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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:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
At the start of the test, two samples (50 mL) were taken from freshly prepared control and test media.
After 48 hours, mid-vessel samples taken from each group were pooled and replicate samples (50 mL) were taken.
Samples were stored in a freezer until analysis.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: water accommodated fractions (WAFs)
At each concentration, the test substance was dispersed in dilution medium in a glass vessel (21.4 mg/5L, 18.8 mg/2L, 20.7 mg/L, 45.5 mg/L or 100 mg/L). The contents of each vessel were stirred for approximately 24 hours and then left to stand for approximately 48 hours. Aliquots (800 mL) were then removed mid vessel to provide the Water Accommodated Fractions (WAF).
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Source: in-house culture originating from a strain supplied by the National Institute for Applied Chemical Research (IRCHA), France
- Age at study initiation: < 24 h
- Method of breeding: Stock cultures of Daphnia magna were maintained in glass vessels containing approximately 0.5 to 0.8 litres of Elendt M4 culture medium in a temperature-controlled laboratory at nominally 20 ± 2°C. A photoperiod of 16 hours light : 8 hours dark was maintained, with periods of subdued lighting at the beginning and end of each light phase. The culture medium was renewed three times each week.
Cultures were fed daily with a suspension of the unicellular green algae, Pseudokirchneriella subcapitata, to provide nominally 0.1 to 0.2 mg carbon per daphnid, per day, except during the initial three days when a slightly lower ration was given. Culture conditions ensure that the stock animals reproduce by parthenogenesis.
The day before the start of the study, all juvenile Daphnia were removed from the laboratory cultures. The following morning, juveniles produced by the gravid (egg-bearing) adult Daphnia were removed from the culture vessels and held in a separate holding vessel.
- Feeding during test: none

ACCLIMATION
- Acclimation period: not relevant, conditions were the same for maintenance and testing
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
236 mg/L as CaCO3
Test temperature:
18-19 °C
pH:
8.0-8.3
Dissolved oxygen:
100-104 % air saturation value
Nominal and measured concentrations:
nominal loading rates: 4.27, 9.39, 20.7, 45.5 and 100 mg test material/L
The TOC could not be reliably determinedat any of the test levels. After background correction for the control, it was not possible to quantify the levels of carbon that were attributable to the test substance at any level.
Details on test conditions:
TEST SYSTEM
- Test vessel: glass dishes containing approx. 100 mL of medium, loosely covered
- Aeration: none
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 20 mL medium per organism

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4 medium (according to guideline), prepared in deionised, reverse osmosis water
- Total organic carbon: 1.7 mg C/L
- Alkalinity: 37.5 mg/L as CaCO3
- Ca/Mg ratio: 3.7:1
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours light : 8 hours dark with periods of subdued lighting at the beginning and end of each light phase

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : numbers of mobile, immobile and floating Daphnia counted approx. 24 and 48 hours after the start of the study

RANGE FINDING STUDY
- Test concentrations: nominal loading rates of 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: Immobility after 48 hours: 100% at 100 mg/L, 0% at 1 and 10 mg/L..
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: results are expressed in terms of loading rates
Duration:
48 h
Dose descriptor:
NOELR
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: results are expressed in terms of loading rates
Details on results:
- Immobilised Daphnia: nosignificant immobility was observed at any of the nominal loading rates (Table 1).
- Behavioural abnormalities: none
- Mortality of control: none
- Other adverse effects control: none
- Abnormal responses: none

The test media were colourless dispersions.

Results with reference substance (positive control):
- 48-hour EC50: 1.3 mg/L (within the range typically obtained in this laboratory)
Reported statistics and error estimates:
Statistical analysis was performed using the SAFEStat LD50 application (version 1.3), SAS 9.1.3 (SAS Institute, 2002).
The “no observed effect loading rate” (NOELR) was derived by direct inspection of the data on the immobility of the animals. An incidence rate of more than 10% was considered to be significant.

After 48 hours, no immobility was observed at any of the tested nominal loading rates.

Validity criteria fulfilled:
yes
Remarks:
In the control, no Daphnia have been immobilised or trapped at the surface of the water. The dissolved oxygen concentration at the end of the test was ≥60% of the air saturation value at the temperature used.
Conclusions:
The results indicate that the test material is not toxic to freshwater invertebrates up to the limits of its water solubility and a NOEC and thus a PNEC cannot be determined.

Description of key information

48-h EL50 (based on loading rates) >100 mg/L for Daphnia magna (OECD 202, EU C.2)

Key value for chemical safety assessment

Additional information

EL50/LL50 for freshwater invertebrates > water solubility


The results indicate that the test material is not toxic to freshwater invertebrates up to the limits of its water solubility and a NOEC and thus a PNEC cannot be determined.