AEGL-2 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 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 susceptible subpopulations, such as infants, children, the elderly, persons with asthma, and those with other illnesses, it is recognized that individuals, subject to unique or idiosyncratic responses, could experience the effects described at concentrations below the corresponding AEGL.
Crotonaldehyde is a colorless, flammable liquid and a potent eye, skin, and respiratory irritant. Inhaled crotonaldehyde can cause a burning sensation in the nasal and upper respiratory tract, lacrimation, coughing, bronchoconstriction, pulmonary edema, and deep lung damage. Crotonaldehyde is used primarily for the manufacture of sorbic acid and other organic chemicals. It is found in tobacco smoke and is a combustion product of diesel engines and wood but also occurs naturally in meat, fish, and many fruits and vegetables.
Crotonaldehyde exists as the cis and the trans isomer; commercial crotonaldehyde is a mixture of the two isomers consisting of >95% trans isomer. Because no in vivo exposure studies were located for the individual isomers (information was for the commercial mixture), the AEGL values in this document apply to both trans-crotonaldehyde (123-73-9) and the cis-trans mixture (4170-30-3).
AEGL-1 values were derived from a Health Hazard Evaluation conducted by National Institute for Occupational Safety and Health (NIOSH) in which workers exposed to approximately 0.56 ppm of crotonaldehyde for <8h reported occasional minor eye irritation (Fannick 1982). The same exposure concentration was adopted for 10 min to 8 h because the critical end point (minor eye irritation in humans) was mild and mild irritant effects do not vary greatly over time. A total uncertainty factor of 3 was applied to account for intraspecies variability, because the eye irritation is a direct surface-contact effect not subject to pharmacokinetic differences between individuals.