3-methoxyestra-2,5(10)-dien-17-one

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:

Dec 2002 - Jan 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to OECD guideline under GLP

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Principles of method if other than guideline:

Not relevant

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

3-methoxyestra-2,5(10)-dien-17-one

EC Number:

241-893-9

EC Name:

3-methoxyestra-2,5(10)-dien-17-one

Cas Number:

17976-32-8

Molecular formula:

C19H26O2

IUPAC Name:

3-methoxyestra-2,5(10)-dien-17-one

Details on test material:

- Name of test material (as cited in study report): Dihydro-Estron-Methylether
- Analytical purity: 99.9%
- Lot/batch No.: 29023001

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 concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Any other information on results incl. tables

Table 1: Inhibition of biomass and the growth rate (%) of Desmodesmus subspicatus after 72 hours exposure to ZK28521

	Inhibition in %
Dilution of ZK 28521 0	Biomass (integral)	Growth rate
1:100	58,4	36
1:50	69,1	41,5
1:25	81,7	66,2
1:10	84,7	64,7
1:5	92,1	92,1
Saturated solution	93,1	85,9

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

ZK 28521 had a concentration-depended inhibitory effect on the growth of Desmodesmus subspicatus at all dilutions. The EbC50 (biomass) and the ErC50 (growth rate) was below the detection limit of 1 mg/L on the basis of TOC analysis.
Consequently, ZK 28521 was considered to be very toxic to the green algae Desmodesmus subspicatus, since the EC50 was below 1 mg/L.

Executive summary:

TThe biomass and growth rate was inhibited at dilutions of 1: 1 00 of the saturated solution and above. This was considered to be a compound related effect.he purpose of this study was to determine the effects of the test compound Dihydro-Estron-Methylether (ZK 28521) on the growth of the green algae Desmodesmus subspicatus. ZK 28521 is an intermediate of the synthesis of Gestonorone. 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 ultrasonified and stirred for 24 hours. This suspension was filtered through a glassfibre filter. The resulting solution served as the highest concentration (equivalent to "saturated solution"), which was a 1: 1.25 dilution by adding nutrient solution and inoculum. It . was further diluted 1 :5, 1: 1 0, 1 :25, 1 :50 and I: 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 TOC analyzer in an sampIe taken at the start of the incubation. The substance concentration was calculated on the basis ofthe molecular formula. It was < 1 mg/L (detection limit).

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 dilutions of 1: 1 00 of the saturated solution and above. This was considered to be a compound related effect.