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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
Study period:
06/08/2011 tp 07/06/2011
1 (reliable without restriction)
according to guideline
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
GLP compliance:
Oxygen conditions:
Inoculum or test system:
mixture of sewage, soil and natural water
Details on inoculum:
Fresh samples were collected from ten sites, mainly in areas where a variety of chemicals were used and discharged. One liter samples were colleted and mix together. Floating material was removed and the sample was allowed to aerate for ~23.5 hours. After settling for 30 minutes, 1/3 of the sample was discarded and an equal volume of a solution (pH7) containing 0.1% each of glucose, peptone and potassium orthohosphate was added and the sample. This was repeated daily for 30 days, during which the sample was aerated and maintained at 25°C +/- 1°C and pH7. After approximately 30 days, the sludge was used as the microbial inoculum in the test.
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 was performed in darkness. The BOD Analyzer was set to 20 +/- 1°C
Key result
% degradation (O2 consumption)
Sampling time:
28 d
Validity criteria fulfilled:
Interpretation of results:
under test conditions no biodegradation observed
The test substance, 1,2-Bis9phenylthio)ethane was not concluded to be readily biodgradable, following OECD 301C guidelines.
Executive summary:

According to the calculations, the theoretic oxygen demand of the test item was 2.66 mg O2/mg test item. The test results showed that after 28 days, the percent biodegradation of 1,2 -Bis(phenylthio)ethane in activated sludge was -0.94%. The accumulated percent biodegradation of the reference item (aniline) in activated sludge after 28 days was 78.84%. Therefore, the test material cannot be considered to be readily biodegradable.

Description of key information

The test results showed that after 28 days, the percent biodegradation of the test material in activated sludge was -0.94%.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information