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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:
Between 16 August 1999 and 19 August 1999 for range finding study and between 27 September 1999 and 30 September 1999 for definitive study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
(1984)
Referenced as C.3 in Commission Directive 92/69/EEC
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Remarks:
Concentration and stability of the test material in the test solutions was verified by chemical analysis at 0 and 72 hours.
Details on sampling:
A range of pre-study test samples was prepared in bottles and analysed initially and then after storage at ambient temperature in light and dark conditions for approximately 72 hours (equivalent to the study exposure period). The test samples have been considered to be sufficiently stable for the purposes of this study. The unsolicited vessel stability samples show no evidence of insolubility or adherence to glass.
Vehicle:
no
Details on test solutions:
The test material was prepared by direct solution in culture medium. An amount of test material was dissolved in culture medium and the volume adjusted to 500 ml to give a 128 mg/l stock solution from which a series of dilutions were made to give 64, 32, 16 and 8.0 stock solutions. An aliquot (250 ml) of each of these stock solutions was separately inoculated with algal suspension (250 ml) to give the required test concentrations of 4.0, 8.0, 16, 32 and 64 mg/l.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Scenedesmus subspicatus strain CCAP 276/20 was used. Liquid cultures of the organism were obtained from the Culture Centre for Algae and Protozoa (CCAP), Institute of Freshwater Ecology, Ferry House, Ambleside, Cumbria. Cultures were maintained in the laboratory by the periodic replenishment of culture medium. The culture was maintained in the laboratory at a temperature of 21 +/- 1 C under continuous illumination (intensity approximately 7000 lux) and constant aeration.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
As described in the Test Guidelines
Post exposure observation period:
No information
Hardness:
Not measured
Test temperature:
24 +/- 1C
pH:
Not mentioned
Dissolved oxygen:
Not mentioned
Salinity:
Not measured
Conductivity:
Not mentioned
Nominal and measured concentrations:
All concentrations were nominal:
4.0, 8.0, 16, 32 and 64 mg/l
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
56 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
59 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Reported statistics and error estimates:
One way analysis of variance incorporating Bartlett's Test for homogeneity of variance and Dunnett's Test for comparison of control mean with treatment mean was carried out on the area under the growth curve data at 72 hours for the control and all test concentrations to determine any statistically significant differences between test and control groups.

Inhibition of growth rate and biomass

Nominal concentration (mg/l) Area under curve at 72 h % inhibition Growth rate (0-72h) % inhibition
Control 6.30E+06 - 0.045 -
4 5.81E+06 8 0.044 2
8 6.46E+06 [3] 0.046 [2]
16 7.95E+06 [26] 0.048 [7]
32 8.61E+06 [37] 0.049 [9]
64 -6.31E+05 110 -0.019 142

Numbers in [] indicate increase in growth compared to controls

Validity criteria fulfilled:
yes
Conclusions:
ErC50 (0 to 72h)= 59mg/l. Water hardness is not measured. Compound should be labelled as harmful to aquatic organisms and may cause long term adverse effects in the aquatic environment.
Executive summary:

Methods

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 (1984) No 201, "Algal Growth Inhibition Test". referenced as Method C.3 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).

Procedure

Following a preliminary range-finding study, Scenedesmus subspicatus was exposed to an aqueous solution of the test material at concentrations of 4.0, 8.0, 16, 32 and 64 mg/l (three replicate flasks per concentration) 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 II Particle Counter.

Results

Exposure of Scenedesmus subspicatus to the test material gave an EbC50 (72h) value of 56 mg/l and an ErC50 (0 -72h) value of 59 mg/l. The No Observed Effect Concentration was 32 mg/l. Analysis of the test solutions at 0 and 72 hours showed the measured test concentrations to be near nominal and so the results are based on nominal test concentrations alone.

Description of key information

A study was performed to assess the effect of the test material on the growth of the green algaScenedesmus subspicatus.The method followed that described in the OECD Guidelines for Testing of Chemicals (1984) No 201, "Algal Growth Inhibition Test". referenced as Method C.3 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).

Exposure of Scenedesmus subspicatus to the test material gave an EbC50 (72h) value of 56 mg/l and an ErC50 (0 -72h) value of 59 mg/l. The No Observed Effect Concentration was 32 mg/l. Analysis of the test solutions at 0 and 72 hours showed the measured test concentrations to be near nominal and so the results are based on nominal test concentrations alone.

Key value for chemical safety assessment

EC50 for freshwater algae:
59 mg/L
EC10 or NOEC for freshwater algae:
32 mg/L

Additional information