3-methoxyoestra-1,3,5(10)-trien-17-one

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Remarks:

Cell multiplication test

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Jan 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Turbidity of control was measured at 0 and approx. 16 h
Turbidity of test solution was measurd after approxx. 16 h
control and test solutions without inoclum were measured after approx. 16 h

Vehicle:

no

Details on test solutions:

Preparation of the stock solution and test solutions of the test substance
For the stock solution 1000 mg of test substance were suspended in 1000 mL sterile distilled water and constantly stirred at room temperature for 24 h. Afterwards, this suspension was filtered through a glassfibre filter. The filtered solution was directly used as the highest test concentrtaion. Then the solution was further diluted 1:10, 1:100 and 1:1000 with sterile distilled water in order to prepare the further test concentrations. 80 mL of the repsective solutions were filled into the test vessels.

Preparataion of the test solutions and addition of the inoculum
7.5 mL nutrient solutions were added to 80 mL test substance solutions. Finally, 10 mL of the inoculum were added.
Each test concentration and the control without test subststance were set up in triplicate. Additionally, one test vessel was used for each test concentration and the control without inoculum in order to analyse the substance-dependent turbidity (blank).

Test organisms (species):

Pseudomonas putida

Details on inoculum:

The bacterium Pseudomonas putida was obtained from the "Deutsche Sammlung für Mikroorganismen und Zellkulturen, Braunschweig" and kept on slant agaar containing a nutrient soltuion at approx. 25°C. During culturing the microorgansims were transferred weekly.

Preparation of the pre-culture for the inoculum
The microorganisms for the pre-culture were taken from a stock up to seven days old, approx. 7 hours prior to the start of the incubation in the test.
They were kept in a pre-culture nutrient solution. 900 mL sterile distilled water were added. The pre-culture had a turbidity of 0.052 extinction units (equivalent to approx. TE/F 10) on the spectrophotometer.
This pre-culture was incubated for 7 hours at room temperature. After the incubation period the turbidity of the pre-culture was measured with 0.425 extinction units, and the pre-culture was diluted to 0.218 extinction units (equivalent to approx. TE/F 50) with the pre-culture medium, ready to be used as inoculum.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

16 h

Test temperature:

room temperature (at beginning: 20.7, at the end: 20.9°C)

Nominal and measured concentrations:

Nominal concentrations: 1000 mg/L (saturated and filtered), Dilutions: 1:10, 1:100, 1:1000
Measured concentration for 1000 mg/L stock solution: 4.3 mg/L

Details on test conditions:

The test vessels were incubated on a shaker for 16 h at room temperature.
Each test concentration and the control without test subststance were set up in triplicate. Additionally, one test vessel was used for each test concentration and the control without inoculum in order to analyse the substance-dependent turbidity (blank).

Key result

Duration:

16 h

Dose descriptor:

EC50

Effect conc.:

> 4.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

not specified

Basis for effect:

growth inhibition

Details on results:

The test substance produced no inhibitory effects as a saturated aqueous solution (approx 4.3 mg/L).

Validity criteria fulfilled:

yes

Conclusions:

Estron-Methylether has no inhibiting effect on microbial populations of Pseudomonas putida up to the saturation limit (4.3 mg/L).

Executive summary:

The toxicity of Estron-Methylether to microorganisms was studied in a bacteria growth test with Pseudomonas putida according to DIN 38412 L8. The microbial organisms were incubated with the test substance over a period of 16 hours.

For the preparation of the test solutions a suspension with a nominal loading of 1000 mg/L was prepared and stirred for 24h. This suspension was filtered through a glassfibre filter. The concentration was estimated by TOC-analyses as approx. 4.3 mg/L. This solution served as the highest test concentration, which was diluted with sterile distilled water at the ratios of 1:10, 1:100, 1:1000. Additionally, one control without the test substance was used. All test solutions including the control were incubated in triplicate.

Furthermore, for each test concentration one test vessel was incubated without addtion of the inclum in order to analyse the inherent turbidity of the test substance.

As a parameter for the growth of the bacterial population, the turbidity of the test and control solutions was analysed photometrically at a wave-length of 436 nm.

No effect on growth was obeserved at the highest concentration tested (4.3 mg/L), which exceeded the maximum solubility of the test substance. Thus, the 16h-EC50 was higher than 4.3 mg/L.

Description of key information

The toxicity of Estron-Methylether to microorganisms was studied in a bacteria growth test with Pseudomonas putida according to DIN 38412 L8. The microbial organisms were incubated with the test substance over a period of 16 hours.

The concentration of a saturated and filtered stock solution was estimated by TOC-analyses as approx. 4.3 mg/L. This solution served as the highest test concentration, which was diluted with sterile distilled water at the ratios of 1:10, 1:100, 1:1000. Additionally, one control without the test substance was used. All test solutions including the control were incubated in triplicate.

Furthermore, for each test concentration one test vessel was incubated without addtion of the inclum in order to analyse the inherent turbidity of the test substance.

As a parameter for the growth of the bacterial population, the turbidity of the test and control solutions was analysed photometrically at a wave-length of 436 nm.

No effect on growth was obeserved at the highest concentration tested (4.3 mg/L), which exceeded the maximum solubility of the test substance. Thus, the 16h-EC50 was higher than 4.3 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

4.3 mg/L