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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

Administrative data

short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes (incl. certificate)

Test material

Details on test material:
ZnS-SACHTOLITH HD-S; lot no 2230100; purity 98.3% +/- 0.6%; expiration date: 7 May 2003; storage conditions: at room temperature at about 20°C away from direct sunlight.

Sampling and analysis

Analytical monitoring:
Details on sampling:
The following samples were taken:
Just before the start: duplicates amples from the test medium (without daphnids) and duplicate samples from the control (without daphnids);
After 48 hours: duplicate samples from the test medium and duplicate samples from the control.
All samples were deep-frozen immediately after sampling. The concentration of the test item was analyzed in the duplicate test medium samples of the single test concentration for both sampling times (0 and 48h). From the control samples only one of the duplicate samples was analyzed from each of both sampling times.

Test solutions

Details on test solutions:
reconstituted water from purified water. The test water was aerated prior to the preparation of the test medium until oxygen saturation was reached. During the test period, the test water was not aerated.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
Study performed on young daphnids of a clone of the species D. magna Straus. The clone is bred in reconstituted water of the quality identical to the water quality used in the tests and under identical temperature and light conditions.
Test organisms were 6-24 hours old and were not first brood progeny.

Study design

Test type:
Water media type:
Limit test:
Total exposure duration:
48 h

Test conditions

Test temperature:
Dissolved oxygen:
8.5-8.7 mg O2/l
Nominal and measured concentrations:
Loading rate of 100 mg/L translated into a mean measured test concentration of 29 µg/L.
Details on test conditions:
Due to the insoluble properties of the test item, the study was performed as a limit test, using an undiluted filtrate of a supersaturated dispersion with the maximum concentration of dissolved test item as the only test concentration. The loading rate of 100mg/l was prepared by weighing 250.1 mg of the test item into 2500 ml test water. No auxiliary solvent or emulsifier was used. The test item was mixed into the test water as homogeneously as possible by ultrasonic treatment for 15 minutes and by intense stirring for 3 hours at room temperature in the dark to dissolve a maximum concentration of the test item in the dispersion. Then the solution was filtered through a membrane filter (0.45 µm) just before the start of the test.
The stirring period of 3h was chosen according to the results of a pre-test (without GLP) which showed that the solution equilibrium was reached after this time. The undiluted filtrate was used as test medium.
The test concentration was based on the results of a range-finding test and on results of a pre-experiment to the solubility of the test item.
The test method is also based on the OECD Guidance document on Aquatic Toxicity testing of Difficult Substances and Mixtures (OECD, 2000).

Results and discussion

Effect concentrationsopen allclose all
48 h
Dose descriptor:
Effect conc.:
> 29 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
Basis for effect:
Remarks on result:
other: dissolved concentration corresponding to 100mg/l loading of ZnS
48 h
Dose descriptor:
Effect conc.:
>= 29 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
Basis for effect:
Remarks on result:
other: dissolved concentration corresponding to 100mg/l loading of ZnS
Details on results:
No effects were observed at the loading rate of 100mg/l of the substance (ZnS), corresponding to 29µg Zn/l in solution. Therefore the EC50 is expressed as ">".The 48h NOEC may even be higher than 29 µg/L but the loading rates in excess of 100 mg/L have not been tested according to the EU Commission Directive.

Applicant's summary and conclusion

Validity criteria fulfilled:
test valid for assessing acute toxicity of the substance to invertebrates; results demonstrate no toxicity accoring to classification criteria
Executive summary:

A standard OECD 202 test on Daphnia magna showes that at loading of 100mg substance/l, no effects are observed.