2-methylbutyraldehyde

Endpoint summary

Description of key information

The oral LD50 of 2-methylbutyraldehyde was determined to be 6880 mg/kg bw in male rats (Carpenter, 1974).
The inhalation LC50 of 2-methylbutyraldehyde was determined to be 50.5 mg/L in rats (Carpenter, 1974).
The dermal LD50 of 2-methylbutyraldehyde was determined to be 5400 mg/kg in male rabbits (Carpenter, 1974).

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

6 880 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

50 500 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

5 400 mg/kg bw

Additional information

For the assessment of the acute toxicity of 2-methylbutyraldehyde (2 -methylbutanal), only one valid study is available which covers all three exposure routes (Carpenter 1974). The data reported by Carpenter are based on the study conducted by Weil for Union Carbide Corporation (Weil, 1970).

 

Acute toxicity: oral

 

The acute oral toxicity of 2-methylbutyraldehyde was determined in groups of 5 male Carworth-Wistar rats receiving the test material by oral gavage at doses of 3.2, 6.4, 12.9, and 25.7 g/kg bw. The observation period was 14 days. The LD50 and a range of ± 1.96 SD was calculated according to the method of Thomson (1947). Overall, the study was conducted in accordance with the recently retracted OECD test guideline 401.

 

The acute oral LD50 was determined to be 6880 mg/kg bw in rats (Carpenter, 1974).

 

Acute toxicity: inhalation

 

For this acute inhalation toxicity study, a standard graduate dose test and an inhalation hazard test were performed. The observation period for both tests was 14 days.

 

Groups of six albino rats were exposed for 4 hours to 2-methylbutyraldehyde vapor in the breathing atmosphere of test animals at doses of 17.9, 35.8, and 71.6 mg/L.

 

In the inhalation hazard test, test animals were exposed for various time periods starting from several minutes up to 8 hours if appropriate (spacing factor of 2) to an atmosphere saturated or close to saturation with vapors of 2-methylbutyraldehyde. Actual atmosphere concentrations were not measured but can be estimated to be saturated or close to saturation by the method the atmosphere was generated.

 

In the inhalation hazard test (saturated vapor), the exposure time was restricted to 10 min in order to produce no mortality (LT50 = 14.1 min).

 

The LC50 for 2-methylbutyraldehyde was determined to be 50.5 mg/L in rats (Carpenter, 1974).

 

Standards of the OECD test guideline 403 (Acute Inhalation Toxicity) are only met with restrictions by this investigation (LC 50 value not statistically derived, only 6 rats used, no concentrations measured, deficiencies in reporting). The deviations from the test guideline are considered not to invalidate the result.

 

Acute toxicity: dermal

 

The acute dermal toxicity of 2-methylbutyraldehyde was determined in groups of 4 male albino New Zealand rabbits receiving doses of 3213, 6426, and 12853 mg/kg bw. The exposure time was 24 hours followed by an observation period of 14 days. From mortality data, the LD50 and a range of ± 1.96 SD was calculated according to the method of Thomson (1947).

 

The acute dermal LD50 for 2-methylbutyaldehyde was determined to be 5400 mg/kg bw in rabbits (Carpenter, 1974).

 

Overall, the study was conducted similar to OECD test guideline 402 with some restrictions (only 4 animals per group, occlusive wrapping, limited reporting). The deviations from the test guideline are considered not to invalidate the result.