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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:
2016-02-16 to 2016-03-17
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Deviations:
no
Qualifier:
according to
Guideline:
ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)
Deviations:
no
Qualifier:
according to
Guideline:
other: ISO International Standard 10634 "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. certificate)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: I15FC2164
- Expiration date of the lot/batch: 2017-06-23 (retest date)
- Purity test date: 2015-07-01

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
- Stability under test conditions: Not indicated

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.
- Preparation of inoculum for exposure: sludge was kept under continuous aeration until further treatment. Before use, the sludge was allowed to settle (40 minutes) and the supernatant liquid was used as inoculum at the amount of 10 mL/L of mineral medium.
- Concentration of sludge: The concentration of suspended solids was determined to be 3.9 g/L in the concentrated sludge.
Duration of test (contact time):
28 d
Initial conc.:
21 mg/L
Based on:
test mat.
Initial conc.:
12 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: a solution of sodium acetate was prepared by dissolving 402.0 mg in Milli-RO water and making this up to a total volume of 100 mL. Volumes of 20 mL from this stock solution were added to 2 litres of the test medium of the positive control bottle and the toxicity control bottle, resulting in a final concentration of 40 mg sodium acetate per litre (12 mg TOC/L). The test solutions were continuously stirred during the test
The test sbustance was not sufficiently soluble to allow preparation of an aqueous solution at a concentration of 1 g/L, weighed amounts were added to the 2-litre test bottles containing medium with microbial organisms and mineral components (test item bottle A: 43.1 mg; test item bottle B: 42.9 mg and toxicity control bottle: 42.6 mg). To this end, 10 mL of Milli-RO water was added to each weighing bottle containing the test item. After vigorous mixing (vortex) the resulting suspension was added quantitatively to the test medium. The test solutions were continuously stirred during the test. Furthermore, starting at day 4, the test medium was daily swirled around to ensure optimal contact between the test item and test medium, since the test item tended to float on the water surface.
- Additional substrate: no
- Test temperature: 22.2-22.8°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: no
- Aeration of dilution water: The test solutions were continuously stirred and aerated during the test.
- Continuous darkness: yes

TEST SYSTEM
- Test flasks: 2 L glass brown coloured bottles
- Number of culture flasks/concentration: 2
- 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).
- Details of trap for CO2 and volatile organics if used: 3 CO2-absorbers (bottles filled with 100 mL 0,0125 M Ba(OH)2) were connected in series to the exit air line of each bottle. The CO2 produced in each test bottle reacted with the barium hydroxide in the gas scrubbing bottle and precipitated out as barium carbonate. The amount of CO2 produced was determined by titrating the remaining ba(OH)2 with 0,05 M standardized HCl.

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, less than 25% biodegradation occurred within 14 days (21%, based on ThCO2). Therefore, the test item was found to have a small inhibiting effect on microbial activity, which was considered to have no effect on the outcome of this study (the criterion for ready biodegradability).
Key result
Parameter:
% degradation (CO2 evolution)
Value:
ca. 3
Sampling time:
28 d
Results with reference substance:
The positive control item was biodegraded by at least 60% (77%) within 14 days.
Validity criteria fulfilled:
yes
Interpretation of results:
not 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 JNJ-4754724-AAA (T002488) was not readily biodegradable under the conditions of the test item (initial concentration 21 mg/L corresponding to 12 mg TOC/L). The results of the test can be considered reliable without restriction.

Description of key information

A 28-d ready biodegradability test (OECD 301B, modified sturm test) using unadapted activated sludge from a predominantly domestic waste water treatment plant indicated JNJ-4754724-AAA (T002488) was not readily biodegradable under the conditions of the test item (initial concentration 21 mg/L corresponding to 12 mg TOC/L). The results of the test can be considered reliable without restriction.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information