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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:
25 January 2018 to 08 March 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Reliable experimental study following OECD 201 guidelines (2006) and EC No. 761/2009 Method C.3 adopted 2009 and GLP standards.
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
2006
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
2009
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Vehicle:
no
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
The test was carried out using Pseudokirchneriella subcapitata strain CCAP 278/4. Liquid cultures of Pseudokirchneriella subcapitata were obtained from the Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd, Scottish Marine Institute, Oban, Argyll, Scotland. Master cultures were maintained in the laboratory by the periodic replenishment of culture medium. The master cultures were maintained in the laboratory under constant agitation by orbital shaker (100 to 150 rpm) and constant illumination at 24 ±1 °C.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24 °C ± 1 °C
pH:
7.5 – 8.6
Nominal and measured concentrations:
Based on the results of a preliminary range-finding test, the green alga was exposed to an aqueous solution of the test item at nominal concentrations of 6.25, 12.5, 25, 50 and 100 % v/v saturated solution (three replicate flasks per concentration).
Details on test conditions:
10 mg/L)
Reference substance (positive control):
yes
Remarks:
Potassium dichromate was the reference item in a study at concentrations of 0.25 mg/L, 0.50 mg/L, 1.0mg/L, 2.0 mg/L and 4.0 mg/L. The results from the positive control with potassium dichromate were within the normal ranges for this reference item.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 other: % v/v saturated soluition
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
100% v/v saturated solution prepared from a test solution with a loading rate of 10 mg/L.
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Test solution prepared with a loading rate of 10 mg/L resulting in a 100% v/v saturation solution.
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
> 100 other: % v/v saturated solution
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
100% v/v saturated solution prepared from a test solution with a loading rate of 10 mg/L.
Duration:
72 h
Dose descriptor:
EL20
Effect conc.:
> 10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Test solution prepared with a loading rate of 10 mg/L resulting in a 100% v/v saturation solution.
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 other: % v/v saturated solution
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
100% v/v saturated solution prepared from a test solution with a loading rate of 10 mg/L.
Key result
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Test solution prepared with a loading rate of 10 mg/L resulting in a 100% v/v saturation solution.
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
100 other: % v/v saturated solution
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
100% v/v saturated solution prepared from a test solution with a loading rate of 10 mg/L.
Duration:
72 h
Dose descriptor:
LOELR
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Test solution prepared with a loading rate of 10 mg/L resulting in a 100% v/v saturation solution.
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
50 other: % v/v saturated solution
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
50% v/v saturated solution was a dilution of the initial test solution of 100% v/v saturated solution; the initial test solution was prepared with a loading rate of 10 mg/L.
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Test solution was a dilution of the initial test solution; the initial test solution was prepared with a loading rate of 10 mg/L resulting in a 100% v/v saturation solution.
Results with reference substance (positive control):
The results from the positive control with potassium dichromate were within the normal ranges for this reference item.
Reported statistics and error estimates:
One way analysis of variance incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf, 1981) and Dunnett's multiple comparison procedure for comparing several treatments with a control (Dunnett, 1955) was carried out on the growth rate and yield data after 72 hours for the control and all test concentrations to determine any statistically significant differences between the test and control groups. All statistical analyses were performed using the SAS computer software package (SAS, 1999 - 2001).

Analysis of the 50% and 100% v/v saturated solution test preparations at 0 and 72 hours showed measured test concentrations of less than the LOQ (0.26 mg/L) of the analytical method. This does not infer that no test item was in solution, just that any dissolved test item present was at a concentration of less than the LOQ.

Given that measurable levels of test item could not be detected in the test preparations, in accordance with the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures (OECD 2000) results were calculated based on nominal test concentrations. Results were also calculated based on the initial loading rate of the 100% v/v saturated solution (10 mg/L).

Validity criteria fulfilled:
yes
Remarks:
Cell concentrations of control increased by a factor of 265 after 72 h (protocol ≥ factor of 16); mean of coeffi of var. for growth rates control 4% (protocol ≤ 35%); coeff. of var.of avg. sp.growth rate in replicate control cultures 3% (protocol ≤ 7%).
Conclusions:
The test substance did not cause a reduction of growth in a series of algal cultures (test units) exposed to the test item for 72 h; therefore, there were no toxic or inhibitory effects at saturation. The 72-h EC50, 72-h EC20, and 72-h EC10 (based on growth rate) were each reported as > 100% v/v saturated solution; the corresponding 72-h EL50, 72-h EL20 and 72-h EL10 (based on growth rate) were each reported as > 10 mg/L (based on the nominal loading rate).

Description of key information

ErL50 (72 h) > 10 mg/L (nominal loading rate)

ErL10 (72 h) > 10 mg/L (nominal loading rate)

Key value for chemical safety assessment

Additional information

The toxicity of the substance to aquatic algae was tested in a guideline study following OECD Guideline 201. The test was set up as a limit test with a nominal test substance concentration of 10 mg/L (initial loading rate). The effects concentrations were based on the nominal test concentration of 100% v/v saturated solution which was prepared from an initial test solution with a nominal loading rate of 10 mg/L. The green algae Pseudokirchneriella subcapitata was exposed for 72 hours. An inhibition of algal growth was not observed. The reported ErL50(72 h) was >10 mg/L (nominal loading rate).   ErL10(72 h) was >10 mg/L (nominal loading rate).