3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate

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:

1999-08-12 to 1999-09-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(1992)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

INOCULUM/TEST ORGANISM
- Species/strain: mixed population of aquatic microorganisms (activated sludge)
- Sampling site: aeration tank of a WWTP of Wupper area water authority, sampled 09 Aug 1999
- Pretreatment: none

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 SYSTEM
- Number of culture flasks per concentration: 3 each for test substance,  blank control and reference substance; 2 for toxicity control

METHOD OF PREPARATION OF TEST SOLUTION
- Direct weighing 

ANALYTICAL  PARAMETER
- Dissolved oxygen

SAMPLING
- days 4, 6, 8, 12, 14, 18, 20, 22, 26, 28

TEST CONDITIONS
- Test temperature: 20 +/- 1 degree C
- Concentration of suspended solids: 30 mg/l

CONTROLS
- blank control, toxicity control, reference substance

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Details on results:

Kinetic of test substance (in %):
= 0 after 4 day(s)
= 0 after 14 day(s)
Kinetic of control substance (in %):
= 69 after 4 day(s)
= 88 after 14 day(s)

Results with reference substance:

For sodium benzoate, 88 % degradation were observed within 14 days.

The used concentrations of the test substance did not show toxic effects to bacteria. In a toxicity control a mean degradation of 55 % was achieved after 28 days. However, degradation of the reference substance was delayed.

Validity criteria fulfilled:

yes

Conclusions:

0% biodegradation was observed during the test.

Executive summary:

No biodegradation (0% degradation within 28 days) was observed in a manometric respiratory test performed with domestic, non-adapted activated sludge according to Directive 92/69/EEC, C.4-D (Bayer AG, 2000). The study was assessed as "reliable without restrictions".

Description of key information

No ready biodegradation (0% degradation within 28 days) was observed in a manometric respiratory test performed with domestic, non-adapted activated sludge according to Directive 92/69/EEC, C.4-D (Bayer AG, 2000).

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Additional information

A manometric respiratory test performed with domestic, non-adapted activated sludge according to Directive 92/69/EEC, C.4-D (Bayer AG, 2000) revealed 0% degradation of isophorone diisocyanate within 28 days. The substance is therefore regarded not readily biodegradable.

Biodegradation is of minor relevance because the reaction with water is expected to eliminate the substance rapidly, forming amines, CO2 and further polyurea.

The hydrolysis product isophorone diamine is not readily biodegradable either in a DOC-DIE Away test (EU method C.4 A) and polyurea is considered to be an inert material unable to be biodegraded.