2-ethylhexanoic acid, cerium salt

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

GLP guideline study (detailed information in Japanese; basic information in English)

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

Daphnia magna

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

Control: 230 to 260 mg/L CaCO3 (measured during exposure period)
Treatments: 230 to 265 mg/L CaCO3 (measured during exposure period)

Test temperature:

20 +-1 °C
Control: 19.6 to 20.3 °C (measured during exposure period)
Treatments: 19.8 to 20.3 °C (measured during exposure period)

pH:

Control: 7.7 to 8.4 (measured during exposure period)
Treatments: 7.4 to 8.5 (measured during exposure period)

Dissolved oxygen:

Control: 7.7 to 8.8 mg/L (measured during exposure period)
Treatments: 5.5 to 8.8 mg/L (measured during exposure period)

Nominal and measured concentrations:

nominal: Control, 10.0, 18.0, 32.0, 56.0 and 100 mg/L
measured (Time weighted mean): Control, 10.8, 18.7, 32.8, 57.5 and 102 mg/L (102 to 108 % of nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel fill volume: 80 mL
- Aeration: no
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: M4 medium according to OECD 211
- Intervals of water quality measurement: measured twice per week and at beginning and at the end of exposure period of 21 days

OTHER TEST CONDITIONS
- Adjustment of pH: information not available in english
- Photoperiod: 16 h light : 8 h darkness
- Light intensity: 800 lux

EFFECT PARAMETERS MEASURED: immobility, reproduction, observed daily

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

18 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

43.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

reproduction

Validity criteria fulfilled:

yes

Description of key information

The chronic 21 -d NOEC based on reproduction for Daphnia magna was determined to be 18.0 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

18 mg/L

Additional information

A study on the toxicity of 2-ethylhexanoic acid (CAS 149 -57 -5) towards aquatic invertebrates was conducted. A non-GLP study according to OECD guideline 211 was performed by EKOLAB Environmental Oy on behalf of Finnish Chemicals Oy. Daphnia magna was used as a test organism. After 21 days of exposure a NOEC of 25 mg/L and an EC50 of 75 mg/L were estimated, based on the measured concentration (EKOLAB Environmental Oy, 1997, report no.: E2702). However, in this study data is missing about the purity of the test substance and no sufficient information for the analytical measurements on English is available.

As a key study, under supervision of the Japanese Ministry of the Environment, a chronic test on Daphnia magna was conducted according to OECD 211 under GLP and published in 2002. In opposite to the study with the acid, this study was conducted under GLP and the test concentrations were analytically verified. The test concentrations were analytically verified and deviated less than 20% from the nominal concentrations. Moreover, the study was performed with the salt of the acid (Sodium 2-ethylhexanoate, CAS 19766-89-3) which resembles the acid after neutralization. By that, in this study, the toxicity of the test substance was not influenced by acidic pH effects. Therefore, the study was used as a key study for the assessment of the toxicity of CAS 149-57-5 to aquatic invertebrates.

The test duration was 21 days, the test solutions were renewed two times per week. The NOEC for reproduction was determined to be 18 mg/L (NITE, 2002, report no.: A010465 -3).