Key studies:

Rotman et al. 1983; D’Alessandro et al. 1996; Shusterman et al. 1998

Toxicity end point:

Transient pulmonary function changes in atopic individual exposed at 0.5 ppm for an interrupted 8 h; non-significant changes in pulmonary peak air flow in eight atopic individuals exposed at 0.5 ppm for 15 min; no statistically significant pulmonary parameter changes in asthmatic subjects exposed at 0.4 ppm for 1 h

Time-scaling:

No time scaling; because there is adaptation to the slight irritation that defines the AEGL-1 end point, the same value (0.5 ppm) was used across all time points

Uncertainty factors:

1, because susceptible individuals were tested and one of the susceptible individuals was exercising, making him more susceptible to sensory irritation (no-effect level in healthy exercising individuals of both genders)

Calculations:

Because the 0.5 ppm concentration was indicative of a NOAEL for more serious pulmonary changes, the 0.5 ppm concentration was used for all exposure durations. The susceptible individual underwent an interrupted 8-h exposure at 0.5 ppm without increased symptoms, so that concentration was also used for the 8-h AEGL-1