Oestr-5(10)-ene-3,17-dione

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

7 Jan - 4 Feb 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Qualifier:

according to guideline

Guideline:

other: Chemicals – Ready Biodegradability – Manometric Respirometry Method (GB/T 21801-2008)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Testing of Chemicals (HJ/T 153-2004)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Chemical Test Methods – Degradation and Accumulation Volume

Version / remarks:

(second edition) (Beijing: China Environment Press, 2013)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

This guideline is referenced in the study.

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Remarks:

According to GLP standards of China.

Oxygen conditions:

not specified

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge was collected mainly from treated household waste-water from the aeration ponds of the Nanjing Tiebei Waste-Water Treatment Plant.

- Laboratory culture: After collection, the activated sludge was placed in a beaker, washed with BSM test culture medium, precipitated after aeration, and the supernatant poured out. Washing was repeated three times; the washed sludge was aerated and cultured in the laboratory.

- Preparation of inoculum for exposure: Prior to use, sludge suspension was centrifuged (5000 r/min, 10 min) and the supernatant was poured out. A small quantity of sludge was weighed and, after drying in a 100°C oven, it was weighed again, until there was little change in the weight of the oven-dried sludge.Then 2.42 g of centrifuged sludge was taken and diluted with culture medium to 50 mL, prepared into an inoculum suspension with a concentration of 4.00 g suspended solid/L and the inoculum cell count under microscopy was measured as 4.1 x 107/L.

- Concentration of sludge: Dry weight of the activated sludge was calculated as 8.26% of total weight.

Duration of test (contact time):

28 d

Initial conc.:

30.4 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: see 'Any other information on materials and methods incl. tables'
- Test temperature: 21.7 - 22.9 °C
- pH: 7.22 - 7.67
- Suspended solids concentration: the inoculum’s suspended solids (SS) concentration in the test system was 30.0 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 510 mL BOD glass bottles
- Number of culture flasks/concentration: two for the measurement with the test substance as well as for the inoclumum blank control), one for each the procedure and toxic control
- Measuring equipment: manometric respirometer (BOD meter); BOD was measured automatically every day
- Test performed in closed vessels: yes
- Details of trap for CO2: NaOH

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (test culture medium and inoculum)
- Procedure control/ reference substance: sodium benzoate (test culture medium, sodium benzoate and inoculum)
- Toxicity control: yes (test culture medium, test substance, reference substance and inoculum)

Preliminary study:

None

Parameter:

% degradation (O2 consumption)

Value:

73.8

Sampling time:

28 d

Remarks on result:

other: No standard deviation stated (the value is a mean of two measurements).

Details on results:

The result is the mean of two measurements at day 28: 73.3 and 74.3%.

Results with reference substance:

The 14-day biodegradation rate of the reference compound sodium benzoate was 90.7%.

Toxicity control

The 14-day degradation rate of the toxicity control was 72.7%.

 

ThOD calculations

ThOD_NH3 of the test substance was 2.70 O₂/mg.

ThOD_NH3 of the reference compound sodium benzoate was calculated as 1.67 mg O₂/mg.

Validity criteria fulfilled:

yes

Remarks:

According to Chinese guidelines.

Interpretation of results:

readily biodegradable

Conclusions:

The 28-day biodegradation rate of the test substance was 73.8%.

Executive summary:

In accordance with Guidelines for the Testing of Chemicals (HJ/T 153-2004), Chemical Test Methods – Degradation and Accumulation Volume (second edition) (Beijing: China Environment Press, 2013), and Chemicals – Ready Biodegradability – Manometric Respirometry Method (GB/T 21801-2008), and with reference to OECD Procedure 301F Manometric Respirometry Test (adopted 17 July 1992), this project employed activated sludge from a domestic waste-water treatment plant in China as the inoculum. The ready biodegradability of the test substance was measured by testing the consumption of dissolved oxygen over 28 days. The 14-day degradation rate of the toxicity control was 72.7%. In the test period the oxygen consumption quantity of the test substance treatment was larger than 60% of the oxygen consumption quantity of the inoculum blank control. The test substance did not have inhibitory effects on the inoculum. 

