2-methylbutyraldehyde

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions (no concentrations and particle size distribution measured, only 6 rats used, sex not specified, reporting not according to test guideline)

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Unnamed

Year:

1974

Report date:

1974

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

1970

Report date:

1970

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

: no concentrations and particle size distribution measured, only 6 rats used, sex not specified, reporting not according to test guideline

Principles of method if other than guideline:

Pre-guideline study, but method is similar to OECD TG 403. A test with graduate doses (standard test) and an inhalation hazard test were performed.

GLP compliance:

no

Remarks:

pre-GLP study

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-methylbutyraldehyde

EC Number:

202-485-6

EC Name:

2-methylbutyraldehyde

Cas Number:

96-17-3

Molecular formula:

C5H10O

IUPAC Name:

2-methylbutanal

Details on test material:

- Name of test material (as cited in study report): 2-Methylbutyraldehyde
- no further information on test substance

Test animals

Species:

rat

Strain:

other: Albino

Sex:

not specified

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: own breeding facility
- Age at study initiation: 4 to 5 weeks
- Weight at study initiation: 90 to 120 g
- Fasting period before study: no
- Housing: no data
- Diet (e.g. ad libitum): Rockland rat diet, complete, ad libitum
- Water (e.g. ad libitum): ad libitum

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

Test with graduate doses (standard test)
Test atmosphere was generated using a suitable proportioning pump by injecting definite amounts of test substance at a constant rate inside of a spirally corrugated surface of a minimally heated one inch Pyrex tube through which metered air is passed.
Inhalation hazard test
Test atmosphere was generated by passing a stream of dried air at 2.5 L/min at room temperature through a fritted glass disc immersed to a depth of at least 1 inch in approximately 50 mL of the test substance contained in a gas washing bottle. Six male or female albino rats were exposed for different exposure times to this atmosphere (flowing stream of air saturated or close to saturation with vapour).

Analytical verification of test atmosphere concentrations:

no

Duration of exposure:

4 h

Remarks on duration:

test with graduate doses

Concentrations:

Standard test
5000, 10000, and 20000 ppm ( 17.9, 35.8, and 71.6 mg/L), doses were spaced in a logarithmic series with a factor of 2.
For the inhalation hazard test, the test atmosphere was saturated or close to saturation with test substance vapor as indicated by the generation method of test atmosphere

No. of animals per sex per dose:

six male or female animals per dose

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: no data
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other: no data

Statistics:

LC50 is calculated by the moving average method based on a 14-day observation period.

Results and discussion

Effect levels

Sex:

not specified

Dose descriptor:

LC50

Effect level:

50.5 mg/L air (nominal)

95% CL:

39 - 65.5

Exp. duration:

4 h

Remarks on result:

other: LC50 value calculated from the reported value of 14,100 ppm

Mortality:

Standard Test: Concentration Mortality
71.6 mg/L 6 / 6
35.8 mg/L 0 / 6
17.9 mg/L 0 / 6
Inhalation Hazard Tests: Maximum exposure time for no death: 10 min (LT50 = 14.1 min)

Clinical signs:

other: 71.6 mg/L: loss of coordination by 4 min; poor coordination by 12 and prostrate by 60 min 35.8 mg/L: as above but prostrate at 2.5 h 17.9 mg/L: slight loss of coordination at 20 min

Gross pathology:

No special findings

Any other information on results incl. tables

Reported data (ppm) are converted to mg/L using a conversion factor of 3.58.

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Exposure to 2-methylbutyraldehyde vapors in air at concentrations of 17.9, 35.8 and 71.6 mg/L for 4 hours resulted in the death of 0, 0 and 6 out of 6 animals respectively (observation period 14 days). From this data, a LC50 of ca. 50,5 mg/L is calculated.

Executive summary:

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 graduate doses of 2-methylbutyraldehyde (2-methylbutanal) vapor in the breathing atmosphere of test animals. Doses were spaced in a logarithmic series with a factor of 2 (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 standard test, concentrations of 5,000, 10,000 and 20,000 ppm (ca. 17.9, 35.8 and 71.6 mg/L) caused a mortality of 0, 0, and 6 out of 6 animals, respectively. From this data, a LC50 of 50.5 mg/L is calculated.

 

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 (no concentrations and particle size distribution measured, only 6 rats used, sex not specified, reporting not according to test guideline). But the results are estimated to be sufficiently valid to assess the acute inhalation toxicity potential of 2-methylbutanal.