Registration Dossier

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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study, OECD guideline

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report Date:
2005

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
2003-02-13

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Sponsor's identification: aquaxyl
Description: yellow solid
Batch number: 173 JG1
Storage conditions: room temperature in the dark

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Samples were taken from the control (replicates R1-R3 pooled) and the 100 mg/L test group (replicates R1-R3 and R4-R6 pooled) at 0 and 72 for quantitative analysis. Duplicate samples were taken at 0 and 72 hours and stored at approximately -20°C for further analysis if necessary.

Test solutions

Vehicle:
yes
Details on test solutions:
Identity and concentration of auxiliary solvent for dispersal: none

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Liquid cultures of Scenedesmus subspicatus were obtained from the culture collection of algae and Protozoa (CCAP), Dunstaffnage Marine Laboratory, Oban, Argyll, Scotland. Culture were maintained in the laboratory by the periodic replenishment of culture medium.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

pH:
from 7.4 to 8.5
Nominal and measured concentrations:
nominal: 100 mg/L
measured: 76 and 77 mg/L
Details on test conditions:
Cell density at the start = 10^4 cell/mL
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 77 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 77 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
77 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
77 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
ErC50-72h > 100 mg/L (nominal concentration)
NOEC = 100 mg/L
Executive summary:

A study was performed to assess the effect of the test material on the growth of the green alga Scenedesmus subspicatus. The method followed that described in the OECD guidelines for testing of chemicals n°201 "alga growth inhibition test" referenced as method C.3 of comission directive 92/69/EEC.

Methods

Following a preliminary range-finding test, Scenedesmus subspicatus was exposed to an aqueous solution of the test material at a concentration of 100 mg/L (six replicate flasks) for 72 hours, under constant illumination and shaking at a temperature of 24 +/- 1 °C.

Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter Multisizer Particle Counter.

Results

Exposure of Scenedesmus subspicatus to the test material gave EC50 values greater than 100 mg/L and correpondingly the No Observed Effect Concentration was 100 mg/L.

It was considered unnecessary and unrealistic to test at concentrations in excess of 100 mg/L.

Analysis of the test preparations at 0 hours showed measured test concentrations to range from 107 to 108 % of nominal. Analysis of the test preparations at 72 hours. showed a marked decline in measured test concentrations in the range of 54 to 55 % of nominal.

Given that the preliminary stability analyses indicates that the test material was stable in culture medium over the test duration this decline was considered to be due to adsorption and/or absorption to algal cells. The preliminary recovery analyses indicated that no immediate adsorption/absorption to algal cells occured, this does however preclude long term adsorption/absorption over the test period.

Given this decline in measured test concentrations it was considered justifiable to base the results on the geometric mean measured concentrations in order to give a "worst case" analyses of the data. The EC50 values based on the geometric mean measured test concentrations were greater than 77 mg/L and correpondingly the No Observed Effect Concentrations was 77 mg/L.