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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:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
14 Mar - 17 Mar 2000
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions
according to guideline
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
- Melting point: 63 °C
- Boiling point: 351 °C
- Water solubility: 0.82 mg/L (at 25 °C)
- log Pow: 5.64
Analytical monitoring:
Details on sampling:
- Concentrations: 10 mg/L (nominal concentration)
- Sampling method: same volume of test water was sampled by each test vessel and mixed in each group at the test initiation and after exposure.
- Sample storage conditions before analysis: analysis was conducted immediately after sampling, no storage
Details on test solutions:
- Method: a stock solution (100 mg/L) was prepared with test substance, growth medium and dispersant. Stock solution was diluted with filter sterilized growth medium up to the concentration, and then filter sterilized.
- Controls: dilution water with/withour vehicle
- Chemical name of vehicle: HCO-50
- Concentration of vehicle in test medium: stock solution: 1000 mg/L, final test solution: 100 mg/L
- Evidence of undissolved material: test water was colurless and no precipitate was observed.
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
- Common name: alga
- Strain: ATCC-22662
- Source: American Type Culture Collection
- Age of inoculum: < 3 days
- Method of cultivation: on a rotary shaker

- Acclimation period: 3 days
- Culturing media and conditions: same as test
- Any deformed or abnormal cells observed: not observed
Test type:
Water media type:
Limit test:
Total exposure duration:
72 h
Test temperature:
22.0 - 23.0 °C (23 ± 2 °C )
at the initiation: 7.5 - 7.6
at the end: 8.4 - 9.1
Nominal and measured concentrations:
nominal concentration: 10.0 mg/L
meaured concentration: 0 hour: 0.9 mg/L, 72 hour: < 0.8 mg/L (under detection limit)
Details on test conditions:
- Test vessel: 300 mL Erlenmeyer flask capped with air-permeable stoppers
- Type: open
- Material, fill volume: glass, 100mL
- Initial cells density: 10000 cells/mL
- Control end cells density: 1884000 ± 59400 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 3

- Standard medium used: yes

- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuously
- Light intensity and quality: 4000 - 5000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter; 24, 48, 72 hours

- Justification for using less concentrations than requested by guideline: 10 mg/L is the highest concentration to be dissolved uniformly with sorvent (100 mg/L)
- Range finding study: performed
- Test concentrations: 100 mg/L
- Results used to determine the conditions for the definitive study: EbC50: > 100 mg/L
Reference substance (positive control):
potassium dichromate (reagent grade)
72 h
Dose descriptor:
Effect conc.:
> 0.9 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
72 h
Dose descriptor:
Effect conc.:
> 0.9 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
72 h
Dose descriptor:
Effect conc.:
> 0.9 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
72 h
Dose descriptor:
Effect conc.:
> 0.9 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
Details on results:
- Exponential growth in the control (for algal test): yes
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- EbC50: 0.52 mg/L
Reported statistics and error estimates:
F & t-test

Table 1: Growth inhibition of Selenastrum capricornutum

Initial Measured




Growth rate

Inhibition (%)

Inhibition (%)




Dispersant control






Description of key information

No effects up to the limit of water solubility are expected.

Key value for chemical safety assessment

Additional information

Studies are available for some pure homologue members of the fatty acid category. In addition some studies are available for certain fatty acid mixtures. Generally it could be stated that toxicity of fatty acids to aquatic organisms increases with increasing chain length up to the water solubility limit at a chain length of C12. For longer chains no effects at saturation are observed.

For the mixture under discussion here no study on algae is available. Thus a read-across is prepared to a study conducted with the pure homologue C16 (CAS 57 -10 -3), one of the main components of the mixture. For the other main constituent, stearic acid, no test on algae is available.

For the evaluation of the mixture only studies available for pure homologues which were determined as key were chosen for read-across.

Fatty acid homologue

EC50for growth rate (as reported in the study)

Water solubility*

Test design and species


C16 - CAS 57-10-3 palmitic acid

> 0.9 mg/L (initial mean measured)

< 0.05 at 20 °C

72 h, static,
Pseudokirchneriella subcapitata

NITE, 2003b

* see category justification

Palmitic acid (C16: CAS 57 -10 -3) was tested on Pseudokirchneriella subcapitata as well under OECD 201 in a GLP-study (NITE, 2003b). One test substance concentration was used (10 mg/L nominal, corresponding to 0.9 mg/L initial mean measured), which was above the reported water solubility limit for this substance (< 0.05 mg/L according to the category justification). As no effects could be observed at this test concentration, the EC50 for growth rate is reported to be above 0.9 mg/L (initial mean measured).

From the reported results of the test available for the fatty acid homologue C16 no adverse effects of the considered fatty acid mixture are expected on algae. In the cited test no effects up to the water solubility limits of the pure homologues were reported. Thus for the considered fatty acid mixture no effects within the range of water solubility is expected.