2-ethylbutyric acid

Endpoint summary

Description of key information

An LD50 (lethal dose, 50 %) of >2000 mg/kg and 2200 mg/kg was obtained for 2-ethylbutyric acid in two studies for acute toxicity in rats via the oral route. As the former result is more conservative and is based on a reliable study report (Klimisch score = 2), the endpoint conclusion for acute toxicity (oral) is concluded to be >2000 mg/kg. This value is outside of the CLP Regulation (EC) No 1272/2008 criteria and, therefore, the registered substance does not require classification as an acute oral toxin.

An LD50 of 0.52 ml/kg (478 mg/kg) was determined in a range-finding acute toxicity (dermal) experiment involving rabbits. The endpoint conclusion for acute dermal toxicity has been selected as LD50 = 478 mg/kg, which is indicative of the registered substance requiring a classification for Acute Toxicity (Dermal) (Category 3) (CLP Regulation (EC) No 1272/2008). 2-Ethylbutyric acid can be regarded as an acute toxin (Category 3) via the dermal route.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1954

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Insufficient information for an assessment of reliability.

Principles of method if other than guideline:

Not available

GLP compliance:

not specified

Test type:

other: Not available

Species:

rat

Route of administration:

oral: unspecified

Key result

Sex:

not specified

Dose descriptor:

LD50

Effect level:

2 200 mg/kg bw

Interpretation of results:

GHS criteria not met

Conclusions:

2-Ethylbutyric acid was found to have an acute oral LD50 (lethal dose, 50 %) of 2200 mg/kg in rats.

Reference 2

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes

Test type:

other: Not available

Limit test:

yes

Species:

rat

Strain:

other: T23-48:Crj:CD(SD)IGS

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

corn oil

Doses:

0 (control) and 2000 mg/kg

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 10 - 15 days.
- Frequency of observations and weighing: Hours after administration: 0-1, 2, 3, 4, 5, and 6; Days of observation: 2, 3, 4, 5, 6, 7, 8, 9, and 10-15.
- Necropsy of survivors performed: Yes.
- Other examinations performed: Body weight change measured on days 1, 2, 4, 8, 11, and 15.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Mortality:

No mortality

Clinical signs:

Transient salivation was evident within 1 hour after the treatment in one male and two females. One male and three females exhibited rales, which continued for several days, and there was a reported decrease in faeces volume and a perianal smudge noted in three males on day 2.

Body weight:

Reduction in body weight in both sexes

Gross pathology:

No abnormalities

Interpretation of results:

GHS criteria not met

Conclusions:

An acute oral LD50 (lethal dose, 50 %) of >2000 mg/kg was determined for 2-ethylbutyric acid in male and female rats.

Executive summary:

A 14-day experiment was undertaken to determine the acute oral toxicity of 2-ethylbutyric acid according to Good Laboratory Practise (GLP) and OECD Guideline 401 (Acute Oral Toxicity). Male and female rats (strain: T23-48:Crj:CD(SD)IGS) were exposed to 0 (control) and 2000 mg/kg in a corn oil vehicle as part of a limit test. Transient salivation was observed in one male and two females at 1-hour and one male and three females exhibited rales, which continued for a number of days. On day 2, three males were observed to have a perianal smudge and decreased faecal volume. Additionally, body weight in exposed rats was significantly lower than the 0 mg/kg control at some observation points. No mortality had been recorded at the termination of the experiment on day 14, nor abnormalities following necropsy that could be associated with the treatment. The acute oral LD50 for 2-ethylbutyric acid was subsequently determined to be 2000 mg/kg, which is outside of the criteria for classification as an acute toxin (oral) (CLP Regulation (EC) No 1272/2008).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1954

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Insufficient information for an assessment of reliability.

Principles of method if other than guideline:

Not available

GLP compliance:

not specified

Species:

rabbit

Key result

Sex:

not specified

Dose descriptor:

LD50

Effect level:

0.52 mL/kg bw

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

A range-finding acute toxicity (dermal) experiment in rabbits obtained an LD50 (lethal dose, 50 %) of 0.52 ml/kg (478 mg/kg). This value falls within the GHS criteria for classification as Acute Toxicity Category 3 via the dermal route.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

478 mg/kg bw