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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:
14 December 2011- 21 February 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
- Name of test material (as cited in study report): Isobutavan
- Physical state: colourless to pale yellow liquid
- Lot/batch No.: SC00003539
- Expiration date of the lot/batch: November 26, 2013
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland) was used.
The sludge was collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.
Duration of test (contact time):
32 d
Initial conc.:
30 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance:
other: sodium benzoate
Remarks:
purity 99% min
Key result
Parameter:
% degradation (O2 consumption)
Value:
94
Sampling time:
28 d
Details on results:
Isobutavan undergoes 94 % biodegradation after 28 days (94 % after 32 days) in the test conditions. The 10-day window criterion is also fulfilled (34 % biodegradation on day 2 and 86 % on day 12).
Isobutavan did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.
Results with reference substance:
Degradation of sodium benzoate exceeded 40 % after 7 days and 65 % after 14 days: the activity of the inoculum was thus verified (validity criterion).
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Isobutavan should be regarded as readily biodegradable according to this test.
Executive summary:

The ready biodegradability of Isobutavan was determined by the Manometric Respiratory Test according to OECD Guidelines No 301F. Under the conditions of the study the test substance underwent 94 % biodegradation after 28 days. The 10-day window criterion is also fulfilled (34% biodegradation on days 2 and 86% on day12). Thus, the test substance should be regarded as readily biodegradable according to this test.

Description of key information

The ready biodegradability of Isobutavan was determined by the Manometric Respiratory Test according to OECD Guidelines No 301F. Under the conditions of the study the test substance underwent 94 % biodegradation after 28 days. The 10-day window criterion is also fulfilled (34% biodegradation on day 2 and 86% on day12). Thus, the test substance should be regarded as readily biodegradable according to this test.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

At the concentration used in the test (30 mg/l), Isobutavan is not inhibitory to the micro-organisms.

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