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STATE OF CALIFORNIASERVICES <br /> DEPARTMENT OF HEALTH <br /> TOXIC SUBSTANCES CONTROL PROGRAM <br /> TOXSCIENTIFICDRISK GUIDANCESMEMO 89-NT UNIT <br /> AUGUST 9, 1989 <br /> Page 3 of 8 <br /> that effects observed in animals are applicable to humans, and <br /> doses in mg/kg/day are equivalent across species. <br /> AAL Calculations: Data from the EC-7 study (Table 2) .,are <br /> used <br /> of the <br /> for quantitative risk assessment (low dose <br /> linearizedlmultistage <br /> carcinogenic effects of PCP. Usingand the method of <br /> model for low dose e thep95�olatlowerGconfidence limit on the dose <br /> Allen et al . (1987) , <br /> (LCL) as with an incremental lifetime risk Pof ocP ne in one <br /> million for the induction of cancer in humans by <br /> llest 95% LCL <br /> mated for each tumor data set. The as chosen to calculate the <br /> most sensitive sex and tumor site) and malignant <br /> MEL. The smallest LCL was that for combined benign <br /> liver tumors in male Nice. <br /> t on <br /> The MEL was calculated from esselifetimew cancerer confidence <br /> rsk of11016 as <br /> dose corresper.ding ,.o an e <br /> follows (70 kg is assumed to be the average weight of a <br /> MEL (ug/day) = 6 . 3 X 10-5 mg PCP/kg/day X 70 kg X 1000 ug/mg <br /> 4 . 40 ug/day <br /> The AALs for PCP were developed by <br /> allocating this MEL to each <br /> medium of exposure. The AAL is equal to the MEL divided by <br /> the <br /> medium to which the recflsich exposed, <br /> average volume of e <br /> corrected for toxicokinetic fac_ors (TF) , actorswh <br /> characteristic of the substance <br /> ption,in tmetabolhe ism�faestpributionosure atand <br /> air, or soil) , such as a _ <br /> t. e <br /> The following assumptions were made: (1) <br /> elimination. y metabolism, storage and <br /> toxicokinetics of PCP distribution, <br /> elimination are simila for <br /> orbedinhalation <br /> the angestiont and inhalation <br /> (2) PCP is completely _ 1. 0) � there is some data to support this <br /> routes (therefore TFs <br /> assumption; (3) any differences between humans and laboratory <br /> metabolism, <br /> animals in the absorption, distribution, <br /> elimination of PCP do not significantly influence the estimated <br /> toxic effects of PCP in humans; and (4) a 70 kg adult consumes an <br /> average of 2 liters of water a day and breathes 20 m3 of air a <br /> day over a 70 year lifetime. <br /> The AALs for PCP were calculated as follows: <br /> MEL x TF (water) = 2 . 20 ug/L <br /> AAL (water) = 2 L/day <br /> AAL (air) = <br /> MSL x TF (air) = 0 . 22 ug/m3 <br /> 20 m'%day <br />