[3] Since MeAN is present in polymeric coating materials as found in many everyday use items, humans are exposed to it by skin absorption.

Aside from this there is an occupational exposure, and low levels of MeAN are also present in the smoke of unfiltered cigarettes made from air-cured or flue-cured tobaccos.

[4] Due to the toxicity of MeAN, the U.S. Department of Health & Human Services has limited the concentration of methacrylonitrile-derived polymer in resinous and polymeric coating materials to 41%.

Its use in food packaging is further limited to 0.5 mg per square inch of food-contact surface, and only 50 ppm, or 0.005% MeAN is permitted in chloroform-soluble coating components in water containers (21 CFR, § 175.300).

A time-weighted average (TWA) threshold limit value of 1 ppm (3 mg/m3) for MeAN exposure was adopted by the American Conference of Governmental Industrial Hygienists.

The extra methyl group of MeAN lessens the electron-withdrawing effect caused by the nitrile so that reactions that form negative charge on the alpha carbon are faster with AN as the reactant.

[7][5] MeAN can undergo electropolymerization, if it is submitted to electroreduction at metallic cathodes in an organic anhydrous medium, for example; acetonitrile.

For example, via epoxide hydratase (EH) or via interactions with a sulfhydryl compound, which leads to the formation of a cyanohydrin that could rearrange to an aldehyde and thereby can possibly result in cyanide release.

[10][11] It has been shown that treatment of mice with carbon tetrachloride, which acts on the mixed function oxygenase system, results in much lower cyanide concentrations than controls and greatly reduced toxicity of MeAN, indicating that cyanide production is indeed the main pathway of toxicity, unlike AN, which is more carcinogenic.

[12] Inhalation, and oral and dermal administration, of methacrylonitrile can cause acute deaths in animals, often preceded by convulsions and loss of consciousness.

Signs of the toxic effects of methacrylonitrile in rats after oral absorption are ataxia, trembling, convulsions, mild diarrhea and irregular breathing.

The main cause of toxic effects at lethal (and threshold) levels of MeAN is damage to the central nervous system.

This is based on another sign of methacrylonitrile poisoning; urine retention, with 58% of rats showing bladder distention at an administered dose of 100 mg/kg.