3,3'-methylenebis[5-methyloxazolidine]

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:

21 September 2016 - 28 October 2016

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:

July 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

municipal wastewater treatment plant Breisgauer Bucht, 30 mg dry solids per litre

Duration of test (contact time):

29 d

Initial conc.:

10 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The test was performed in accordance to OECD Guideline 301B (CO2 evolution Test).
18.1 mg of 3,3'-methylenebis(5-methyloxazolidine)N,Nmethylenbismorpholine/L, corresponding to 10 mg C/L were exposed in triplicate at 22.2 – 23.3°C in the dark in an inoculated culture medium.
Activated sewage sludge from the municipal wastewater treatment plant Breisgauer Bucht was used as inoculum. The dried solids concentration was 30 mg/L. The culture vessels were sealed and aerated with CO2-free air at a rate of 30 - 100 mL/min (1.6 – 5.5. bubbles/s) and stirred. The culture vessels were equipped with two subsequent absorber vessels.
CO2 analysis was done on day 0, 4, 7, 11, 14, 21, 28. At day 29, 2 mL of 4 M hydrochloric acid was added to drive out any inorganic carbonates, vessels resealed, aerated overnight and CO2 analysed. Controls with inoculated culture medium and standard material (sodium benzoate, 34.3 mg/L, corresponding to 20 mg C /L) were incubated in triplicate.
One toxicity control with 18.1 mg/L test item and 34.3 mg/L sodiumbenzoate, resulting 30 mg C/L, was performed.

Reference substance:

other: sodium benzoate

Parameter:

% degradation (CO2 evolution)

Value:

89.8

Sampling time:

29 d

Details on results:

The degradation extent of the test item at the end of the test was 89.8% (28 d after acidification,
mean of three replicates, see table°1 and fig°1). On day 4 the degradation extent of the test
item was already 66.1% (mean of three replicates, see table 1). The 10 d-window was therefore
met.

Results with reference substance:

The reference compound sodium benzoate reached the pass levels for ready biodegradability
within 4 days.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The substance can be regarded as readily biodegradable, including the 10 days window criterion.

Executive summary:

The degradation extent of the test substance at the end of the test was 89.8% (28 d after acidification, mean of three replicates, see table°1 and fig°1). On day 4 the degradation extent of the test item was already 66.1% (mean of three replicates, see table 1). The 10 d-window was therefore met. The degradation extent in the toxicity control was 84.3% within 14 days, the test substance had no inhibitory effect on the inoculum.

The inorganic carbon content of the mineral medium was below 5%. The total CO2 evolution of the inoculum blank was below 40 mg/L. Therefore; the validity critera can be considered as fulfilled. Studies on hydrolysis of the active substance indicate that at large dilutions the hydrolysis products are expected which are both readily biodegradable. Therefore, the substance as well as its hydrolysis products are expected to be extensively removed in biological treatment plants as well as in aquatic compartments. The constituents of the reaction product (active substance) are not expected to be volatile from aqueous solutions, therefore this removal mechanism could not influence the test results. It is not expected that the the low adsorptivity of the test substance influenced the CO2 evolution.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater