N,N''-(methylenedi-4,1-phenylene)bis[N'-octyl]urea

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:

12 December 2002-10 January 2003

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)

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: water treatment plant of Evreux, France, containing effluent from predominantly domestic origin. The inoculum was sampled on 05/12/2002
- Method of cultivation: air was bubbled through the inoculum until use. The temperature was 22 +/- 2 degrees C. The reconstituted water (OECD and EEC recommended) was prepared using deionised water which contained no more than 5% OC.
- Storage conditions: at 22 +/- 2 deg C, in mineral medium under continous aeration
- Storage length: 7 days
- Preparation of inoculum for exposure: the inoculum was prepared by initially decanting and sieving the the sewage sludge. After centrifugation for 5 min, the supernatant was discarded and the pellet was redispersed in the mineral medium.
- Concentration of sludge: 15 mg/L suspended solids (dw) in 3L suspension

Duration of test (contact time):

29 d

Initial conc.:

13.3 mg/L

Based on:

test mat.

Initial conc.:

10 mg/L

Based on:

other: Total Organic Carbon

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium according to OECD 301B
- Test temperature: 20 - 23 deg C
- pH: 7.46 - 7.75
- pH adjusted: no
- Aeration of dilution water: aeration at the rate of 30 - 100 ml/min
- Suspended solids concentration: 15 mg/L dry weight. In the control flask 2 the quantity of inoculumadded (by an error) was higher 30 mg/L
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 3L flasks, dark glass
- Number of culture flasks/concentration: 2
- Measuring equipment: titration equipment. Each time CO2 was analyzed, 100 ml of Ba(OH)2 solution was titrated with 0.05 M HCl.
- Other: the test flask were aerated with CO2-scrubbed air overnight to purge the system of CO2 and then attached in parallel to a series of 3 wash bottles filled 100 ml of 0.0125 Ba(OH)2 to trap any CO2 released from the test vessels. The test and reference (sodium acetate) item were added, where appropriate, to the flasks to give a test and reference item concentrations of 10 mg TOC per liter (39.8 mg of KY-EU and 102.4 mg of sodium acetate). When all the substances have been added, the volume of the suspensions was made up to 3 L.

SAMPLING
- Sampling frequency: measurements of CO2 were made at the following times: days 1, 4, 6, 8, 11, 14, 18, 22, 25 and 29
- Sampling method: For each measurement, the first wash bottle nearest to the test flask was disconnected and titrated with 0.05 M HCl, using phenolphthalein as an indicator. The remaining CO2 absorber bottles were connected absorber bottles to the test flasks so that the second wash wash bottle replaced the first one and an extra bottle containing fresh Ba(OH)2 was added to the far end of the series. On the 28th day, 1 ml of concentrated HCl was added to each test flask to stop the biodegradation and test flasks were aerated overnight to drive off the remaining CO2. A final CO2 analysis of all wash bottles was made on the 29th day.


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: no
- Other: reference item, sodium acetate at 10 mg/L TOC

Reference substance:

other: sodium acetate at 10 mg/L TOC

Parameter:

% degradation (CO2 evolution)

Value:

32.4

St. dev.:

2.8

Sampling time:

28 d

Details on results:

The 10 days window started on day 18 and the average %Degr was 12.86 on day 18.

Validity criteria:
- The CO2 evolution in the blank control bottles at the end of the test was 35.2 mg CO2/L, which is < 70 mg CO2/L
- The difference in biodegradation of test item replicates was <20% at the end of the 10d-window
- The reference substance biodegraded > 60% in 14 days

Results with reference substance:

Biodegradation in the reference test was 71% after 14 days and 98.6% after 28 days.

Validity criteria fulfilled:

yes

Interpretation of results:

other: 32.4% biodegradation observed after 28 days

Conclusions:

Under the conditions of OECD 301B, KY-EU is not readily biodegradable.

Executive summary:

The ready biodegradability of KY-EU was investigated in a OECD 301B study, carried out according to GLP.

32.4% biodegradation was observed after 28 days. It was concluded that under the conditions of OECD 301B, KY-EU is not readily biodegradable.

The study is considered reliable without restrictions.

Description of key information

32.4% biodegradation was observed after 28 days. It was concluded that under the conditions of OECD 301B, KY-EU is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The ready biodegradability of KY-EU was investigated in a OECD 301B study, carried out according to GLP.

32.4% biodegradation was observed after 28 days. It was concluded that under the conditions of OECD 301B, KY-EU is not readily biodegradable.

The study is considered reliable without restrictions.