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Biodegradation in water: screening tests

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biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
Oxygen conditions:
Inoculum or test system:
activated sludge, domestic, adapted
Details on inoculum:
Activated sludge from a biologic sewage treatment plant was used as inoculum. The cho-sen plant treats mostly domestic sewage.
Source and Pre-Treatment of inoculum
The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf.
Date of collection: 12. Jan. 2018, batch no: 20180112.
The sludge was filtrated, washed with test medium (2x) and re-suspended in test medium. It was then aerated until use. The dry matter was determined to contain 4900 mg of sus-pended solids/L.
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 27.6 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
positive control
Test performance:
All validity parameters and values are presented in the following table:
Parameter Criterion Found Assessment
IC content of test item solution in medium ≤ 5% of TC 0 % valid
CO2 emitted by the controls < 70 mg/L 8.9 mg/L valid
Difference within replicates ≤ 20% 11.1 % valid
Degradation of positive control > 60% ≤ 14 days 9 days valid
Degradation in the toxicity flask on day 14 > 25% 83.7% non-toxic
Note: All calculations are performed with unrounded values. Therefore, re-calculation with rounded values may lead to slightly different results.
Key result
% degradation (CO2 evolution)
ca. 91
Sampling time:
29 d
Remarks on result:
other: The test item gamma-Dodecalactone is considered as “readily biodegradable“
Details on results:
The test item gamma-Dodecalactone is considered as “readily biodegradable“.
The degree of biodegradation reached 91 % after 28 days.
The 10-day-window began on day 2, at its end, 80 % degradation were reached (graphical evaluation), surpassing the pass level of 60 % given in the OECD guide-line.
The abiotic degradation reached 1.4 %.
Validity criteria fulfilled:
Interpretation of results:
readily biodegradable
The test item gamma-Dodecalactone is considered as “readily biodegradable“.

Description of key information

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:

Additional information