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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2000-07-28 to 2001-08-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
17 july 1992
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Inoculum was collected from a water treatment plant containing effluent from a predominantly domestic origin. The inoculum consisted of sewage sludge sampled from the aeration tank of a sewage treatment plant and then aerated for 7 days. Inoculum concentration was 12.0 mg/L (dry weight) in all test vessels.
The inoculum was prepared by initially sieving sewage sludge. The sludge was then centrifuged for 5 minutes, the supernatant was rejected and the pellet was redispersed in the mineral medium. In order to wash out the dissolved organic carbon (DOC) and to lower the carbon organic content, the inoculum was preconditioned for 7 days before use. Air was bubbled through the inoculum during this preconditioning period.
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
The test was carried out in dark glass bottles fitted with dark glass stoppers and aeration tubes to reduce the quantity of light reaching the test suspensions.
- pH: 7.58 to 8.45,
- temperature: 19°C to 24°C.
Reference substance:
acetic acid, sodium salt
Parameter:
% degradation (CO2 evolution)
Value:
65
Sampling time:
10 d
Key result
Parameter:
% degradation (CO2 evolution)
Value:
99
Sampling time:
28 d
Details on results:
The 10-day window of the peroxide started on the 2nd day. Biodegradation of CUMYLPEROXYNEODECANOATE totalled 65% (mean of the two flasks) at the end of this 10-day window on the 12th day and 99% over the test period
Results with reference substance:
Biodegradation in the reference test was 61% after 14 days then it was at least 60% within this period
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The biodegradation of CUMYLPEROXYNEODECANOATE reached 65% at the end of the 10-day window (the 10 days immediately following the attainment of 10% biodegradation) and 99% at the end of the test.
Under the experimental conditions, the peroxide CUMYLPEROXYNEODECANOATE was therefore readily biodegradable in the 28-day modified Sturm test.
Executive summary:

The ready biodegradability of cumylperoxyneodecanoate (containing 30 % isododecane as stabiliser) was evaluated in a 28-day modified Sturm test according OECD guideline 301 B at an initial test substance concentration of 10 mg/L TOC. Carbon dioxide evolution was corrected for the isododecane content, whose biodegradability was studied in separate experiments. The 10-day window for degradation of cumylperoxyneodecanoate started on the 2nd day. At the end of the 10-day window biodegradation of the test substance totalled 65 %. At the end of the study period biodegradation of the test substance totalled 99 % (after 28 days; value for peroxide without isododecane).

Under the conditions of the CO2 evolution test, cumylperoxyneodecanoate is readily biodegradable.

Description of key information

In the CO2 evolution test (modified Sturm test) 1-methyl-1-phenylethyl peroxyneodecanoate is readily biodegradable (fulfilling the 10-day window).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The ready biodegradability of cumylperoxyneodecanoate (containing 30 % isododecane as stabiliser) was evaluated in a 28-day modified Sturm test according OECD guideline 301B at an initial test substance concentration of 10 mg/L TOC. Carbon dioxide evolution was corrected for the isododecane content, whose biodegradability was studied in separate experiments. The 10-day window for degradation of cumylperoxyneodecanoate started on the 2nd day. At the end of the 10-day window biodegradation of the test substance totalled 65 %. At the end of the study period biodegradation of the test substance totalled 99 % (after 28 days; value for peroxide without isododecane).

Under the conditions of the CO2 evolution test, cumylperoxyneodecanoate is readily biodegradable.

The test item contains isododecane (30 %) as a stabiliser. Isododecane was degraded by 3.33 % within the 28 day test period.