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Long-term toxicity to aquatic invertebrates

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long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
GLP guideline study (detailed information in Japanese; basic information in English)
according to guideline
OECD Guideline 211 (Daphnia magna Reproduction Test)
GLP compliance:
not specified
Analytical monitoring:
Test organisms (species):
Daphnia magna
Test type:
Water media type:
Limit test:
Total exposure duration:
21 d
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)
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 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

- 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

- 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

- Spacing factor for test concentrations: 1.8
Key result
21 d
Dose descriptor:
Effect conc.:
18 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
21 d
Dose descriptor:
Effect conc.:
43.3 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
Validity criteria fulfilled:

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).