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 concentrations that could 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 concentrations 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 idiosyncratic responses, could experience the effects described at concentrations below the corresponding AEGL.
Boron trifluoride-dimethyl ether is one of several different complexes that can be formed with boron trifluoride. The complexes are generally formed for ease of handling boron trifluoride. The ether complexes consist of a 1:1 molar ratio of boron trifluoride and the dimethyl or diethyl ether and can dissociate under the proper temperature and pressure conditions. A single study was found that addressed the toxicity of boron trifluoride-dimethyl ether, but it reported only nominal concentrations. Because the complex can dissociate to form boron trifluoride, the AEGL values are based on this one chemical species.
Boron trifluoride is a colorless gas with an odor described both as pungent and suffocating and as pleasant. Although the gas is stable in dry air, it immediately forms a dense white mist or cloud when exposed to moist air. Boron trifluoride reacts with moisture (even at low concentrations) to form the dihydrate, BF3•2H2O. Boron trifluoride dihydrate is strongly corrosive to the eyes and skin of rabbits. Boron trifluoride is an excellent catalyst, and has fire retardant and antioxidant properties, nuclear applications, and insecticidal properties.
No definitive data were available on the toxicity of inhaled boron trifluoride in humans. One study reported that a worker could detect the odor of boron trifluoride at a concentration of 4.1 mg/m3 (1.5 ppm) (Torkelson et al. 1961). Acute toxicity studies with dogs, rats, mice, and guinea pigs were available, but exposure concentrations were generally expressed only in terms of nominal concentrations. Studies that measured exposure concentrations and compared them with nominal concentrations found that actual concentrations