The results indicated that the 28-day biodegradation rate of the test substance was 73.8%; in the 10-day observation period, the biodegradation rate was larger than 60%.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

The activated sewage sludge was collected from a well-operated municipal sewage treatment plant (Kläranlage Berlin-Ruhleben), predominantly dealing with domestic sewage on the day when the experiment started. Upon arrival in the laboratory, the activated sludge was stirred and aerated for approximately two hours. Thereafter, the sludge was allowed to settle for about thirty minutes. 3 mL corresponding to 9 to 15 mg of suspended solids were taken from the supernatant for each test vessel.

Duration of test (contact time):

28 d

Initial conc.:

200 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

The test solutions were incubated at 22 +/- 1 °C for 28 days in a temperature controlled incubator. On day 29 the pH of all the test vessels was measured. It should range from 6.0 to 8.5. When the pH is outside that range and the oxygen consumption by the test substance is less than 60%, repeat of the test with a lower substance concentration should be considered.

Reference substance:

acetic acid, sodium salt

Test performance:

In the assay with the test compound, an O2 uptake of 22 mg O2 was observed, which corresponds to 11 % of the theoretical oxygen demand. However, one replicate showed a O2 consumption of 63 mg on day 29, corresponding to 31% degradation. The other vessels showed uptakes of 1 to 2 mg/l, corresponding to less than 2 % degradation.

Parameter:

% degradation (O2 consumption)

Value:

2

Sampling time:

10 d

Parameter:

% degradation (O2 consumption)

Value:

5.2

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

7.9

Sampling time:

18 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

11

Sampling time:

29 d

Details on results:

In the toxicity control, the reference compound (sodium acetate) plus the test compound were degraded to 81 % on day 29 (28 days of incubation).

Results with reference substance:

The reference compound sodium acetate was degraded to 92% on day 29 (28 days of incubation). 60% degradation was reached on day 4.

Table 1: Biological degradation (cumulative) in percent (corrected for blank O2 consumption) of the test item (selected time-points)

		Day of sampling
Compound	Concentration expressed in theoretical O2 demand	2	6	10	14	18	22	26	29
Test item	200 mg/L	0,9	0,4	2	5,2	7,9	9,4	10,3	11,2
Reference (sodium acetate)	200 mg/L	25,3	86,4	89,9	90,7	92,2	92,8	92,1	92
Toxicity control (test item + sodium acetate)	100 mg/L + 100 mg/L	23,3	39,5	51,9	65,2	76,7	79,3	79,6	81

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

5(10)-Estrene-3,17-dione is not readily biodegradable under the conditions of the test, since the stringent criteria for "ready degradability" i.e. degradation of 60% within a 10 day window, were not met. However, the degradation pattern suggests that the test item may be biodegradable under certain circumstances, which can be enhanced by a co-metabolite. The test item was not toxic to the microbes of activated sludge.

Executive summary:

The purpose of this study was to determine the ready biodegradability of 5(10)-Estrene-3,17-dione, in the manometric respiration test. The study was conducted in agreement with OECD 301F.

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, magnesium sulphate, iron chloride, ammonium chloride and calcium chloride. The test substance was incubated at a concentration of 200 mg theoretical oxygen demand (ThOD) per litre. 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 100 mg ThOD/L (reference substance) plus test item at 100 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 O2 consumption during the test period. O2 consumption was continuously monitored and recorded by an automated device. The O2 consumption was calculated as the percentage of total O2 that the test material could theoretically have consumed, based on the molecular formula. The blank O2 consumption was subtracted for correction.

The test compound was degraded to 11 % on day 29 (28 days of incubation). However, there was a large difference between one individual vessel (31 % degradation) to the other two (< 2% degradation). The reference compound sodium acetate was degraded to 92% on day 29 (28 days of incubation). 60% degradation was reached on day 4. In the toxicity control, the reference compound (sodium acetate) plus the test compound, was degraded to 81 % on day 29 (28 days of incubation). This was higher than the degradation in the individual sets indicating a co-metabolite activity of sodium acetate in respect of the degradation of 5(10)-Estrene-3,17-dione.

In conclusion, the test item is not readily biodegradable according to the OECD criteria.

Description of key information

5(10)-Estrene-3,17-dione is readily biodegradable as indicated by the key study, since the stringent criteria for "ready degradability" i.e. degradation of 60% within a 10 day window, were met. The substance was not toxic to the microbes of activated sludge.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The criteria for "ready biodegradability" i.e. degradation of 60 % within a 10 day window, was not met.