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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Administrative data

Endpoint:
biodegradation in water and sediment: simulation tests
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented estimatioon program, using data from Biowin, a validated QSAR model
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6

Data source

Reference
Reference Type:
other: software
Title:
PBT profiler
Author:
United States Environmental Protection Agency
Year:
2012
Bibliographic source:
http://www.pbtprofiler.net/default.asp

Materials and methods

Principles of method if other than guideline:
The half-life for degradation of a chemical in water and sediment is determined using the ultimate biodegradation expert survey module (Biowin 3) of the BIOWIN estimation program [Boethling, R.S., Howard, P.H., Meylan, W.M., Stiteler, W., Beauman, J., and Tirado, N., Group Contribution Method for Predicting Probability and Rate of Aerobic Biodegradation. Environmental Science and Technology 28: 459-65 (1994)]. The mean value within the estimated time range returned by the ultimate biodegradation survey model (Biowin 3) is converted to a half-life using a set of conversion factors.
It is known that ultimate biodegradation is generally slower under anaerobic conditions than under aerobic conditions. The BIOWIN ultimate survey model that is used in this Profiler assumes aerobic conditions, but deeper layers of aquatic sediments are usually anaerobic. To account for the slower rate of ultimate biodegradation in sediment, the rate of ultimate biodegradation in sediment in the PBT profiler is on average one-ninth (1/9) of that in the water column (which is assumed to be aerobic).

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
PBT profiler is entered with the CAS number

Study design

Oxygen conditions:
aerobic/anaerobic

Results and discussion

% Degradation
Key result
% Degr.:
ca. 70
Parameter:
other: QSAR
Sampling time:
28 d
Remarks on result:
other: ForATBC the ultimate biodegradation is estimated to take DAYS and the MITI probability is >0.5 (1.394). Therefore ATBC is regarded to be readily biodegradable by BIOWIN
Half-life of parent compound / 50% disappearance time (DT50)open allclose all
Transformation products:
not specified

Applicant's summary and conclusion

Conclusions:
Half lives were estimated with the PBT profiler (US-EPA) which calculates half life values from ultimate biodegradation estimations in BIOWIN. The calculated half life values for Acetyl tributyl citrate are 7.8 days for surface water and 78 days for sediment.
Executive summary:

Half lives were estimated with the PBT profiler (US-EPA) which calculates half life values from ultimate biodegradation estimations in the Biowin 3 model included in BIOWIN. The calculated half life values for Acetyl tributyl citrate are 8.7 days for surface water and 78 days for sediment. To account for the slower biodegradation under anaerobic conditions in the deeper layers of the sediment, the overall half life in sediment is estimated to be about 9 times higher than the half life in water. The calculated result has no impact on classification but can be used for risk assessment.