1,3-dimethyl-1,3-diphenylurea

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:

02.11.-02.12.2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

anaerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

The inoculum contained a mixed population of microorganisms obtained from the secondary effluent of the waste water treatment plant of Pardubice processing predominantly municipal sewage.

PREPARATION OF INOCULUM
The fresh collected waste water was filtered through paper filter. COD was determined and waste water was aerated till using.

Justification of the test system
The inoculum preparation is in conformity with the recommendations of the test guideline.

Duration of test (contact time):

28 d

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 20+/-1 °C
- pH of medium: 7.4
- pH adjusted: no
- Illummination: in the dark

PREPARATION OF SOLUTIONS FOR THE TEST
- Inoculated medium: TThe volume of waste water for the inoculation of mineral medium was chosen 1.9 mL per 1 L of medium (COD of waste water: 71 mg·L-1). 30 L aerated mineral medium was prepared for the test and before the beginning of the test it was inoculated with 57 mL of modified waste water. The pH value of medium: 7.5.

- Test substance: The stock solution of the test substance was prepared in concentration 0.1001 g·L-1
of deionized water. Because the test substance was poorly soluble, the stock solution was stirred for period 24 hours for achieving the highest solubility.
From this stock solution 120 mL (20 mL·L-1) were transferred to a large glass bottle and completed with the inoculated medium to the volume of 6 L.
The solution prepared in this way contained 2.00 mg·L-1 of the test substance. The pH value of solution: 7.3.

TEST SYSTEM
Test substance series: 2 x 9 bottles with test substance and inoculum
Reference substance series: 2 x 9 bottles with reference substance and inoculum
Blank series: 2 x 9 bottles with inoculated medium only
Toxicity test series: 2 x 5 bottles with test substance, reference substance and inoculum
Series for nitrification determination: 1 x 9 bottles with test substance and inoculum
The prepared dosing solutions for each series was filled in two parallel bottle replicates (except series for nitrification determination).
The bottles were placed into thermostat.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, the inoculated mineral medium
- Toxicity control: yes, the test and reference substance mixture

Measurement: At the zero-time and at the 3rd, 7th, 10th, 14th, 17th, 21st, 24th and 28th day of test the
appropriate bottles from each series were taken off and they were analysed for dissolved oxygen by the Winkler method.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

69.2

Sampling time:

28 d

Key result

Parameter:

BOD5

Value:

0.16 other: mg/mg

Key result

Parameter:

COD

Value:

2.088 other: mg/mg

Parameter:

ThOD

Value:

2.796 other: mg/mg

Remarks on result:

other: with total nitrification

Parameter:

ThOD

Value:

2.264 other: mg/mg

Remarks on result:

other: without total nitrification

Results with reference substance:

COD of reference substance 1.640 mg.mg-1 and 85.9 %

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

In this 28-day study of ready biological degradability the degradation of 69.2 % of the test substance, Methylcentralit, was attained in the end of study.

Executive summary:

The test substance, Methylcentralit,was tested forthe ready biological degradability in Closed Bottle Test.

Test performance

The test was performed according to:

Method C.4E - Closed Bottle Test, Council Regulation (EC) No. 440/2008, published in O.J.L 142, 2008.

 

The results of biological degradation are related to experimentally determined COD values of the test and reference substance at the beginning of the test.

The test substance was soluble in used mineral medium. The stock solution of the test substance was stirred for period 24 hours and then the dosage from the stock solution was carried out.

 

Sodium benzoate was used as the reference substance. The dosage was carried out from the stock solution.

Specific COD of the test substance in medium:                   2.088 mg·mg^-1

Specific COD of the reference substance in medium:         1.640 mg·mg^-1

In parallel to the main test the toxicity test was performed.

Based on the test substance contains nitrogen in the chemical composition, the oxidized nitrogen forms were determined and the correction for nitrification was carried out.

The test was performed at temperature of 20 ± 1 °C with the pH values of solutions 7 – 8
at the beginning of the test.

 

Validity of the test

The prescribed validity criteria in the test were fulfilled.

The test substance was not inhibiting for the used inoculum.

Since all criteria of acceptability were met, this study is considered to be valid.

 

Test results

In this28-day study of ready biological degradabilitythe degradation of 69.2 % of the test substance,Methylcentralit,was attained in the end of study.

Description of key information

Only one study is available.

The test was performed according to: Method C.4E - Closed Bottle Test, Council Regulation (EC) No. 440/2008, published in O.J.L 142, 2008.

GLP study.

Klimish score 1.

The test substance, Methylcentralit, was tested for the ready biological degradability in Closed Bottle Test.

Based on results of this 28 days study Methylcentralit is not ready biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed