Mutagenesis and skin tumour initiation by shale- and coal-derived oils and their distillation fractions

Abstract

Crudes and distillation fractions of three shale- and four coal-derived liquids and petroleum were screened for mutagenic activity in Salmonella typhimurium strains TA1535, TA1537, TA1538, TA98 and TA100, and for tumour initiating activity in mouse skin. Selected analytical tests were also conducted to identify and characterize the crudes and fractions. Low boiling (naphtha) fractions of all crudes showed no biological activity. The higher boiling fractions, the residues and the crude oils were mutagenic and initiated tumours. Some coal-derived liquid fractions were significantly more active by either test than similar boiling range fractions of petroleum and shale-derived oils. The mutation frequencies (revertants μg -1) as well as the total number of tumours were also related to the C/H weight ratios of the various fractions, supporting the view that aromatic compounds may be responsible for some of those activities. In most cases, the expression of mutagenic activity required an activation system, although a few fractions of shale- and coal-derived oils were weakly active without activation. In general, there was a strong positive relationship between the mutation data and the initiation-promotion data. Two linear relations were observed between the total number of skin tumours and the mutation frequencies in strains TA1538, TA98, TA1537 and TA100: one is associated with the medium boiling fractions while the other includes the residues and crude liquids.