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Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study according to international accepted guidelines but not GLP compliant.

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 201 (Alga, Growth Inhibition Test)
The concentrations of test substance were not analysed in this study.Only nominal concentrations were
GLP compliance:

Test material

Constituent 1
Chemical structure
Reference substance name:
Trimethyloxosulphonium iodide
EC Number:
EC Name:
Trimethyloxosulphonium iodide
Cas Number:
Molecular formula:
trimethyl(oxo)-λ⁶-sulfanylium iodide
Test material form:
solid: crystalline
Details on test material:
Test item: Trimethylsulfoxonium Iodide (CAS 1774-47-6)
Batch No.: 20130228
Physical state: solid, crystalline powder
Colour: white or light-yellow
Content (Chemical Titration): 99.66 %
Storage: on cool and dry place, protected from light

Sampling and analysis

Analytical monitoring:
Details on sampling:
At 24, 48 and 72 hours after the beginning of the test the alga cell concentrations were determined by microscopically counting with a Bürker chamber.

Test solutions

Details on test solutions:
OECD medium was used for inoculum and test cultures according to OECD 201 guideline. Deionised water was used for preparing the media. The media was sterilized by filtration. For the solid medium of seed stock cultures 5 % agar is added to the OECD medium.

Test organisms

Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
Test species: Pseudokirchneriella subcapitata (Korshikov) F.Hindák
Source: National Institute of Environmental Health
The seed stock culture was maintained on solid OECD medium. The alga cells were passed from old seed stock cultures to fresh solid medium in every two or three weeks. The new seed cultures were kept under continuous illumination for five or seven days. After this grow phase they were kept in refrigerator.

Study design

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

Test conditions

Test temperature:
21 ± 2 °C
The pH was measured at the beginning and the end of the test. At the beginning the pH was determined in an additionally prepared replicate. In the end the vessels were measured directly.
Nominal and measured concentrations:
The following concentrations were applied: 3.125, 6.25, 12.5, 25.0, 50.0, 100.0, 200.0 and 400.0 mg/l ogthe test item.
The evaluation of toxic effect was based on the nominal concentrations of test item.
Details on test conditions:
Eight test solutions of different concentration were prepared by mixing appropriate volume of OECD medium and stock solution of the test substance. Using serial dilution of the test solutions, the initial test concentration was multiplied by two to get the next concentration in the series. Range of concentration of the test item for the test was determined previously in a range-finding test. The alga cell concentration in every dilution and the control levels were 5 001 cells/ml.
Three replicates were prepared at every test and six at the control level. The vessels contained 75 ml test media.
At 24, 48 and 72 hours after the beginning of the test the alga cell concentrations were determined by microscopically counting with a Bürker chamber. The initial alga cell density was calculated from the dilution ratio of inoculum culture.

Results and discussion

Effect concentrations
72 h
Dose descriptor:
Effect conc.:
>= 400 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
The NOEC and LOEC were determined by the ToxRat® statistic software.
The results of the test showed that the test item had not got any toxic effect for the growth rate of Pseudokirchneriella subcapitata even at the highest concentration (400 mg/l).

Applicant's summary and conclusion

Validity criteria fulfilled:
In this Freshwater Alga and Cyanobacteria, Growth Inhibition Test for “Trimethylsulfoxonium Iodide” (CAS No. 1774-47-6) the results indicated that the test item is not hazardous to the aquatic environment and should not be categorized into any GHS classification categories.