complete description of the derivation and use of the MCL, HA, and SNARL values can be found in Nowell and Resek (1994). Values of these criteria for the pesticides observed in the reviewed studies are shown in Table 6.1. In some cases, there are large differences between the different criteria values for a particular pesticide. Nowell and Resek (1994) have recommended that, for sources of drinking water, the MCL, if available, should be used for comparison of observed concentrations with criteria values. If no MCL has been established, the HA should be used. If neither MCL nor an HA has been established, the SNARL should be used. While the MCL, HA, and SNARL values do not directly pertain to ambient concentrations of pesticides in surface waters, they do provide values with which the observed levels can be compared. Since these values are based on the toxicity of the compounds, they can give some idea of the potential significance of the levels observed in surface waters. Pesticides that exceeded a criteria value in at least one of the reviewed studies (Tables 2.1 and 2.2) are noted in Table 6.1. Some compounds with established criteria have not been included in any of the reviewed studies, or have been targeted very infrequently. Five pesticides with established MCLs dalapon, dibromochloropropane (DBCP), endothall, ethylene dibromide (EDB), and glyphosate-were not included in any of the reviewed studies listed in Tables 2.1 and 2.2. Of these five, only glyphosate (Figure 3.12) and endothall are currently used in United States agriculture. Several important qualifications should be mentioned regarding the data in Table 6.1. First, many of the studies reviewed did not give information on the maximum concentration detected for each analyte. Thus, the number of studies in which criteria values were exceeded may actually be higher than is shown in Table 6.1. Second, studies listed in Table 6.1 cover 1958 to 1993, so that the data do not necessarily reflect the current situation. Finally, in the table, a reported concentration higher than a criteria value in a single sample in one study is counted the same as many samples with concentrations above criteria values in another study. Despite these limitations, several important points are evident. 1. Relatively few of the pesticides targeted in the reviewed studies were detected at a level exceeding a drinking water criteria value. Of the 52 pesticides or transformation products with an established criterion, 15 were detected at a concentration exceeding it in at least one sample. Eight of these were organochlorine compounds or degradation products detected in studies primarily from the 1970's. 2. In recent years, the pesticides most often detected at levels exceeding criteria values have been the triazine and acetanilide herbicides atrazine, alachlor, cyanazine, and simazine. The large number of studies in which these compounds exceeded criteria values is, in part, due to more intensive sampling of midwestem surface waters in recent years. In several of the studies in which criteria values were exceeded, rivers were sampled frequently during the spring runoff, increasing the likelihood of sampling during peak herbicide concentrations. As discussed in Section 5.1, the increased use of these compounds, coupled with their relatively high potential for transport in runoff, results in elevated concentrations in surface waters of the Midwest in spring and early summer. Peak concentrations of these compounds can exceed criteria values, especially in the smaller rivers. 3. Herbicides other than the triazines and acetanilides, including the high-use compounds 2,4-D, dicamba, butylate, and trifluralin, were never detected in surface waters at levels exceeding criteria values in the reviewed studies. 4. Insecticides commonly used in recent years rarely reach levels in surface waters that exceed drinking-water criteria concentrations. © 1998 by CRC Press, LLC 272 PESTICIDES IN SURFACE WATERS Atrazine concentrations exceeded an established criteria value most often in the reviewed studies, and can be used to more fully explain the human health implications of the levels of pesticides detected in surface waters. As discussed earlier, atrazine concentrations have a seasonal pattern in many rivers throughout the central United States (Figures 3.46,5.2, and 5.7). In some of these rivers, the MCL of 3 mg/L is exceeded for days to weeks. Peak concentrations generally are higher in smaller rivers, but the duration of elevated concentrations often is longer in larger rivers (Goolsby and Battaglin, 1993). Drinking water for millions of people is obtained from surface water sources in the central United States. Community water supplies drawing water from the three major rivers in this region-the Mississippi, Ohio, and Missouri Rivers- serve approximately 10.5 million people (Ciba-Geigy, 1992d). Smaller rivers and reservoirs provide drinking water to approximately 4.3 million people in Ohio, Illinois, and Iowa (Ciba-Geigy, 1992d), and the situation is similar in other states of the region. A series of exposure assessments has been done for populations served by these various water sources (Ciba-Geigy, 1993a,b, 1994b; Richards and others, 1995). In these assessments, annual average concentrations of atrazine were estimated for water bodies used as sources of drinking water, using existing monitoring data from Ciba-Geigy, Monsanto, U.S. Geological Survey (USGS), water utilities, and other sources. The number of people exposed to various levels of atrazine in drinking water then was calculated and expressed as a percentage of the total population covered in each of the different assessments. The results of these assessments indicate that the vast majority of people whose drinking water is derived from surface water in the central United States are exposed to annual average atrazine concentrations well below the MCL. In the assessment covering the Mississippi, Missouri, and Ohio Rivers, 85 percent of the population whose drinking water is derived from these rivers was exposed to average concentrations between one-tenth and one-third of the MCL, and approximately 40 percent were exposed to average concentrations slightly over one-third of the MCL. No segment of the assessed population was exposed to average atrazine concentrations above the MCL. In the assessment for Iowa, 97.8 percent of the assessed population using drinking water derived from surface waters was exposed to average atrazine concentrations of less than one-third of