3-methoxy-N,N-dimethylpropionamide

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:

24 October 2006 - 19 December 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: ''Method for Testing the Biodegradability of Chemical Substances by Microorganisms" stipulated in the "Testing Methods for new Chemical Substances" (November 21, 2003, Yakushokuhatsu No.1121002, November 13, 2003 Seikyoku No.2, Kanpokihatsu No.031121002)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Solubility in water: 300 g/100 g or more
Solubility in hexane: 50 g/100 g
Stability under storage conditions: stable

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: sludge was collected from 10 different sites in Japan, among which three city sewage plants, one industrial sewage plant, three rivers, one lake and two bays.
- Method of sampling: Sewage plants: return sludge from the sewage plants was collected; River, lake and sea: surface water and surface soil, which was in contact with the atmosphere, was collected.
- Preparation of sludge: in order to maintain uniformity of the inoculum used in the test, filtrate (5 L) of the supernatant of cultivated sludge (cultivated for approx. 3 months) was mixed with filtrate (5 L) of the supernatant of a sludge collected newly at each location. The mixture (10 L) was aerated after the pH value of the mixture was adjusted to 7.0 ± 1.0.
- Method of cultivation: Roughly 30 minutes after ceasing aeration of the sludge mixture, supernatant corresponding to about 1/3 of the whole volume was removed. Dechlorinated water was added to the remaining portion so that the total volume reached 10 L. This mixture was aerated (for 30 minutes or more). Subsequently, synthetic sewage was added to 50 g/L of the synthetic water so that the concentration of the synthetic sewage was 0.1% in the volume of dechlorinated water added. This procedure was repeated once every day. Cultivation was carried out at 25 ± 2 °C.
- Concentration of sludge: 2890 mg suspended solids/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: 3 mL solutions were made up to 1L with purified water and the pH was adjusted to 7.0. This was according to OECD 301C.
- Test temperature: 25 +/- 1 °C
- pH: 6.1 - 7.0 in different vessels at the start of the test
- pH adjusted: no
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Culturing apparatus: 300 mL vessels
- Number of culture flasks/concentration:
Abiotic control (water + test item): 1
Positive control (aniline): 1
100 mg test item/L: 3
Blank control: 1
- Measuring equipment: closed system oxygen consumption measuring apparatus
- Details of trap for CO2: Soda lime was used as a CO2 absorber

SAMPLING
- Sampling frequency: at the end of the exposure period
- Sampling method: 10 mL of test solution was collected and centrifuged for 15 minutes, the supernatant was used for TOC analysis and HPLC analysis.
- Sample storage before analysis: samples were analysed directly after collection

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 1 replicate
- Abiotic sterile control: yes, 1 replicate
- Toxicity control: no
- Other: aniline was used as a reference control to test the activity of the sludge

STATISTICAL METHODS: none

Reference substance:

aniline

Key result

Parameter:

% degradation (DOC removal)

Value:

2

Sampling time:

28 d

Remarks on result:

other: Mean of 3 replicates

Key result

Parameter:

% degradation (test mat. analysis)

Value:

0

Sampling time:

28 d

Remarks on result:

other: Mean of 3 replicates

Key result

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

28 d

Remarks on result:

other: Mean of 3 replicates

Details on results:

- The test item was not sufficiently biodegraded by microorganisms to pass the criterium of 60% biodegradation.

Results with reference substance:

78% biodegradation after 14 days and 87% biodegradation after 28 days.

Validity criteria fulfilled:

yes

Remarks:

The reference item biodegraded for 78% in 14 days, the difference between vessels containing test solution was ≤6%, the BOD value of the blank control was 8.1 mg (corresponding to 27 mg O2/L).

Interpretation of results:

not readily biodegradable

Conclusions:

Under the conditions of the Modified Miti Test, MDMPA is not readily biodegradable.

Executive summary:

A Biodegradation test was performed according to OECD 301C (Modified Miti Test) to assess the ready biodegradability of MDMPA over a period of 28 days. The concentration tested was 100 mg/L, with an activated sludge concentration of 30 mg/L (suspended solids). Besides three replicates containing test item, an abiotic control, a reference control and a blank control were included. At the end of the exposure period, samples from all test vessels were taken for TOC and HPLC analysis. Results showed the test item biodegraded for 1% based on oxygen consumption (BOD), 2% based on DOC and 0% based on HPLC analysis. Therefore, MDMPA is determined to be not readily biodegradable under the conditions of the Modified Miti Test. The reference item (aniline) biodegraded for 78% in 14 days. All acceptability criteria were met and the study was considered to be valid.

Description of key information

A Biodegradation test was performed according to OECD 301C (Modified Miti Test) to assess the ready biodegradability of MDMPA over a period of 28 days. The concentration tested was 100 mg/L, with an activated sludge concentration of 30 mg/L (suspended solids). Besides three replicates containing test item, an abiotic control, a reference control and a blank control were included. At the end of the exposure period, samples from all test vessels were taken for TOC and HPLC analysis. Results showed the test item biodegraded for 1% based on oxygen consumption (BOD), 2% based on DOC and 0% based on HPLC analysis. Therefore, MDMPA is determined to be not readily biodegradable under the conditions of the Modified Miti Test. The reference item (aniline) biodegraded for 78% in 14 days. All acceptability criteria were met and the study was considered to be valid.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Also an Inherent Biodegradation test was conducted according to OECD 302C and in compliance with GLP.

The inherent biodegradability of the test substance was determined in triplicate in a 28-day test (non-adapted micro-organisms) in an aerobic aqueous medium based on Biochemical Oxygen Demand (BOD) and the analysis of residual test substance in BOD bottles. In parallel, an abiotoc control, a reference substance and untreated control were tested.

During the test, the temperature was kept at 25±1 °C. The test was valid because the level of biodegradation of the reference substance sodium benzoate exceeded 40% after 7 days, and 65% after 14 days.

Based on the BOD results, biodegradation of the test substance was 3.83% during the testing period. Based on residue analysis, biodegradation of the test substance was 1.96% after 28 days. Therefore, the test substance is not inherently biodegradable under the conditions of the Modified MITI (II) test.