10-min

30-min

1-h

4-h

8-h

 

44 ppm

27 ppm

14 ppm

2.6 ppm

1.5 ppm

 

Exposure route/Concentrations/Durations: Inhalation: see below for exposure times and concentrations.

Effects: Most deaths occurred by 4 days after exposure, and the animals had clear or slightly blood-tinged nasal exudate (rats that died within 1 day also had terminal convulsions); some had pulmonary congestion.

5-min ppm–mortality

10-min ppm–mortality

15-min ppm–mortality

30-min ppm–mortality

60 min ppm–mortality

240-min ppm–mortality

1,920 – 0/5

800 – 1/12

550 – 0/10

370 – 0/10

370 – 4/10

50 – 1/10

2,420 – 1/5

1,110 – 4/12

680 – 2/10

420 – 2/10

400 – 6/10

60 – 2/10

2,680 – 1/5

1,380 – 6/12

750 – 5/10

530 – 4/10

490 – 7/10

70 – 4/10

3,180 – 3/5

1,820 – 7/12

850 – 7/10

675 – 6/10

590 – 7/10

100 – 6/10

4,160 – 4/5

2,050 – 9/12

980 – 7/10

800 – 8/10

640 – 10/10

120 – 8/10

4,640 – 5/5

LC50 = 1480

1,090 – 8/10

890 – 9/10

LC50 = 391

200 – 9/10

LC50 = 3132

LC01 = 440

1,290 – 10/10

LC50 = 593

LC01 = 138

LC50 = 88

LC01 = 1492

 

LC50 = 809

LC01 = 268

 

LC01 = 26

 

 

LC01 = 419

 

 

 

End point/Concentration/Rationale: LC01 values, representing the NOEL for lethality, were obtained by probit analysis and used to obtain the 10-, 30-, 1-h, and 4-h AEGL-3 values. The 8-h values were derived from the 4-h LC01 by exponential time scaling and using n = 1.2.

Uncertainty factors/Rationale: Total uncertainty factor: 10

Interspecies: 3: Interspecies variability was small (LC50 values for rats, mice, and guinea pigs were within a factor of 2.5, and these studies yielded similar or higher AEGL-3 values).

Intraspecies: 3: Great human variability in unlikely given the homogeneity of the animal data, and a larger uncertainty factor yields 8-h AEGL-3 concentrations that caused only mild irritation in workers exposed for up to 8 h (Fannick 1982).

Modifying factor: None.

Animal to human dosimetric adjustment: Not applied

Time scaling: Performed only for 8-h time point by exponential scaling; i.e., Cn × t = k, where n = 1.2 was derived by ten Berge et al. (1986) from the Rinehart (1967) rat LC50 data.

Data adequacy: Database quality was considered adequate, and the key study was well conducted: 30-60 animals were tested per exposure time at five to seven crotonaldehyde concentrations, and a clear dose-response was obtained. Similar or higher AEGL-3 values could be obtained with mice, rats, and guinea pigs.



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