COAL TAR PHOTOTOXICITY: ACTIVE COMPOUNDS AND ACTION SPECTRA*

Eight compounds present in crude coal tar were tested for phototoxicity on guinea-pig skin. Four concentrations (5 μM to 5 mM) of each compound in ethanol were applied to the dorsal surface of 6 guinea-pigs. Each animal received 1.0 x 105 j/m2 of UVA radiation. The erythematous (phototoxic) response was evaluated after 20 h. Pyrene, anthracene and fluoranthene were strongly phototoxic. Acridine was markedly less phototoxic. Action spectra based on erythema as an endpoint were determined in guinea-pigs for anthracene, pyrene and fluoranthene. Each compound was applied to 5 animals which received irradiations from 274 to 502 nm in 12 nm bands for 3, 6, 9, 12 and 15 min. The maximum erythema response to anthracene was observed between 346 and 382 nm, to fluoranthene between 322 and 382 nm and to pyrene between 322 and 358 nm.