Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
APTER 6 Analysis of Key Topics-Environmental 6.1 IMPLICATIONS FOR HUMAN HEALTH Significance 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. | CHAPTER 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 concenttation 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 tteatment 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 pentachlorophenol 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 .
