Reaction products of cyclohexylamine and 4-alkylaniline and 1,1'-methanediylbis(4-isocyanatobenzene)

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 1996-01-30 to 1996-03-29

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Although a guideline study (OECD 301B & 301D and EU Methods C4-C & C4-E.) conducted according to the principles of Good Laboratory Practice, the purity and expiry date of the test substance was not supplied and its stability under the test conditions was not determined.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- Substance type: technical material
- Physical state: a fine cream-coloured cohesive powder
- Storage condition of test material: at ambient temperature
- Other: Test concentrations quoted in the report refer to the test material as received; no allowance has been made for a purity of less than 100%

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Oakley STW, a sewage treatment works that treats predominantly domestic waste.
- Storage conditions: Not reported
- Storage length: 24 hours
- Preparation of inoculum for exposure: Aerated in the Laboratory for four hours and a sample of the mixed liquor was then homogenized in a
mechanical blender and allowed to settle for 50 minutes.
- Pretreatment: Aerated overnight with air that had been passed through cylinders containing calcium chloride and Carbosorb AS followed by two
bottles containing 0.025 N barium hydroxide to remove CO2.
- Concentration of sludge: Not reported
- Initial cell/biomass concentration: 1%
- Water filtered: yes

Duration of test (contact time):

29 d

Initial conc.:

39.5 other: mg/100mL

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral salts medium (MSMS)
- Test temperature: 20 to 24 °C
- pH: 7.2 - 7.5
- pH adjusted: No
- Aeration of dilution water: Continuously flushed with treated air
- Continuous darkness: Yes for the preliminary study (Bacterial inhibition test) but not stated in the report for the main study

TEST SYSTEM
- Culturing apparatus: Five test vessels (five litre brown glass carboys)
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Aerated with air via an inlet tube reaching approx. 15cms below the liquid surface and an air outlet
tube just below the stopper.
- Test performed in open system: yes
- Details of trap for CO2 and volatile organics if used: The air outlet from each vesel was connected to three Drechsel bottles in series, each
containing 0.025N barium hydroxide (100 mL).

SAMPLING
- Sampling frequency: Days 2-6, 8, 15, 18, 25, 28 and 29

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Toxicity control: Sodium benzoate 1.72 g/Liter

Reference substance:

benzoic acid, sodium salt

Remarks:

AR Grade, product number S/2441

Preliminary study:

The five-day bacterial inhibition assay was conducted before the main test to determine whether the test item, at a concentration of 10 mgC/L inhibited the normal degradative activity of the bacterial inoculum on the reference material, sodium benzoate. The presence of test material at this test concentration was was not significantly inhibitory, neither was it readily degradable in the preliminary test.

Test performance:

The rate of degradation of sodium benzoate (60% of its TCO2 after six days and 88% after 29 days) and for cumulative CO2 in the control (30.5 and 25.1 mg) fulfill the validity criteria for this test.

Parameter:

% degradation (CO2 evolution)

Value:

1

Sampling time:

15 d

Remarks on result:

other: cumulative (Culture 1)

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

15 d

Remarks on result:

other: cumulative (Culture 2)

Parameter:

% degradation (CO2 evolution)

Value:

4

Sampling time:

29 d

Remarks on result:

other: cumulative (Culture 1)

Parameter:

% degradation (CO2 evolution)

Value:

1

Sampling time:

29 d

Remarks on result:

other: cumulative (Culture 2)

Details on results:

In the Modified Sturm Test, mean cumulative CO2 production by mixtures containing test item at 10 mgC/L was equivalent to 3% of the TCO2. Substances are considered to be readily degradable in the test if CO2 production is equal to or greater than 60% of the theoretical value within ten days of the level first achieving 10%. The test item cannot therefore be considered to be readily degradable.

Parameter:

BOD5*100/ThOD

Value:

0

Results with reference substance:

Sodium benzoate was degraded to 63% of its ThOD after five days of incubation which indicates that the inoculum was viable and exerting normal biodegradative activity.

The pH of test mixtures ranged between 7.2 and 7.5 at the start of the test and between 7.4 and 7.5 at the end.

The rate of air flow during the test ranged from 38 to 43 mL/minute. Temperatures of the test area ranged from 21.2 °C to 23.9 °C. Due to a failure in the control system on Day 27, the temperature of the test area dropped to 14.80℃. Although this value falls outside the minimum recommended for this assay (20 °C) it is not thought to be significant or to have affected the integrity of the test.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

In this study, a five day bacterial inhibition assay demonstrated that the presence of test item at a concentration of of 10 mgC/Litre was not significantly inhibitory on the reference substance sodium benzoate, neither was it readily degradable. The Modified Sturm Test further demonstrated that the test substance is not readily degradable.

Executive summary:

A Modified Sturm Test was conducted to assess the biodegradability of the substance. The main study was performed in accordance with Procedure C.4 -C 'CO2 Evolution test' of the Annex to Directive 92/69/EEC (OECD Procedure 301B). Prior to the main test, a five-day bacterial inhibition was performed (Procedure C.4 -E, of the Annex to Directive 92/69/EEC, OECD Procedure 301D) which showed that the test substance at a nominal concentration of 10 mgC/Litre did not significantly inhibit degradation of the reference material sodium benzoate, it also showed no significant evidence of biodegradation. In the main test, the same concentration of the test substance was used over a period of 29 days which resulted in a mean cumulative CO2 production equivalent to 3% of the of the theoretical value. It was concluded therefore, that in the test conditions, the test item is not considered to be readily degradable.

Description of key information

A Modified Sturm Test was conducted to assess the biodegradability of the substance in accordance with Procedure C.4 -C 'CO2 Evolution test' of the Annex to Directive 92/69/EEC (OECD Procedure 301B). Mean cumulative CO2 production by mixtures containing test item at 10 mg C/L was equivalent to 3% of the theoretical value (TCO2 106.4 mgCO2). The test item is not considered to be readily degradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

In this study, a five day bacterial inhibition assay demonstrated that the presence of test item at a concentration of 10 mgC/Litre was not significantly inhibitory on the reference substance sodium benzoate, neither was it readily degradable. The Modified Sturm Test further demonstrated that the test substance is not readily degradable.