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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:
From January 1998 to April 1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Qualifier:
according to guideline
Guideline:
other: ISO 7827
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from laboratory wastewater treatment plants fed with municipal and synthetic sewage
- Concentration of activated sludge: 30 mg/L dry solids
Duration of test (contact time):
28 d
Initial conc.:
70 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Reference substance:
aniline
Key result
Parameter:
% degradation (DOC removal)
Value:
ca. 10 - ca. 20
Sampling time:
28 d
Results with reference substance:
99% biodegradation (based on DOC removal) on day 5

The substance was not found to be inhibitory to activated sludge respiration: the degradation in the toxicity control reached 59% on day 14.

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Under the study conditions, the test substance was not considered to be readily biodegradable.
Executive summary:

A study was conducted to determine the ready biodegradability of the test substance (62% purity) according to OECD Guideline 301 A, in compliance with GLP. Municipal activated sludge was inoculated with the substance at 70 mg/L, equivalent to 20 mg/L dissolved organic carbon (DOC). DOC removal was monitored over a period of 28 d. A positive control, aniline, was also evaluated. The test substance degraded by 10 -20% within 28 d. The reference substance was degraded by 99% within 5 d. Under the study conditions, the test substance was not considered to be readily biodegradable (Schwarz, 1998).

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 test substance according to OECD Guideline 301 A, in compliance with GLP. Municipal activated sludge was inoculated with the substance at 70 mg/L, equivalent to 20 mg/L dissolved organic carbon (DOC). DOC removal was monitored over a period of 28 d. A positive control with the reference item aniline was also evaluated. It reached a mean degradation of 99% on day 5. The test substance degraded by 10-20% within 28 d. Under the study conditions, the test substance was not considered to be readily biodegradable (Schwarz, 1998). The substance was not found to inhibit activated sludge respiration as shown in the toxicity control.