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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
no analytical determination of the content of the test item in the test solution was made. The composition of stock solution II must be stated as deviation
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
yes
Remarks:
no analytical determination of the content of the test item in the test solution was made. The composition of stock solution II must be stated as deviation
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
White powder
Specific details on test material used for the study:
Batch : 839411/006Purity : 100.9 %Expiry date : 10.02.2008Storage : room temperature (20 +/-5°C), dry

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
Three treatments tested : 1/ 10/ 100 mg/L

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Strain : ChodatFamily : ChlorophyceaaOrder : ChlorococcalesObtained in August 2007 from the Collection of Alga, institut fur Pflanzenphysiologie of Universitat Gottingen. The Alga are kept as stock culture on solid agar at 8°C.

Study design

Test type:
not specified
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
0, 24, 48, 72h

Test conditions

Test temperature:
26-29°C
pH:
7.5 to 8
Details on test conditions:
light intensity : 6500 - 6900 lux
Reference substance (positive control):
yes
Remarks:
Potassium Dichromate (CAS 7778-50-9)

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC100
Effect conc.:
ca. 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: The test solution with the concentration of 100 mg/L turned brown and showed precipitation during the test. As in the concentration 100 mg/L, no algal growth wwas determined microscopically at the end of the test, inhibition was stated as 100%.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 10 - < 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 1 - < 10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 1 - < 10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
72 min
Dose descriptor:
LOEC
Effect conc.:
ca. 1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Details on results:
In all test concentrations, significant inhibition of the algal growth was determined. The test item changes its colour when getting in contact with the test medium. As the lowest test concentration (1 mg/L) could be evaluated properly, it can be statedn that the EC50 is higher than 1 mg/L but lower that 100 mg/L (and in the of EC50 of biomass and cell number lower than 10 mg/L).
Results with reference substance (positive control):
For the estimation of the EC50 of the reference item, the fits showed sufficient statistical correspondence of the data with the dose response-equation. The EC50 of potassium dichromate was tested in a current reference test. The values were withi the normal range of the laboratory
Reported statistics and error estimates:
T-test used

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The study conducted in accordance with OEC n°201 indicates; for the mephtamnin HCL ! 72h LOEC = 1mg/L - 72h EC50 (growth rate) = 10 -100 mg/L - 72h NOEC = not detectable.
Executive summary:

The study was performed using three concentrations ranging from 1 to 100 mg/L. The treatment were used to incubate the unicellular freshwater green alga Desmodesmus subspicatus for a period of 72 hours. The cell concentration of each replicate was determined by measuring the absorption of the cuvettes at 440 nm every 24 hours with a spectral photometer. With there measured values, the number of cells was calculated (linear correlation between cell concentration and adsorption given). Then the growth rate, the area under the growth curv and the yield were determined.

As the test item showed reaction with the test medium turing brown during the test, the highest test concentration couldn't be evaluated. In this concentration, no algal growth was visible microscopically ; therefore, the concentration 100 mg/L was stated as EC100. The EC50 of potassium dichromate was tested in a current reference test. The values were within the normal range of the laboratory.

The following results fo the tests item were determined : 72h LOEC = 1mg/L - 72h EC50 (growth rate) = 10 -100 mg/L - 72h NOEC = not detectable.