3β-hydroxyandrost-5-en-17-one acetate

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:

2017-05-03 to 2017-06-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: ISO10364 "Water Quality - Guidance for the preparation and treatment of poorly water-soluble organic compounds for the subsequent evaluation of their biodegradability in an aqueous medium" 1995

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: M16GB2547
- Expiration date of the lot/batch: 2018-07-01(retest date)
- Purity test date: 2016-08-28 (certificate of analysis release date)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature
- Solubility and stability of the test substance in the solvent/vehicle: not reported

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source: Municipal sewage treatment plant receiving predominantly domestic sewage, 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands.
- Storage conditions: The freshly obtained sludge was used immediately
- Preparation of inoculum for exposure: Before use, the sludge was allowed to settle (30 minutes) and the supernatant liquid was used as inoculum.
- Pretreatment: no
- Concentration of sludge: The concentration of suspended solids was determined to be 3.5 g/L in the concentrated sludge.
- Water filtered: Tap-water purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon.

Duration of test (contact time):

28 d

Initial conc.:

15.5 mg/L

Based on:

test mat.

Initial conc.:

12 mg/L

Based on:

other: TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: test water prepared according to test guidelines, analytical grade salts dissolved in tap-water purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon.
* mineral stock solution A: 8.5 g KH2PO4, 21.75 g K2HPO4, 67.20 g Na2HPO4.12H2O, 0.5 gNH4Cl dissolved in 1 L Milli-Q water, pH 7.4 ± 0.2
* mineral stock solution B: 22.50 g MgSO4.7H2O dissolved in 1 L Milli-Q water
* mineral stock solution C: 36.4 g CaCl2.2H2O dissolved in 1 L Milli-Q water
* mineral stock solution D: 0.25 g FeCl3.6H2O dissolved in 1 L Milli-Q water
* Final test medium: 10 mL of solution A and 1 mL of solutions B, C and D per L of test medium
- Additional substrate: no
- Test temperature: 22.1-23.3°C
- pH: 7.6-7.8, measured prior to testing in each test flask before addition of inoculum, and again in each test flask at the end of the incubation period
- pH adjusted: yes from a pH 7.7 to a pH 7.6 using 1 M HCl (Merck, Darmstadt, Germany)
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 2-L all-glass brown coloured bottles
- Number of culture flasks/concentration: 2
* test substance and inoculum: 2 replicates
* inoculum blank: 2 replicates
* positive control: 1 replicate
* toxicity control: 1 replicate
- Method used to create aerobic conditions: A mixture of oxygen (~20%) and nitrogen (~80%) was passed through a bottle, containing 0,5 - 1 L 0,0125 M Ba(OH)2 solution to trap CO2. The synthetic air was sparged through the scrubbing solutions at a rate of ~1-2 bubbles per second ( ~30-100 mL/min). The initial suspension of unspiked test medium and inoculum was aerated with this CO2-free air overnight to purge the system of CO2 prior to testing. This CO2-free air was also used for aeration during the test.
- Measuring equipment: CO2-evolution was determined through titration of the remaining Ba(OH)2 with 0.05 M standardized HCl.
- Details of trap for CO2 and volatile organics if used: Three CO2-absorbers (bottles filled with 100 mL 0.0125 M Ba(OH)2 were connected in series to the exit air line of each test bottle.

SAMPLING
- Sampling frequency: titrations were made every second or third day during the first 10 days, and thereafter at least every fifth day until the 28th day, for the inoculum blank and test item. Titrations for the positive and toxicity control were made over a period of at least 14 days.
- Sampling method: the absorber bottle closest to the incubation system was sampled each time, the second and third bottle were moved one position closer to the system and a new bottle was added at the end
- On the 14th day (positive and toxicity control) and on the 28th day (inoculum blank and test item), pH of test suspensions was measured and 1 mL of concentrated HCl was added to each bottle. Bottles were aerated overnight to drive off CO2 present in the test suspension. The final titration was made on day 29.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, two replicates with only inoculum
- Toxicity control: yes, one replicate with test item, reference substance, and inoculum
- Procedure control: yes, 1 replicate with reference item and inoculum

Reference substance:

acetic acid, sodium salt

Test performance:

In the toxicity control more than 25% degradation occurred within 14 days (66% based on ThCO2). Therefore, the test substance was assumed to be not inhibitory on microbial activity.
The positive control substance was degraded at least 60% (91%) within 14 days.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 85

Sampling time:

28 d

Remarks on result:

other: mean of test bottle A and B

Details on results:

The criterion for ready biodegradability (at least 60% biodegradation within 10 days of biodegradation exceeding 10%) was met.

Results with reference substance:

The positive control item was biodegraded by at least 60% (91%) within 14 days, confirming suitability of the activated sludge.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

A 28-d ready biodegradability test (OECD 301B, modified Sturm test) using unadapted activated sludge from a predominantly domestic waste water treatment plant indicated that JNJ-83317-AAA (T008506) was readily biodegradable under the conditions of the test (initial concentration 15.5 mg/L). The test substance showed 75% and 95% biodegradation (test bottle A and B, respectively, based on % ThCO2). The test substance did not inhibit microbial activity at the concentration used in the test. The results of the test can be considered reliable without restriction.

Description of key information

One study (Timmer, 2017) is included in this dossier and regarded as a key study (Klimisch score of 1).  The biodegradability of T008506 was determined according to OECD Guideline 301B and EU Method C.4-D.

The test item was tested in duplicate at 15.5 mg/L, corresponding to 12 mg TOC/L. The inoculum was unadapted activated sludge from a predominantly domestic waste water treatment plant.

Under the conditions of the test, T008506 was determined to be readily biodegradable within 28 days.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable