Benzo[a]pyrene site of contact mutagenicity in skin of Muta Mouse.

Benzo[a]pyrene (BP) has been investigated for the ability to induce mutation at the site of contact. Skin painting treatments with BP caused a time-dependent and statistically significant increase in mutation frequency (MF) in the treated areas of skin. The MF exceeded 500 x 10(-6) 21 days after either 1 x 25 or 5 x 5 micrograms treatments. Increases to > 700 x 10(-6) were seen when doses of 1 x 50 or 5 x 10 micrograms were used. Neither the liver nor the lung showed any increase in mutation frequency after 21 days in animals exposed to the 5 x 10 micrograms treatment regime. It is concluded that following topical administration, BP is able to induce mutation in the skin at the site of application, but not in either the lung or liver.