Gona-1,3,5(10)-trien-17-ol, 13-ethyl-3-methoxy-, (17.beta.)-

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:

Jan - Mar 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:

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:

3-Methoxy-18-methyl-1,3,5(10)-estratrien-17 beta-ol

EC Number:

609-222-8

Cas Number:

3625-82-9

Molecular formula:

C20 H28 O2

IUPAC Name:

3-Methoxy-18-methyl-1,3,5(10)-estratrien-17 beta-ol

Details on test material:

- Name of test material (as cited in study report): D-ET-Trienol
- Analytical purity: 101.4%
- Lot/batch No.: 21545002

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.:

> 7.8 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.:

> 7.8 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 ZK 46060

Dilution of ZK46060	Concentration of ZK46060 (mg/L)	Inhibition of Biomass (integral) %	Inhibition of Growth rate %
0	0,0 (control)	0	0
1:100	0,1	-14,9	1,2
1:50	0,2	0	2,4
1:25	0,4	19,3	21,3
1:10	1	7,8	1,2
1:5	2	-1,8	8,7
1:1,25	7,8	-31,7	3,6

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

ZK 46060 had no concentration-depended inhibitory effect on the growth of Desmodesmus
subspicatus. The EbC50 (biomass) and the ErC50 (growth rate) was higher than a saturated solution
(7.8 mg/L on the basis of TOC measured concentrations).

Executive summary:

The purpose of this study was to determine the effects of the test compound D-ET-Trienol (ZK 46060) on the growth of the green algae Desmodesmus subspicatus. D-ET-Trienol is an intermediate of the synthesis of Norgestrel. The study was conducted in agreement with the test guideline OECD no. 201.

The test substance was incubated in an aqueous solution inc1uding 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 of the test substance, was suspended in water, ultrasonified for approximately 30 min and constantly stirred for approximately 24 hours. This suspension was filtered through a glassfibre filter. The resulting solution was used for the preparation of the test solutions. The highest concentration was obtained from a 1: 1.25 dilution by adding nutrient solution and inoculum, the further concentrations were obtained by dilutions of 1:5,1:10,1:25,1:50 and 1:100 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 in a sample taken at the start of the incubation. The substance concentration was calculated on the basis of the molecular formula. It was 9.7 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 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 ca1culated 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.

There was a relatively high variability in the inhibition of biomass (19% decrease to 32% increase), but no concentration relationship. Therefore, this variation is considered to represent natural variability.