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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:
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 (incl. certificate)
Remarks:
WCA-003/4-20/G
Analytical monitoring:
yes
Details on sampling:
Sampling at test start before distribution to replicates and sampling of aged test solution by pooling replicate concentration samples.
Vehicle:
no
Details on test solutions:
- Stock concentration: 220 mg/L
- Stock solution preparation: stirred for 1h at ca. 20⁰C
Test organisms (species):
Daphnia magna
Details on test organisms:
- Strain: Clone V
- Source: Fraunhofer IME
- Age at study initiation (mean and range, SD): 4-24h
- Feeding during test: no
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
70 - 120 mg/L as CaCO3 - below recommended range; historical conditions at laboratory indicate that this range is acceptable for the Daphnia magna strain used at the IME
Test temperature:
20.3⁰C
pH:
7.8- 8.2
Dissolved oxygen:
8.4 - 8.9mg/L
Nominal and measured concentrations:
Nominal concentrations: 4.3. 9.4. 20.7. 45.5. 100. 220 mg/L
Measured concentrations at 0h: 4.28, 8.99, 20.38, 47.23, 106.96, 233.15 mg/L
Measured concentrations at 48h: 4.58, 10.67, 22.68, 49.72, 104.97, 231.22 mg/L
Mean measured concentrations were 96 - 107% of nominal for freshly prepared test solutions and 105 - 114% in aged test solutions therefore nominal concentrations were used for reporting of results.
Details on test conditions:
- Test vessel: glass beaker
- Type: open
- Material, size, headspace, fill volume: 50mL
- Aeration: no
- No. of organisms per vessel:5
- No. of vessels per concentration (replicates):4
- Control: dilution water
- Light intensity: 10.7-11.1 uE/m2/s
- Light/dark cycle: 16/8

All water quality guidelines (except for water hardness) recommended by the OECD guideline were met.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
81.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL: 31.8-324.3 mg Rh/L
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
45.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
48 h
Dose descriptor:
EC10
Effect conc.:
28.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL: 0.4-56.3 mg Rh/L
Details on results:
No significant signs of disease or stress were observed.
Results with reference substance (positive control):
24h EC50 immobilisation with K2Cr2O7: 1.19 mg/L
95% CL: 1.05-1.36 mg/L
Reported statistics and error estimates:
95% confidence intervals calculated by Probit-analysis, assuming log-normal distribution of the values.
Statistical calculations performed with ToxRat.
   Mortality
NOEC  45.5
 LOEC  100
 EC10 (95% CL)  28.3 (0.4 -56.3)
 EC20 (95% CL)  40.6 (2.2 -78.6)
 EC50 (95% CL)  81.3 (31.8 -324.3)
Validity criteria fulfilled:
yes
Conclusions:
The EC50 was determined to be 81.3 mg/L.
Executive summary:

The influence of diammonium sodium hexakis (nitrito-N) rhodate on the mortality of Daphnia magna was investigated according to OECD guideline 202 and EC method C.2 (Simon 2014). The daphnids were placed in water containing the test item in a nominal concentration range of 4.3 to 220 mg/L, and as measured test concentrations did not deviate by more than 20% of nominal, nominal concentrations were used for reporting of results. The test was conducted under static conditions for 48 h. The study was conducted in accordance with GLP and all validity criteria were met. This study has been given a reliability rating of 1 as it is well-documented and adheres to guideline procedures.

No significantly increased mortality was determined up to a concentration of 45.5 mg/L. The EC50 for the tested species was found to be 81.3 (95 % CL: 31.8 – 324.3) mg/L.

Description of key information

The EC50 was determined to be 81.3 mg L-1. 

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
81.3 mg/L

Additional information

Acute toxicity to Daphnia was assessed according to OECD guideline 202 and EC method C.2 (Simon 2014). The daphnids were placed in water containing the test item in a nominal concentration range of 4.3 to 220 mg L-1, and as measured test concentrations did not deviate by more than 20% of nominal, nominal concentrations were used for reporting of results. The test was conducted under static conditions for 48 h. The study was conducted in accordance with GLP and all validity criteria were met. This study has been given a reliability rating of 1 as it is well-documented and adheres to guideline procedures.

No significantly increased mortality was determined up to a concentration of 45.5 mg L-1. The EC50 for the tested species was found to be 81.3 mg test item L-1 (95 % CL: 31.8 – 324.3).

For PNEC derivation all data for rhodium(III) substances has been pooled and the PNEC values derived based on the most sensitive result. In the risk assessment, emissions of different rhodium substances are not analysed separately and therefore measured environmental concentrations are available based on total rhodium concentrations. As the measured emissions data is not apportioned to a particular rhodium(III) substance, a single set of PNECs covering all rhodium substances in the same oxidation state is considered to be the most appropriate approach for conducting the risk assessment. For aquatic PNECs the lowest EC50 value is for the rhodium(III) substance rhodium(III) chloride. There is some indication that rhodium substances containing a chloro ligand may be more toxic than those without, and therefore using the value for rhodium trichloride as the key value for PNEC derivation for all rhodium(III) substances is likely to be worst case. The value taken forward for PNEC derivation is therefore a 48-hour EC50 of 0.290 mg Rh L-1, based on a study using rhodium chloride (hydrate).