The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 2
AEGL-3
10 min
30 min
1 h
4 h
8 h
3.6 ppm
1.5 ppm
0.75 ppm
0.20 ppm
0.09 ppm
Reference:
Zwart, A. et al. 1990. Determination of concentration-time-mortality relationships to replace LC50 values. Inhalation Toxicol. 2:105–117.
Test species/Strain/Sex/Number: Wistar rats/5 males and 5 females
Exposure route/Concentrations/Durations: Rats/Inhalation: 12, 15, 16, 17, or 24 ppm for 30 min (the highest concentration causing no mortality in the rat after a 30-min exposure of 15 ppm was determinant for AEGL-3)
Effects:
Concentration
Mortality
12 ppm
0/10
15 ppm
0/10
16 ppm
1/10
17 ppm
5/10
24 ppm
9/10
End point/Concentration/Rationale: The highest concentration causing no mortality in the rat after a 30-min exposure 30-min experimental no-effect-level for death (15 ppm) was used as a threshold for death in rats for the 30-min, 1-, 4-, and 8-h values. The highest concentration causing no mortality in the rat after a 10-min exposure (36 ppm) was utilized for the 10-min value.
Uncertainty Factors/Rationale:
Total uncertainty factor: 10
Interspecies: 3—little species variability is observed with both lethal and nonlethal end points in many studies after exposure to phosgene
Intraspecies: 3—due to the steep concentration-response curve and effects appear to be due to irritation and binding to macromolecules are not expected to differ greatly among individuals .
Modifying factor: Not applicable
Animal to human dosimetric adjustment: Insufficient data
Time scaling: Cn×t=k where n=1. Haber’s Law (C×t=k) has been shown to be valid for phosgene within certain limits (EPA 1986). Haber’s Law was originally derived from phosgene data (Haber 1924). Reported 30-min data point used to determine the 30-min AEGL value. AEGL-3 values for 1-, 4-, and 8-h were based on extrapolation from the 30 min value. The 10-min value was based on a reported 10-min data point.
Data adequacy: The AEGL-3 values are based on a well-conducted study in rats and the database is rich.
