2-ethylbutyric acid

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

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 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes

Test organisms (species):

Oryzias latipes

Test type:

semi-static

Limit test:

no

Total exposure duration:

96 h

Nominal and measured concentrations:

0 (control), 50, and 100 mg/l

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 50 - < 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Key result

Duration:

96 h

Dose descriptor:

LC100

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Details on results:

No mortality was recorded during the 72-hour study period at 0 and 50 mg/l. Acute toxicity was observed at 100 mg/l, with Oryzias latipes exhibiting abnormal behaviour and respiration, immobilisation, and mucus secretion.

Validity criteria fulfilled:

not specified

Conclusions:

Exposure of freshwater fish Oryzias latipes to 0 - 100 mg/l 2-ethylbutyric acid resulted in a 96-hour LC50 of >50 and <100 mg/l and a LC100 of >100 mg/l. The registered substance can subsequently be regarded as non-acutely toxic to freshwater fish under the conditions of the experiment (CLP Regulation (EC) No 1272/2008).

Executive summary:

A short-term (96-hour) aquatic toxicity experiment was undertaken according to Good Laboratory Practise (GLP) and OECD Guideline 203 (Fish, Acute Toxicity Test) to determine the potential toxicity of 2-ethylbutyric acid in freshwater fish Oryzias latipes. The following concentrations were tested within a semi-static system: 0 (control), 50, and 100 mg/l. Although the substance was considered to be acidic, the pH was not adjusted in the test and so it would not be possible to ascertain whether any adverse effect was due to low pH and/or a true toxic effect. At test termination, the 96-hour LC50 and LC100 was determined to be >50 - <100 mg/l and >100 mg/l, respectively. No mortality was observed in the control or 50 mg/l treatment, while at 100 mg/l Oryzias latipes was found to exhibit abnormal behaviour and respiration, immobility, and mucus secretion. As the 96-hour LC50 was >1 mg/l it can be concluded that 2-ethylbutyric acid is not acutely toxic to freshwater fish under the conditions of the experiment (CLP Regulation (EC) No 1272/2008).

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2000

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Insufficient information for an assessment of reliability.

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

not specified

Test organisms (species):

Oryzias latipes

Total exposure duration:

96 h

Test temperature:

24 ± 1 °C

Nominal and measured concentrations:

50 and 100 mg/l

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

85.4 mg/L

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Validity criteria fulfilled:

not specified

Conclusions:

2-Ethylbutyric acid was determined to have an LC50 (lethal concentration, 50 %) of 85.4 mg/l in the freshwater fish Oryzias latipes.

Description of key information

An LC50 of >50 - <100 mg/l and LC100 of >100 mg/l was obtained in an key acute toxicity study (Klimisch score = 2) with the freshwater fish Oryzias latipes following exposure to 2-ethylbutyric acid at 50 and 100 mg/l. An additional experiment in Oryzias latipes, which was considered to be less reliable (Klimisch score = 4) concluded the registered substance to have an LC50 of 84.5 mg/l. A conservative approach was taken and an LC50 of 50 mg/l selected as the key value for chemical safety assessment given that this was obtained under reliable experimental conditions. 2-Ethylbutyric acid can be regarded as being non-acutely toxic to freshwater fish such as Oryzias latipes under the conditions of this test (CLP Regulation (EC) No 1272/2008).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

50 mg/L