Effect of antidotes of the acute toxicity of methacrylonitrile.

When rats were exposed for 30 min to methacrylonitrile at concentrations between 3180 and 5700 ppm, the clinical symptoms observed suggested a toxic activity of metabolically formed cyanide. This is in contrast to the signs of toxicity observed in the same species after inhalation of acrylonitrile where metabolic cyanide formation plays only a minor role. The acute toxicity of methacrylonitrile could be antagonized with cyanide antidotes (4-dimethylaminophenol plus sodium thiosulfate) as well as with N-acetyl-cysteine which directly reacts with alpha,beta-unsaturated nitriles.