RESUMO
The Provisional Advisory Level (PAL) protocol was applied to estimate inhalation exposure limits for phosgene (CG). 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. Data on humans are limited to occupational exposures or accounts from the use of phosgene as a chemical warfare agent in World War I. Animal studies with phosgene show a steep dose-response curve for pulmonary edema and mortality, with little species variability in effects. Although immediately upon exposure lacrimation and upper respiratory irritation can occur, the main effect in the target organ, a progressive pulmonary edema, occurs after a latency period of 1-24 hours. PAL estimates were approved by the Expert Consultation Panel for Provisional Advisory Levels in May 2007. Exposure limits for oral exposure to CG are not developed due to insufficient data. PAL estimates for inhalation exposure to CG are presented: The 24-hour PAL values for severity levels 1, 2, and 3 are 0.0017, 0.0033 and 0.022 ppm, respectively. The 30- and 90-day PAL values are 0.0006 and 0.0012 ppm for the PAL 1 and 2 values, respectively. These inhalation values were also accepted as the 2-year PAL 1 and 2 values because severity of lesions in the key study did not increase when exposures were extended from 4 weeks to 12 weeks. Data were not available for deriving 30-day, 90-day, and 2-year PAL 3 values.