Further investigations of the capacity of polynuclear aromatic hydrocarbons to elicit atherosclerotic lesions.

Treatment of chickens for up to 20 wk with varying doses (0.1-10 mg/kg) of benzo[a]pyrene (BaP) or 7,12-dimethylbenz[a]anthracene (DMBA) resulted in significant increases in incidence and size of atherosclerotic lesions at the two higher doses utilized (1 and 10 mg/kg). Maximal lesion formation for birds treated chronically with BaP occurred at 1 mg/kg, while development of lesions in birds treated with DMBA was roughly linear over the dose range tested. The largest doses of BaP or DMBA (10 mg/kg for 20 wk) produced the highest percentage of chickens with detectable lesions (75 and 89%, respectively). Lower doses of BaP or DMBA resulted in a smaller percentage of birds (per group) with lesions, and the lowest dose (0.1 mg/kg) produced no statistical increase in lesion incidence. At approximately equimolar doses, DMBA appeared to be more potent than BaP in enhancing the development of lesions in the chickens. Administration of a single dose of BaP or DMBA followed by weekly doses of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) for 20 wk did not result in enhancement of lesion formation over the respective controls. Blood cholesterol was not significantly altered after treatment of chickens with DMBA, BaP, or TPA.