In vitro dermal absorption of flame retardant chemicals

• Published in: Food and chemical toxicology 2001-12, Vol.39 (12), p.1263-1270
• Main Authors: Hughes, M.F, Edwards, B.C, Mitchell, C.T, Bhooshan, B
• Format: Article
• Language: English
• Subjects: Administration, Cutaneous; Animals; Biological and medical sciences; Bromobenzenes - administration & dosage; Bromobenzenes - pharmacokinetics; Carbon Isotopes; Chemical and industrial products toxicology. Toxic occupational diseases; Chemical Phenomena; Chemistry, Physical; Chromatography, High Pressure Liquid; decabromodiphenyl oxide; Dermal absorption; Dose-Response Relationship, Drug; Female; Flame retardant chemicals; Flame Retardants - administration & dosage; Flame Retardants - pharmacokinetics; flame retardent chemicals; Halogenated Diphenyl Ethers; In vitro; In Vitro Techniques; Medical sciences; Mice; Mice, Hairless; Molecular Weight; Organophosphorus Compounds - administration & dosage; Organophosphorus Compounds - pharmacokinetics; Phenyl Ethers; Polybrominated Biphenyls; Skin Absorption; Toxicology; tris-(1,3-dichloro-2-propyl)phosphate; Various organic compounds
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/S0278-6915(01)00074-6

Flame retardant chemicals may be used in furniture fabric in the future to reduce the flammability of the fabric. As a part of the process to evaluate the potential for exposure to these chemicals, this study examined the in vitro dermal absorption of two flame retardant chemicals. The chemicals were [ 14C]decabromodiphenyl oxide (DBDPO) and [ 14C]tris-(1,3-dichloro-2-propyl)phosphate (TDCP). Skin from the adult hairless female mouse (SKH1) was removed and mounted in flow-through diffusion cells. The chemicals, at three dose levels (DBDPO: 6, 30 and 60 nmol; TDCP: 20, 100 and 200 pmol), were applied in a volatile vehicle (tetrahydrofuran for DBDPO; acetone for TDCP) to the skin. Fractions of receptor fluid, pumped below the skin, were collected over a 24-h period. The skin was washed with solvent (tetrahydrofuran for DBDPO; ethanol for TDCP) to remove unabsorbed chemical 24 h after application. The receptor fluid, skin wash and skin were analyzed for chemical-derived radioactivity. The skin from the high-dose group of both chemicals, and the receptor fluid from TDCP high-dose samples, were analyzed for parent compound and metabolites by HPLC. The 24-h cumulative percent of the dose of DBDPO in the receptor fluid was very low (0.07–0.34%). The applied dose of DBDPO detected in the skin ranged from 2 to 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 h after application of DBDPO, and ranged from 77 to 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 h. 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 minor unknown peak. TDCP more readily penetrated hairless mouse skin and diffused into the receptor fluid than 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 dissimilar absorption through hairless mouse skin.