Appendix D Food Codes for NHANES - OEHHA

Scientific Review Panel Draft February, 2012
Recommended point estimate for dermal uptake from soil: 3%
F. 4.5.1 Studies Considered
A. Key Study
The only study located regarding dermal absorption of HCHs from soil was that
of Duff and Kissel (1996) who conducted in vitro dermal absorption studies using
human full-thickness skin and two lindane-contaminated soils. The organic
content of the sieved sub-150 µm soils were 3.87% (sandy loam) and 0.73% (silt
loam). The lindane-spiked soils were stored for up to 19 days prior to testing.
No effect of aging was observed within this time frame. The studies were carried
out for 24 hours with soil loading at 1, 5 or 10 mg/cm 2 . The relative percent
absorption decreased significantly with soil loads of 5 and 10 mg/cm 2 . This was
attributed to monolayer coverage of skin occurring at about 2 mg/cm 2 , resulting in
reduced fractional absorption at the higher soil loadings.
Results of this study showed that most of the mass of absorbed lindane was
found in the skin. The average fraction of total dermal uptake found in the
receptor fluid for both soils was only about 4%. Mean 24-hour total dermal
absorption values (found in receptor fluid + skin) at a soil load of 1 mg/cm 2 was
1.96 and 2.35%, for low and high organic content soil, respectively.
Approximately 40% of the lindane was lost to volatilization with a soil load of 1
mg/cm 2 , while significantly lesser amounts were lost in the higher loading trials
(less than 10% for the sandy loam soil at 10 mg/cm 2 ; less than 20% for the silt
loam soil at 10 mg/cm 2 ).
B. Supporting Studies
Feldman and Maibach (1974) examined the percutaneous absorption of lindane
dissolved in acetone and applied to the skin of human subjects (n = 6).
Radiolabeled lindane (4 µg/cm 2 ) was applied to ventral forearm skin and the
urinary excretion of 14 C was measured for 5 days after the single topical
application. The skin sites were not protected and subjects were asked not to
wash the area for 24 hours. Data obtained after i.v. dosing were used to correct
the skin penetration data for incomplete urinary recovery. Results indicate that
9.3% (SD 3.7) of the dose was absorbed. However, when skin was occluded,
the percent of absorbed dose increased dramatically to 82.1%.
In another human study, lindane was dissolved in acetone and applied to the
ventral forearm of volunteers and covered with a nonocclusive patch (Dick et al.,
1997a). Six hours after application approximately 80% of the applied lindane
dose (120 mg lindane per ml acetone) had not been absorbed and 14% of the
dose was found in the stratum corneum (measured by tape-stripping). The
authors conclude that 5% of the applied dose was absorbed to the systemic
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