Appendix D Food Codes for NHANES - OEHHA

Scientific Review Panel Draft February, 2012
was from a soil sample with about 710 µg Cr(VI) per g soil and contained
chromate crystals on the soil surface. The contaminated soil probably represents
a matrix described by Bartlett (1991) in which high concentrations of Cr(VI)
exhausted the readily available reducing power of the soil and excess Cr(VI)
persists on the soil surface without being reduced. Thus, multiplying 2.9% by
0.83 and rounded to the nearest whole number provides an ABS point estimate
of 2% for Cr(VI) from soil vehicle.
The Hot Spots risk assessment procedures have previously assumed no
reduction of deposited Cr(VI) because typically Cr(VI) deposition is modeled
without soil sampling monitoring for the Cr(VI)/Cr(III) ratio and without an
evaluation of the redox potential of the soil. This assumption may result in
overestimation of Cr(VI) soil concentrations in situations where Cr(VI) is readily
reduced to Cr(III). Bioaccessibility is determined in part by the Cr(VI)/Cr(III) ratio.
The use of soil with high concentrations of Cr(VI) to determine bioaccessibility is
not likely to underestimate bioaccessibility under the conditions typically found in
Hot Spots risk assessments, where Cr(VI) is deposited over a long period of time
and typically results in lower soil concentrations than the 710 µg/g observed in
the study by Wainman et al. (1994).
A Limitations for the ABS not discussed above include lack of a factor for
absorbed chromium lost through skin desquamation. Studies show that some
Cr(VI) will be reduced to Cr(III) in skin and bind to cellular constituents
(Gammelgaard et al., 1992; Hostynek, 2003). If this occurs in the stratum
corneum, the chromium will likely be removed through desquamation before
systemic absorption can occur. Another limitation includes reliance on studies in
which Cr(VI) is applied directly onto the skin (i.e., neat), rather than combined
with soil, for estimation of fractional dermal absorption. Kissel (2011) has noted
that fractional absorption is dependent on skin loading conditions for application
of organic chemicals directly to skin. However, Baranowska-Dutkiewicz (1981)
showed that for Cr(VI) the flux through skin increases proportionally with
increasing Cr(VI) load applied to skin, resulting similar fractional absorption
values independent of load onto skin. The constraints in estimating fractional
absorption for organic chemicals applied neat, which assumes a constant flux
through skin, does not appear to be relevant for the metal salt Cr(VI).
F.3.5 Fluoride and Soluble Fluoride Compounds
Recommended use of default inorganic compound ABS estimate of 13.0%.
F.3.5.1 Studies Considered
Excessive exposure to the negatively charged fluoride ion deposited on soil as
an aerosol or as a soluble inorganic fluoride salt is known to have toxic effects in
animals through ingestion of contaminated soil (Eagers, 1969). However, no
quantitative data could be found regarding the fractional dermal absorption of
F-30