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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
From January 14, 1999 to February 11, 1999
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
RA study
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test)
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Mixed population of aquatic microorganisms form secondary effluent of a domestic sewage treatment plant (kläranlage Odenthal)
Treatment given: separation of coarse particles by filtration
Concentration of effluents in reaction mixture: 0.5 mL/L
Pretreatment: none
Duration of test (contact time):
28 d
Initial conc.:
18.6 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
Test temperature: 22°C
Number of flasks: Two each for the test substance and the reference substance and one for the toxicity control
Reference substance:
aniline
Remarks:
purity: 99.5%; initial conc.: 19.6 mg/L DOC
Key result
Parameter:
% degradation (DOC removal)
Value:
18
St. dev.:
0.5
Sampling time:
28 d
Details on results:
% degradation (DOC removal) after 7, 14, 21, 27 and 28 d: 18, 22, 20, 21 and 18, respectively (mean of two flasks).
Results with reference substance:
% degradation (DOC removal) after 28 d for the reference substance (aniline): 96.5
% degradation (DOC removal) after 28 d for the toxicity control: 57
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Under the study conditions, the substance was not considered to be readily biodegradable.
Executive summary:

A study was conducted to determine the ready biodegradability of the read-across substance in water according to EU Method C.4 -B, in compliance with GLP. Non-adapted activated sludge (domestic) was exposed to the equivalent of 18.6 mg/L DOC of test substance under aerobic conditions. Removal of dissolved organic carbon (DOC) was monitored for 28 d. A blank control and a reference substance (aniline) were kept in the study. The test substance biodegaraded up to 18% by test end. Under the study conditions, the substance was not considered to be readily biodegradable (Müller, 1999).

Description of key information

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

A study was conducted to determine the ready biodegradability of the read-across substance in water according to EU Method C.4 -B, in compliance with GLP. Non-adapted activated sludge (domestic) was exposed to the equivalent of 18.6 mg/L DOC of test substance under aerobic conditions. Removal of dissolved organic carbon (DOC) was monitored for 28 d. A blank control and a reference substance (aniline) were kept in the study. The test substance biodegraded up to 18% by test end. Under the study conditions, the substance was not considered to be readily biodegradable (Müller, 1999).