Influence of acetaldehyde, dietary protein, carbon tetrachloride and butylatedhydroxytoluene on the toxicity of methylmercury in rats.

The influence of environmental or dietary factors on the toxicity of methylmercury (MeHg) was investigated due to possibilities that humans exposed to methylmercury may have been sensitized. Groups of 8 rats were exposed to 0, 20 or 40 ppm MeHg in a semisynthetic diet and fed 0.5% BHT, 5% protein (instead of 15%), or injected with 250 mg/kg CC14 or acetaldehyde. In control rats neurotoxicity occurred at 4 weeks and 9 weeks with 40 and 20 ppm MeHg, respectively. Mortality was observed at 6 weeks with 40 ppm and 1 rat died in week 9 with 20 ppm MeHg. Acetaldehyde injected rats died at week 4 and 6 when fed 40 or 20 ppm MeHg. Neurotoxicity was observed in week 3 and 5 in these groups, respectively. Treating rats with the low protein or BHT accelerated neurotoxicity and mortality by 1 week with 40 ppm MeHg. These agents had killed all test animals within 7 weeks at 20 ppm MeHg. Neither acetaldehyde nor BHT influenced 0 ppm MeHg controls while 5% protein induced precipitous weight loss. In the case of CC14, the rats lived longer in combination experiments than one would have expected from the individual treatments.