Appendix A. Drinking Water Standards and Guidelines for Pesticides Sampled in Oregon Ground and Surface Water

Transcription

1 Appendix A Drinking Water Standards and Guidelines for Pesticides Sampled in Oregon Ground and Surface Water Jeffrey J Jenkins Department of Environmental and Molecular Toxicology Oregon State University

2 A. INTRODUCTION Oregon groundwater monitoring is conducted primarily by two state agencies the Oregon Department of Environmental Quality and the Oregon Health Division. Each agency has different responsibilities and regulatory objectives. Surface water monitoring is conducted by the Oregon Department of Environmental Quality and the U.S. Geological Survey (USGS). The following section describes some important regulations that relate to ground and surface water and the Oregon agencies responsible for implementing them. B. OREGON GROUNDWATER PROTECTION ACT The Oregon Groundwater Protection Act of 1989 was designed to address nonpoint sources of groundwater contamination. The Act was developed by an interagency working group and included recommendations from representatives of agricultural, industrial, and environmental groups. The Act focuses on voluntary, rather than regulatory, approaches to groundwater protection. However, an important feature of the Groundwater Protection Act is the specification of regulatory triggers, i.e., actions in response to documented contamination. The Act requires DEQ to declare an area of groundwater concern when nonpoint source contaminants are found in groundwater. In these areas, DEQ is required to create groundwater management action plans that include: Contaminant source identification Evaluation of the threat posed by nonpoint contaminants Identification and evaluation of alternate practices or best-management practices Recommendations for research, education, and demonstration projects Groundwater management areas are established by DEQ if nitrate contaminants are greater than 70% of their Maximum Measurable Levels (MMLs) or if other contaminants are found at levels greater than 50% of their respective MMLs. MMLs are the maximum allowable concentration of a contaminant or substance of concern that is established by the EQC in accordance with the rules given in House Bill DEQ uses MMLs to initiate the process of designating groundwater management areas. C. SAFE DRINKING WATER ACT The Safe Drinking Water Act passed by Congress in 1974 focuses on setting national drinking water standards with EPA acting as the primary enforcement agency. Drinking water standards limit the population s exposure to hazardous substances through drinking water. Prior to 1980, EPA had established standards for 23 contaminants. Regulations specified maximum contaminant levels (MCLs) and sampling frequencies for each contaminant. In August 1996, President Clinton signed the reauthorization of the Safe Drinking Water Act. Details of the new amendments can be found on the Web at

3 D. DRINKING WATER STANDARDS AND GUIDELINES The EPA Office of Water has established Health Advisories (HAs), which are non-enforceable guidelines for chemical residues in drinking water, for approximately 200 chemicals, including about 50 pesticides. These include 1-day and 10-day HAs for children and adults and lifetime HAs for adults. The HA is the concentration of a chemical in drinking water that is not expected to cause adverse non-carcinogenic effects over the period of exposure. EPA has also established HAs for some pesticides classified as carcinogens. In addition, as a part of rulemaking under the Safe Drinking Water Act, the agency has established the Maximum Contaminant Level (MCL) and Maximum Contaminant Level Goal (MCLG) for about 25 pesticides in drinking water. The MCL, an enforceable standard, is the maximum allowable level of a contaminant in water delivered by a public water system. The MCLG is the concentration of a drinking water contaminant that is thought to be protective of adverse human health effects. In almost all cases, the MCL and MCLG are the same. In a few instances, the MCLG has been set at zero. Pesticides looked for in Oregon groundwater with zero MCLGs are these: acifluorfen, alachlor, chlordane, HCB, heptachlor, heptachlor epoxide, and pentachlorophenol (PCP). In determining the lifetime HAs and MCLGs, the estimated dose is based on a 70 Kg person consuming 2 liters per day. For non-carcinogens, lifetime HAs and MCLs are derived from the drinking water equivalent to the Reference Dose (RfD). The RfD is an estimate of total human daily exposure to contaminants that is unlikely to result in adverse health effects over a lifetime. For carcinogens, the excess cancer risk associated with lifetime ingestion of drinking water is estimated. The target for the lifetime HA or MCLG is a concentration in drinking water that results in less than 1 in 10,000 (1 x 10-4 ) excess lifetime cancer risk. In determining the risk of consuming contaminated drinking water, other routes of exposure, such as diet, are considered so that the risk associated with the total daily exposure from all sources does not exceed the drinking water equivalent to the RFD for non-carcinogens or the 1 in 1,000,000 (1 x 10-6 ) excess lifetime cancer risk for carcinogens. In the absence of actual data, it is generally assumed that drinking water comprises 20% of all routes of exposure. The EPA supports a toll-free Drinking Water Hotline for questions from the general public at The World Health Organization (WHO) also publishes drinking water quality guidelines that are intended to be used as a basis for the development of national standards. See WHO Guidelines for Drinking Water Quality, Volume 2 (1996). Table 1 gives drinking water standards and guidelines for pesticides looked for in Oregon groundwater. Table 2 gives drinking water standards and guidelines for pesticides found in Willamette River tributaries as a part of the USGS National Water Quality Assessment Program Willamette basin Study, Phase I and II. Listed in order of preference are the MCLs, followed by HAs. If these values are not available, the WHO drinking water guideline is given. If MCL, HA, or WHO data are not available, then a HA was calculated from the DWEL (Drinking Water Equivalence Level, EPA, 1989). The DWEL is determined from the RfD assuming a 70 Kg person consumes 2 liters per day for a lifetime. To determine the HA, the DWEL is adjusted assuming that drinking water comprises 20% of the allowable daily intake of a given chemical. Use a HA determined from the DWEL assumes that there is no non-threshold lifetime cancer risk, or the HA calculated for cancer risk would be greater than that calculated using the DWEL.

