sensory 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 levels 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 AEGLs 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 idiosyncratic responses, could experience the effects described at concentrations below the corresponding AEGL.

SUMMARY

Phosphorus oxychloride is a colorless fuming liquid with a pungent odor. It is stable to over 300°C but is highly reactive with water yielding phosphoric acid and hydrogen chloride. It is used in the manufacture of plasticizers, hydraulic fluids, gasoline additives, fire-retarding agents, and in the manufacture of alkyl and aryl orthophosphate trimesters.

Information regarding exposure of humans to phosphorus oxychloride are qualitative reports that indicate notable dermal, ocular, pharyngeal, and pulmonary irritation following acute and subchronic (intermittent) exposures. Most reports lacked exposure concentrations, with the exception of one report of occupational exposure to phosphorus oxychloride of 1.6-11.2 ppm. Effects often persisted after cessation of exposure, especially in individuals experiencing more severe effects. Neither odor detection data nor lethality data are available for humans.

Quantitative data in animals are limited to reports of lethality. These data include a 4-h LC50 (concentration lethal to 50% of test animals) of 44.4 ppm for rats and 52.5 ppm for guinea pigs, and an unverified 4-h LC50 of 32 ppm for rats. A 5-15 min exposure of rats and guinea pigs to phosphorus oxychloride at 0.96 ppm was stated to be a “threshold response” in one report. A brief report from industry indicated immediate adverse responses (at 2 min) and death (18 min) after exposure to a very high concentration (25,462 ppm). The studies affirm the extreme irritation properties of phosphorus oxychloride, although the exposures



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