The dermal bioavailability of radiolabelled benzo[a]pyrene from acetone or from oils of differing viscosity, assessed by DNA and protein binding.
Tritium-labelled benzo[a]pyrene ([3H]BaP) was applied to mouse skin in acetone or mineral oils of differing viscosity. Epidermal DNA and protein were extracted after 24 or 48 h and the degree of adduct formation determined by the radioactivity present. When [3H]BaP was applied in acetone, the degree of DNA and protein binding was around 15-20 times greater than that observed when a low-viscosity oil was used as a vehicle. When applied in oils of differing viscosity, however, only a twofold difference was seen across the whole viscosity range (13.5 cSt* at 40 degrees C to 1665 cSt at 60 degrees C). From measurements made of urine and faecal radioactivity and from small-scale investigations using other routes of administration, it was clear that the grooming activity of the animals had a marked effect on skin absorption and macromolecular binding. It is possible that greater grooming activity with low-viscosity oils may explain why oil viscosity did not have a greater effect on binding levels, but further studies are needed to investigate this. These findings may have important implications in the interpretation of long-term skin painting studies and may assist in the interpretation of analytical data and short-term biological assays.
Ingram
A J
AJ
BP Group Occupational Health Centre, Guildford, Surrey, UK.
Phillips
J C
JC
D000096:Acetone; D000818:Animals; D001564:Benzo(a)pyrene / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001682:Biological Availability; D004247:DNA / Q000032:analysis*; D004817:Epidermis / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D006120:Grooming; D051379:Mice; D008815:Mice, Inbred Strains; D009821:Oils; D014677:Pharmaceutical Vehicles; D011485:Protein Binding; D011506:Proteins / Q000032:analysis*; D012869:Skin Absorption; D014783:Viscosity
D009821:Oils; D014677:Pharmaceutical Vehicles; D011506:Proteins; D000096:Acetone; D001564:Benzo(a)pyrene; D004247:DNA