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

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05/2020-09/2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

For determination of precision, accuracy and limit of quantification of the analytical method three fortification levels at approx. 0.50 µg/L (LOQ); 60.0 µg/L and 220 µg/L were prepared.
For the fortification samples, approx. 30 mg reference standard were weighed to the nearest 0.1 mg in 100 mL volumetric flask and filled up to the mark with acetonitrile to obtain stock solution of approx. 300 mg/L test item. Six individual samples were prepared. These stock solutions were diluted further three times with acetonitrile to obtain dilution solutions with approx. 0.50 µg/L, 60.0 µg/L and 200 µg/L test item. Further dilution may be needed to fit with the calibration range.
In addition, algae medium and acetonitrile was used as analytical blank.

Vehicle:

no

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21-24°C

Nominal and measured concentrations:

3.1, 6.3, 12.5, 25, 50 and 100 mg/L

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

< 0.16 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.084 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.021 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.04 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

 Treatm.[mg/L]         Mean          Std. Dev.                       n       %Decrease

            Control       44.789              2.0853                       3                   0.0

             0.0054       42.923              3.0091                       3                   4.2

             0.0112       42.775              3.3127                       3                   4.5

             0.0209       43.856              4.6271                       3                   2.1

             0.0399       29.782              3.3835                       3                  33.5

             0.0870       24.841              3.4623                       3                  44.5

             0.1608       25.680              2.3707                       3                  42.7

Validity criteria fulfilled:

yes

Conclusions:

The EC50 for Estron-Methylether was observed to be 0.16 mg/L.

Executive summary:

A study was performed to assess the adverse effects ofEstron-Methyletheron the growth rate (= rate of increase in cell density with time) and the yield (= biomass at time t minus initial biomass) of the planktonic freshwater algal speciesDesmodesmus subspicatus(former name:Scenedesmus subspicatus) over several generations.

The EC50 for Estron-Methylether was observed to be 0.16 mg/L.

Description of key information

The EC50 for Estron-Methylether was observed to be 0.16 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.16 mg/L

EC10 or NOEC for freshwater algae:

0.021 mg/L