Prasterone

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:

Jan - Feb 2002

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)

Version / remarks:

no version available

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sewage treatmant plant Ruhleben (Berlin, Germany)
- Storage conditions: room temperature, dark
- Preparation of inoculum for exposure: stirring and aerating for approx 2 h.
- Pretreatment: homogenized in a blender. Then it was allowed to settle for approximately 30 minutes. 3 mL corresponding to 9 to 15 mg suspended solids were taken from the supernatant for each test vessel.

Duration of test (contact time):

29 d

Initial conc.:

200 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 22 °C
- pH: 7.5 -7.6
- pH adjusted: yes

SAMPLING
- Sampling frequency: 2, 6, 10, 14, 18, 22, 26, 29 d
- Measuring equipment: For the determination of the O2 consumed, an electronical manometric device, mounted on the top of each bottle was mployed (WTW OxyTop C6). The produced CO2 was absorbed by an absorbing agent (soda lime) installed inside.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 3 replicates
- Toxicity control: yes, 1 replicate

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

29 d

Details on results:

The 10-day window was not met. However, the substance was degraded to a high extent.
The toxicity control was degraded to 71% after 14 d and 82% after 29 d indicating no inhibitory effects of the inoculum.

Results with reference substance:

The reference substance was degraded to 86% after 28 d

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable, not fulfilling specific criteria

Conclusions:

75% degradation after 29 d (10-day window not met)

Executive summary:

A test on ready biodegradability of Prasterone was conducted. 75 % degradation was observed after 29 d. However, the 10-day window was not met. Therefore, the test substance is not readily biodegradable but can be considered being biodegradable based on the high amount of degradation at test end. 

Description of key information

A test on ready biodegradability of Prasterone was conducted. 75 % degradation was observed after 29 d. Since the 10-day window was not met, the substance is not considered being readily biodegradable. However, due to the high amount of degradation at the end of the test, Prasterone is biodegradable in the environment.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, not fulfilling specific criteria

Type of water:

freshwater