(ClO2). The toxic effects of ClF3 are due, at least in part, to the actions of HF and ClO2.

Chlorine trifluoride is a potent, rapidly-acting mucous membrane irritant. Skin and eye contact with ClF3 produces burns and inhalation causes acute pulmonary irritation and edema. Inhalation studies with the monkey, dog, rat, and mouse for several end points and exposure durations have been performed. Data on irritant effects were available for the dog and rat; data on sublethal and lethal concentrations were available for the monkey, rat, and mouse. One report of a very brief (1-2 min) human exposure was located, but no data on exposure concentrations were available. The data were considered adequate for derivation of the three AEGL classifications for five exposure periods. Regression analyses of the reported concentration-exposure durations for lethality for the animal species determined that the relationship between concentration and time is C1.3 × t = k.

The AEGL-1 was based on slight irritation as evidenced by rhinorrhea (nasal discharge) observed in two of two dogs during the first 3 h of a 6-h exposure to an average concentration of 1.17 ppm (Horn and Weir 1956). Nasal discharge in response to an irritant gas in the sensitive nose of dogs was considered a NOAEL for the AEGL-1. No signs were observed in 20 rats exposed to this concentration for 6 h. Exposure of the dogs for longer than 3 h resulted in obvious lacrimation. Repeated, daily exposures of rats and dogs to 1.17 ppm resulted in severe signs of irritation. The rhinorrhea in dogs exposed for 3 h was considered an appropriate end point for development of the AEGL-1. Exposure to 1.17 ppm for 3 h was extrapolated using a combined interspecies and intraspecies uncertainty factor of 10 (3 for interspecies differences [the dog was more sensitive than the rat] and 3 for intraspecies differences in sensitivity [slight irritation should occur at a similar level among the general population]). Time-scaling was not applied to the AEGL-1 as adaptation to slight sensory irritation occurs. Therefore, the calculated value of 0.12 ppm was adopted for all AEGL-1 time points. The 0.12 ppm value is similar to the ClO2 AEGL-1 of 0.15 ppm and is one-eighth of the HF AEGL-1 value of 1.0 ppm. Application of an intraspecies factor of 3 is sufficient, since application of a larger factor would result in AEGL-1 values that are not consistent with those of ClO2 and HF, two of the major decomposition products of ClF3 (breakdown of one mole of ClF3 potentially forms three moles of HF and one mole of ClO2).

The AEGL-2 was based on signs of irritation (salivation, lacrima-



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