4,4'-methylenedicyclohexyl diisocyanate

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

Cited as Directive 92/69/EEC, C.4-D

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Type: mixed population of aquatic microorganisms
- Origin: aeration tank of a waste water plant treating predominantly domestic sewage (Wupper area water authority, Germany)
- Pretreatment: none
- activated sludge concentration in test flasks: 30 mg 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:

INITIAL CONCENTRATION:
- Direct weighing
- Test substance: 100 mg/l
- Reference substance: 100 mg/l

EXPOSURE CONDITION:
- 28 days incubation at 20 +/- 1 °C

Reference substance:

benzoic acid, sodium salt

Remarks:

purity 99 %

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Details on results:

Kinetic of Desmodur W: 8 day(s) 0 %
14 day(s) 0 %
20 day(s) 0 %

Results with reference substance:

Kinetic of reference substance (in %): 79 after 8 days
87 after 14 days
91 after 28 days

The used concentration of the test substance did not show toxic effects  to bacteria (toxicity control)

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Executive summary:

4,4-methylenedicyclohexyl diisocyanate is not readily biodegradable. After 28 days 0 % of the test substance had been degraded in a manometric respiratory test (Directive 92/69/EEC, C.4-D) (Bayer AG, 2000).

Description of key information

In a GLP-study which was conducted according to Directive 92/69/EEC C.4-D (Manometric Respirometry Test), the biodegradation of 4,4’-methylenedicyclohexyl diisocyanate was investigated with a test substance concentration of 100 mg/l. Within the test period of 28 days, a degradation of 0 % was determined (Bayer AG, 2000a).

In a GLP-study which was conducted according to OECD TG 301F, the biodegradation of 4,4’ methylenedicyclohexyl diisocyanate was tested at an initial concentration of 12 mg/l. Within the test period of 28 days, a degradation of 0 % was observed (Bayer AG, 1992).

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed