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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:
29.05.2017 - 29.06.2017
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
adopted 17th July 1992.
Deviations:
no
GLP compliance:
yes (incl. certificate)
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, procedure): Non-adapted activated sludge from the aeration tank of the ARA Werdhölzli (CH-8048 Zürich), a municipal biological waste water treatment plant. 30 mg/l dry matter in the final mixture.
- Concentration of sludge: 30 mg/l dry matter in the final mixture.
However, the sludge was pre-conditioned for 7 days (aerated but not fed) to reduce the amount of O2 consumed by the blank controls. For this pre-conditioning phase, the sludge was washed twice with tap water and once with test medium. After centrifugation, the sludge was suspended in test medium as described in Table 1, at about 2 g/l dry matter. Before the test, this suspension was diluted down to 60 mg/l dry matter, i.e. twice the final concentration, since this suspension was diluted 1:1 (v:v) afterwards (see below).
Duration of test (contact time):
28 d
Initial conc.:
34 mg/L
Based on:
test mat.
Initial conc.:
99 mg/L
Based on:
ThOD
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: containing inoculum, test medium and test item (two replicates)
- Additional substrate: None, N-(3-Dimethylaminopropyl)-methacrylamide and/or reference item as sole organic carbon sources
- Solubilising agent: no
- Test temperature: 22 ± 2°C, controlled at ± 1°C, in a thermostat cabinet in the dark
- pH: 7.4 (±0.2) adjusted with NaOH or HCl
Test concentrations:
- Test suspension, T: 34.0 mg/l test item (99.0 mg ThOD/l)
- Procedure control, R: 60.0 mg/l reference item (99.9 mg ThOD/l)
- Toxicity control, X: 34.0 mg/l test item and 60.0 mg/l reference item (total 199 mg oxygen demand /l)
- Abiotic sterile control, C: 34.0 mg/l test item (99.0 mg ThOD/l)


TEST SYSTEM
- Culturing apparatus: 510 ml glass bottles (tightly closed with manometric BOD measuring devices) containing a total volume of test solution of 200 ml. The bottles are equipped with stirring rods and butyl rubber quivers which contain 2 pellets of sodium hydroxide each to absorb the produced CO2 from the head space.

The test vessels were stirred by an inductive stirring system for a maximum test period of 28 days. During the test the O2 uptake was continuously measured with a manometric BOD measuring device. Temperature was recorded with a data logger.
At the end of the test, the pH was measured in all flasks except the abiotic sterile control (C), and the DOC content was determined in flasks T, B and R

- Number of culture flasks/concentration: 2
Reference substance:
benzoic acid, sodium salt
Preliminary study:
n/a
Test performance:
n/a
Key result
Parameter:
% degradation (O2 consumption)
Value:
87
Sampling time:
28 d
Remarks on result:
other: readily biodegradable, 10-day window achieved
Details on results:
The biodegradability of N-(3-Dimethylaminopropyl)-methacrylamide based on O2 consumption was calculated to be 87% after 28 days as compared to the theoretical oxygen demand (ThOD).
While the lag-phase was different in each test unit (5 and 11 days for units 1 and 2 respectively), the kinetics of the biodegradation was highly comparable, yielding very similar values of biodegradation at the end of the respective 10-d windows: 82% and 84% days for units 1 and 2 respectively.
The procedure control with sodium benzoate reached 85% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.
The total elimination calculated based on dissolved organic carbon (DOC) measurements reached 99% for N-(3-Dimethylaminopropyl)-methacrylamide and for sodium benzoate. This data is in line with the degradation calculated based on O2 consumption.
N-(3-Dimethylaminopropyl)-methacrylamide (CAS no. 5205-93-6) reached the pass level of 60% for ready biodegradability in the Manometric Respirometry Test within the 10-d window and, therefore, can be termed as readily biodegradable.
All validity criteria were fulfilled.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The ready biodegradation of DMAPMA investigated in a Manometric Respirometry test over a period of 28 days and using domestic sewage as inoculum. Inoculum blank and procedural/functional control with the reference substance benzoic acid, sodium salt were performed.
While the lag-phase was different in each test unit (5 and 11 days for units 1 and 2 respectively), the kinetics of the biodegradation was highly comparable, yielding very similar values of biodegradation at the end of the respective 10-d windows: 82% and 84% days for units 1 and 2 respectively.
The biodegradability of N-(3-Dimethylaminopropyl)-methacrylamide based on O2 consumption was calculated to be 87% after 28 days as compared to the theoretical oxygen demand (ThOD).
The test item proved to be readily biodegradable and fulfilling the 10-d window criterion.
Executive summary:

The ready biodegradation of DMAPMA was investigated in a study conducted according to OECD Guideline 301 F (Manometric Respirometry Test), adopted 17th July 1992, and EU Method C.4 -C, 31 July 1992, over a period of 28 days using sewage sludge sampled from the aeration tank of a predominantly domestic sewage treatment plant as inoculum. The biodegradation rate was determined by measurement of O2 consumption. Inoculum blank and procedural/functional control with the reference substance benzoic acid, sodium salt were performed.

The test item proved to be readily biodegradable and fulfilling the 10-d window criterion.

While the lag-phase was different in each test unit (5 and 11 days for units 1 and 2 respectively), the kinetics of the biodegradation was highly comparable, yielding very similar values of biodegradation at the end of the respective 10-d windows: 82% and 84% days for units 1 and 2 respectively.

The biodegradability of N-(3-Dimethylaminopropyl)-methacrylamide based on O2consumption was calculated to be 87% after 28 days as compared to the theoretical oxygen demand (ThOD).

This study is regarded as reliable without restriction and satisfies the guideline requirements for ready biodegradation. DMAPMA proved to be readily biodegradable and fulfilling the 10-d window criterion.

Description of key information

N-[3-Dimethylamino)propyl]methacrylamide is readily biodegradable in a Manometric Respirometry test according OECD 301 F. 87 % degradation within 28 days, fulfilling 10 day window.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

N-[3-Dimethylamino)propyl]methacrylamide is readily biodegradable in a Manometric Respirometry test according OECD 301 F. 87 % degradation within 28 days, fulfilling 10 day window.