[2R-[2α(E),3β]]-2-[2-(3,4-dihydro-6-methoxy-1(2H)-naphthylidene)ethyl]-2-ethyl-3-hydroxycyclopentan-1-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:

Nov - Dec 2001

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:

2005

Report date:

2005

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:

[2R-[2α(E),3β]]-2-[2-(3,4-dihydro-6-methoxy-1(2H)-naphthylidene)ethyl]-2-ethyl-3-hydroxycyclopentan-1-one

EC Number:

257-409-4

EC Name:

[2R-[2α(E),3β]]-2-[2-(3,4-dihydro-6-methoxy-1(2H)-naphthylidene)ethyl]-2-ethyl-3-hydroxycyclopentan-1-one

Cas Number:

51773-49-0

Molecular formula:

C20H26O3

IUPAC Name:

17 beta-Hydroxy-3-methoxy-18-methyl-8,14-seco-1,3,5(10),9(11)-estratetraen-14-one

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

- Name of test material (as cited in study report): 13-Ethylsecol
- Analytical purity: 99.9%
- Lot/batch No.: 71004011

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.:

11.4 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 11.0 - 11.8 mg/L

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

10.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 7.8 - 12.1 mg/L

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 46072

		Inhibition in percent
Dilution of ZK46072	Concentration of ZK 46072 (mg/L)	Biomass (integral)	Growth
0	0,0 (control)	0	0
1:100	0,2	6,2	4,5
1:50	0,4	-3,4	0,5
1:25	0,9	-29,5	-3,7
1:10	2,2	-13,3	0,6
1:5	4,4	0,4	5,0
Saturated solution	17,7	89	86,8

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

13-Ethylsecol had an inhibitory effect on the growth of Desmodesmus subspicatus. The EbC50 (biomass) was 11.4 mg/L [95% confidence limits: 11.0 -11.8], the ErC50 (growth rate) was 10.1 mg/L [95% confidence limits: 7.8-12.1] on the basis of measured concentrations.
Consequently, 13-Ethylsecol was considered to be toxic to the green algae Desmodesmus subspicatus, since the EC50 was approximately 10 mg/L.

Executive summary:

The purpose of this study was to determine the effects of the test compound 13 -Ethylsecol (ZK 46072) on the

growth of the green algae Desmodesmus subspicatus. 13 -Ethylsecol is an intermediate of the synthesis of gestodene and levonorgestrel. 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 nominal loading of 100 mg/L the test substance in water was kept for approximately 30 min in an ultrasonic bath and stirred for approximately 24 hours. The highest concentration was a 1: 1.25 dilution obtained by adding nutrient solution and inoculum, the further concentrations were obtained by dilutions of 1: 100; 1:50; 1:25; 1: 10 and 1:5 with demineralized water, nutrient

solution and inoculum. 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 at the start of the incubation. The substance concentration was calculated on the basis of the molecular formula. It was 22.1 mg/L. 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 standardized conditions (continous light, controlled temperature).

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. 13-Ethylsecol was considered to be toxic to the green algae Desmodesmus subspicatus, since the EC50 was approximately 10 mg/L.