[No public or meaningful name is available]

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:

2022-06-23 to 2022-07-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

Version / remarks:

2014

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Municipal sewage treatment plant, Hildesheim, Germany.
- Pretreatment:The activated sludge was washed twice with chlorine free tap water. After the second washing the settled sludge was resuspended in mineral salts medium and was maintained in an aerobic condition by aeration for 2 hours. Thereafter, the sludge was homogenized with a blender. After sedimentation the supernatant was decanted and was maintained in an aerobic condition by aeration with CO2-free air for 3 days until test start. 8.99 mL/L were used to initiate inoculation (4 mg/L dry weight). pH-adjustment was not necessary.
- Concentration of sludge: 4 mg/L dry weight
- Initial cell/biomass concentration: 10^5 - 10^8 CFU/L

Duration of test (contact time):

28 d

Initial conc.:

15 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral salts medium acc. to OECD 310 and inoculum
- Test temperature: Nominal 20 ± 1 °C, actually measured 18.5 – 21.8 °C
- Photoperiod: Low light conditions

TEST SYSTEM
- Culturing apparatus: Sealed bottles
- Number of culture flasks/concentration: Total number of replicates of test item 26, total number of replicates of inoculum control 26, total number of replicates of functional control 14, total number of replicates of toxicity control 14.
- Method used to create aerobic conditions: Headspace of air
- Measuring equipment: Determination of CO2 was carried out by IC analysis with a carbon
analyser.

SAMPLING
- Sampling frequency: IC analysis was carried out at test start, and on 7 further sampling times. The inoculum control and test item replicates were sampled at test start and on day 1, 4, 7, 11, 14, 21 and 28.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

76

Sampling time:

28 d

Details on results:

Degradation kinetics (%):
-Day 4: 8%
-Day 11: 56%
-Day 28: 76%

Toxicity control after 14 days: 80% (it is assumed that the test item is not inhibitory). After 28 days: 84%.

Results with reference substance:

Biodegradation:
- Day 14: 92%
- Day 28: 92%

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The study showed that the test item is readily biodegradable. The test item fulfilled the 10-d window criterion (started within 7 days) and reached its pass level (60%) at day 14.

Executive summary:

The present study was conducted in order to evaluate the biodegradability of the test item by measuring its percentage of biodegradation with inoculum in a period of 28 days. The test method was performed following the OECD Test Guideline 310 and GLP.

The test item concentration was 15 mg/L. Benzoic acid was used as reference substance in the functional control as well as in the toxicity control. The 10-d window was fulfilled. After the 28-d period the biodegradation of the test item was calculated to be 76%. Therefore, the test item is regarded as readily biodegradable. 

Description of key information

Readily biodegradable: 76% after 28 d (OECD 310)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The present study was conducted in order to evaluate the biodegradability of the test item by measuring its percentage of biodegradation with inoculum in a period of 28 days. The test method was performed following the OECD Test Guideline 310 and GLP.

The test item concentration was 15 mg/L. Benzoic acid was used as reference substance in the functional control as well as in the toxicity control. The 10-d window was fulfilled. After the 28-d period the biodegradation of the test item was calculated to be 76%. Therefore, the test item is regarded as readily biodegradable.