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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:
2001
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: complete and under GLP
Qualifier:
according to
Guideline:
other: Closed Bottle Test, OECD method 301 and EU test method C.6.
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Duration of test (contact time):
28 d
Reference substance:
other: sodium acetate
Parameter:
% degradation (O2 consumption)
Value:
3
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
65
Sampling time:
140 d
Details on results:
Points of degradation plot (test substance):
0 % degradation after 7 d
0 % degradation after 14 d
3 % degradation after 28 d
13 % degradation after 56 d
39 % degradation after 84 d
59 % degradation after 120 d
65 % degradation after 140 d
Results with reference substance:
Points of degradation plot (reference substance):
59 % degradation after 7 d
75 % degradation after 14 d
Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily but inherently biodegradable
Conclusions:
Under the conditions of the test, methylethylketone peroxide trimer is not readily biodegradable, but is inherently biodegradable from the results of the extended biodegradation test.

Description of key information

The result of an OECD 301D tests indicate that 3,6,9-Triethyl-3,6,9-trimethyl-1,4,7-triperoxonane is not readily biodegradable.

An OECD 302B study did not show biodegradation either.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

Two tests on ready biodegradability are available. An OECD 301B (CO2 evolution test) performed in 1997 (result: not biodegradable). The OECD 301D (O2 consumption) test. The test was extended to 140 days because the pass level of 60% was not reached in 28 days. At day 140 a degradation percentage of 65% was reached. It is concluded that although the substance is not readily biodegradable, this results demonstrates that the substance is not recalcitrant in nature. A biodegradation percentage > 60% indicates that the test substance is completely mineralised.

No biodegradation was found in the OECD 302B study. MEK was not formed in the tests with 3,6,9-Triethyl-3,6,9-trimethyl-1,4,7-triperoxonane

spiked to mineral salt medium or spiked to mineral salt medium with heat killed activated sludge. This demonstrates that in the Zahn Wellens test the peroxide bonds in this substance are not reduced by a chemical reaction. MEK was however also not measured for

3,6,9-Triethyl-3,6,9-trimethyl-1,4,7-triperoxonane

in the presence of living activated sludge. The substance is therefore not removed by alkyl hydroperoxide reductases. The active site of alkyl hydroperoxid reductase most likely cannot accommodate ketone peroxides such as

3,6,9-Triethyl-3,6,9-trimethyl-1,4,7-triperoxonane.

Studies with a mixture of organic peroxide (CAS 1613243-54-1) with the registered substance as main constituent showed similar results. This mixture was not found readily biodegradable and neither inherently biodegradable.