Reaction mass of 2-ethylhexyl (6-isocyanatohexyl)-carbamate and bis(2-ethylhexyl) 1,6-hexan-1,6-diylbiscarbamate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: screening tests

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

yes

Remarks:

The study was conducted with adapted inoculum.

Principles of method if other than guideline:

The study was conducted with adapted inoculum.

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, adapted

Details on inoculum:

- Type mixed population of aquatic microorganisms (activated sludge)
- Origin Aeration tank of sewage treatment plant Leverkusen Buerrig (Germany)
- Date of collection: 2001-02-12
- Adaptation of the activated sludge to the test substance: 100 mg/L test substance and activated sludge 1 g/L; suspended solids were incubated at room temperature for 4 weeks in a flask and has been permanently aerated
- Concentration of activated sludge in reaction mixture: 0.3 g ss/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST DESIGN:
I. Pre-treatment of the test item:
- 25 mg of the test item were weighed out on aluminium foil; the test item inclusive the aluminium foil was added to the test vessels to give a test concentration of 100 mg/L test substance

II. Exposure conditions:
- Test volume: 250 mL
- Test apparatus: Voith Sapromat
- Mixing: 1 magnetic stirrer per test vessel
- Incubation time: 28 days
- Incubation temperature: 20 ± 1 °C
- Measurements of oxygen consumption: after 2, 6, 8, 10,  14, 16, 20, 22, 24 and 28 days

An inoculum blanc and a toxicity test, containing both the  test substance and the reference substance, were carried out under the same conditions. Further the oxygen uptake by nitrification was determined.

Reference substance:

other: Sodium benzoate (Purity 99 %)

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

2 d

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

10 d

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

20 d

Parameter:

% degradation (O2 consumption)

Value:

4

Sampling time:

28 d

Details on results:

No oxygen consumption by nitrification has been observed in the flask with test substance at the end ofthe test and the used test concentrations did not show toxic effects to bacteria. The pH-value of the test vessels at the end of the test was 7.6.

Results with reference substance:

The reference compound showed 64 % degradation after 14 days. After 6 days the reference substance had reached the level for ready biodegradability.

Validity criteria fulfilled:

yes

Remarks:

(-Ready biodegradation of reference compound ≥60 % within 14 days. - The toxicity control exhibited degradation rates >25 % within 14 days. - Replicates difference <20 %. - Oxygen uptake of the inoculum blank was ≤60 mg/L. - No pH influence.)

Interpretation of results:

not inherently biodegradable

Conclusions:

Within 28 days a degradation rate of 4 % was determined at pH 7.6. The reference compound sodium benzoate showed 64 % degradation after 14 days.

Executive summary:

The study was conducted with a modified protocol of Council Directive 92/69/EEC Method C.4-D "Manometrie Respirometry Test". The difference to Method C.4-D was that an adapted inoculum has been used. A measured volume of inoculated mineral medium, containing a known concentration of test chemical of 100 mg/L of the test substance, to give at least 50 - 100 mg ThOD/L as the nominal sole source of organic carbon, was stirred in a closed flask at a constant temperature (20 ± 1 °C) for up to 28 days. The consumption of oxygen was determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant gas volume in the respirometer flask. Evolved carbon dioxide is absorbed in a solution of potassium hydroxide. The amount of oxygen taken up by the test chemical (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of theoretical oxygen demand (ThOD) or chemical oxygen demand (COD). An inoculum blanc and a toxicity test, containing both the test substance and the reference substance, were carried out. Further the oxygen uptake by nitrification was determined because the test item is an N-containing substance. Within 28 days the substance showed 4 % degradation after 28 days at pH 7.6. Therefore the substance has to be classified as "Not Inherently Biodegradable". The reference compound showed 64 % degradation after 14 days.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Type: mixed population of aquatic microorganisms (activated sludge)
- Origin: secondary effluent of a domestic sewage treatment plant (Kläranlage Odenthal, Germany)
- Date of collection: 2001-02-12
- Preconditioning: separation of coarse particles by filtration
- Aeration: mineral medium plus inoculum (filtrate) for 7 days
- Effluent concentration in reaction mixture: 5 mL/L

Duration of test (contact time):

28 d

Initial conc.:

3.2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST DESIGN:
I. Pre-treatment of the test item/reference compound:
- The test item were weighed out on aluminium foil; the test item inclusive the aluminium foil was added to the test vessels
- Initial concentration: 3.2 mg/L (test substance), 2.9 mg/L (reference compound)

II. Exposure conditions:
- Incubation time: 28 days
- Incubation temperature: 20 ± 1 °C
- Measurements of oxygen consumption: after 0, 7, 14, 21 and 28 days

An inoculum blanc and a toxicity test, containing both the test substance and the reference substance, were carried out under the same conditions.

Reference substance:

benzoic acid, sodium salt

Remarks:

(purity 99 %)

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

21 d

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

28 d

Details on results:

The used concentrations of the test substance did not show toxic effects to bacteria.

Results with reference substance:

The reference compound sodium benzoate showed 75 % degradation after 14 days.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Within 28 days a degradation rate of 1 % was determined at pH 7.6. The reference compound sodium benzoate showed 75 % degradation after 14 days.

Executive summary:

The study was conducted with a modified protocol of Council Directive 92/69/EEC Method C.4-E "Closed Bottle Test". A measured volume of inoculated mineral medium, containing a known concentration of test chemical of approx. 3 mg/L of the test substance, to give at least 2180 mg O₂/g as the nominal sole source of organic carbon, was stirred in a closed flask at a constant temperature (20±1 °C) for up to 28 days. The consumption of oxygen was determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant gas volume in the respirometer flask. Evolved carbon dioxide is absorbed in a solution of potassium hydroxide. The amount of oxygen taken up by the test chemical (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of theoretical oxygen demand (ThOD) or chemical oxygen demand (COD). An inoculum blanc and a toxicity test, containing both the test substance and the reference substance, were carried out. Within 28 days the substance showed 4 % degradation after 28 days at pH 7.6. Therefore the substance has to be classified as "Not Readily Biodegradable". The reference compound showed 75 % degradation after 14 days.

Description of key information

In the study on inherent biodegradability a degradation rate of 4 % was determined within 28 days. In another study on ready biodegradability a degradation rate of 1 % was determined at pH 7.6 within 28 days. The reference compound sodium benzoate showed 75 % degradation after 14 days (Mueller, 2001).

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The substance has to be classified as "not inherently biodegradable".