Provisional Advisory Levels (PALs) for acrylonitrile.

Application of Provisional Advisory Level (PAL) protocols was performed for acrylonitrile, as experimental data permitted. Three levels (PAL 1, PAL 2, and PAL 3), distinguished by severity of toxic effects, are developed for 24-hour, 30-day, 90-day, and 2-year durations of potential drinking water and inhalation exposures for the general public. For background on the PAL Program and a description of the methodology used in deriving PALs, the reader is referred to accompanying papers in this Supplement. Human data were limited to inhalation exposures. The animal experimental data set for this chemical was robust for inhalation and oral studies, with the exception of appropriate data for inhalation 30-day, 90-day, and 2-year PAL 3 values. PAL estimates were approved by the Expert Consultation Panel for Provisional Advisory Levels in October 2007. Oral 24-hour PALs for acrylonitrile are PAL 1 = 7 mg/L; PAL 2 = 23 mg/L; and PAL 3 = 88 mg/L. Oral 30-day and 90-day PALs are PAL 1 = 0.35 mg/L; PAL 2 = 7 mg/L; and PAL 3 = 17 mg/L. Oral 2-year PALs are PAL 1 = 0.35 mg/L; PAL 2 = 3.5 mg/L; and PAL 3 = 12 mg/L. Acrylonitrile inhalation PAL values for 24-hour exposure are PAL 1 = 0.17 ppm; PAL 2 = 3.5 ppm; and PAL 3 = 5.1 ppm; the 30-day and 90-day inhalation exposure values are PAL 1 = 0.15 ppm and PAL 2 = 0.60 ppm. The 2-year inhalation values are PAL 1 = 0.014 ppm and PAL 2 = 0.12 ppm. PAL 3 values for 30 days, 90 days, and 2 years are not recommended due to insufficient data.