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IN VITRO DERMAL ABSORPTION OF FLAME RETARDANT CHEMICALS
Citation:
Hughes, M F., B C. Edwards, C T. Mitchell, AND B. Bhooshan. IN VITRO DERMAL ABSORPTION OF FLAME RETARDANT CHEMICALS. FOOD AND CHEMISTRY TOXICOLOGY 39:1263-1270, (2001).
Description:
ABSTRACT
The use of flame retardant chemicals in furniture fabric could pose a potential health risk to consumers from dermal absorption of these compounds. The objective of this study was to examine the in vitro dermal absorption of two flame retardant chemicals, [14C]-decabromodiphenyl oxide (DBDPO) and [14C]-tris-(1,3-dichloro-2-propyl)phosphate (TDCP). Skin from the adult hairless female mouse (SKH1) was used as the barrier to penetration of these chemicals. The chemicals, at three dose levels (DBDPO: 6, 30, and 60 nmole; TDCP: 20, 100, and 200 pmole), were applied in a volatile vehicle (tetrahydrofuran for DBDPO; acetone for TDCP) to the skin, which was mounted in flow-through diffusion cells. Fractions of receptor fluid, pumped below the skin, were collected over a 24 hr period. The skin was washed with solvent (tetrahydrofuran for DBDPO; ethanol for TDCP) to remove unabsorbed chemical 24 hr after application. The receptor fluid, skin wash and skin were analyzed for chemical-derived radioactivity. The skin of the high dose group from both chemicals, and the receptor fluid from TDCP high dose treated samples, were also analyzed for parent compound and metabolites.
The 24-hr cumulative % of the dose of DBDPO in the receptor fluid was very low (0.07-0.34%). The dose detected in the skin ranged from 2-20%. The lowest dose of DBDPO had the highest percentage of the dose (20%) in the skin. The major portion of the applied dose was removed by washing the skin 24 hr after application of DBDPO, and ranged from 77-92%. HPLC analysis of homogenate extract prepared from the high dose of DBDPO-treated skin showed the presence of DBDPO and a minor unknown peak.
TDCP was readily detected in the receptor fluid; 39-57% of the applied dose of TDCP was in the receptor fluid by 24 hr. The solvent wash removed 11-25% of the dose from the skin and 28-35% remained in it. HPLC analysis of the skin homogenate extract and receptor fluid extract from the TDCP high dose treated samples showed the presence of parent compound and a small unknown peak.
Thus, TDCP more readily penetrates hairless mouse skin and diffuses into the receptor fluid compared to DBDPO. TDCP has a lower molecular weight and log octanol:water partition coefficent than DBDPO. The differences in the physico-chemical properties of these two chemicals most likely explains their dissimilarity in penetrating through hairless mouse skin.