Isobutyraldehyde

Endpoint summary

Description of key information

The LD50 for acute oral toxicity was determined to be 3730 mg/kg bw.
The LC50 for acute inhalation toxicity was determined to be above 23.6 mg/L air after a 4 hour exposure.
The LD50 for acute dermal toxicity was determined to be 5583 mg/kg bw.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Principles of method if other than guideline:

Five female Carworth Wistar per dose were exposed to the test substance. Based upon mortalities during a 14-day observation period, the most probable LD50 value and its fiducial range are estimated by the method of Thompson using the tables of Weil.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

other: Carworth Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Mellon Institute of Industrial Research, University of Pittsburg
- Age at study initiation: 5-6 weeks
- Weight at study initiation: 90 – 120 g
- Fasting period before study: not performed
- Diet: Rockland rat diet

Route of administration:

oral: gavage

Vehicle:

other: 1% solution of sodium 3,9-diethyl-6-tridecanol sulfate (Tergitol Penetrant 7)

Details on oral exposure:

Administered as a 20% aqueous dispersion in 1% Tergitol Penetrant 7

Doses:

2000, 3980, 7950 mg/kg

No. of animals per sex per dose:

5

Control animals:

not specified

Details on study design:

Duration of observation period following administration: 14 days

Statistics:

LD50 and its fiducial range are estimated by the method of Thompson using the tables of Weil.

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

3 730 mg/kg bw

Based on:

test mat.

95% CL:

2 680 - 5 210

Gross pathology:

Severe gastrointestinal tract necrosis was observed. The liver, spleen and kidneys were also necrosed where they contacted the stomach wall. Lungs wer markedly congested or hemorrhagic.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

3 730 mg/kg bw

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Principles of method if other than guideline:

Inhalation of known vapor concentrations by rats is conducted with flowing streams of vapors prepared by various styles of proportioning pumps . Nominal concentrations are recorded and not confirmed by analytical methods. Exposures are four hours long. Concentrations are in an essentially logarithmic series with a factor of two. The concentration yielding fractional mortality among six rats within 14 days was reported. Where no fractional mortality was observed, both the concentration yielding no mortality and that yielding complete mortality are indicated.

GLP compliance:

no

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

not specified

Sex:

male

Route of administration:

inhalation: vapour

Type of inhalation exposure:

not specified

Vehicle:

air

Details on inhalation exposure:

Inhalation of know vapor concentrations by rats is conducted with flowing streams of vapors prepared by various styles of proportioning pumps.

Analytical verification of test atmosphere concentrations:

no

Duration of exposure:

4 h

Concentrations:

8000 and 16000 ppm

No. of animals per sex per dose:

6

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days

Sex:

female

Dose descriptor:

LC50

Effect level:

> 23.6 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: 1/6 animals died (8000 ppm)

Mortality:

8000 ppm: Mortality (one animal of six animals) occurred after exposure for 4 hours within 14 days.
16000 ppm: All animals died

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

discriminating conc.

Value:

23 600 mg/m³ air

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Penetration of rabbit skin is estimated by a technique closely to the one-day cuff method of Draize and associates (Draize, J.H. et al.: J. Pharmacol. Exp. Therap. 82, 377, 1944), using groups of four male rabbits. The fur is removed from the entire trunk by clipping, and the dose is retained beneath an impervious plastic film. Animals were observed for 14 days.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rabbit

Strain:

New Zealand White

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 3-5 months
- Weight at study initiation: average 2.5 – 3.5 kg
- Diet: Rockland rabbit ration

Type of coverage:

occlusive

Vehicle:

not specified

Details on dermal exposure:

Penetration of rabbit skin is estimated by a technique closely to the one-day cuff method of Draize and associates, using groups of four male rabbits weighing. The fur is removed from the entire trunk by clipping, and the dose is retained beneath an impervious plastic film. The animals are immobilized during the 24-hour contact period, after which the film is removed and the rabbits are caged for the subsequent 14-day observation period.

Duration of exposure:

24 h

Doses:

5, 10 mL/kg

No. of animals per sex per dose:

2 (low dose), 4 (high dose)

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days

Statistics:

Thompson's method was used for calculating the LD50.

Sex:

male

Dose descriptor:

LD50

Effect level:

ca. 7.13 mL/kg bw

Based on:

test mat.

Remarks on result:

other: original value

Sex:

male

Dose descriptor:

LD50

Effect level:

5 583 mg/kg bw

Based on:

test mat.

