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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
03 July 2018 to 01 September 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.20 (Daphnia magna Reproduction Test)
Version / remarks:
Method C.20 of Commission Regulation (EC) No. 440/2008
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
For the pre-test, the test solutions were prepared by adding the test item directly to dilution water at concentration of 0.010, 0.10, 1.0 and 10 mg/L. Test solutions prepared by this method were clear and colourless and retained this appearance throughout the exposure period.
At the start and throughout the definitive test all control and test preparations were observed to be clear colorless solutions. The test preparations were renewed three times per week on Days 0, 3, 5, 7, 10, 12, 14, 17 and 19.
Test organisms (species):
Daphnia magna
Details on test organisms:
The test was carried out using 1st instar Daphnia magna derived from in-house laboratory
cultures.
Adult Daphnia were maintained in 150 mL glass beakers containing Elendt M7 medium in a temperature controlled room at approximately 20 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Each culture was fed daily with a mixture of algal suspension (Desmodesmus subspicatus) and GM300 feed suspension. Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
The water hardness was observed to be in the range 242 to 260 mg/L as CaCO3 in the control and the highest surviving test group throughout the test.
Test temperature:
Temperature was maintained at 20 °C to 22 °C throughout the definite test.
pH:
There were no treatment related differences for pH.
Dissolved oxygen:
There were no treatment related differences for oxygen concentration.
Salinity:
npt applicable
Nominal and measured concentrations:
Based on the results of a preliminary range-finding test, test concentrations of 0.63, 1.25, 2.5, 5.0 and 10 mg/L were selected for the definitive test. In the range-finding test, nominal concentrations of 0.10, 1.0, 10, and 100 mg/L were used
Details on test conditions:
The diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study
Reference substance (positive control):
no
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
immobilisation
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: body length
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
> 10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
immobilisation
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
9.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Key result
Duration:
21 d
Dose descriptor:
EC10
Effect conc.:
> 10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: body length
Details on results:
In the pre-test, there was no effect observed on the parental survival in any of the test concentrations compared to the control group. In terms of the time to first brood and neonates in the first brood, no effect was observed at concentrations of 0.010, 0.10 and 1.0 mg/L, however, there was a slight effect observed at 10 mg/L. Based on these results, the definitive study was conducted at nominal concentrations of 0.63, 1.25, 2.5, 5.0 and 10 mg/L.
Reported statistics and error estimates:
The 21-Day ECx (immobilization) values and associated confidence limits were calculated by the Maximum-Likelihood Weibull method using the ToxRat statistical software.
The ECx (reproduction) values and associated confidence limits after 21 days were calculated by the Maximum-Likelihood Logit method using the ToxRat statistical software.
The ECx (body length) values and associated confidence limits after 21 days were calculated by the 3-Parameter Normal Cumulative Distribution Function method.
All statistical analyses were performed using the ToxRat computer software package (ToxRat).
Validity criteria fulfilled:
yes
Conclusions:
Exposure of Daphnia magna to the test item resulted in no significant mortalities at any of
the concentrations employed during the test.
The 21-Day EC50 (immobilization) value, based on the nominal concentrations for the parental Daphnia generation (P1) was estimated to be greater than 10 mg/L.
The 21-Day EC50 (reproduction) based on the nominal concentrations was greater than
10 mg/L.
The 21-Day EC50 (body length) based on nominal concentrations was greater than 10 mg/L.
The LOEC and the NOEC based on the nominal concentrations were 10 and 5.0 mg/L
respectively
Executive summary:

A study was performed to assess the chronic toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (2012) No 211, "Daphnia magna Reproduction Test" referenced as Method C.20 of Commission Regulation (EC) No. 440/2008. Based on the results of a preliminary range-finding test, Daphnia magna were exposed (10 replicates of a single daphnid per group) to solutions of the test item at nominal concentrations of 0.63, 1.25, 2.5, 5.0 and 10 mg/L for a period of 21 days. The numbers of live and dead adult Daphnia and young daphnids (live and dead) were determined daily. The Daphnia were fed daily with a mixture of algal suspension and GM 300 feed suspension.

The NOECs for immobilisation, reproduction and body length were at 10, 5.0 and 5.0 mg/L, respectively. The respective EC10s were at >10, 9.5 and >10 mg/L; all EC50s were at >10 mg/L and. LOECs were at >10, 10 and 10 mg/L, respectively.

Description of key information

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
5 mg/L

Additional information