Appendix D Food Codes for NHANES - OEHHA

Scientific Review Panel Draft February, 2012
respectively, represented percent of applied dose penetrating to the receptor
fluid.
B. Supporting Studies
Radiolabeled mercuric chloride ( 203 HgCl2) was mixed with soil and applied in vitro
onto fresh human breast skin (obtained within 24 hrs of harvest) for 24 hrs by
means of Bronaugh diffusion cells (Moody et al., 2009b). The same amount of
203 HgCl2 was also applied without soil to human skin samples. The soil had been
sieved to 90-710 µm prior to spiking with the Hg salt. The soil mixture (3.2 mg
soil) was added to the diffusion cells resulting in a soil loading of 5 mg/cm 2 . At
24 hrs, mean percent dermal absorption including the skin depot was 46.6 and
78.3% with and without soil, respectively. The fraction of total absorbed Hg that
entered the diffusion cell in 24 hrs was 1.5 and 1.4% with and without soil,
respectively.
A radiolabeled mercury compound ( 203 HgCl2) was applied in soil or water vehicle
to human skin in vitro (0.5 µg/cm 2 containing 1 µCi) for 24 hours (Wester et al.,
1995; Wester and Maibach, 1998c). The investigators used Yolo County soil
(26% sand, 26% clay, 48% silt, 0.9% organic) sieved for 180-300 µm particles.
Receptor fluid accumulation from either water vehicle or soil vehicle was 0.07%
of applied dose. Previously frozen or fresh skin gave similar results. Skin
content of mercury from water vehicle averaged 29% of total dose applied.
Using soil loads of 5, 10, and 40 mg, skin content of mercury was 10.4, 6.1, and
7.2% of dose applied, respectively.
In other human in vitro studies by the same research group, 5.5% absorption into
skin and 0.01% penetration of pure HgCl2 into receptor fluid was observed with a
30 min exposure (Wester et al., 1995; Wester and Maibach, 1998c). Continued
perfusion for 48 hrs following the 30 min exposure increased skin absorption and
penetration to receptor fluid to 6.3% and 0.09%, respectively, exhibiting the
ability of Hg to migrate through skin after removal of Hg from the skin surface.
When the in vitro exposure was increased from 30 min to 24 hrs, mercury skin
absorption and penetration to receptor fluid was increased to 35.4% and 0.06%,
respectively. No other results or methodology details were provided.
The dermal bioavailability of liquid and soil-bound 203 HgCl2 was tested on
dermatomed human male skin in vitro (Sartorelli et al., 2003). For the liquid
vehicle, HgCl2 was added to buffered water solution (pH = 4.0). For the soil
vehicle, HgCl2 was added to loam soil consisting of 60% sand, 30% silt and 10%
clay sieved to a particle size of