Toxicological studies on MX, a disinfection by-product

MX may be the most important single mutagen so far identified in chlorine-disinfected waters. The objective of these studies was to determine the toxicity of MX to mammals by repeatedly administering varying dosages of the compound to B6C3FI mice and Fischer rats. Toxicity was evidenced in rats by decreased food and water consumption--and decreased body weight gain at a high MX dosage. Similar weight loss was observed in male mice at MX dosages of 8, 16, and 64 mg/kg body weight. Based on these decreased body weight gains, the presence of stomach lesions, and other changes, 8 mg/kg was considered to be the lowest adverse effect level for oral exposure to MX for 14 days in mice and rats. Additional research is required to elucidate the effect of MX in drinking water on human health.