Clastogenic potential of heavy oil extracts and some aza-arenes in Chinese hamster cells in culture.

Chromosomal aberration tests in vitro, with a Chinese hamster fibroblast cell line, CHL, were carried out on B class heavy oil fractions, obtained by silica-gel column chromatography and a liquid-liquid extraction method. The original oil and basic nitrogen-containing fractions induced structural chromosomal aberrations in the CHL cells in the presence of rat-liver microsome fraction (S9 mix). 8 tricyclic or pentacyclic aza-arenes, which possibly exist in the positive fractions, were also examined for their clastogenic activities in the system with or without S9 mix. Acridine, benzo[f]quinoline, pyrenoline and pyrenoline 4,5-oxide induced chromosomal aberrations both with and without S9 mix. Benzo[h]quinoline was positive without S9 mix, whereas dibenz[c,h]acridine and dibenz[a,j]acridine were only positive with S9 mix. The results suggest that the clastogenic effects of the heavy oil may in part be due to the presence of nitrogen-containing polycyclic hydrocarbons such as aza-arenes.