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Drinking Water Regulations and Health Advisories: Front Page http://www.epa.gov/OST/1'ools/dwstds.htmi <br />• • <br />Lame disarpancics between Lifetime and Longer-term HA values may occur because of [he <br />Agency's consavativc policies, especially with regv'd to carcinogenicity, relative source <br />contribu[ion.:utd Icss-than-lifetime exposures in chronic toxicity tcs[in g. These factors can <br />result in a cumulative UP (uncertainty factor) of up [o > to 1000 when calculating a Lifetintc <br />H A. <br />The scheme for categorizing chemicals according [o their carcinogenic potential is as <br />follows: <br />Group r1: <br />Human carcinoeen <br />Group B: <br />Probable human carcinogen <br />Group C: <br />Possible human carcinogen <br />Group D: <br />Nut classifiable <br />Sufficient evidence in epidemiologic studies to support <br />causal association between exposure and cancer <br />Limited evidence in epidentiologic studies (Group B I ) <br />and/or sufficient evidence from animal sutdics (Group E <br />Limited evidence loom animal studies and inadequate or <br />data in humans <br />hutdequate or no human and animal evidence of <br />carcinogenicity <br />Group R: <br />No evidence of carcino~enichv for <br />human s <br />No evidence of carcinogenicity in at least nvo atleyuate <br />unintal tests in different species or in adequate <br />epidemiologic and :mintal studies <br />Drinking Water 1-Iculth Ach~isorics (I IAs) arc defined as follows: <br />One-dav~ HA: <br />"fhe concentration of a chemical in drinking water that is not e.xpecled to cause any <br />adverse nuncarcinogenic ellects for up to ~ consecutive days of exposure, with a <br />margin of safety. <br />"fen-day HA: <br />The concentration of a chemical in drinking water that is not expected to cause any <br />ach~erse noncarcinogenic ellects up to 14 consecutive clays of exposure. with a margin <br />of safety. <br />Long-term HA: <br />The concenration of a chemical in drinking water that is no[ expected to cause any <br />adverse noncarcinogenic effects up to approximately 7 years (109n of an individual's <br />lifetime) of cxposurc, with a margin of safety. <br />Lifetime HA: <br />The concentration of a chemical in chinking water that is not expected to cause any <br />advcr:~e noncarcinogenic effects over a lifetime of cxposurc, with a margin of safety. <br />Nurc:''l3PA is in [hc pr'ocess of revising the Cancer Guidelines. <br />Previous I Next I Flonte <br />3 0(~l 6/ 1 I /99 5:22 PM <br />