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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:
2016-01-26 to 2016-03-03
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
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: I15FB2768
- Expiration date of the lot/batch: 01 July 2017 (retest date)
- Purity: 100 % (based on base titration assay)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature
- Stability under test conditions: no data
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 (33 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 4.3 g/L in the concentrated sludge.
Duration of test (contact time):
28 d
Initial conc.:
18.5 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: weighed amounts were added to the 2-litre test bottles containing medium with microbial organisms and mineral components (test item bottle A: 37.7 mg; test item bottle B: 37.8 mg and toxicity control bottle: 37.6 mg). To this end, 10 mL of Milli-RO water was added to each weighing bottle containing the test item. After vigorous mixing (vortex) and shaking the resulting suspension was added quantitatively to the test medium. The test solutions were continuously stirred during the test, to ensure optimal contact between the test item and the test organisms.
- Additional substrate: no
- Test temperature: 21.3-22.7°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
Parameter:
% degradation (CO2 evolution)
Value:
ca. 1
Sampling time:
28 d
Details on results:
The toxicity control JNJ-1806792-AAA (T001325) was found to have a slight inhibiting effect on microbial activity. Since all criteria for validity of the test were met, this study was considered to be valid.
Results with reference substance:
The positive control item was biodegraded by at least 60% (78%) within 14 days, confirming suitability of the activated sludge.
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 that JNJ-1806792-AAA (T001325) was not readily biodegradable under the conditions of the test (initial concentration 18.5 mg/L corresponding to 12 mg TOC/L). The results of the test can be considered reliable without restriction.

Description of key information

One study (Desmares-Koopmans, 2016) is included in this dossier and regarded as a key study (Klimisch score of 1).  The biodegradability of T001325 was determined according to OECD Guideline 301B and EU Method C.4-D. Under the conditions of the test, T001325 was determined to be not biodegradable within 28 days.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information