Ethanol, 2,2'-iminobis-, N-tallow alkyl derivs., N-oxides

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:

2018-08-01 to 2018-09-25

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Version / remarks:

17 July 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of activated sludge: Sludge was obtained from a municipal sewage treatment plant: receiving predominantly domestic sewage from the Sewage Treatment plant, Chandana Complex, Tumkur -572103.
- Pretreatment: Secondary effluent was filtered through a coarse filter paper; the first 200 mL was discarded. The filtrate was kept aerated up to inoculation. After complete re-suspension of the effluent, the dry weight of the suspended solids was determined to be 3.158 g/L.
- Preparation of inoculum for exposure: The inoculum was prepared by adding the required amount of activated sludge and dilution water.

Duration of test (contact time):

28 d

Initial conc.:

250 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: According to OECD guideline
- Test temperature: 22 ± 2 °C
- pH: 7.46
- pH adjusted: no
- Aeration of dilution water: Yes
- Suspended solids concentration: 3.158 g/L
- Continuous darkness: no

TEST SYSTEM
- Culturing apparatus: Standard flasks
- Measuring equipment:
Balance (Satorius)
Shimadzu TOC analyzer (Shimadzu)
HQ40D multimeter (HACH)
Deep freezer (Carrier)
pH: Digisun Electronics

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: Yes
- Toxicity control: Yes

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

63.68

Sampling time:

28 d

Results with reference substance:

The reference substance (sodium acetate) attained a 65.63% biodegradation level (greater than 60% degradation) within 14 days based on ThOD.

Validity of the Test Results

The percentage degradation of the procedure control substance should reach 60% after 14 days. The percentage degradation of the toxicity control has to reach a minimum of 25% after 14 days. If degradation is less than 25%, the test substance was assumed to be inhibitory to the microbial inoculum.

Oxygen depletion in the inoculum blank should not exceed 1.5 mg dissolved O2/L after 28 days. The residual concentration of oxygen in the test bottles should not fall below 0.5 mg/L at any time. The difference of extreme replicate values of the removal of the test substance at the end of the test or at the plateau, as appropriate, should be less than 20%.

The test substance should reach 60% of degradation (% of ThOD) after 28 days. The pass level for ready biodegradability is 60% degradation. This pass value should be reached in a 10 day window within a 28 days period. The 10 day window begins when the degree of biodegradation should reach 10% and should end before day 28 of the test. Chemicals which reach the pass levels after the 28-day period are not deemed to be readily biodegradable.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item is readily biodegradable under the conditions of the closed bottle test according to the OECD guideline 301 D.

Executive summary:

The ready biodegradability of the test item was determined using the closed bottle method (OECD guideline No. 301 D, 1992).

During the study, the determination of oxygen concentrations were performed at the start of the experiment (day 0) and on 7, 10, 14, 21 and 28 days. The test item reached a maximum biodegradability of 63.68% based on ThOD of the main component within 28 days of biodegradation exceeding 60%. All differences of duplicate biodegradation values expressed as mg 02/L were less than 20% (-1.18%). After 28 days oxygen depletion in the inoculum blank obtained was 0.98 mg O2/L which is below 1.5 mg O2/L. The residual concentrations of oxygen in the test bottles were found to be > 0.5 mg/L at all durations. The reference substance (sodium acetate) attained a 65.62% biodegradation level (greater than 60% degradation) within 14 days based on ThOD. The percentage degradation of the toxicity control has attained a maximum of 67.24%) (greater than 25% degradation) by 14 days. Therefore the test item was concluded to be non- inhibitory to the microbial inoculum. The total nitrogen (N) was determined at all the pre-determined intervals and observed there was no significant increase in Oxidized Nitrogen from the start to end of the experiment. Since all criteria for acceptability of the test were met, this study was considered to be valid.

Based on these results the test item is readily biodegradable under the conditions of the closed bottle test according to the OECD guideline 301 D.

Description of key information

The test item is readily biodegradable under the conditions of the closed bottle test according to the OECD guideline 301 D.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The ready biodegradability of the test item was determined using the closed bottle test (OECD guideline No. 301 D, 1992). During the study, the determination of oxygen concentrations were performed at the start of the experiment (day 0) and after 7, 10, 14, 21 and 28 days. The test item reached a maximum biodegradability of 63.68% based on ThOD of the main component within 28 days of biodegradation exceeding 60%. All differences of duplicate biodegradation values expressed as mg O2/L were less than 20% (-1.18%). After 28 days oxygen depletion in the inoculum blank obtained was 0.98 mg O2/L which is below 1.5 mg O2/L. The residual concentrations of oxygen in the test bottles were found to be > 0.5 mg/L at all durations. The reference substance (sodium acetate) attained a 65.62% biodegradation level (greater than 60% degradation) within 14 days based on ThOD. The percentage degradation of the toxicity control has attained a maximum of 67.24% (greater than 25% degradation) by 14 days. Therefore the test item was concluded to be non- inhibitory to the microbial inoculum. The total nitrogen (N) was determined at all the pre-determined intervals and there was no significant increase in Oxidized Nitrogen from the start to end of the experiment. Since all criteria for acceptability of the test were met, this study was considered to be valid.

Based on these results the test item is readily biodegradable under the conditions of the closed bottle test according to the OECD guideline 301 D.