4 Table 1. Drinking Water Standards and Guidelines for Pesticides Sampled in Oregon Groundwater ( ). Pesticide or metabolite 1 Standard/guideline ug/l (ppb) Source 2,4-D 70 MCL 2 2,4-DB 90 WHO 3 2,4,5-T 7 70 HA 4 acifluorfen 100 HA 5 acetochlor 140 HA from DWEL 6 alachlor 2 MCL aldicarb 7 MCL aldicarb sulfone 1 7 MCL aldicarb sulfoxide 1 7 MCL aldrin HA 5 AMPA 1 (glyphosate) atrazine 3 MCL atrazine, desethyl 70 HA from DWEL azinphos-methyl 21 HA from DWEL azinphos-methyl oxygen analog benefin (benfluralin) 2100 HA from DWEL bentazon 20 HA BHC, alpha (alpha-hch) 7 BHC, beta (beta-hch) 7 BHC, delta (detla-hch) 7 BHC, gamma (lindane) 0.2 MCL bromacil 90 HA bromoxynil 140 HA from DWEL butachlor HA from DWEL butylate 350 HA captan 130 HA from DWEL carbaryl 700 HA carbofuran 40 MCL carbofuran, 3-hydroxy- 1 carboxin 700 HA chloramben (Amiben) 100 HA chlordane 7 2 MCL chlordane, alpha 7 chlordane, gamma 7 chlorothalonil (Daconil) 150 HA 5 chlorpropham (CIPC) 1400 HA from DWEL chlorpyrifos 20 HA chlorpyrifos oxygen analog clopyralid 3500 HA from DWEL cresol, ortho cyanazine (Bladex) 1 HA cycloate 35 HA from DWEL DCPA (Dacthal) 70 HA DCPA, mono-acid 1

5 Pesticide or metabolite 1 Standard/guideline ug/l (ppb) Source DDD* (4,4) 7 2 WHO DDE, p, p'* (4,4) 7 2 WHO DDT (4,4) 7 2 WHO demeton HA from DWEL diazinon 0.6 HA dicamba (Banvel) 200 HA dichlobenil 91 HA from DWEL dichlorprop 100 WHO diethylanaline 1 (alachlor, metolachlor) dieldrin HA 5 dimethoate 1.4 HA from DWEL dinoseb 7 7 MCL diphenamid HA disulfoton 0.3 HA diuron 10 HA DNOC 7 endosulfan 42 HA from DWEL endosulfan sulfate 1 endrin 7 2 MCL EPTC 175 HA from DWEL esfenvalerate 140 HA from DWEL ethalfluralin 280 HA from DWEL ethoprop 0.7 HA from DWEL ethylene dibromide (EDB) 0.05 MCL fenamiphos 2 HA fenuron 7 fluometuron fonofos (Dyfonate) 7 10 HA glyphosate 700 MCL heptachlor MCL heptachlor epoxide MCL hexachlorobenzene (HCB) 1 MCL hexazinone 200 HA iprodione 280 HA from DWEL linuron 14 HA from DWEL malathion 100 HA malathion oxygen analog MCPA 10 HA MCPB 70 HA from DWEL methiocarb 35 HA from DWEL methomyl 200 HA methoxychlor 40 MCL methyl parathion 2 HA metolachlor 100 HA metribuzin 200 HA mevinphos (Phosdrin) 1.8 HA from DWEL

