DNA binding of methyl iodide in male and female F344 rats.

The genotoxic potency of methyl iodide was investigated in a DNA binding study. Male and female F344 rats were exposed to 14C-labelled methyl iodide orally or by inhalation in a closed exposure system. DNA adducts were detected in the liver, lung, stomach and forestomach of the exposed animals. [14C]3-Methyladenine, [14C]7-methylguanine and [14C]O6-methylguanine could be identified by a combination of three different methods of hydrolysing DNA and subsequent HPLC or GC/MS analysis. The highest values of methylated guanines were determined in the stomach and forestomach of the animals following both oral and inhalative exposure. These results demonstrate a systemic genotoxic effect of methyl iodide.