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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
From March 15, 1999 to March 18, 1999
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
RA study
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Remarks:
TOC determination
Details on sampling:
Analysis of the only test concentration plus a control at start and after 72 h of exposure
Vehicle:
no
Remarks:
direct weighing
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Origin: Institute of Plant Physiology University of Göttingen
Conditions: in a light chamber et 23 +/- 2°C and with a quantum flux which equals 120 µE/m2.s
Initial cell density: 10,000 cells per mL
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
23 +/- 2°C
pH:
8.3 - 10.3
Nominal and measured concentrations:
0 and 100 mg/L (measured)
Details on test conditions:
Erlenweyer flasks (300 mL) with stoppers
100 mL of test medium
Light chamber and magnetic stirrer
Observations: growth and growth rate within a 72 h exposure period
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
84.8 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth and growth rate
Remarks on result:
other: 84.8 mg/L (organic components)
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
>= 84.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
84.8 mg/L of the organic components is equivalent to 103.4 mg/L of the test substance including the inorganic components
Basis for effect:
other: growth rate and biomass
Details on results:
Growth (integral of biomass): -16.3% (increase of growth)
Growth rate: -6.7% (increase of growth rate)
No toxic effects against algae at 84.8 mg/L of the organic components of the test substance (equals to 103.4 mg/L of the test substance including the inorganic components).
Results with reference substance (positive control):
-
Validity criteria fulfilled:
yes
Conclusions:
Under the study conditions, the mean measured 72 h NOEC of the substance in Desmodesmus subspicatus was determined to be greater than 84.8 mg/L of the organic components (equivalent to 103.4 mg/L of the substance including inorganic components). The EC10 and EC50 could not be determined due to absence of adverse effects.
Executive summary:

A study was conducted to determine the short-term toxicity of the read-across substance to aquatic algae and cyanobacteria according EU Method C.3, in compliance with GLP. Desmodesmus subspicatus were exposed for 72 h to the test substance at nominal concentrations of 0 and 100 mg/L. Growth rate and cell density were assessed at start and end of 72 h of exposure period. Analytical verification of test concentrations was conducted by TOC determination. The growth rate was determined to be -6.7%. No toxic effects against the algae were observed at the test substance concentration. Under the study conditions, the mean measured 72 h NOEC of the substance in Desmodesmus subspicatus was determined to be greater than 84.8 mg/L of the organic components (equivalent to 103.4 mg/L of the test substance including inorganic components) (Caspers, 1999). The EC10 and EC50 could not be determined due to absence of adverse effects.

Description of key information

Under the read-across study conditions, the mean measured 72 h NOEC of the substance in Desmodesmus subspicatus was determined to be greater than 84.8 mg/L of the organic components (equivalent to 103.4 mg/L of the test substance including inorganic components). The EC10 and EC50 could not be determined due to absence of any adverse effects.

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

A study was conducted to determine the short-term toxicity of the read-across substance to aquatic algae and cyanobacteria according EU Method C.3, in compliance with GLP. Desmodesmus subspicatus were exposed for 72 h to the test substance at nominal concentrations of 0 and 100 mg/L. Growth rate and cell density were assessed at start and end of 72 h of exposure period. Analytical verification of test concentrations was conducted by TOC determination. The growth rate was determined to be -6.7%. No toxic effects against the algae were observed at the test substance concentration. Under the study conditions, the mean measured 72 h NOEC of the substance in Desmodesmus subspicatus was determined to be greater than 84.8 mg/L of the organic components (equivalent to 103.4 mg/L of the substance including inorganic components) (Caspers, 1999). The EC10 and EC50 could not be determined due to absence of any adverse effects.