Ethisterone

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

other information

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: well documented GLP study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Ethisterone

EC Number:

207-096-5

EC Name:

Ethisterone

Cas Number:

434-03-7

Molecular formula:

C21H28O2

IUPAC Name:

(1R,3aS,3bR,9aR,9bS,11aS)-1-ethynyl-1-hydroxy-9a,11a-dimethyl-1H,2H,3H,3aH,3bH,4H,5H,7H,8H,9H,9aH,9bH,10H,11H,11aH-cyclopenta[a]phenanthren-7-one

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

200 mg/L

Based on:

ThOD/L

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

14 d

% Degradation 2

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

28 d

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test compound ethisterone (ZK4957) is not biodegradable under the test conditions. Because there was no indication of toxicity in the toxicity
control, ethisterone is not toxic to microbial organisms from sewage sludge.

Executive summary:

The test substance ethisterone (ZK4957) was incubated in an aqueous solution including nutrients with microorganisms from a municipal sewage treatment plant for 28 days.

The test substance was incubated in triplicate at a concentration of 200 mg theoretical oxygen demand (ThOD) per liter. Additionally, a reference substance (sodium acetate) was tested in a single set according to the same procedure, in order to verify the viability and activity of the degrading microorganisms. One further set was incubated with sodium acetate at 200 mg ThOD/L (reference substance) plus ethisterone at 200 mg ThOD/L representing a toxicity control. Furthermore, a blank control was tested in triplicate without any test or reference substance.

The biological degradation of the test and reference substances was evaluated by measurement of the O₂consumption during the test period. O₂consumption was continuously monitored and recorded by an automated device. The O₂consumption was calculated as the percentage of total O₂that the test material could theoretically have consumed, based on the molecular formula. The blank O₂consumption was subtracted for correction.

In accordance with the OECD 301F(1), the test compound ethisterone is not readily biodegradable under the conditions of the test and it was not toxic to the microbes of activated sludge.