(4R)-2-oxo-1,3-oxazolidine-4-carboxylic acid

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:

2020-05-28 until 2020-06-25

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, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedu
re): sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany
- Date of sampling: 28th May 2020
- Storage conditions: No storage
- Preparation of inoculum for exposure: Filtered (2 mm) to remove coarse particles, washed once with tap water, the concentration was adjusted to 3.5 g/L and verified by dry mass measurement.
- Pretreatment: Kept aerobic until use
- Concentration of sludge in the test: 29.5 mg dry mass/litre

Duration of test (contact time):

28 d

Initial conc.:

88 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

(95.7 mg ThOD/L considering total nitrification, 53.2 mg ThOD/L considering total lack of nitrification)

Details on study design:

Details on study design
- The concentration in the test assays were 88 mg per litre mineral test medium (22 mg/250 mL). This amount (88 mg) test item corresponds to 95.7 mg theoretical oxygen demand (ThOD) considering total nitrification and 53.2 mg ThOD considering the total lack of nitrification, after correction for the purity of the test item. No emulsifiers or solvents were used. The solution of the test item in the mineral medium equivalent to a concentration of 88 mg/L was prepared using an aqueous stock solution (10 g/L). The aqueous stock solution was prepared by dissolving 1000 mg of the reference substance in 100 mL deionised water. An aliquot (2.2 mL) of the aqueous stock solution was then diluted to 250 mL with inoculated mineral medium.
- The concentration in the test vessels with reference item (procedural control, toxicity control) was 100 mg per liter mineral test medium (25 mg/250 mL).
- A further solution containing both test and reference item at the same concentrations as in the individual solutions (test item 88 mg/L, reference item 100 mg/L) was prepared to determine the possible toxicity of the test item against the inoculum.
- Further flasks with mineral medium only were prepared for inoculum controls.
- Abiotic controls were also prepared to measure any possible abiotic degradation; a solution of the test item at about 88 mg/L was sterilized by the addition of 10 mL/L NaN3 (100 g/L).
- In all test assays except of the abiotic controls, 2.11 mL of the inoculum stock solution were trans ferred for inoculation (per 250 mL) resulting in a concentration of 29.5 mg dry mass/litre (7.4 mg dry mass/250 mL).

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

87

St. dev.:

3

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

156

St. dev.:

5

Sampling time:

28 d

Remarks on result:

other: As these results are indicative of nitrification, degradation of the test item has to be evaluated based on ThODNO3.

Details on results:

The average percent biodegradation of the test item in the test media was found to be 87% (SD = 3) after 28 days of incubation considering total nitrification. The 10-day window started on Day 13, and an average biodegradation of 60% (SD = 1%) was observed at the end of the window (Day 23).

Results with reference substance:

The reference item was degraded by an average of 85% by Exposure Day 14, thus confirming suitability of the activated sludge. At the end of the test (Day 28), the reference item was degraded by an average of 91%.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item was readily biodegradable under the conditions of the test. This study is considered to be relevant, reliable, adequate for risk assessment, and adequate for classification purposes.

Executive summary:

The ready biodegradability of the test item was investigated under GLP to the manometric respirometry test carried out according to the OECD TG 301 F (1992). The test concentration was 88 mg/L in a manometric respirometry test using domestic aerobic activated sewage sludge incubated at 22 °C in the dark over 28 days under continuous stirring. The biochemical oxygen demand (BOD) was measured daily and the percentage degradation was calculated from the theoretical oxygen demand (ThOD) after correcting for the BOD of inoculum controls. The average percent biodegradation of the test item in the test media was found to be 156% (SD = 5%) based on ThOD_NH3 and 87% (SD = 3%) based on ThOD_NO3 after 28 days of incubation.  As these results are indicative of nitrification, degradation of the test item was evaluated based on ThOD_NO3. Considering total nitrification, the 10-day window started on Day 13, and an average biodegradation of 60% (SD = 1%) was observed at the end of the window (Day 23). Since the threshold value of 60 % was reached in a 10-day-window within the 28-d period, the test item was readily biodegradable under the test conditions. As the percent degradation of the test item was ≥60% based on complete nitrification, corrections, using measured Nitrite-N and nitrate-N concentrations, to account for nitrification were not applied. The test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration. In the procedural controls, the reference substance sodium benzoate was degraded by an average of 85% by exposure day 14, and reached an average biodegradation of 91% by the end of the test (day 28), thus confirming suitability of the activated sludge.

Description of key information

Readily biodegradable, OECD TG 301F, Simon 2020

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The substance was found to be readily biodegradable in a manometric respirometry test performed to OECD TG 301F (1992). Degradation of the test item was evaluated based on ThODNO3. The threshold value of 60% degradation was reached in a 10-day-window within the 28-day period, and the test item was readily biodegradable under the test conditions. No corrections using measured Nitrite-N and nitrate-N concentrations were applied. The test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration. The reference substance sodium benzoate was degraded by an average of 85% by exposure day 14, and reached an average biodegradation of 91% by the end of the test, confirming suitability of the activated sludge.