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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:
1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- mixed population of aquatic microorganisms, origin from the secondary effluent of a domestic waste water treatment plant
(Wupper area water authority, Germany)
- activated sludge concentration in test flask: 30 mg/L
- Sampling date: 1998-05-04
- 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:
The test substance is suspended in a mineral medium (by direct weighing of the test substance), inoculated with a mixed population of aquatic microorganisms and incubated for 28 days under aerobic conditions in the dark at 20 +/- 1 °C. During this period, the biodegradation of the test substance is determined by registration of the oxygen consumption using a respirometer.
Reference substance:
aniline
Remarks:
Purity: >99.5 %
Parameter:
% degradation (O2 consumption)
Value:
23
Sampling time:
28 d
Remarks on result:
other: mean value of two replicates
Details on results:
All validity criteria were met apart from the criteria "differences of extremes of replicate values is less than 20 % at the end of the test". The test substance has been degraded 35 % and 10 % in the parallels at the end of the test. The test substance did not meet the criteria "readily biodegradable".
The used concentration of the test substance did not show toxic effects to bacteria (toxicity control).
Parameter:
COD
Value:
1 840 mg O2/g test mat.
Results with reference substance:
Aniline was used as the reference substance and with the same inoculum, 67 % degradation was observed. The rate and extent of aniline degradation
fulfilled the validity criteria of the test.
Validity criteria fulfilled:
yes
Remarks:
All validity criteria were met apart from the criteria "differences of extremes of replicate values is less than 20 % at the end of the test".
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Within 28 days, a degradation rate of 23 % was determined for the substance. Therefore, the test substance is considered to be “Not Readily Biodegradable“ .
Executive summary:

A test on ready biodegradability was conducted according to EU Method C.4-D (Manometric Respirometry Test). The test substance is suspended in a mineral medium, inoculated with a mixed population of aquatic microorganisms and incubated for 28 days under aerobic conditions in the dark at 20 +/- 1 °C. During this period, the biodegradation of the test substance is determined by registration of the oxygen consumption using a respirometer. After 28 days the substance showed 23 % degradation. Therefore the test substance has to be classified as "not ready biodegradable".

Description of key information

Within 28 days, a degradation rate of 23 % was determined for the substance.

Therefore, the test substance is considered to be “Not Readily Biodegradable“.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The test for determining the biodegradable potential of the substance was performed using the test substance diluted in an 8 : 17 mixture of 1-methoxy-2-propyl acetate (CAS: 108-65-6) and solvent naphtha 100 (CAS: 64742-95-6), respectively. The test solution consisted to 75 % of the test item and to 25 % of the 1-methoxy-2-propyl acetate/solvent naphtha mixture. As the test substance is only marketed in the above described composition, these tests can be used for the evaluation of the environmental risks of the substance. As further no ready biodegradability could be observed, this result also displays the worst case for the substance and therefore could be used for further evaluation of the test substance.