Urinary excretion and DNA binding of coal tar components in B6C3F1 mice following ingestion

Urinary excretion of polycyclic aromatic hydrocarbon (PAH) metabolites and DNA binding of coal tar components in male mice were investigated following the ingestion of a coal tar adulterated diet. Male B6C3F1 mice were able to tolerate an F0927 basal gel diet which contained from 0.1 to 1% coal tar (tar weight/dry food weight) for 15 days. Mice maintained on a 0.1 and 0.2% coal tar diet had body weight gains similar to those of control animals. However, mice maintained on the 0.5 and 1.0% diet had body weight gains considerably lower than control values. Chemical-DNA adduct formation was detected and quantified in lung and forestomach tissue of animals on 0.1, 0.2, 0.5, and 1% coal tar containing diets. A dose-related effect was observed in lung DNA adduct formation while no dose effect was observed in forestomach tissue. In addition, overall adduct levels in lung tissue were considerably higher than forestomach levels for animals on the 0.5 or 1% diet. In contrast, DNA adduct levels were highest in the forestomach of animals on diets lower in coal tar content (0.1 or 0.2%). Chemical-DNA adducts of coal tar components were also evaluated for four other coal tar samples which varied in chemical composition. Mice were maintained on diets containing 0.25% of each coal tar for 15 days. Chemical-DNA adducts were detected in lung, liver, and spleen for all animals receiving these coal tar diets. DNA adduct patterns were similar while quantitative differences were observed between coal tar samples and tissue sites. Highest adduct levels were detected in lung DNA. Benzo[a]pyrene content in coal tar samples could not account for the DNA adduct levels observed with coal tar ingestion. The urinary excretion of select PAH metabolites following coal tar ingestion was evaluated by using urine collected on days 1 and 14 of diet administration. The levels of 1-hydroxypyrene in urine, the major PAH metabolite detected, correlated with the pyrene content of these coal tars. These data demonstrate that coal tar components are readily bioavailable following ingestion.