United States Environmental Protection Agency uv.ice of Water Office of Pesticides and Toxic Substances Fall 1990 wEPA National Pesticide Survey Alachlor What Is Machlor? How Does Alachlor Behave in Soil and Ground Water? How Does Alachlor Gat into Ground Watar? CHj-CH, XCH2-O-CH3 NC— CH,CI l' II * o CH2-CHj Alachlor The U.S. Environmental Protection Agency (EPA) has completed its five-year National Survey of Pesticides in Drinking Water Wells (NPS), a study of the presence of 127 pesticides, pesticide degradates, and nitrate in community water system (CWS) wells and rural domestic drinking water wells. Alachlor was one of the pesticides detected in the Survey. This fact sheet provides a description of alachtor. its potential health effects, and guidance on both treating and preventing well contamination. Alachlor is the common name of an herbicide which is a member of the chemical family of acetanilides. Alachlor was registered for use in 1969. It has been sold under the trade names of Lasso, Pillarzo, and the discontinued trade name of Alatox. Alachlor is also a component of other herbicides such as Bronco, Bullet, Cannon, Freedom, and Lariat Alachlor is used to control most annual grasses and certain broadleaf weeds in com, cotton, dry beans, peanuts, potatoes, and soybeans. It may also be used on sunflowers, cabbage, tobacco, sugarcane, and certain ornamental and established turf species. The behavior of a pesticide after it is released to the environment is dependent upon its movement in air, water, and soil as well as the rate at which it is transformed or broken down. Pesticides applied to crops or the soil surface may volatilize (vaporize) to the atmosphere, be carried off by surface runoff, be carried to ground water through leaching, or remain in the son through adsorption (adherence) to soil particles and undergo little movement in air or water. Pesticides may be transformed by reaction with water, microorganisms, and exposure to sunlight The likelihood that afacNor wffl migrate into ground water is influenced by its tendency to be transported (mow) from soil to air and water and to be transformed by these various processes, at wal at by the characteristics of the site such as soil type, moisture, temperature, and depth to ground water. Alachlor has a medium potential to be transported, and a medium potential to be transformed. Alachlor migration into ground water could result from the presence of alachkx in the soil due to agricultural applications. Alachlor could also reach ground water from direct entry into a well through accidental chemical spills or improper storage ntarawaU. NPS Altehlor ------- Findings of the National Pesticide Survey What Health Effects Might be Caused by Alachlor in Drinking Water? How is Water Treated to Remove Contami- nants? How Can Water Contamina- tion be Prevented? Based on the results of the NFS, EPA estimates that alachlor is present, at or above the analytical detection level of 0.50 /;g/L used in the Survey, in about 3,140 (0.03%) rural domestic wells nationwide. Considering the precision of the Survey, EPA estimates that this number could be as high as 101,000. Alachlor is measured in micrograms per liter (^g/L) which is equivalent to parts per billion (ppb). Alachlor was sometimes detected at concentrations above EPA's proposed Maximum Contaminant Level (MCL) of 2 pg/L EPA notified well owners and operators within 24 hours when detections were above health-based guidelines or standards. Alachlor was not detected in any CWS wells. Non-Cancer Effects: A Lifetime Health Advisory Level for alachlor in drinking water has not been established by EPA. Ingesting alachlor has been shown to result in adverse health effects in animal studies, resulting in damage to the liver, kidneys, spleen, and eyes. Cancer R/sfc: Alachlor also causes cancer in laboratory animals that are given high doses of the pesticide over the course of their lifetimes. Therefore, EPA considers alachior to be a probable human carcinogen (cancer-causing agent). EPA estimates that if an individual consumes water containing alachlor at 0.4 pg/L over his or her entire lifetime, that person would theoretically have no more than a one-in-a-million chance of developing cancer as a direct result of drinking water containing this pesticide. Standard: EPA sets enforceable standards for public water systems, called MCLs. These regulatory standards set achievable levels of drinking water quality to protect human health. The proposed MCL for alachlor is 2 pg/L (proposed as of May 22, 1989). Alachlor can be detected in drinking water by a laboratory using an EPA method such as #507. If alachlor is detected in well water and confirmed by retesting, State or County health officials should be consulted. They may advise periodic retesting to get an accurate overall picture of the water quality because changes in seasonal precipitation and changes in pesticide use can cause variations in the amount of chemicals found in water wells. They also may advise using an alternative drinking water supply (bottled water is an example of a temporary alternative), treating the water, or drilling a new or deeper well. Public water suppliers are required to notify customers if the drinking water that they deliver contains a contaminant