effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure.

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.

SUMMARY

Piperidine is a cyclic aliphatic amine (Eller et al. 2000). It is a clear, colorless, and flammable liquid that produces vapors that reach explosive concentrations at room temperature. Piperidine has a dissociation constant (pKb) of 2.88 and a pH of 12.6 (100 g/L, 20°C). Therefore, it is expected to be very corrosive. It has a strong pepper- or amine-like and pungent odor. Piperidine has many commercial uses, including use as a solvent, a curing agent for rubber and epoxy resins, an intermediate in organic synthesis, a food additive, and a constituent in the manufacturing of pharmaceuticals.

Daily exposure to piperidine is evidenced by its presence in the food supply and its excretion in human urine. It is a natural constituent in white and black pepper. Piperidine is formed naturally in the body from the degradation of lysine, cadaverine, and pipecolic acid. Exogenous piperidine is absorbed from the respiratory tract, gastrointestinal tract, and skin. It is found in most tissues of the body, including the brain, and is excreted as unchanged piperidine or its metabolites.

Studies in rats showed that nasal irritation and signs of ocular irritation occur at the lower concentrations of piperidine followed by corrosion around the nose and dyspnea at higher concentrations. Corneal damage, central nervous system (CNS) toxicity, and prostration occurred at the highest concentrations;



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