Covalent binding of benzo[a]pyrene to dna in fish liver

Benzoa]pyrene became bound to the hepatic DNA in juvenile English sole ($\text{Parophrys vetulus}$) force fed tritiated benzoa]pyrene. No statistically signïficant change was observed in the level of the binding from 16 h to 2 wk after the single exposure. Specific activities of binding were similar for both DNA and protein. Moreover, a binding index was calculated to represent the number of benzoa]pyrene molecules bound per 10⁶ nucleotides after administration of a theoretical dose of 1 mmole of hydrocarbon per kg body weight. The value for English sole liver DNA was of the same order of magnitude as the values reported for mouse skin and mammary gland in which benzoa]pyrene is carcinogenic.