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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
17/03/2008 - 08/05/2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report Date:
2008

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
OECD guidelines for Testing of Chemicals, guideline No. 201: "Freshwater alga and Cyanobacteria, Growth Inhibition Test", Adopted March 23, 2006
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
European Economic Community (EEC), EEC directive 92/69, Part C: Methods for the determination of ecotoxicity, Publication No. L383, December 1992, C-3: "Algal inhibition Test"
Qualifier:
according to
Guideline:
ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)
Version / remarks:
ISO International Standard 8692: "Water quality - Freshwater algal growth inhibition test with unicellular green algae", Second edition, 01 October 2004
Qualifier:
according to
Guideline:
other: Guidance document 23
Version / remarks:
Guidance document on aquatic toxicity testing of difficult substances and mixtures, OECD series on testing and assessment number 23, December 14, 2000
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Test material form:
solid: particulate/powder
Details on test material:
- Description: dark purple powder
- Solubility in the water: <= 0.412 g/L
- Melting point: > 250 °C
- Boiling point: > 250 °C
- Explosion: not explosion
- Log Pow: >= 3.3
- Test substance storage: at room temperature in the dark, 20°C, dry store
- Stability under storage conditions: stable
Specific details on test material used for the study:
solubility in water: poorly

Test solutions

Details on test solutions:
Preparation of the test solutions started with a loading rate of 100 mg/l applying a 15-minute treatment period with ultrasonic waves followed by 35 minutes of magnetic stirring to obtain maximum solubility in the test medium. Subsequently, the mixture was left to stabilise for 2 hours after which the Water Soluble Fraction (WSF) was siphoned off. However, very small particles were observed in this WSF. Therefore, the WSF was left to stabilise for another 30 minutes and a second WSF was siphoned off. The lower test concentrations were prepared by subsequent dilutions of the second WSF in test medium. The final test solutions were all clear and ranged from colourless to dark pink.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Source: in-house laboratory culture
Reason for selection: This system is an unicellular algal species sensitive to toxic substances in the aquatic ecosystem and has been selected as an internationally acceptes species

Study design

Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h

Test conditions

Test temperature:
Temperature of medium: Continuously in a temperature control vessel
pH:
Measurements: pH: At the beginning 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
Reference substance (positive control):
yes
Remarks:
This report includes the results of the most recent reference test with potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 12 mg/L
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
ca. 1.2 mg/L
Basis for effect:
other: yield inhibition
Details on results:
The EC50 for growth reduction (ERC50: 0-72h) was 12 mg/l with a 95% confidence interval ranging from 7.7 to 18 mg/l
The EC50 for yield inhibition (EYC50: 0-72h) was 1.2 mg/l with a 95% confidence interval ranging from 0.39 to 3.7 mg/l

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the present study with Pseudokirchneriella subcapitata, SXjul2006 reduced growth rate of this fresh water algae species significantly at average exposure concentrations of 0.86 mg/l and higher.

The EC50 for growth reduction (ERC50: 0-72h) was 12 mg/l with a 95% confidence interval ranging from 7.7 to 18 mg/l

The EC50 for yield inhibition (EYC50: 0-72h) was 1.2 mg/l with a 95% confidence interval ranging from 0.39 to 3.7 mg/l

The NOEC for growth rate reduction was 0.21 mg/l, while the NOEC for yield inhibition was < 0.21 mg/l.

Effect parameters were based on a worst case scenario. It can not be excluded that a least part of the effect was due to absorption of wavelenghts necessary for algal growth by the colour of the test solutions.