Remarks on result:

other: density used for conversion: 0.783 g/cm3

Mortality:

Four animals dosed at 10 mL/kg died
The 2 animals dosed at 5 mL/kg survived.

Clinical signs:

other: erythema, edema and necrosis of the skin at the site of contact, with congestion and hemorrhage of the lungs in rabbits dying on study.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

5 583 mg/kg bw

Additional information

Acute toxicity: oral

Smyth et al. (1954) reported an oral toxicity study in which five female Carworth Wistar per dose were exposed to the test substance. Based upon mortalities during a 14-day observation period, the most probable LD50 value and its fiducial range are estimated by the method of Thompson using the tables of Weil. Animals were exposed to 2000, 3980 and 7950 mg/kg bw dissolved in 1% solution of sodium 3,9-diethyl-6-tridecanol sulfate (Tergitol Penetrant 7). Severe gastrointestinal tract necrosis was observed. The liver, spleen and kidneys were necrotic at the parts where they contacted the stomach wall. Lungs were markedly congested or hemorrhagic. The LD50 was determined to be 3730 (2680 – 5210) mg/kg bw. This is supported by the LD50 value cited in Industrial hygiene and toxicology (Fassett, 1962), which was between 1600 and 3200mg/kg in rats. No further information was provided.

Acute toxicity: inhalation

Smyth et al. (1954) reported an inhalation toxicity study, in which 6 male rats were exposed to 8000 ppm and 16000 ppm of the test substance for 4 hours. Animals were observed for 14 days. 1 of the 6 animals died at the lower concentration, while all animals died after exposure to 16000ppm. The LC50 was determined to be above 8000 ppm, which is equivalent to 23.6 mg/L. This value is supported by a Russian publication (Solotov 1972), in which the LC50 for mice is given as 39.5mg/L after exposure for 2h.

In an inhalation hazard test (BASF 1958) performed according to BASF-internal standards, three groups of 6 rats, were exposed to a saturated atmosphere of the test substance for 2, 8, and 30 min. Mortality in each group was recorded and surviving rates were observed for another 14 days. After 2 min exposure, no mortality occurred. After 8 min exposure 3/6 animals died and after 30 min exposure all animals died (death occurred 8-17 minutes after the start of exposure). Based on a vapour pressure of 230.65 hPa, the saturated vapour pressure was calculated to be 671 mg/L. Smyth et al. (1954) also reported a study in which six male albino rats per group were exposed to a flowing steam of air approaching saturation with vaporized isobutyraldehyde. One group was exposed for 15 min and the other for 30 min. 4 out 6 rats exposed for 30 min died, and 0 out of 6 rats exposed for 15 min died. In an article published by Salem et al. (1960) fifty mice, twenty guinea pigs and five rabbits were exposed to the aerosol form of the test substance for ten hours. Animals were exposed to 8967 mg/m3. The mean fatal dose was determined to be 14.5, 26.2, 22.7 mg x min/m3, respectively. Considering the low concentrations compared to the saturated vapour concentration, exposure solely to aerosol is unlikely.

Animals exposed to the saturated vapors (BASF, 1958 and Smyth, 1954) were only exposed for short periods of time to very high concentrations, which do not permit the calculation of LC50 values. The animals in the study of Salem (1960) were exposed for 10 hours presumably to an aerosol-vapour mixture and the LC50 was not determined. The study by Smyth et al. (1954) is therefore considered most reliable to determine the LC50 value. It is above 23.6 mg/L but below 47.2 mg/L for vapor exposure of 4 hours, which fits the reported LC50 for mice of 39.5mg/L after 2h exposure.

Acute toxicity: dermal

In a study performed by Smyth et al. (1954) penetration of rabbit skin is estimated by a technique closely to the one-day cuff method of Draize and associates, using male New-zealand White rabbits. The fur was removed from the entire trunk by clipping, and the dose was retained beneath an impervious plastic film. The animals were immobilized during the 24-hour contact period, after which the film was removed and the rabbits were caged for the subsequent 14 -day observation period. Two and four animals were exposed to 5 or 10 mL/kg bw, respecitively. All high dose animals died, while all low dose animals survived. Erythema, edema and necrosis of the skin at the site of contact was observed, with congestion and hemorrhage of the lungs of the animals that died. The LD50 was determined to be 7.13 mL/kg bw, which corresponds to 5583 mg/kg bw.

Justification for classification or non-classification

Based on the available information classification for acute oral, inhalation or dermal toxicity is not warranted in accordance with EU Classification, Labeling and Packaging of Substances and Mixtures (CLP) Regulation No. 1272/2008.