13-β-ethyl-3-methoxygona-2,5(10)-dien-17-one

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Nov - Dez 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

Principles of method if other than guideline:

not relevant

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

DOC

Parameter:

% degradation (CO2 evolution)

Value:

5

Sampling time:

28 d

Details on results:

The reference compound sodium acetate was degraded to 92% on day 30. The time required for 60% biodegradation of the reference compound was 11 days ( 10 days of incubation). In the toxicity control, the reference compound (sodium acetate) plus the test compound ZK 28520 was degraded up to 42% on day 25 and reached a plateau, thus reflecting the degradation of the substances incubated separately.

Table 1: Biological degradation (cumulative) in percent (corrected for blank CO2-production) of ZK 28520

Test	Nominal	Day of sampling
compound	concentration
	of carbon	3	4	7	11	16	21	25	28	30
ZK 28520	10 mg/L	0	0	0	1	2	3	4	5	3
Sodium acetate	10 mg/L	13	25	54	68	79	86	87	90	92
(reference)
ZK 28520 +	10 mg/L +	5	14	29	35	38	41	42	42	42
sodium acetate (toxicity control)	10 mg/L

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

In accordance with the OECD guideline, the test compound D-ET-Dienon is not readily biodegradable under the conditions of the test and it was not toxic to the microbes of activated sludge.

Executive summary:

The purpose of this study was to determine the ready biodegradability of D-ET-Dienon (ZK 28520). ZK 28520 is an intermediate of the synthesis of levonorgestrel. The study was conducted in agreement with the following test guideline: OECD guideline for testing of chemicals, Ready biodegradability: C02-evolution test, no. 301B.

The test substance was incubated in an aqueous solution including nutrients with microorganisms from a municipal sewage treatment plant for 28 days (start of treatment = day 1). The nutrient solutions were made up of phosphates, ammonium sulphate,

magnesium sulphate, iran chloride, ammonium chloride and calcium chloride.

The test substance was incubated in a concentration of 10 mg carbon/L in triplicate. 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 10 mg carbon/L (reference substance) plus ZK 28520 at 10 mg carbon/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 carbon dioxide (CO2) produced during the test period. CO2-production was determined on days 3, 4, 7, 11, 16, 21, 25, 28 and 30. On day 29 the solutions were acidified in order to expel all dissolved CO2, and CO2 was determined on day 30. The CO2-production was calculated as the percentage of total CO2 that the test material could theoretically have produced, based on carbon content. The blank C02-production was subtracted for correction.

The test compound D-ET-Dienon was degraded to 5% on day 28 (~ 27 days of incubation).

Description of key information

In accordance with the OECD guideline, the test compound D-ET-Dienon is not readily biodegradable under the conditions of the test and it was not toxic to the microbes of activated sludge.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater