Light-dependent toxicity of α-terthienyl and anthracene toward late embryonic stages ofRana pipiens.

Alpha-terthienyl is toxic to late embryonic stages ofRana pipiens in the presence of sunlight. Neither α-terthienyl alone in the dark nor a previously photolyzed solution of α-terthienyl has comparable activity. The LC50 was 0.11 ppm with 30 min of exposure and 0.018 ppm with 2 hr of exposure to sunlight. Anthracene, a representative example of polycyclic aromatic hydrocarbons widely distributed in the environment, also showed similar phototoxicity, with an LC50 of 0.065 ppm after 30 min of exposure and 0.025 ppm after 5 hr.