Registration Dossier

Diss Factsheets

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

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:
31 May 2017 - 17 October 2017
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:
1992
Deviations:
no
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: Beijing Xiaojiahe Sewage Treatment Co., Ltd.
- Preparation of inoculum for exposure: The sludge was washed 3 times in the mineral medium through centrifugation (at 1100 g for 10 minutes). Thereafter the sludge was aerated before using. For pre-conditioning of the inoculum the aerated sludge was kept under test condition for about 6 days.
- Concentration of sludge: 21.87 g/mL
Duration of test (contact time):
28 d
Initial conc.:
30 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral salts medium according to OECD 301 F
- Test temperature: 20.8 – 22.9 °C
- pH: 7.42 - 7.95
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: amber bottler
- Test volume: 500mL
- Number of culture flasks:
Two flasks containing test substance and inoculum (test suspension); two flasks- containing only inoculum (inoculum blank); two flasks containing reference compound and inoculum (procedure control); one flask containing test substance, reference compound and inoculum (toxicity control); one flask containing test substance and sterilising agent (abiotic sterile control).
- Test performed in closed vessels due to significant volatility of test substance: yes
- Details of trap for CO2: the developed CO2 was captured using excess NaOH.

CONTROL AND BLANK SYSTEM
- Inoculum blank: only inoculum
- Abiotic sterile control: test substance and sterilising agent
- Toxicity control: test substance, reference compound and inoculum
- Procedure control: reference compound and inoculum
Reference substance:
benzoic acid, sodium salt
Remarks:
CAS No. 532-32-1, Purity: 99.5%, Expiry date: 2019-10-19, Test concentration: 50 mg/L, ThOD: 83 mg/L
Key result
Parameter:
% degradation (O2 consumption)
Value:
91.33
Sampling time:
28 d
Details on results:
The test item underwent 91.33% biodegradation after 28 days under the test conditions. The 10-day window criterion was also fulfilled (11.18% on day 3 and 61.60% on day 13). Therefore, the test item should be regarded as readily biodegradable.
Results with reference substance:
For the procedure control (reference compound and inoculum), the average biodegradation on the 1st day after exposure was 47.41%, which was over 10%, so it has entered the 10-day window period. The average biodegradation increased to 84.36% on day 14, it means it reached pass level of ready biodegradation (60%ThOD). On the 28th day after exposure, the average biodegradation reached to 82.50%.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test item underwent 91.33% biodegradation after 28 days under the test conditions. The 10-day window criterion was also fulfilled (11.18% on day 3 and 61.60% on day 13). Therefore, the test item should be regarded as readily biodegradable.
Executive summary:

This study was conducted according to OECD Test Guideline 301F to estimate whether the test substance is ready biodegradabe by measuring the percentage biodegradation of inoculum exposed to the test substance over a period of 28 days.

This test set one treatment group at the concentration 50.02 mg test item /mL (corresponding to a ThOD of 90.336 mg O2/L) with 2 repeats, control group with 2 repeats and procedure control group at the concentration 50.20 mg reference item /mL (corresponding to a ThOD of 83.633 mg O2/L) with 2 repeats, toxicity control group at the concentration 50.04 mg test item /mL (corresponding to a ThOD of 90.372 mg O2/L) and 50.04 mg reference item /mL (corresponding to a ThOD of 83.367 mg O2/L) without repeat and abiotic sterile control group at the concentration 55.02 mg test item /mL (corresponding to a ThOD of 99.366 mg O2/L) without repeat and tested in BOD- bottles at the test condition for 28 days.

The maximum oxygen uptake of the inoculum blank was 26.7 mg/L in 28 days that did not be greater than 60 mg/L. For the procedure control, the average biodegradation increased to 84.36% on day 14 that meant it reached pass level of ready biodegradation (60%ThOD). For the toxicity control test, the biodegradation was 63.95% at the 14th day, and the acceptance of more than 25%ThOD was met according to OECD 301 (F) guideline. So the test substance has no inhibitory effect on the sludge at the test dose level. For the abiotic sterile control test, the biodegradation was 8.45% which did not reached 10% at the end of the test, and it belong to lag phase. So the test substance does not occur abiotic degradation.

The test item underwent 91.33% biodegradation after 28 days under the test conditions. The 10-day window criterion was also fulfilled (11.18% on day 3 and 61.60% on day 13). Therefore, the test item should be regarded as readily biodegradable.

Description of key information

The ready biodegradability of the test substance was investigated according to the OECD guideline 301F. The test item underwent 91.33% biodegradation after 28 days under the test conditions. The 10-day window criterion was also fulfilled (11.18% on day 3 and 61.60% on day 13). Therefore, the test item should be regarded as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

This study was conducted according to OECD Test Guideline 301F to estimate whether the test substance is ready biodegradabe by measuring the percentage biodegradation of inoculum exposed to the test substance over a period of 28 days.

This test set one treatment group at the concentration 50.02 mg test item /mL (corresponding to aThOD of 90.336 mg O2/L) with 2 repeats, control group with 2 repeats and procedure control group at the concentration 50.20 mg reference item /mL (corresponding to a ThOD of 83.633 mg O2/L) with 2 repeats, toxicity control group at the concentration 50.04 mg test item /mL (corresponding to a ThOD of 90.372 mg O2/L) and 50.04 mg reference item /mL (corresponding to a ThOD of 83.367 mg O2/L) without repeat and abiotic sterile control group at the concentration 55.02 mg test item /mL (corresponding to a ThOD of 99.366 mg O2/L) without repeat and tested in BOD- bottles at the test condition for 28 days.

The maximum oxygen uptake of the inoculum blank was 26.7 mg/L in 28 days that did not be greater than 60 mg/L. For the procedure control, the average biodegradation increased to 84.36% on day 14 that meant it reached pass level of ready biodegradation (60%ThOD).For the toxicity control test, the biodegradation was 63.95% at the 14th day, and the acceptance of more than 25%ThOD was met according to OECD 301 (F) guideline. So the test substance has no inhibitory effect on the sludge at the test dose level.For the abiotic sterile control test, the biodegradation was 8.45% which did not reached 10% at the end of the test, and it belong to lag phase. So the test substance does not occur abiotic degradation.

The test item underwent 91.33% biodegradation after 28 days under the test conditions.The 10-day window criterion was also fulfilled (11.18% on day 3 and 61.60% on day 13).Therefore, the test itemshould be regarded as readily biodegradable.