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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Justification for type of information:
The test institution reported that the test substance hydrolyzed rapidly to form precipitates. And according to hydrolysis test results, the hydrolysis rate is estimated to be within 1 hr The hydrolysis products have been identified to be 2-propanol, isostearic acid and titanium dioxide. The biodegradation data of those organic parts have been well-investigated separately.
Endpoint:
biodegradation in water: ready biodegradability
Data waiving:
study technically not feasible
Justification for data waiving:
the study does not need to be conducted because the substance is inorganic
Justification for type of information:
Titanium dioxide is one of the hydrolysis products.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
2-propanol is one of the hydrolysis products.
Qualifier:
according to
Guideline:
EU Method C.5 (Degradation: Biochemical Oxygen Demand)
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic, non-adapted
Details on inoculum:
Settled domestic wastewater filtered through glass wool
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 3 mg/L
Based on:
test mat.
Initial conc.:
ca. 7 mg/L
Based on:
test mat.
Initial conc.:
ca. 10 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 80
Sampling time:
15 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 78
Sampling time:
20 d
Interpretation of results:
readily biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
isostearic acid is one of the hydrolysis products.
Qualifier:
no guideline followed
Version / remarks:
Assessment reports based on a number of studies.
Principles of method if other than guideline:
Assessment reports based a number of studies and computer modelling.
GLP compliance:
no
Remarks:
The study is based on compouter modelling.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Duration of test (contact time):
>= 28 d
Key result
Parameter:
other: % biodegradation unspecified.
Value:
>= 60
Sampling time:
28 d
Remarks on result:
readily biodegradable based on QSAR/QSPR prediction
Interpretation of results:
readily biodegradable
Conclusions:
Based on available data and computer modelling isostearic acid is considered to be readily biodegradable.

Description of key information

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

On the basis that if entering the environmental, this substance will quickly dissociate to form the inorganic (poorly soluble) titanium dioxide and two organic substances – 2 -propanol and isostearic acid.

The titanium dioxide is not considered further in this report as biodegradation and partition coefficient assessments do not apply.

It is possible to assess the hydrolysis products using public data and validated modelling methods. Both have been registered and a number of references have been found for the respective end-points.

Isostearic acid is evaluated to be rapidly biodegradable and to have no risk of bioaccumulation. (Denehurst Chemical Safety Ltd., 2017).

2 -Propanol is also readily biodegradable according to a 20 -d biodegradation test. (Price, 1974).

Based on these findings, the target substance is exptected to be readily biodegradable.