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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:
other information
Study period:
Aug 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: well documented GLP study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report date:
2010

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Ethisterone
EC Number:
207-096-5
EC Name:
Ethisterone
Cas Number:
434-03-7
Molecular formula:
C21H28O2
IUPAC Name:
(1R,3aS,3bR,9aR,9bS,11aS)-1-ethynyl-1-hydroxy-9a,11a-dimethyl-1H,2H,3H,3aH,3bH,4H,5H,7H,8H,9H,9aH,9bH,10H,11H,11aH-cyclopenta[a]phenanthren-7-one

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.:
0.5 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.003 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.03 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
cell number

Any other information on results incl. tables

The EC50 (growth rate) was slightly higher than the highest concentration tested.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The EC50 for ethisterone (ZK4957) is below 1 mg/L. The NOEC is 0.003, the LOEC 0.03 mg/L.
Executive summary:

The test substance ethisterone (ZK 4957) was incubated in an aqueous solution including nutrients with an algae population of Desmodesmus subspicatus for a test duration of approximately 72 hours. The test solutions were a saturated solution and a 1:10 and 1:100 dilution. The concentrations of the test solutions were extrapolated from a solubility test which gave a maximum solubility of 0.2 mg/L.

The growth of Desmodemus subspicatus was inhibited at the two highest concentrations. The EC50 was estimated with 0.5 mg/L, the NOEC was 0.003, the LOEC 0.03 mg/L.