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EPA's IRIS Site - Drinlung Water Health Advisories http://www.epa.gov/ngispgm3liris/dwater.htrrJ <br />• • <br />DWEL = (RfD) (BW) / (_ L/day) <br />where: RfD is the unrounded oral RfD derived in Section I of the chemical file, and, BW <br />and _ L/day are the adult reference values for body weight and water consumption, <br />respectively. Lifetime HAs assume that only a given percentage of the total compound <br />intake is by drinking water and are derived by the equation: <br />Lifetime HA = DWEL x RSC <br />where: RSC =relative source contribution; the assumed exposure from drinking <br />water. <br />Lifetime HAs are not derived for compounds potentially carcinogenic for humans because <br />of the difference in assumptions concerning toxic thresholds for carcinogenic and <br />noncarcinogenic effects. <br />In situations where data are not available to calculate Longer-term HAs, the DWEL may be <br />recotmnended for the longer-term HA. For the child Longer-term HA, the DWEL may be <br />recalculated using the child's weight and water consumption. <br />For more information about Health Advisories, call the Office of Drinking Water at <br />(202)382-7571 or FI'S 382-7571. <br />Reference: NAS (National Academy of Sciencies). 1977. Drinking Water and Health, Vol. <br />1. Washington. DC. <br />+I+IIJ%IsCu`lJ.1JJ.~ ~ ~,rYJiJ71J~tv3~;~LG-+lr~t; <br />/`..1~ <br />r~ <br />Send Scarth IL'CEA OR© EPA <br />Commrnts N.orne Page Ftorme Page i}Coeree Page <br />Last updated: 20 February 1998 <br />URL: httpawww.cpa.govliris/~?94?'t1Tt.htm <br />i o(3 b/I 1/99 425 PM <br />