2-ethylbutyric acid

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-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 211 (Daphnia magna Reproduction Test)

GLP compliance:

yes

Test organisms (species):

Daphnia magna

Total exposure duration:

21 d

Nominal and measured concentrations:

6.25, 12.5, 25.0, 50.0, and 100 mg/l

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

48.9 mg/L

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 48.9 - < 101 mg/L

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

21 d

Dose descriptor:

other: LC100

Effect conc.:

101 mg/L

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 48.9 - < 101 mg/L

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

48.9 mg/L

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

At 100 mg/l, a significant reduction in pH was observed.

Validity criteria fulfilled:

not specified

Conclusions:

2-Ethylbutyric acid was exposed to Daphnia magna at five concentrations between 6.25 - 100 mg/l, resulting in a parental mortality NOEC, EC50, and LC100 of 48.9, >48.9 - <101, and 101 mg/l, respectively. The 21-day EC50 and NOEC based on effects on reproduction was >48.9 - <101 and 48.9 mg/l, respectively. The registered substance is concluded not to be a long-term (chronic) aquatic hazard (CLP Regulation (EC) No 1272/2008).

Executive summary:

An experiment was performed to determine the long-term (21-day) aquatic toxicity of 2-ethylbutyric acid to Daphnia magna according to Good Laboratory Practise (GLP) and OECD Guideline 211 (Daphnia magna Reproduction Test). Daphnia magna were treated with 6.25, 12.5, 25.0, 50.0, and 100 mg/l 2-ethylbutyric acid. Although the registered substance is acidic, this parameter was not corrected for in the test system and, therefore, any resulting adverse effect may be a result of low pH as well as, or rather than, a true toxic effect, if present. At the highest concentration of 100 mg/l, there was a significant reduction in pH. Parental mortality and effects to reproduction were monitored. A 21-day NOEC of 48.9 mg/l, EC50 of >48.9 - <101 mg/l, and LC100 of 101 mg/l was determined for parental mortality, while an EC50 of >48.9 - <101 mg/l and NOEC of 48.9 mg/l was calculated for reproductive effects. In line with CLP Regulation (EC) No 1272/2008, 2-ethylbutyric acid can be regarded as not possessing the potential for long-term aquatic toxicity to aquatic invertebrates such as Daphnia magna.

Reference 2

Endpoint:

long-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 211 (Daphnia magna Reproduction Test)

GLP compliance:

not specified

Test organisms (species):

Daphnia magna

Total exposure duration:

21 d

Test temperature:

20 ± 1 °C

Nominal and measured concentrations:

6.25, 12.5, 25, 50, and 100 mg/l

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

48.9 mg/L

Conc. based on:

test mat.

Basis for effect:

not specified

Key result

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

71.2 mg/L

Conc. based on:

test mat.

Basis for effect:

not specified

Validity criteria fulfilled:

not specified

Conclusions:

A long-term (21-day) experiment was undertaken in Daphnia magna to assess the potential toxicity of 2-ethylbutyric acid. The 21-day NOEC was determined to be 48.9 mg/l and the EC50 was calculated to be 71.2 mg/l.

Description of key information

In an experiment to evaluate the long-term (21-day) aquatic toxicity potential of 2-ethylbutyric acid, an EC50 of >48.9 to <101 mg/l and a NOEC of 48.9 mg/l was determined in Daphnia magna for both parental mortality and effects to reproduction. All Daphnia magna perished at the highest concentration (LC100 = 101 mg/l). Based on these results and under the conditions of this study, the registered substance can be regarded as non-toxic to aquatic invertebrates over a long-term timeframe (CLP Regulation (EC) No 1272/2008). A supporting 21-day study in Daphnia magna that was undertaken to assess toxicity similarly reported an EC50 of 71.2 mg/l and NOEC of 48.9 mg/l.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

48.9 mg/L