36 ppm

19 ppm

13 ppm

5.7 ppm

5.7 ppm

Key Reference: Keplinger, M.L., and L.W. Suissa. 1968. Toxicity of fluorine short-term inhalation. Am. Ind. Hyg. Assoc. J. 29(1):10-18.

Test Species/Strain/Number: Swiss-Webster mice (sex not stated), 10/exposure group

Exposure Route/Concentrations/Durations:

Inhalation: 38, 79, 174, 300, 467, 600 ppm for 5 min

32, 65, 87, 188, 375 ppm for 15 min

16, 32, 67, 113, 225 ppm for 30 min

5, 30, 50, 75, 150 ppm for 1 h

Effects: The 1-h substudy using the mouse was considered

15 ppm: no toxic signs, no gross lung pathology

30 ppm: no toxic signs, very mild diffuse lung congestion (basis for AEGL-2)

50 ppm: labored breathing, mild diffuse lung congestion

75 ppm: irritation and labored breathing, severe diffuse lung congestion

150 ppm: LC50

End Point/Concentration/Rationale: 75 ppm for 1 h resulted in irritation and labored breathing and severe diffuse lung congestion in the mouse. No deaths occurred. Severe diffuse lung congestion was considered the threshold for lethality.

Uncertainty Factors/Rationale:

Total uncertainty factor: 3

Interspecies: 1 - The effects (lung congestion) as well as LC50 values reported in the study were very similar for the rat, rabbit, and guinea pig (indicating similar species sensitivity). With the exception of the 5-min LC50 for the rabbit, the LC50 values for all four species a t 15, 30, and 60 min were very similar. Thus, the concentration:end point did not differ greatly among species.

Intraspecies: 3 - Lung congestion at a specific concentration is not expected to differ greatly among individuals.

Modifying Factor: 2 - to account for a limited data base

Animal to Human Dosimetric Adjustment: Not applied.

Time Scaling: Cn × t = k where n = 1.77; based on regression analysis of the mouse (the most sensitive species) LC50 data from the study conducted at 5, 15, 30, and 60 min (Keplinger and Suissa 1968). The values were time scaled from the 1-h data. The 8-h value was set equal to the 4-h value as was done for the AEGL-2. The safety of setting the 8-h value equal to the 4-h value is supported by another study in which a 7-h exposure to 100 ppm resulted in an overall 60% mortality in four species (Eriksen 1945; Stockinger 1949). The time-scaled 7-h LC50 values from the key study for the mouse (50 ppm) and rat (65 ppm) are lower.

Data Adequacy: The key study was well conducted and documented, but there were limited confirming data from other laboratories.

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