Abstract
Single-dose rabbit dermal and rat intragastric studies indicate that methacrylonitrile is highly toxic by both routes. The LG50 values for single four-hour inhalation periods varied from 700 ppm of the vapor for female rats to 36 ppm for male mice. Methacrylonitrile formed cyanide ion in the blood of rats and rabbits and its effects were diminished by the standard therapy for cyanide intoxication. Human sensory response studies showed that the vapor has very poor warning properties. The response of rats and dogs to repeated 7-hour exposures of methacrylonitrile vapor for 91 and 90 days respectively, suggest that humans should not be allowed to inhale more than three ppm vapor for eight hours per day, five days per week. It should be emphasized that this “Hygienic Standard,” is an estimate based on experimental data and therefore is subject to modification as data are gathered on human experience.