Testing of p-dichlorobenzene and hexachlorobenzene for their ability to induce DNA damage and micronucleus formation in primary cultures of rat and human hepatocytes.

The genotoxicity of p-dichlorobenzene (DCB) and hexachlorobenzene (HCB) was evaluated in primary cultures of rat and human hepatocytes. DNA fragmentation was measured by the alkaline elution technique and clastogenic activity by the increase in micronucleus formation. In rat hepatocytes, exposure to concentrations of DCB ranging from 0.56 to 3.2 mM and of HCB from 0.1 to 0.56 mM did not induce any significant increase in the frequency of DNA breaks but consistently produced a statistically significant increase in the frequency of micronucleated cells. In human hepatocytes, under the same experimental conditions, the response to DCB was negative in terms of both DNA fragmentation and clastogenic effect, whereas HCB produced a significant increase in the frequency of both DNA breaks and micronuclei. Taken as a whole these results suggest that of the two pesticides examined only HCB should be considered as a weak genotoxic carcinogen.