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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:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.20 (Daphnia magna Reproduction Test)
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Routinely, the samples were analysed immediately. Only in exceptional cases, they were stored overnight deep frozen and protected from light.
Vehicle:
no
Details on test solutions:
A direct weighing was prepared to produce the only test concentrations. 2 mg of the test item were added to 2 litres of dilution water,treated for 60seconds at 8000 rpm with an ultra turrax and were stirred for 24 h on a magnetic stirrer. Finally undissolved particles of the test item were removed by filtration using a folded filter with a pore size of 7-12 μm and an aseptic filter (Sartoban sterile capsule) of pore size 0.45 μm +0.2 μm. The pH was measured and ranged between 7.8 and 8.0. 100 mL of each test item concentration were taken per replicate and one neonate was added. For each test item concentration and the control 10 replicates were prepared.
Test organisms (species):
Daphnia magna
Details on test organisms:
Name : Daphnia magna STRAUS, parthenogenetic females
Source : Strain of Bundesgesundheitsamt Berlin
Maintenance and Acclimatisation :
A population of parthenogenetic females of synchronized age structure has been maintained for more than 15 years in the test facility under constant temperature conditions (20 +/- 1 °C) at a 16 : 8 hour light-dark photoperiod (light intensity: < 20 μE x m-2 x s-1). The culture water (so-called 'M4 medium') was partly renewed once a week. The Daphnia were exclusively fed unicellular green algae (Desmodesmus subspicatus) 'ad libitum'. Mortalities of parent Daphnia during the culture period were recorded daily in a semi-quantitative way. The neonates were separated from their parent Daphnia by filtration prior to the acute test.
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
21 d
Hardness:
14.5 - 16.5° dH (= 259 - 295 mg/L CaCO3)
Test temperature:
20.0 - 21.1°C
The temperature fluctuation in the course of the study exceeded 1.0 °C, which is regarded to be not relevant to the results as all validity criteria were met.
pH:
7.8 - 8.2
Dissolved oxygen:
8.4 - 10 mg/L (=96 - 110 %)

Nominal and measured concentrations:
limit test concentration of nominally 1 mg/L
Details on test conditions:
Exposure conditions:
Test vessels : 150 mL glass beakers holding 1 neonate in 100 mL of test medium
Experimental design : 1 test concentration plus 1 control; 1 neonate per vessel, 10 replicates per concentration/control; Semi static system (renewal of the test media on Monday, Wednesday and Friday)
Method of initiation : neonates were placed in prepared media
Photoperiod : 16 h light: 8 h dark
Light intensity : not exceeding 20 μE x m-2 x s-1
Temperature of incubation unit : 20.1 to 20.5 °C
Aeration : none
Test item concentration/s : 1 mg/L
Food source and feeding rate: Desmodesmus subspicatus, day 0-7: 0.1 mg C / Daphnia / day; day 8-21: 0.2 mg C / Daphnia / day
Reference substance (positive control):
no
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
> 1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
> 1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
No toxic effects against daphnia were observed at a limit test concentration of nominally 1 mg/L, corresponding to a measured concentration of < 0.0334 mg/L, which reflects the maximum water solubility under exposure conditions.
Validity criteria fulfilled:
yes
Remarks:
The mortality rate in the controls <20 % by the end of the test. The dissolved oxygen concentration > 3 mg/L throughout the test. Mean number of live offspring ≥ 60 (perparent daphnia at the end); pH: 6 - 9; water hardness > 140 mg/L (as CaCO3)
Conclusions:
The chronic toxicity of the substance to Daphnia magna was investigated in a semi-static test according to OECD Guideline 211 (Daphnia magna Reproduction Test). After 21 days of exposure a NOEC(Reproduction) of >=1 mg/L (nominal) was determined. No toxic effects against daphnia were observed at a limit test concentration of nominally 1 mg/L, corresponding to a measured concentration of < 0.0334 mg/L, which reflects the maximum water solubility under exposure conditions.
Executive summary:

The study was conducted in accordance with Council Regulation (EC) No 440/2008, Method C.20 'Daphnia magna Reproduction Test'', which equals in all relevant parts to the OECD Test guideline 211 (Daphnia magna Reproduction Test). Young female Daphnia, aged less than 24 hours at the start of the test, were exposed to a limit test concentration of nominally 1 mg/L of the substance dissolved in water. Auxiliaries used to prepare the test media were an ultra turrax, a magnetic stirrer, folded filters of pore size 7-12 μm and aseptic filters. After a 21d-exposure period, the total number of living offspring produced per parent animal alive at the end of the test was assessed. The reproductive output of the Daphnia exposed to the substance was compared to that of the control in order to determine the Lowest Observed Effect Concentration (LOEC) and the No Observed Effect Concentration (NOEC) according to STUDENT t-Test and Fisher`s Exact Binomial Test Procedure. Additionally, the survival of the parent Daphnia and the time to production of first brood was determined.

Results:

21d-NOEC (reproduction): ≥ 1 mg/L

21d-LOEC (reproduction): > 1 mg/L

21d-NOEC (mortality): ≥ 1 mg/L

21d-LOEC (mortality): > 1 mg/L

No toxic effects against daphnia were observed at a limit test concentration of nominally 1 mg/L, corresponding to a measured concentration of < 0.0334 mg/L, which reflects the maximum water solubility under exposure conditions.

Description of key information

The chronic toxicity of the substance to Daphnia magna was investigated in a semi-static test. After 21 days of exposure a NOEC(Reproduction) of >=1 mg/L (nominal) was determined. No toxic effects against daphnia were observed at a limit test concentration of nominally 1 mg/L, corresponding to a measured concentration of < 0.0334 mg/L, which reflects the maximum water solubility under exposure conditions.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
1 mg/L

Additional information

"should read: NOEC >= 1 mg/L"