ceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape.

AEGL-3 is the airborne concentration (expressed as ppm or mg/m³) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life-threatening health effects or death.

Airborne concentrations below the AEGL-1 represent exposure levels that can produce mild and progressively increasing but transient and nondisabling odor, taste, and sensory irritation or certain asymptomatic nonsensory effects. With increasing airborne concentrations above each AEGL, there is a progressive increase in the likelihood of occurrence and the severity of effects described for each corresponding AEGL. Although the AEGL values represent threshold levels for the general public, including sensitive subpopulations, such as infants, children, the elderly, persons with asthma, and those with other illnesses, it is recognized that certain individuals, subject to unique or idiosyncratic responses, could experience the effects described at concentrations below the corresponding AEGL.

Iron pentacarbonyl is one of several iron carbonyls. It is formed by the interaction of carbon monoxide with finely divided iron. Iron pentacarbonyl is used in the manufacture of powdered iron cores for electronic components, as a catalyst and reagent in organic reactions, and as an antiknock agent in gasoline. Iron pentacarbonyl is pyrophoric in air (50 C auto ignition point), burning to ferric oxide.

Quantitative toxicity data and odor detection data for humans are unavailable. Qualitative descriptions of the signs and symptoms of iron pentacarbonyl exposure include giddiness and headache and occasionally dyspnea and vomiting. With the exception of dyspnea, these signs and symptoms are alleviated upon removal from exposure, but fever, cyanosis, and coughing may occur 12-36 h after exposure. This information could not be validated, and additional details were unavailable.

Animal data are limited to lethality findings in rats, mice, and rabbits. Based on the limited data available, the rat appears to be the most sensitive species as determined by the 30-min LC₅₀ of 118 ppm and a 4-h LC₅₀ of 10 ppm relative to the 30-min LC₅₀ of 285 ppm for the mouse. For mice a 1.35-fold increase in the LC₅₀ exposure concentration resulted in near 100% mortality for the same exposure duration, suggesting a steep exposure-response relationship for this species above the lethality threshold. Similarly, a 2.8-fold increase in exposure concentration (from 86 to 244 ppm) resulted in an increased mortality rate in rats from 4/12 to 11/12. No reproductive/developmental toxicity, genotoxicity, or carcinogenicity data are available for iron pentacarbonyl.