the MCL. One lake included in the assessment had an annual average atrazine concentration of over 6 pg/L-more than twice the MCL. This reservoir supplies drinking water to approximately 0.7 percent of the assessed population using surface water sources. Results were similar in the assessments for Ohio and Illinois. In Ohio, no surface water source had an annual average concentration over the MCL, and sources for approximately 8 percent of the assessed population relying on surface water had annual concentrations of slightly over 2 pg/L, or two-thirds of the MCL. In Illinois, no surface water source had an annual average concentration over the MCL, and sources for approximately 4 percent of the assessed population relying on surface water had annual concentrations over 1 pg/L. In both Ohio and Illinois, a large portion of the drinking water derived from surface water comes from the Great Lakes, where atrazine concentrations are quite low. In Illinois, Lake Michigan accounts for nearly 80 percent of the drinking water derived from surface waters; in Ohio, Lake Erie accounts for about 42 percent. Annual mean atrazine concentrations used in the assessments for Lakes Michigan and Erie were 0.1 and 0.07 yg/L, respectively. The results from these assessments probably can be extrapolated to much of the Midwest. Illinois, Iowa, and Ohio ranked first, fourth, and sixth among states, respectively, in atrazine use in the late 1980's, the period in which much of the data for these assessments was collected. The Mississippi, Ohio, and Missouri Rivers drain much of the area of heaviest atrazine use in the United States (Figure 3.7). Similar results also would be expected for several other herbicides with established criteria values used in the Mississippi River Basin, based on the results of recent studies of rivers © 1998 by CRC Press, LLC [...]... used in United States agriculture in recent years have also been shown (in laboratory testing) to disrupt the endocrine systems of certain organisms, including the herbicides alachlor, atrazine, 2,4-D, metribuzin, and trifluralin; the insecticides aldicarb, carbaryl, parathion, and synthetic pyrethroids; the fungicides benomyl, mancozeb, maneb, zineb, and ziram; and the marine biocide tributyltin, or... non-regulation As the Wisconsin experience shows, ground water sampling programs, as indispensable as they are, can grossly mislead us into believing that ignorance about substances in our water is bliss Unless national and state drinking, surface, and ground water monitoring programs recognize the metabolite issue, and begin looking for parents plus metabolites in samples, the extent of contamination... data in Table 6. 1 do not provide much information on whether aquatic ecosystems are adversely affected by pesticides in surface waters In addition, the aquatic-life criteria for pesticides are based on toxicity tests involving exposure to a single chemical (Nowell and Resek, 1994) Potential synergistic or antagonistic effects of exposure to mixtures of pesticides, and to mixtures of pesticides and pesticide... Topics-Environmental Significance f 273 and reservoirs in the region (Thurman and others, 1992; Goolsby and Battaglin, 1993; Goolsby and others, 1993; Periera and Hostettler, 1993; Richards and Baker, 1993) In these studies, atrazine was usually present in surface waters at higher concentrations and for longer periods of time than were alachlor, metolachlor, metribuzin, propachlor, cyanazine, butylate, and. .. treatment procedures, including sand filtration, clarification, softening, and chlorination, have little effect on concentrations of many of the pesticides used in recent years Exceptions include the insecticide carbofuran, which apparently was completely transformed at the elevated pH used in the softening step, and the herbicide metribuzin, which reacted during the chlorination step (Miltner and others, 1989)... F I 1-Naphthol F, I HERBICIDES Atrazine Deethylatrazine Deisopropylatrazine Diamino atrazine Hvdroxvatrazine © 1998 by CRC Press, LLC F F I 1 A A A A I 282 PESTICIDES IN SURFACE WATERS Table 6. 2 Relative toxicity of pesticides and their transformation products to aquatic organismsContinued Toxicity Relative to Parent Compound Parent Pesticide Less Equal More HERBICIDES Continued Chlorpropham 3-Chloroaniline... between 1 960 and 1 963 in the Mississippi and Atchafalaya Rivers and associated bayous in Louisiana The insecticide endrin was singled out as the major cause of the mortality (Madhun and Freed, 1990) More recent fish-kill data have been evaluated for coastal areas of the United States A 1991 National Oceanic and Atmospheric Administration (NOAA) report (Lowe and others, 1991) of fish kills in coastal... sources of error in the exposure assessments discussed above should be noted First, in each of the assessments, some water bodies that served as drinking-water sources had insufficient concentration data to estimate an annual average In some cases, this resulted in a portion of the population not being included in the assessment In the Illinois and Iowa assessments, approximately 8 and 12 percent, respectively,... not be determined from available data In 41 percent of the fish-kill events, the direct cause was low dissolved-oxygen levels caused by both natural phenomena and human activities Trim and Marcus (1990) evaluated fish-kill data from coastal areas of South Carolina Fish kills in this report were defined as mortality in tidal saltwater species, including crustaceans, finfish, gastropods, and bivalves... Toxicity Abbreviations: A, algae; F, fish; I, invertebrate insects] Toxicity Relative to Parent Compound Parent Pesticide Less Equal More INSECTICIDES DDT DDD DDE Endosulfan Endosulfan sulfate Endosulfan diol Aldrin Photoaldrin Endrin Ketoendrin Fenitrothion Fenitrooxon Aminofenitrothion Carboxyfenitrothion Demethvlfenitrothion 3-Methyl-4-nitrophenol 3-Methyl-4-aminophenol Malathion Diethvl fumarate Dimethyl . the triazines and acetanilides, including the high-use compounds 2,4-D, dicamba, butylate, and trifluralin, were never detected in surface waters at levels exceeding criteria values in the reviewed. LLC Table 6. 1. Standards and criteria for protection of human and aquatic organism health for pesticides targeted in surface waters Continued rv -J 'DDT totals include five studies in which. maximum contaminant level (MCL) allowed in drinking water for certain pesticides with past or present use in the United States (Table 6. 1). The MCLs are health-based standards and are results