THE CARCINOGENIC POTENCY OF CARBON PARTICLES WITH AND WITHOUT PAH AFTER REPEATED INTRATRACHEAL ADMINISTRATION IN THE RAT

The role of carcinogenic PAH in soot- and carbon black-related lung tu mour induction in rats was investigated after intratracheal administra tion of carbon blacks (CB) and two types of diesel soot (DS), either a s original or as toluene extracted particles. The total particle dose per animal was 15 mg subdivided into 16-17 weekly applications. There was one vehicle control and two groups were treated with a total dose of either 30 or 15 mg pure BaP as positive control. The main tumour re sults were: (a) original DS induced a higher tumour rate than extracte d DS; (b) the carcinogenic potency of extracted CB probably depends on the size of the primary carbon particles and on the specific surface area of the particles; (c) extracted DS covered with 11 mu g BaP per m g carbon particles caused a lower lung tumour rate than original DS co ntaining only 0.9 ng BaP per mg, but a variety of other PAH and NO2-PA H; (d) a total dose of 15 mg pure BaP caused a lung tumour rate very s imilar to that of 30 mg extracted DS, 15 mg original DS or 15 mg Print er 90(TM) CB extracted or covered with approximately 29.5 mu g BaP per mg CB.