Appendix D Food Codes for NHANES - OEHHA

Scientific Review Panel Draft February, 2012
circulation by 6 hours. Although the disappearance method was used to
estimate systemic absorption, measurable levels of lindane were found in the
bloodstream and lindane metabolites were found in the urine. By 24 hours, tape
stripping of the remaining volunteers showed the stratum corneum contained
very little of the applied lindane and only about 0.01% of the dose had been lost
through desquamation, suggesting that nearly all the lindane detected in the
stratum corneum at 6 hours had been systemically absorbed or absorbed into
deeper skin layers by 24 hrs.
F.4.5.2 Discussion and Recommendation for a Hexachlorocyclohexane ABS
Although only one study for dermal absorption of lindane from soil is available,
the findings provided consistent results for a human in vitro fractional absorption
range of 0.45 to 2.35% under different soil loadings and soil types (Duff and
Kissel, 1996). The highest fractional absorption of 2.35% was chosen as the
basis for the HCH ABS, given that the soil loading (1 mg/cm 2 ) used was the only
one that was at or below monolayer skin coverage. An average of only 4% of the
absorbed dose (approximately 0.09% of the applied dose) was found in the
receptor fluid after 24 hrs. However, in vivo studies show extensive absorption of
lindane into all skin layers, with continued absorption of lindane beyond the
stratum corneum 6 hrs after removal of lindane from the skin surface (Dick et al.,
1997a). Thus, lindane retained in skin depots should be presumed to be
available for eventual systemic absorption.
Duff and Kissel (1996) noted the unexpected result that the soil with the higher
organic carbon content generated a higher fractional absorption (2.35%) than the
soil with low organic carbon content (1.96%) at equivalent soil loadings of 1
mg/cm 2 . Increasing organic carbon content of soil generally reduces transport,
and dermal absorption, of organic compounds in soil. The authors theorized that
this inconsistent finding at 1 mg/cm 2 was due to inter-individual differences in
skin absorption, which would not have occurred had the same skin donors been
used for both soils.
To account for known effects of organic content of soil the ABS of 2.35% is
rounded up, rather than down, to one significant figure for a final ABS of 3%. In
support of this ABS adjustment, soil loadings of 5 and 10 mg/cm 2 from high
organic content soil did reduce fractional absorption of lindane compared to
lindane in soil with low organic content (Duff and Kissel, 1996). However,
monolayer coverage of skin was exceeded at these higher soil loads, resulting in
lower fractional absorption compared to fractional absorption at 1 mg/cm 2 .
Other data available on percutaneous absorption of lindane or other HCH
isomers, which are obtained from studies that use acetone or topical creams and
lotions as the vehicle, are not relevant for estimating fractional absorption of
lindane from soil (Franz et al., 1996). Use of topical creams and lotions as a
F-61