2-octyldodecyl 5-oxo-L-prolinate

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:

From January 17, 2017 to February 16, 2017

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)

Deviations:

yes

Remarks:

study plan deviations but the integrity was not adversely affected

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

yes

Remarks:

study plan deviations but the integrity was not adversely affected

GLP compliance:

yes

Specific details on test material used for the study:

Batch no.: CH 192955/01
Purity: 88.88%
Appearance: clear yellow liquid

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
- Treatment: The freshly obtained sludge was kept under continuous aeration until further treatment. The concentration of suspended solids was determined to be 5.6 g/L in the concentrated sludge. Before use, the sludge was allowed to settle (55 min) and the supernatant liquid was used as inoculum at 10 mL/L of mineral medium.

Duration of test (contact time):

28 d

Initial conc.:

16.5 mg/L

Based on:

TOC

Remarks:

corresponding to 12 mg TOC/L

Parameter followed for biodegradation estimation:

CO2 evolution

Remarks:

with a TOC analyser (ThCO2)

Details on study design:

- The test substance was tested in duplicate at a target concentration of 16.5 mg/L, corresponding to a TOC of 12 mg/L. The organic carbon content was based on the purity/composition and the molecular formulae of the components. The Theoretical CO2 production (ThCO2) of the test substance was calculated to be 2.68 mg CO2/mg.
The study consisted of six bottles (2 L brown coloured glass bottles):
- 2 inoculum blanks (no test substance),
- 2 test bottles (test substance),
- 1 positive control (sodium acetate) and
- 1 toxicity control (test substance plus sodium acetate).

- Since the test substance 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 L test bottles containing medium with microbial organisms and mineral components. To this end, 10 mL of Milli-RO water was added to each weighing bottle containing the test substance. After vigorous mixing (vortex) 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 substance and test medium. The test duration was 28 d (last CO2 measurement on Day 29).

Reference substance:

acetic acid, sodium salt

Remarks:

Purity 99,1%, used with the final concentration of 12.0 mg/L of organic carbon (TOC)

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 35 - <= 43

Sampling time:

28 d

Details on results:

- Theoretical CO2 production:
The ThCO2 of the test substance was calculated to be 2.68 mg CO2/mg.
- Biodegradation:
The relative biodegradation values calculated from the measurements performed during the test period revealed 35% and 43% biodegradation of the test substance (based on ThCO2), for the duplicate bottles tested. Thus, the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. In the toxicity control, more than 25% biodegradation occurred within 14 d (40%, based on ThCO2). Therefore, the test substance was assumed not to inhibit microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid.

Results with reference substance:

- Theoretical CO2 production
The ThCO2 of sodium acetate was calculated to be 1.07 mg CO2/mg.
- Biodegradation:
Functioning of the test system was checked by testing the reference substance sodium acetate, which showed a normal biodegradation curve.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the study conditions, the test substance was not considered to be readily biodegradable.

Executive summary:

A study was conducted to determine the ready biodegradation of the test substance according OECD Guideline 310B and EU Method C.4 -C, in compliance with GLP. Activated sludge freshly obtained from a municipal sewage treatment plant were exposed to the test substance for 28 d under continuous aeration. The test substance was tested in duplicate at a target concentration of 16.5 mg/L, corresponding to 12 mg TOC/L. The Theoretical CO2 production (ThCO2) of the test substance was calculated to be 2.68 mg CO2/mg. Negative control, positive control (sodium acetate) and toxicity controls were included in the experiment. The pH and temperature were monitored throughout the experiment. The relative biodegradation values calculated from the measurements performed during the test period revealed 35% and 43% biodegradation of the test substance (based on ThCO2). The criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. Since all criteria for acceptability of the test were met, this study was considered to be valid. The positive and toxicity controls were valid. Under the study conditions, the test substance was not considered to be readily biodegradable (Desmares-Koopmans, 2017).

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

A study was conducted to determine the ready biodegradation of the test substance according OECD Guideline 310B and EU Method C.4 -C, in compliance with GLP. Activated sludge freshly obtained from a municipal sewage treatment plant were exposed to the test substance for 28 d under continuous aeration. The test substance was tested in duplicate at a target concentration of 16.5 mg/L, corresponding to 12 mg TOC/L. The Theoretical CO2 production (ThCO2) of the test substance was calculated to be 2.68 mg CO2/mg. Negative control, positive control (sodium acetate) and toxicity controls were included in the experiment. The pH and temperature were monitored throughout the experiment. The relative biodegradation values calculated from the measurements performed during the test period revealed 35% and 43% biodegradation of the test substance (based on ThCO2). The criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. Since all criteria for acceptability of the test were met, this study was considered to be valid. The positive and toxicity controls were valid. Under the study conditions, the test substance was not considered to be readily biodegradable (Desmares-Koopmans, 2017).