Provisional Advisory Levels (PALs) for phosgene (CG)

Area of Science:

• Environmental Health
• Toxicology
• Risk Assessment

Background:

• Phosgene (CG) is a toxic industrial chemical and chemical warfare agent.
• Human data on phosgene exposure is limited, primarily from occupational settings and historical warfare accounts.
• Animal studies reveal a steep dose-response for pulmonary edema and mortality, with minimal species variation.

Purpose of the Study:

• To establish Provisional Advisory Levels (PALs) for inhalation exposure to phosgene (CG).
• To develop exposure limits for different durations (24-hour, 30-day, 90-day, 2-year) and severity levels (PAL 1, 2, 3).
• To provide public health guidance for potential phosgene exposure scenarios.

Main Methods:

• Application of the Provisional Advisory Level (PAL) protocol.
• Utilized data from animal studies demonstrating phosgene's toxic effects, particularly pulmonary edema.
• Extrapolated findings to establish exposure limits for various durations and severity levels.

Main Results:

• Developed 24-hour PAL values for phosgene inhalation: 0.0017 ppm (PAL 1), 0.0033 ppm (PAL 2), and 0.022 ppm (PAL 3).
• Established 30- and 90-day PAL values: 0.0006 ppm (PAL 1) and 0.0012 ppm (PAL 2).
• The 2-year PAL 1 and 2 values were set equal to the 90-day values due to lack of increased lesion severity.

Conclusions:

• The Expert Consultation Panel approved the PAL estimates in May 2007.
• Inhalation exposure limits for phosgene (CG) were successfully derived for public health protection.
• Sufficient data for oral exposure limits or PAL 3 values for longer durations were unavailable.