VOL.: 35 (1985) (p. 39)
Blended or fluxed bitumens, which represent a relatively small percentage of the total usage, may contain aromatic oils, thermally-cracked petroleum residues or coal-tar products, which contain polynuclear aromatic compounds.
When air-refined (oxidized) bitumens were applied to the skin of mice, no tumour was found with undiluted bitumens; but, in one experiment, an air-refined bitumen in solvent (toluene) produced topical skin tumours.
Two cracking-residue bitumens produced skin tumours when applied to the skin of mice.
A pooled mixture of steam- and air-blown petroleum bitumens in benzene produced tumours at the site of application on the skin of mice.
One sample of heated, air-refined bitumen injected subcutaneously into mice produced a few sarcomas at the injection sites.
A pooled mixture of steam- and air-blown petroleum bitumens produced sarcomas at the site of subcutaneous injection in mice. Steam-distilled bitumens injected intramuscularly produced local sarcomas in one experiment in rats.
Both an extract of road-surfacing bitumen and its emissions were mutagenic to Salmonella typhimurium.
Subsequent to the meeting of the Working Group, the Secretariat became aware of a study showing that solutions of the fumes from two types of roofing bitumens, generated at 232 °C or 316 °C, produced skin tumours when applied topically to mice (Thayer et al., 1983).
There is limited evidence for the carcinogenicity of undiluted steam-refined bitumens and for cracking-residue bitumens in experimental animals.
There is inadequate evidence for the carcinogenicity of undiluted air-refined bitumens in experimental animals.
There is inadequate evidence that bitumens alone are carcinogenic to humans.
For definition of the italicized terms, see Preamble Evaluation.
Subsequent evaluation: Suppl. 7 (1987)
See Also: Toxicological Abbreviations Bitumens (IARC Summary & Evaluation, Supplement7, 1987)