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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
Study period:
Oct 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: According to OECD guideline under GLP
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001
Report Date:
2001

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Principles of method if other than guideline:
Not relevant
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Canrenone
- Analytical purity: 98.4%
- Lot/batch No.: 90515001

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.8 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% CL=0.7-8.6
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
4.2 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate

Any other information on results incl. tables

Table 1: Inhibition of biomass and the growth rate (%) of Desmodesmus subspicatus after 72 hours exposure to canrenone

 Dilution of   Concentration    Inhibition in percent  
 canrenone    of canrenone (mg/L)    Biomass (integral)  Growth rate  
0  0,0 (control)    ----   ---- 
 1 :100   0,12 15 5,3
 1:50 0,23 13,6 10,1
 1:25   0,46 10,7 5,7
 1:10   1,16 17,1 5,9
 1:5   2,32 70,7 34,9
 Saturated solution   9,3 96,4 105,3

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Canrenone had an inhibitory effect on the growth of Desmodesmus subspicatus. The EbC50
(biomass) was 1.8 mg/L [95% confidence limits: 0.7-8.6], the ErC50 (growth rate) was 4.2 mg/L
[95% confidence limits not calculated] on the basis of measured TOC concentrations.
Consequently, canrenone was eonsidered to be toxic to the green algae Desmodesmus
subspicatus, since the EC50 was smaller than 10 mg/L.
Executive summary:

The test substance canrenone was incubated in an aqueous solution including nutrients with an algae population of Desmodesmus subspicatus for a test duration of approximately 72 hours in an electronically controlled dosing and incubation apparatus. The nutrient solution was made up of mainly nitrate, phosphates and some trace elements. For the preparation of the test solutions a suspension with a nominal loading of 100 mg/L canrenone in water was stirred for 24 hours. This suspension was filtered through a glassfibre filter. The resulting solution served as the highest concentration (saturated solution). It was further diluted 1 :5, 1: 1 0, 1 :25, 1 :50 and 1:100 with demineralized water. Additionally, a control solution was prepared with demineralized water without test material. The organic carbon concentration of the stock solution was analyzed with a TOG analyzer at the start of the incubation. The substance concentration was calculated on the basis of the molecular formula. It was 11.6 mg/L. Accordingly, for the highest test concentration (equivalent to "saturated solution") it was 9.3 mg/L. The concentrations of the further test concentrations were extrapolated from the result of the TOC-analysis. The algae were exposed to each concentration in triplicate. Six vessels were prepared for the control. The algae were incubated under continuous light, controlled temperature and standard conditions. As a parameter for the growth of the algae population, the fluorescence of the algal cells was measured with a fluorescence-photometer. The increase of biomass and the growth rate were calculated on the basis of the fluorescence.

The biomass and growth rate were inhibited at the dilution of 1:5 and in the saturated solution. The marginal reduction in growth at the lower concentrations was not considered to be a compound related effect, since it was not concentration related. It is likely that the lower growth was due to natural variation.