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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guidelineopen allclose all
according to
EU Method C.3 (Algal Inhibition test)
according to
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. certificate)

Test material

Specific details on test material used for the study:
Identification: Nitrile Iso C 11
Description: Colourless liquid
Batch: 004925
Test substance storage: At room temperatre in the dark
Expiry date: 08 March 2003

Sampling and analysis

Details on sampling:
During the final test, samples for analysis were taken from all test concentrations and the acetone-control.
Frequency: at t=0 h, t=24 h and t=72 h
Volume: 10 ml
Storage: Not applicable, samples were analysed on the day of sampling

Compliance with the Quality criteria regarding maintenance of actual concentrations was demonstrated by running a test vessel at the highest substance concentration but without algae and samples for analysis were taken at the start and the end of the test period.

Additionally, reserve samples of 10ml were taken from all test solutions for possible analysis. If not already used, these samples were stored in a freezer for possible analysis until delivery of the final report with a maximum of three months.

Test solutions

not specified
Details on test solutions:
Test concentrations: 0.2, 0.4, 0.8, 1.6 and 3.2 mg/l
Controls: Test medium without test substance or other additives (blank) and one control containing the additive (acetone) used in the treatment of the stock solutions.
Replicates: 3 replicates of each test concentration
6 replicates of the blank and acetone-control
2 replicates of the highest concentration without algae
1 extra replicate of each test concentration with algae for sampling after 24 hours

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Reason for selection: This system is a unicellular algal species sensitive to toxic substances in the aquatic ecosystem and has been selected as an internationally accepted species.
Stock culture: Algae stock cultures were started by innoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light (4000-9000 lux) in a climate room at a temperature of 23 +/- 2 °C
Pre-culture: 4 days before the start of the test, cells from the algal stock culture were inoculated in culture medium at a cell density of 2.10^4 cells/ml. The pre-culture was maintained under the same conditions as used in the test. The cell density was measured immediately before use.

Study design

Test type:
Water media type:
other: tap-water
Total exposure duration:
72 h

Test conditions

Test temperature:
Measured every day in a temperature control vessel.
Measurements were taken at the begining and at the end of the test. The pH of the solutions should preferably not deviate by more than 1.5 units during the test.

Results and discussion

Effect concentrationsopen allclose all
Key result
72 h
Dose descriptor:
Effect conc.:
0.26 mg/L
Conc. based on:
test mat.
Basis for effect:
other: cell growth inhibition
Key result
72 h
Dose descriptor:
Effect conc.:
1.6 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
72 h
Dose descriptor:
Effect conc.:
0.84 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate

Any other information on results incl. tables

Acceptability of the test:

1. In the controls, cell density increased by an average factor of > 16 within three days.

2. Analysis of samples taken during the final study showed that the actual exposure concentrations could not be maintained within 80% relative to the initial concentrations. This could not be prevented, as the experimental design does not allow for intermittent renewal. As a consequence, toxicity parameters were based on time weight average exposure concentrations.

3. Further, all test conditions (temperature and pH) remained within the ranges prescribed by the protocol, except for the pH in most treatment levels. The pH increased by more htat 1.5 unit, but this was related to a relative high rate of algal growth. Hence, this deviation did not affect the validity criterion for algal growth.

Applicant's summary and conclusion

Validity criteria fulfilled:
A guideline study, conducted according to GLP, Floridile was found to have an ErC50 (72 hr) for growth rate reduction of 1.6 mg/L, ErC10 (72 hr) for growth rate reduction of 0.84 mg/L and a NOEC (72 hr) for cell growth inhibition of 0.26 mg/L