(R)-6-(isopropyl)-3-methylcyclohex-2-en-1-one

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:

24 Aug - 21 Sep 2000

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)

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Kläranlage Odenthal, Germany
- Preparation of inoculum for exposure: aeration of mineral medium plus inoculum (filtrate) for 6 days (effluent concentration in reaction mixture 5 ml/L)
- Pretreatment: seperation of coarse particles by filtration

Duration of test (contact time):

28 d

Initial conc.:

2.5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium (no further specification)
- Test temperature: 20 ± 1 °C
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: closed bottles
- Number of culture flasks/concentration: 10

CONTROL AND BLANK SYSTEM
- Inoculum blank: 10 bottles
- Procedure control: 10 bottles
- Toxicity control: 10 replicates

Reference substance:

benzoic acid, sodium salt

Remarks:

2.9 mg/L

Key result

Parameter:

other: % degradation (dissolved oxygen)

Value:

77

Sampling time:

28 d

Details on results:

Theoretical oxygen demand: 2838 mg O2/g

Test item samples: 47, 59, 74 and 77% biodegradation was determined after 7, 14, 21 and 28 d, respectively

Toxicity control: 62, 64, 77 and 77% degradation was determined after 7, 14, 21 and 28 d

Results with reference substance:

Theoretical oxygen demand: 1665 mg O2/g

69, 79, 82 and 84% degradation was determined after 7, 14, 21 and 28 d.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The substance is readily biodegradable (77% degradation after 28 days).

Description of key information

Readily biodegradable: 77% within 28 d (EU Method C.4-E, activated sludge, domestic)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

There is one GLP study available investigating the ready biodegradability of the test substance in an aerobic, aqueous medium, according to the Council Directive 92/69/EEC Method C.4-E.

In a closed bottle test a nominal concentration of 2.5 mg/L test substance was inoculated with 5 mL/L secondary effluent from a local, domestic sewage treatment plant for 28 d under aerobic conditions in completely full, closed bottles. A procedure and toxicity control as well as an inoculum blank were run in parallel. Biodegradation was followed by analysis of dissolved oxygen and was expressed as % of the theoretical oxygen demand (ThOD).

The biodegradation of the test substance was 47%, 59%, 74% and 77% after 7, 14, 21, and 28 d. Therefore, the test substance is classified as readily biodegradable (77% within 28 d, 14-d window passed). The toxicity control indicated that the test substance did not inhibit the biodegradation of the reference substance.