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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Decmber 10,2018-January 07.2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
anaerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Remarks:
pre-conditioned
Details on inoculum:
Secondary effluent from the JRF Sewage Treatment Plant treating predominantly domestic sewage was used as the inoculum. The Secondary effluent was filtered through a Whatman N°. 1 filter paper. The inoculum was pre-conditioned by aerating at 22 +- 2 °C for 6 days. The Inoculum was analysed for microorganism concentration and confirmed as 4.90 x 10e4 CFU/mL
Duration of test (contact time):
28 d
Initial conc.:
2.07 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
The ready biodegradability of the substance was determined in a closed bottle test in accordance with OECD test guideline 301D at a concentration of 2.0 mg/L in mineral medium inoculated with secondary effluent from a treatment plant (1 mL/L). Sodium benzoate was used as a reference substance to check the validity of the method. Mineral medium with inoculum (1 mL/L) without test item and Sodium benzoate served as an inoculum blank and mineral medium with inoculum (1 mL/L) and silicon oil was served as test blank. Separate test solutions were maintained in parallel (in duplicate) for test, reference and control samples for observation on day 0, 7, 14, 21, and 28.
Key result
Parameter:
other: % degradation based on theorethical oxygen demand
Value:
11.08
Sampling time:
7 d
Key result
Parameter:
other: % degradation based on theorethical oxygen demand
Value:
10.32
Sampling time:
14 d
Key result
Parameter:
other: % degradation based on theorethical oxygen demand
Value:
14.59
Sampling time:
21 d
Key result
Parameter:
other: % degradation based on theorethical oxygen demand
Value:
18.3
Sampling time:
28 d
Details on results:
The percent biodegradation data concluded that the substance is not readily biodegradable. The test item showed a maximum degradation of 18.30% on day 28, whereas the reference substance exhibited a normal pattern of degradation (up to 98.14%) within 28 days. The percent degradation by the toxicity control was less than 25% after 14 days. Therefore, the test item is regarded as not readily biodegradable and toxic to microorganisms in the inoculum.
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The percent biodegradation data concluded that the substance is not readily biodegradable. The test item showed a maximum degradation of 18.30% on day 28, whereas the reference substance exhibited a normal pattern of degradation (up to 98.14%) within 28 days. The percent degradation by the toxicity control was less than 25% after 14 days. Therefore, the test item is regarded as not readily biodegradable and toxic to microorganisms in the inoculum.

Description of key information

The percent biodegradation data concluded that the the substance is not readily biodegradable. The test item showed a maximum degradation of 18.30% on day 28, whereas the reference substance exhibited a normal pattern of degradation (up to 98.14%) within 28 days. The percent degradation by the toxicity control was less than 25% after 14 days. Therefore, the test itemis regarded as not readily biodegradable and toxic to microorganisms in the inoculum.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information