2-ethylbutyric acid

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

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 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes

Vehicle:

no

Test organisms (species):

Daphnia magna

Total exposure duration:

48 h

Details on test conditions:

29.6, 44.4, 66.7, 100, and 150 mg/l

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

70 mg/L

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

100 mg/L

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

66.7 mg/L

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

At 66.7, 100, and 150 mg/l, a significant reduction in pH was recorded.

Validity criteria fulfilled:

not specified

Conclusions:

2-Ethylbutyric acid was determined to have an LC50, EC100, and LOEC of 70, 100, and 66.7 mg/l, respectively, in a 48-hour aquatic acute toxicity experiment in Daphnia magna.

Executive summary:

An experiment was performed according to Good Laboratory Practise (GLP) and OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) in order to determine the acute toxicity of 2-ethylbutyric acid to the aquatic invertebrate Daphnia magna. The experiment ran for a 48-hour period, at the start of which Daphnia magna were exposed to 29.6, 44.4, 66.7, 100, and 150 mg/l. Although 2-ethylbutyric acid was considered to be acidic, the pH of the test system was not adjusted and, therefore, any negative effect observed relative to the control may be a result of the low pH as well as potential toxicity. The immobilisation of Daphnia magna was selected as a reliable indicator of toxicity. At the end of the 48-hour experiment, an LC50, EC100, and LOEC of 70, 100, and 66.7 mg/l, respectively, had been calculated. The LC50 of 70 mg/l is outside of the range considered to be hazardous to the aquatic environment under CLP Regulation (EC) No 1272/2008. This data was not published.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

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 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

not specified

Test organisms (species):

Daphnia magna

Total exposure duration:

48 h

Test temperature:

20 ± 1 °C

Nominal and measured concentrations:

29.6, 44.4, 66.7, 100, and 150 mg/l

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

44.4 mg/L

Conc. based on:

test mat.

Basis for effect:

not specified

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

71.7 mg/L

Conc. based on:

test mat.

Basis for effect:

not specified

Key result

Duration:

48 h

Dose descriptor:

LC100

Effect conc.:

100 mg/L

Conc. based on:

test mat.

Basis for effect:

not specified

Validity criteria fulfilled:

not specified

Conclusions:

2-Ethylbutyric acid was concluded to have a NOEC, LC50, and LC100 of 44.4, 71.7, and 100 mg/l, respectively, in the aquatic invertebrate Daphnia magna following a 48-hour exposure period.

Description of key information

An LC50, EC100, and LOEC value of 70, 100, and 66.7 mg/l, respectively, was concluded as part of a 48-hour aquatic acute toxicity experiment in Daphnia magna exposed to 29.6 - 150 mg/l 2-ethylbutyric acid. As the 70 mg/l LC50 is outside of the range considered to be hazardous to the aquatic environment (CLP Regulation (EC) No 1272/2008), the registered substance can be regarded as being non-acutely toxic to aquatic invertebrates under the conditions of the test. A supporting study that involved 48-hour exposure of Daphnia magna to 2-ethylbutyric provided a relatively similar NOEC, LC50, and LC100 of 44.4, 71.7, and 100 mg/l, respectively. The LC50 of 70 mg/l was selected as the key value for chemical safety assessment given that this was derived from a key study (Klimisch score = 2) and is most conservative.  

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

70 mg/L