3,5,5-trimethylcyclohex-2-enone

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EU Method C.9 (Biodegradation: Zahn-Wellens Test)

Version / remarks:

Cited as Directive 87/302/EEC, part C, p. 99

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

INOCULUM/TEST ORGANISM
- Source: municipal WWTP Marl-West
- dry weight of inoculum used: 1.0 g/l

Duration of test (contact time):

28 d

Initial conc.:

1 290 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Test temperature: 20-22 °C
- pH value: 5.8 - 7.3

- Concentration of suspended solids: 1 g inoculum/l (dry wt)

Reference substance:

diethylene glycol

Parameter:

% degradation (DOC removal)

Value:

100

Sampling time:

21 d

Details on results:

Kinetic of test substance (in %):
= 3 after 3 hour(s)
= 5 after 3 day(s)
= 86 after 9 day(s)
= 89 after 14 day(s)
Kinetic of control substance (in %):
= 1 after 3 day(s)
= 100 after 9 day(s)

Results with reference substance:

100% degradation after 9 days

The test was performed in Nov/Dec 1985.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Executive summary:

The biodegradability of the test item was studied in a "Zahn-Wellens-Test" in accordance with EU method C9. The results indicate that the test item is inherently biodegradable under the present test conditions. 100% of the test item degraded within a period of 21 days.

The study was classified as "reliable with restrictions".

Reference 2

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:

other: Guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

INOCULUM/TEST ORGANISM
- Source: municipal WWTP Marl-Ost, sampled 12 Aug 1992
- Preparation of inoculum: centrifugation (10 min at 1100 g), discard  supernatant, resuspend in mineral medium, centrifugation (as above),  resuspension of sludge (4.6 g dry weight/l), keep aerated
- Initial inoculum concentration: 23 mg/l

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST SYSTEM
- Culturing apparatus: 2000 ml Erlenmeyer flask covered loosely with  aluminum sheet, filled with 900 ml test solution
- Number of culture flasks per concentration: each 2: test substance  (11.48 mg DOC/l) and inoculum; control substance (11.69 mg DOC/l) and  inoculum, inoculum only
- Aeration device: shaking for 28 days at 22 °C in the dark

METHOD OF PREPARATION OF TEST SOLUTION: 
- stock solution: 765 mg DOC/l

SAMPLING
- Sampling frequency: at day 0, 7, 14, 21 , 27, 28
- Sampling method: samples filtered (0.2 um)

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (DOC removal)

Value:

95

Sampling time:

28 d

Details on results:

Kinetic of test substance (in %):
= 5 after 7 day(s)
= 71 after 14 day(s)
= 93 after 21 day(s)
= 99 after 27 day(s)
= 95 after 28 day(s)
Kinetic of control substance (in %):
= 98 after 14 day(s)
= 100 after 28 day(s)

Results with reference substance:

100% degradation after 10 days

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Isophorone was observed to be readily biodegradable (95% degradation within 28 days. The 10-day window was passed.

Executive summary:

The biodegradability of the test item was studied in a "DOC-Die-Away Test" in accordance with EU method C4 -A. The results indicate that the test item is readily biodegradable under the present test conditions. 95% of the test item degraded within a period of 28 days. The study was classified as "reliable without restrictions".

Description of key information

The biodegradability of the test item was studied in a "DOC-Die-Away Test" in accordance with EU method C4 -A. The substance was incubated with sludge from a municipal WWTP for 28 days. 95% of the test item degraded within this period and >60% in the 10 day-window (Hüls, 1992).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Biodegradation of the test item was determined in a DOC-die-away- test for readily biodegradability (Hüls, 1992) and the Zahn-Wellens test for inherent biodegradability (Hüls, 1996). The results of both tests indicate that the test item is biodegradable under the present test conditions. Since the substance is readily biodegradable (>60% within the 10 day-window) this test was chosen for the chemical safety assessment.