DNA ADDUCT FORMATION IN MICE FOLLOWING TREATMENT WITH USED ENGINE OIL AND IDENTIFICATION OF SOME OF THE MAJOR ADDUCTS BY P-32 POSTLABELING

Used engine oil from a petrol-powered vehicle was fractionated by column chromatography into seven parts for which the major polycyclic aromatic hydrocarbon (PAH) components were determined by GC. Topical treatment of mice with the fractions and P-32-postlabelling of the skin DNA resulted in the detection of multiple adduct spots on TLC for some, but not all, of the fractions. The majority of the DNA binding capacity of the used engine oil was possessed by the first three fractions, (equivalent to 25, 15 and 14.5 %, respectively) of the adduct forming ability of the unfractionated oil. The chromatographic mobilities of the adduct spots induced by these fractions were compared to those produced by unfractionated used engine oil. In addition, mice were also treated topically with reference PAHs, either singly or as mixtures, dissolved in unused oil at the concentrations at which they were present in the used oil. Comparisons were made between the chromatographic mobilities of the adducts formed in mouse skin DNA by synthetic mixtures with those formed by the used oil. From these data, some of the major adducts produced by treatment with used engine oil are suggested to be formed by reactive metabolites of benzo[b]naphtho[1,2-d]thiophene, benzo[c]phenanthrene, benzo[g,h,i]fluoranthene, chrysene, benzo[a]pyrene and benzo[g,h,i]perylene.