10 min 30 min 1 h 4 h 8 h
370 ppm (1,295 mg/m3) 180 ppm (630 mg/m3) 110 ppm (385 mg/m3) 45 ppm (158 mg/m3) 28 ppm (98 mg/m3)
Reference: BASF. 1980. Determination of the Acute Inhalation Toxicity LC50 of Piperidine as Vapor in Sprague-Dawley Rats After a 4-h Exposure. BASF Gewerbehygiene und Toxikologie.
Test species/Strain/Number: Rats, Sprague-Dawley, 10 of each sex
Exposure route/Concentration/Durations: Inhalation; 290, 810, 1,190, 1,540, and 2,190 ppm; 4 h (single exposure)
290 ppm: No deaths; nasal and ocular irritation.
810 ppm: One of 20 rats died; nasal and ocular irritation, corrosion around the nose (1 rat), and dyspnea.
1,190 ppm: 10 of 20 rats died; nasal and ocular irritation, corneal damage, corrosion around the nose, dyspnea, and CNS toxicity.
1,540 ppm: seven of 20 rats died; prostration and same effects noted at 1,190 ppm
2,190 ppm: 20 of 20 rats died; effects same as at 1,540 ppm
End point/Concentration/Rationale: Lethality threshold (LC01) for piperidine is 448 ppm. That concentration is lower than the lowest concentration (810 ppm) where one of 20 rats died and had signs of dyspnea, which could be associated with death, and is greater than the highest concentration (290 ppm) that caused no deaths or clinical moribund signs.
Uncertainty factors/Rationale:
Total uncertainty factor: 10
Interspecies: 3, because the linear correlation coefficient for the concentration vs. time relationship for LC50 values for three species is -0.96 and the concentrationtime relationships are similar, not varying by more than 30%, indicating the response is similar among the three species.
Intraspecies: 3, because a factor of 10 would produce AEGL values for the 4- and 8-h durations that are lower than the irritation threshold.
Modifying factor: None
Animal-to-human dosimetric adjustment: None
Time scaling: Cn × t = k; n = 1.5 based on regression analysis of LC50 values for the rat exposed for 4 h, the mouse exposed for 2 h, and the guinea pig exposed for 1 h.
Confidence and support of AEGL values: Time scaling was based on LC50 values of three different species. The acute inhalation study was conducted according to standard protocol and showed a reasonable concentration-response relationship for lethality and a clear concentration-response relationship for severity of clinical signs. The LC01 was a good approximation of the lethality threshold; therefore, the AEGL-3 values should be within the limits that would protect humans from lethal exposure to piperidine vapor.

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