Cytogenetic studies of three triazine herbicides II. In vivo micronucleus studies in mouse bone marrow

Atrazine, simazine, and cyanazine are widely used preemergence and postemer gence triazine herbicides that have made their way into the potable water s upply of many agricultural communities. Although there are several contradi ctory genotoxicity studies in the literature, our previous in vitro studies with human lymphocytes showed that atrazine, simazine, and cyanazine did n ot induce sister chromatid exchanges (SCEs) or chromosome aberrations (CAs) up to the limits of solubility in aqueous medium using 0.5% dimethyl sulfo xide. To expand upon these results and to ensure that our in vitro findings could be replicated in an in vivo system, mice were treated with each tria zine by two intraperitoneal injections, 24 h apart. The animals were sacrif iced and the bone marrow removed for micronucleus (MN) analysis, 24h after the last injection. Two to four independent trials were performed for MN an alysis in polychromatic erythrocytes, and in some trials the spleen was rem oved, cultured, and analyzed for SCEs and CAs. None of the triazines invest igated induced MN in the bone marrow, even at doses that caused significant bone marrow suppression and/or death. These results indicate that atrazine , simazine, and cyanazine are not genotoxic as measured by the bone marrow MN assay in mice following high dose exposures. Published by Elsevier Scien ce B.V.