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David Stavarek, R.G. <br /> June 29, 1998 <br /> Page 8 <br /> algorithm is modified to incorporate only the probabilistic age-specific exposure factors. <br /> Although the example is for the estimation of the inhalation dose, similar procedure may be <br /> used for the dermal exposure, soil ingestion rates, and food ingestion rates. <br /> a. Inhalation dose in children. Children are here defined as ranging from one month up to <br /> 12 years of age. The traditional approach for estimating the average inhalation dose for <br /> children received at a specific location, is estimated with the expression: <br /> DOSEinhch;;d= 1x10-3 • Cair, • ABS; h • BR • EF • ED / [BW • AT] [Eq. 1] <br /> In the probabilistic approach,the algorithm is modified by separating common from the age- <br /> specific exposure factors,for example: <br /> For 1 mo-to-3 years age range: DOSEI13 =Cair,• ABS;,,h • BRl • EM • ED / [BWl • AT] <br /> for 4-to-6 years age range: DOSE416 =Cain ABSinh • BR2 • EF2 •ED2/ [BW2 • AT] <br /> for 7-to-12 years age range: DOSEM2 =Cain ABSM • BR3 • EF3 • ED3/ [BW3 • AT] <br /> Combining these equations, a general algorithm for children between lmo and 12 years of <br /> age, can be written as: <br /> DOSEinh�h;ld = 11x10 3 Cain• ABSinh/AT] • BRi•EFi•EDi [Eq 2] <br /> BWi <br /> where: <br /> subscript i denotes a specific age range within 1 month and 12 years of age <br /> DOSEinh�h;;d=Av. inhalation dose of contaminant i in a 1 mo<12 y old child, mg/kg•d <br /> 1x10-3= Conversion factor(1 mg/1000 µg) <br /> Cain Average annual air concentration of contaminant c, in µg/m3 <br /> ABSinh=Inhalation absorption factor <br /> AT=Averaging Time(period over which exposure is averaged, in days); <br /> for noncarcinogenic effects: AT= 12 y x 365 d/y=4,380 d <br /> for carcinogenic effects: AT= 70 y x 365 d/y=25,550 d <br /> The AT values are constant for both default and stochastic approaches <br /> BRl =Average breathing rate for the first age range in(M+F) children, in m3/d; and, <br /> BR2 =Average breathing rate for the second age range in(M+F) children, in m3/d; etc. <br /> EF 1 =Exposure frequency for the first age range, in d/y; and, <br /> EF2 =Exposure frequency for the second age range, in d/y; etc. <br /> ED 1 =Exposure Duration for children(M+F) in the first age range, in years; and, <br /> ED2=Exposure Duration for children(M+F)in the second age range, in years; etc. <br /> BWl =Average body weight for children(M+F) in the first age range, in kg; and, <br /> BW2=Average body weight for children(M+F) in the second age range, in kg; etc. <br />