Journal of Toxicology

Research Article

Modeling the Human Kinetic Adjustment Factor for Inhaled Volatile Organic Chemicals: Whole Population Approach versus Distinct Subpopulation Approach

Table 5

HKAFs obtained by the “distinct subpopulation” approach on the basis of 100,000 Monte Carlo iterations in adults, neonates, infants, and pregnant women and by the “whole population” approach for the Canadian population.
HKAF assumptionDose metrics
Benzene1,4-Dioxane
CAssRAMCAssRAM
“Whole population” approach
   H K A F a d ( a )
   Based on 95th percentile1.21.32.11.4
   Based on 99th percentile1.31.42.81.6
   H K A F p o p ( b )
   Based on 95th percentile 1.21.22.11.4
    Based on 99th percentile1.31.42.81.6
“Distinct subpopulation” approach
 In adults
   H K A F a d ( c )
   Based on 95th percentile1.21.22.11.4
    Based on 99th percentile1.31.32.81.6
   H K A F p o p ( d )
   Based on 95th percentile1.21.2 2.01.4
   Based on 99th percentile1.31.32.71.6
 In neonates
   H K A F a d ( c )
   Based on 95th percentile1.61.16.61.2
   Based on 99th percentile1.71.28.51.4
   H K A F p o p ( d )
   Based on 95th percentile1.61.16.51.2
   Based on 99th percentile1.7 1.28.31.4
 In infants
   H K A F a d ( c )
   Based on 95th percentile1.31.23.11.4
   Based on 99th percentile1.41.33.81.6
   H K A F p o p ( d )
   Based on 95th percentile1.31.23.01.4
   Based on 99th percentile1.41.33.81.5
 In pregnant women
   H K A F a d ( c )
   Based on 95th percentile1.41.52.71.8
   Based on 99th percentile1.51.63.52.1
   H K A F p o p ( d )
   Based on 95th percentile1.41.52.61.8
   Based on 99th percentile1.51.63.52.1
Italicized values indicate the highest HKAF among each subpopulation for a given dose metric.
( a ) Computed as the ratio of the upper percentile value in the Canadian population (95th or 99th) to the median in 100,000 adults. ( b ) Computed as the ratio of the upper percentile value in the Canadian population (95th or 99th) to its median. ( c ) Computed as the ratio of the upper percentile value in the subpopulation (95th or 99th) to the median in adults. ( d ) Computed as the ratio of the upper percentile value in the subpopulation (95th or 99th) to the median in the Canadian population.
CAss: blood concentration of parent compound; HKAF(ad/pop): human kinetic adjustment factor using either the median in adult (“ad”) or whole population (“pop”) as referent; RAM: rate of metabolism.