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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
May - Sept 2000
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: According to guideline under GLP
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 201 (Alga, Growth Inhibition Test)
Principles of method if other than guideline:
Not relevant
GLP compliance:

Test material

Details on test material:
- Name of test material (as cited in study report): 1-Alpha-Methylandrostendion
- Analytical purity: 98.7%
- Lot/batch No.: 1365

Sampling and analysis

Analytical monitoring:

Test solutions


Test organisms

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

Study design

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

Results and discussion

Effect concentrationsopen allclose all
72 h
Dose descriptor:
Effect conc.:
0.014 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
72 h
Dose descriptor:
Effect conc.:
0.057 mg/L
Nominal / measured:
meas. (arithm. mean)
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 ZK 62096

Inhibition in %
 Dilution of ZK 62096 of saturated solution    Concentration of ZK 62096 (mg/L)   Biomass   Growth rate  
0  0,0 (control)   0 0
 1:800    0,05 64,8 40
 1:400    0,11 87,5 91,1
 1:200    0,21 84,9 94,5
 1:100    0,42 89,9 112,4
 1:50    0,85 91,9 120,4
 1:30    1,41 94,8 137,7

Applicant's summary and conclusion

Validity criteria fulfilled:
ZK 62096 had a concentration-depended inhibitory effect on the growth of Desmodesmus subspicatus. The EbC50 (biomass) was 0.014 mg/L
(95% confidence limits were not calculated). The ErCso (growth rate) was 0.057 mg/L (95% confidence limits were not calculated) on the basis
of concentrations extrapolated from TOC measurement of the stock solution. Consequently, ZK 62096 was considered to be very toxic to the
green algae Desmodesmus subspicatus, since the EbC50/ ErC50 were below 1 mg/L.
Executive summary:

The purpose of this study was to determine the effects of the test compound ZK 62096 on the growth of the green algae Desmodesmus subspicatus. 1-Alpha-Methylandrostendion is an intermediate of the synthesis of mesterolone. The study was conducted in agreement with the test guideline OECD no. 201.

The test substance 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 nominalloading of 100 mg/L test substance in water was treated in an ultrasonic bath for 30 minutes and thereafter stirred for 24 hours at room temperature. This suspension was filtered through a glassfibre filter. The resulting solution (stock solution) was diluted

1 :20 (predilution). This predilution was further diluted 1: 1.5, 1 :2.5, 1 :5, 1: 1 0, 1 :20 and 1 :40 with demineralized water. Additionally, a control solution was prepared with demineralized water without test material. The organic carbon concentration of the undiluted stock solution was analyzed with a TOC analyzer at the start of the incubation. The substance concentration was calculated on the basis of the molecular formula. It was 42.4 mg/L. The further test concentrations were extrapolated from the result of the TOC-analysis and are shown in the table below. 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 calculated biomass and growth rate of each concentration were compared to those of the controls, and the inhibition was calculated.

The biomass and growth rate was inhibited at all concentrations (65 to 95% for the biomass and 40 to 100% for the growth rate). This was considered to be a compound related effect.