Photocarcinogenicity of 8-methoxypsoralen and aflatoxin B1 with longwave ultraviolet light

The carcinogenicity of 8-methoxypsoralen (8-MOP) and aflatoxin B1 (AFB1) with longwave ultraviolet light (UVA) to hairless mouse skin was investigated. Skin tumors were induced efficiently by 8-MOP + UVA, and the time to 50% tumor incidence was about 24 weeks. Histopathologically, some tumors were squamous cell carcinomas. AFB1 did not show any phototoxic and photocarcinogenic effects on mouse skin in this study. Although the structure and the photoreactivity of AFB1 to DNA were similar to those of 8-MOP, the photocarcinogenic response of these compounds to mouse skin was quite different.