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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:
2012-2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study without restrictions
Qualifier:
according to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
The test substance is poorly soluble in water (information from sponsor). Therefore the test solutions were prepared following general guidance provided in OECD 23 in order to generate a saturated solution of the test substance in test medium.
The test solution was prepared by directly adding test substance to test medium according to the loading concentration described below.
Loading concentration (mg/L): 0 (control), 10
Saturation concentration (%): 0, 100
Weight amount of test substance (mg): -, 20
Final Volume of test media (mL): 2000, 2000

The required volume (2-L) of test media was placed into a beaker (3-L nominal volume) and the test substance was weighed in. The beakers were covered with Parafilm and shaken gently (approx. 50 RPM, to avoid emulsion formation) for about three (3) days to ensure that the saturation concentration is reached. Undissolved test substance was removed by filtration with a membrane filter (Whatman OE66, cellulose acetate, pore width 0.2μm). To minimize test substance loss from adsorption, the filer was first saturated using approx. 300 mL of test solution. Centrifugation at 17700xg for 20 minutes did not adequately separate the undissolved test substance, therefore filtration was the method of choice.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Source: The clone of Daphnia magna STRAUS 1820 used was supplied by the Institut National de Recherche Chimique Appliquée, France, in 1978. From this date on this clone was cultured and bred continuously in the Ecotoxicology Laboratory of Experimental Toxicology and Ecology, BASF SE, Ludwigshafen Germany.
- Age of parental stock (mean and range, SD): Daphnia brood stocks are kept in mass cultures consisting of approx. 20 – 30 individuals for a maximum of 4 weeks. All individuals in the mass culture originate from a single female. After approximately 14 days the adults have produced at least 3 broods and the young can be used in tests.
- Feeding during test: Yes
- Food type: During the test daphnids were fed daily a diet of live green algae Desmodesmus subspicatus, cultured in a synthetic medium.
- Amount: The algae were separated from their culture medium by centrifugation, resuspended in daphnid's medium (M4) corresponding to concentrations of 1583 mg and 1720 mg TOC*/L (respectively) in the algal concentrates used. The daphnids were fed a defined volume (≤ 126 μL) of the concentrate.
- Frequency: daily

ACCLIMATION
- Acclimation period: The Daphnia are cultured under the identical conditions as the test including test media (Elendt M4), water quality, temperature (20 ±1°C), and diet.
- Acclimation conditions (same as test or not): yes
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
21 d
Hardness:
total hardness: 2.20 – 3.20 mmol/L
Test temperature:
20.9 - 21.6 °C
pH:
control: 7.9 - 8.1
10 mg/L concentration group: 7.9 - 8.1
Dissolved oxygen:
control: 6.6 - 9.0 mg/L
10 mg/L concentration group: 6.5 - 9.1 mg/L
Nominal and measured concentrations:
nominal: 10 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: glass beakers
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 100 mL nominal, filled with 50 mL
- Aeration: none
- Renewal rate of test solution (frequency/flow rate): semi-static, daily renewal
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10
- Biomass loading rate: 0.02 animals / mL

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: A synthetic fresh water (Elendt M4) is used as media for culture and test purposes
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16:8 light/dark
- Light intensity: about 603 - 722 lux at a wave length of 400 - 750 nm

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality, reproduction and other sublethal effects. Additional
endpoints (i.e. growth, immobile young, time to first brood, or aborted eggs) were checked
Reference substance (positive control):
yes
Remarks:
sodium chloride
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: The concentration of the test substance could not be verified analytically. Therefore the effect concentration is based on the nominal concentration.
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
> 10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: The concentration of the test substance could not be verified analytically. Therefore the effect concentration is based on the nominal concentration.
Details on results:
No significant mortality, reduced reproduction or any other additional significant adverse effects or abnormal behavior were observed in any of the test treatments.
Validity criteria fulfilled:
yes

Description of key information

No toxic effects could be recorded at a saturated test solution. 

Key value for chemical safety assessment

Additional information

The available study on long-term toxicity to aquatic invertebrates did not reveal any toxic effects at a saturated test solution of nominal 10 mg/L. Concentration control analysis was not performed since the analytical detection limit was above the water solubility of the test substance. However, all reasonable efforts were taken to produce a saturated solution of the test substance in test media, following the guidance in OECD 23. According to OECD 23, for tests with chemicals that cannot be quantified by analytical methods at the concentrations causing effects, the effect concentration can be expressed based on the nominal concentrations.