6 Pesticide or metabolite 1 Standard/guideline ug/l (ppb) Source molinate 6 WHO NAA (naphthaleneacetamide) napropamide 700 HA from DWEL neburon 7 norflurazon 30 estimated HA 8 oryzalin 350 HA from DWEL oxamyl 200 MCL parathion 2.3 HA from DWEL PCNB (Terrachlor) 21 HA from DWEL Pentachlorophenol (PCP) 1 MCL pebulate 49 HA from DWEL pendimethalin 20 WHO permethrin, cis 20 WHO permethrin, trans 20 WHO phorate 3.5 HA from DWEL phosmet (Imidan) 140 HA from DWEL phosmet oxygen analog picloram 500 MCL prometon 100 HA prometryn 28 HA from DWEL pronamide 50 HA propachlor (Ramrod) 90 HA propanil 20 WHO propargite 140 HA from DWEL propazine 10 HA propham HA propoxur (Baygon) 3 HA silvex (2,4,5-TP) 50 MCL simazine 4 MCL tebuthiuron 500 HA terbacil 90 HA terbufos 0.9 HA thiobencarb 70 HA from DWEL triadimefon 210 HA from DWEL triallate 91 HA from DWEL triclopyr (Garlon) 350 HA from DWEL trifluralin (Treflan) 5 HA 1 Pesticide metabolite from degradation in soil or water. 2 MCL: Maximum Contaminant Level; an enforceable drinking water standard. 3 WHO: World Health Organization drinking water guideline. 4 HA: Health Advisory, a non-enforceable drinking water guideline for lifetime exposure. 5 HA (cancer risk): Based on non-threshold lifetime cancer risk of 1 x 10-4 ; others based on the adjusted HA from DWEL 6 HA from DWEL: The Drinking Water Equivalent Level (DWEL) is based on the Reference dose (RfD) and assumes a 70 Kg person drinks 2 liters per day over a lifetime. The HA is determined from the DWEL by assuming that drinking water comprises 20% of the allowable daily intake. Also assumed; there is no lifetime cancer risk, or the HA calculated for cancer risk would be greater than that calculated using the DWEL. 7 No longer used in Oregon. 8 Estimated HA developed by EPA Office of Pesticide Programs using DWEL with an additional 10X safety factor to account for possible carcinogenic effects (class C carcinogen.)

7 Table 2. Drinking Water Standards and Guidelines for Pesticides Detected in Tributaries to the Willamette River (USGS National Water Quality Assessment Program Willamette basin Study, Phase I and II). Pesticide or metabolite 1 Standard/guideline ug/l (ppb) Source See footnotes above alachlor 2 MCL 2 atrazine 3 MCL atrazine, desethyl 1 atrazine, desisopropyl 1 carbaryl 700 HA carbofuran 40 MCL chlorpyrifos 20 HA cycloate 35 HA from DWEL DCPA 4000 HA DDD* (4,4) 7 2 WHO DDE, p, p'* (4,4) 7 2 WHO DDT (4,4) 7 2 WHO diazinon 0.6 HA dieldrin 0.2 HA 5 diuron 900 HA endosulfan 28 WHO 3 EPTC 175 HA from DWEL ethoprop 0.7 HA from DWEL fonofos 10 HA hexazinone 200 HA lindane 0.02 MCL malathion 200 HA metolachlor 40 HA metribuzin 200 HA napropamide 700 HA from DWEL pendimethalin 20 WHO prometon 100 HA pronamide 50 HA propachlor 90 HA propargite 140 HA from DWEL simazine 4 MCL tebuthiuron 500 HA terbacil 90 HA triallate 91 HA from DWEL trifluralin 5 HA

8 References Anderson, C.A.; Rinella, F.; Rounds, A Occurrence of Selected Trace Elements and Organic Compounds and Their Relation to Land Use in the Willamette River Basin, Oregon, ; Water-Resources Investigations Report ; U.S. Geological Survey. Drinking Water Health Advisory: Pesticides United States Environmental Protection Agency. Office of Drinking Water Health Advisories, Lewis Publishers. 819 p. Guidelines for Drinking Water Quality Volume World Health Organization, Geneva Switzerland. 973 p. Jenkins, J. J., P. Thomson, and D. Buchwalther Pesticides and Groundwater Quality in Oregon. Report to the Oregon Department of Agriculture. Jenkins, J. J Pesticide Use and Water Quality in the Willamette Valley. Report to the City of Wilsonville, OR, May 3, 1999.