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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
The concentration and stability of the test substance in the test solutions were verified by chemical analysis at 0 and 48 h.
Vehicle:
no
Details on test solutions:
Test substance preparation:
For the purpose of the definitive study the test substance was prepared by direct solution in water.
200 mg of the test substance was dissolved in reconstituted water and the volume was adjusted to 2 L to give the l 00 mg/L test concentration.
The reconstituted water for both the range-finding and definitive studies was the same as that used to maintain the stock animals.
Test organisms (species):
Daphnia magna
Details on test organisms:
The test was carried out using 1st instar Daphnia magna. Daphnia magna were maintained in a laboratory culture originating from a strain by the Institut National de Chimique Appliquee France.
Adult Daphnia were maintained in polypropylene vessels containing approximately 2 L of reconstituted water in a temperature controlled room at 21 °C. The lighting cycle was controlled to give a 16 h and 8 h darkness cycle with 20 min dawn and transition periods. Each culture was fed daily with a suspension mixed algae (predominantly ChloreIla spp.). Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated 24 h prior to the initiation of the test, the young daphnids produced overnight were then removed testing. The diet and diluted water are considered not to contain any contaminant that would affect the integrity or outcome of the study.
Test type:
static
Water media type:
other: reconstituted water
Limit test:
yes
Total exposure duration:
48 h
Test temperature:
21 ± 1 °C
pH:
The pH of the 100 mg/L test concentration was observed to be 0.5 units lower than the control values throughout study duration. effect is considered to be due to the acidic nature of the substance. The test substance, as supplied, has a value in the range 5.9 - 7.2.
Dissolved oxygen:
7.9 - 8.1 mg O2/L
Nominal and measured concentrations:
Range-finding study: 0.010, 0.10, 1.0, 10 and 100 mg/L.
Definitive study: 100 mg/L.
Details on test conditions:
Range-finding study:

- In the range-finding study Daphnia magna were exposed to a series of nominal test concentrations of 0.010, 0.10, 1.0, 10 and 100 mg/L.
- The test substance was dissolved directly in water. 100 mg of the test substance was dissolved in reconstituted water and the volume was adjusted to 1 L to give the 100 mg/L, from which serial dilutions were made to give the remainder of the test series of 0.010, 0.10, 1.0 and 10 mg/L.
- In the range-finding study 10 daphnids were placed in each test and control vessel and maintained in a temperature controlled room at 21 °C with a photoperiod of 16 h light and 8 h darkness for a period of 48 h with 20 min dawn and dusk transition periods. Each 250 mL test and control vessel contained 200 mL of test media and was covered to reduce evaporation.
- After 24 and 48 h the number of immobilised Daphnia magna were recorded.
- The control group was maintained under identical conditions but not exposed to the test substance.

Definitive study:

- Based on the results of the range-finding study a "Limit test" was conducted for the definitive study at a test concentration of 100 mg/L.
- In the definitive study 250 mL glass jars containing approximately 250 mL of test solution were used. At the start of the study 10 daphnids were placed in each test and control vessel at random, in the prepared test solutions. Four replicate test vessels were prepared duplicate control vessels. The test vessels were then covered to reduce evaporation and maintained in a temperature controlled room at 21 °C with a photoperiod of 16 h light and 8 h darkness with 20 min dawn and dusk transition periods. The daphnids were not individually identified, received no food during exposure and the test vessels were not aerated.
- The control group was maintained under identical conditions but not exposed to the test substance.
- The test solutions were not renewed during the exposure period. Any immobilisation or adverse reactions to exposure were recorded at 24 and 48 h after the start of exposure.
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
Analysis of the test preparations at O and 48 h showed the measured test concentrations to be near nominal and so it was considered justifiable to estimate the EC50 va]ues in terms of the nominal test concentrations only.

Expressed as % of the nominal concentrations:
At 0 h: 103 % and 103 % in two replicates
At 48 h: 102 and 101 %

Stability:
The test samples have been shown to be sufficiently stable for the purposes of this study. The unsonicated vessel stability showed no evidence of insolubility or adherence to glass.
Validity criteria fulfilled:
yes
Conclusions:
Under the study conditions, the nominal 48 h EC50 for Daphnia magna  was greater than 100 mg/L and the corresponding 48 h NOEC was 100 mg/L.
Executive summary:

A study was conducted to determine toxicity of the test substance (Ammonium 2-mercaptopropionate) towards Daphnia magna according to OECD Guideline 202 and EU Method C.2. Following a preliminary range-finding study, forty Daphnids (4 replicates of 10 animals) were exposed to an aqueous solution of the test substance at a concentration of 100 mg/L for 48 h under static test conditions. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 h. Analysis of the test solutions at 0 and 48 h showed the measured test concentrations to be near nominal, therefore results were based on nominal concentrations. Under the study conditions, the nominal 48 h EC50 for Daphnia magna  was greater than 100 mg/L and the corresponding 48 h NOEC was 100 mg/L (Sewell, 2000).

Description of key information

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
100 mg/L

Additional information

A study was conducted to determine toxicity of the test substance (Ammonium 2-mercaptopropionate) towards Daphnia magna according to OECD Guideline 202 and EU Method C.2. Following a preliminary range-finding study, forty Daphnids (4 replicates of 10 animals) were exposed to an aqueous solution of the test substance at a concentration of 100 mg/L for 48 h under static test conditions. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 h. Analysis of the test solutions at 0 and 48 h showed the measured test concentrations to be near nominal, therefore results were based on nominal concentrations. Under the study conditions, the nominal 48 h EC50 for Daphnia magna  was greater than 100 mg/L and the corresponding 48 h NOEC was 100 mg/L (Sewell, 2000).