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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
07/01/1998-08/04/1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
According to the OECD Guideline and it is GLP
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
The algal stock culture was diluted to an initial cell concentration of =10^5 cells/mL (alga suspension) using the preculture medium.
Test solutions (Screening Test): 0.125g/500mL
Test solutions( Main Test): 125mg/500mL
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
- Origin: Sammlung von algenkulturen, pflanzenphysiologisches Institut der Universität Göttingen
The alga were purified from accompanying bacteria during the study and further cultivated under strictly aseptic conditions.
Test type:
not specified
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
25±1ºC
pH:
t0: 8.29
t72h: 10.08
Nominal and measured concentrations:
0; 0.125; 0.25; 0.5; 1.0 and 2.0 mg/L
Details on test conditions:
Three days prior to starting the test, a pre-culture was prepared using the algal stock culture.
3 days before start of the main test an algal pre-culture was prepared and inoculated with the algl stock solution. The concentration range was chosen after the results of the screening test.
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.28 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
2 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 2 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.2 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Remarks on result:
other: Screening-Test
Details on results:
The inhibition of the growth rates was calculated by extrapolation of the concentration/response curve.
Validity criteria fulfilled:
yes
Conclusions:
The inhibition of the biomass production to 10 and 50% was calculated as 0.28 mg/L and 2.0mg/L, respectively. The inhibition of the growth rate to 10 and 50% was calculated as 2.0 mg/L and >2.0mg/L by extrapolation of the concentration/response curve, respectively, in comparison to the non affected control.
Executive summary:

The chronic toxicity of the substance towards algae was tested according to OECD Guideline 201 and under GLP compliance.

The toxic effect was investigated by determination of the inhibition of the biomass production and the growth rate of the algae after an exposure period of 72 h. The test has been done at the following nominal concentrations: 0; 0.125; 0.25; 0.5; 1.0 and 2.0 mg/L.

Under the conditions being tested a NOEC as well as a 100% inhibition could not be determined. The inhibition of the biomass production to 10 and 50% was calculated as 0.28 mg/L and 2.0mg/L, respectively. The inhibition of the growth rate to 10 and 50% was calculated as 2.0 mg/L and >2.0mg/L by extrapolation of the concentration/response curve, respectively, in comparison to the non affected control. Within the screening-test at 20 mg/L, the inhibition of the biomass production was found to be 99.3% and that of the growth rate was 75.8%.

Description of key information

Based on a study performed according to the OECD 201 guideline and under GLP compliance, the inhibition of the biomass production to 10 and 50% was calculated as 0.28 mg/L and 2.0mg/L, respectively. The inhibition of the growth rate to 10 and 50% was calculated as 2.0 mg/L and >2.0mg/L by extrapolation of the concentration/response curve, respectively, in comparison to the non-affected control.

This study was considered acceptable for that endpoint.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
2 mg/L

Additional information

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