that exceeds its MCL You may also be able to treat your well water to remove pesticides and other contaminants. Treatment by granular activated carbon can remove alachlor from water. However, this technique is not necessarily appropriate or available in every situation. State or County health officials should be able to provide advice on the best approach to f oflow. Several steps may be taken to prevent pesticides or nitrate from entering wells, such as eliminating direct entry through the well wait, drilling a new wen, or modifying or reducing pesticide and fertilizer use. £//m/nata O/rtct Entry of Pa*tfcJtfat Through tfta HW Wall If pesticides or nitrate are present in wefl water, they may be entering the ground water through the well itsetf rather than through the soil. If the well is old or poorly constructed, or if there are visible cracks in the well casing, obtain expert advice on whether or not improvements can be made to the well. In addition, investigate simple methods of capping the well or sealing it at the surface to prevent NPS Altchlor ------- Why was the National Pesticide Survey Conducted? Where to Go for More Information entry. Do not conduct any mixing activities near the well it you use well water to mix pesticides because a spill could lead to direct contamination of the well. Drill» New W»ll n If the soil surrounding the well is the source of contamination, drilling a new or deeper well may make sense if water can be drawn from a deeper, uncontaminated aquifer. Unfortunately, it often is difficult to know the quality of the ground water without drilling or extensive testing. Seek expert advice before you drill. Learn More about Pcst/c/de Use If you use pesticides, whether for agricultural or home lawn and garden purposes, you should consider attending training courses given by your State or County agriculture department on how to reduce activities that can contaminate ground water. You may find that you can eliminate or lessen the frequency or quantity of your pesticide usage by choosing alternative methods of pest control. EPA conducted this Survey to determine the frequency and concentration of pesticides, pesticide degradates, and nitrate in drinking water wells nationwide and to examine the relationship between the presence of pesticides in drinking water wells and patterns of pesticide use and ground-water vulnerability. The Survey sampled 566 community water system wells and 783 rural domestic wells for 127 pesticides, pesticide degradates, and nitrate. The wells were selected as a representative statistical sample to provide nationwide estimates of the presence of pesticides and nitrate in drinking water wells, and are not meant to provide an assessment of pesticide contamination at the local, County, or State level. This fact sheet is part of a series of NFS outreach materials, fact sheets and reports. The following additional fact sheets are available through EPA's Public Information Center (401 M Street SW, Washington, DC 20460, (202) 382-2080): Survey Des/gn Survey AiM/ytes Qua/fry Assurance/ Out/fry Control AmtytJctl Method* Summary Retu/ts Fact Sheet for each detected •rw/vte Pro/ecf Summary G/otsary How EPA Will Ute The NFS Resufts Additional information on the Survey and on pesticides in general can be obtained from the following sources: U.S. EPA Safe Drinking Water Hotline 1-800-426-4791 On Washington, DC (202) 382-5533) Monday-Friday, 8:30 am to 4:30 pm Eastern Time National Pesticide Telecommunications Network 1-800-858-7378 24 hours a day U.S. EPA Office of Pesticide Programs (OPP) Docket Public Information Branch (H75O6C) 401 M Street/ SW Washington, DC 20460 Telephone: (703) 557-2805 Information on regulation of pesticides in drinking water Information on health effects and safe handling of pesticides Background documents for Survey (available for review) NPSAltcMor ------- National Technical Information Service (NTIS) Copies of the 5285 Port Royal Road NPS Phase I Report Springfield, VA 22161 (available 1991) (703) 487-4650 and NPS Phase II Report (when available) If you are concerned about the presence of pesticides and nitrate in your private water well, contact your local or State health department. Other experts in your State environmental agency or agriculture and health departments may also be helpful to you. If you receive your drinking water from a community water system and have questions about your water quality, contact your local community water system owner/operator or the State water supply agency. Bibliography Meister Publications. Farm Chemicals Handbook. Ohio: Meister Publications, 1990. U.S. Environmental Protection Agency. Drinking Water Health Advisory: Pesticides. Michigan: Lewis Publishers, 1989. U.S. Environmental Protection Agency. Drinking Water Regulations and Health Advisories. April, 1990. U.S. Environmental Protection Agency. Health Advisory Summaries. January 1989. U.S. Environmental Protection Agency. Pesticides in Drinking Water Wells. September 1989. Weed Science Society of America Herbicide Handbook of the Weed Science Society of America 5th ed. Illinois: Weed Science Society of America, 1983. Worthing, Charles R, ed. The Pesticide Manual. 8th ed. Thornton Heath: The British Crop Protection Council, 1987. WPS Altchlor ------- |