Tumorigenicity of fluoranthene in a newborn mouse lung adenoma bioassay

A 24 week lung adenoma bioassay using newborn mice was employed to determine the tumorigenicity of fluoranthene, a common environmental polynuclear aromatic hydrocarbon. A 6.5-fold elevation of lung tumor incidence (58%) and a 12-fold increase in numbers (1.08 tumors/mouse) was observed in animals treated with the highest dose (3.5 mg/mouse), but no increase in tumor incidence was induced by 700 micrograms/mouse. Benzo[a]pyrene, used as a positive control at a comparatively low dose (280 micrograms/mouse), was highly potent, inducing lung tumors in 94% of the animals and elevating their number by 44-fold (4.0 tumors/mouse). Most of the mice treated with the highest dose of benzo[a]pyrene (1.4 mg/mouse) died with massive injection site sarcomas. Male mice, surviving for 24 weeks in fluoranthene and benzo[a]pyrene treatment groups that developed lung tumors, had 2- to 3-fold more tumors than comparably treated females. This is the first reported evidence of tumorigenicity of fluoranthene. The significance of these findings in terms of bioassay sensitivity and the implications regarding human health have been discussed.