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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP-compliant, guideline study with some deviations
Justification for type of information:
Read across valid as the substnace tested is also titanate complex with alkylphosphate, degrading in water to form simple alcohols including 2-propanol and phosphate esters.
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Principles of method if other than guideline:
No analytical monitoring was described in the study report and so it could not be confirmed that concentrations were maintained within 80% of nominal.
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
Source: HRC Ltd sewage treatment plant (aeration stage). Collection: 30 May 1986. Preparation: sample was settled and Whatman GFA filter paper was used to filter the supernant after the first 250 ml was discarded. Dilution water: standard nutrient medium.
Duration of test (contact time):
28 d
Details on study design:
Temperature: 20 +/- 1°C, incubated in water bath. Vessels: 300 ml darkened glass bottle with glass stoppers. Concentrations: (1) 2 mg/L titanium butyl phosphate; (2) 3 mg/L sodium benzoate; (3) inoculated dilution water; (4) non-inolculated dilution water. 1 drop of activated sludge filtrate per litre was used to inoculate media. Bottles were filled and stoppered in a manner to exclude all air bubbles.
Reference substance:
benzoic acid, sodium salt
Preliminary study:
No data reported
Test performance:
Oxygen depletion at test termination: 2.875 mgO2/L. Chemical Oxygen Demand: 3.00 mgO2/L.
Parameter:
% degradation (O2 consumption)
Value:
96
Sampling time:
28 d
Details on results:
Inoculated and non-inoculated controls all had oxygen depletion in the prescribed limits.
Results with reference substance:
Sodium benzoate reached 97% degradation in 28 days.
Validity criteria fulfilled:
not applicable
Interpretation of results:
readily biodegradable
Conclusions:
The target substance is readily biodegradable based on studies read across from structural analogue.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
30 May to 27 June 1986
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP-compliant, guideline study with some deviations
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
No analytical monitoring was described in the study report and so it could not be confirmed that concentrations were maintained within 80% of nominal.
Principles of method if other than guideline:
No analytical monitoring was described in the study report and so it could not be confirmed that concentrations were maintained within 80% of nominal.
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
Source: HRC Ltd sewage treatment plant (aeration stage). Collection: 30 May 1986. Preparation: sample was settled and Whatman GFA filter paper was used to filter the supernant after the first 250 ml was discarded. Dilution water: standard nutrient medium.
Duration of test (contact time):
28 d
Details on study design:
Temperature: 20 +/- 1°C, incubated in water bath. Vessels: 300 ml darkened glass bottle with glass stoppers. Concentrations: (1) 2 mg/L titanium butyl phosphate; (2) 3 mg/L sodium benzoate; (3) inoculated dilution water; (4) non-inolculated dilution water. 1 drop of activated sludge filtrate per litre was used to inoculate media. Bottles were filled and stoppered in a manner to exclude all air bubbles.
Reference substance:
benzoic acid, sodium salt
Preliminary study:
No data reported
Test performance:
Oxygen depletion at test termination: 2.875 mgO2/L. Chemical Oxygen Demand: 3.00 mgO2/L.
Parameter:
% degradation (O2 consumption)
Value:
96
Sampling time:
28 d
Details on results:
Inoculated and non-inoculated controls all had oxygen depletion in the prescribed limits.
Results with reference substance:
Sodium benzoate reached 97% degradation in 28 days.
Validity criteria fulfilled:
no
Remarks:
No analytical monitoring and so concentrations could not be verified to have been maintained with 80% of nominal.
Interpretation of results:
readily biodegradable
Conclusions:
The oxygen depletion indicated that IA10 biodegraded 96% in 28 days, indicating that it is readily biodegradable.
Executive summary:

Doulgas (1986) is a GLP-compliant, closed bottle ready biodegradability test following OECD guideline 301D. No analytical monitoring was described in the study report and so it was not verified that concentrations were maintained within 80% of nominal. However the vessels were kept tightly shut and other studies have shown that the test substance hydrolyses rapidly on contact with water, this is not considered to have had an adverse effect on the outcome of the results. The study is considered reliable and suitable for use for this endpoint.

Description of key information

No study was conducted on the target substance. Read-across from structural analogue, Titanium butyl phosphate, is valid in that both substances are hydrolytically unstable and forms simple alcohols, including 2-propanol, and phosphate esters.

Based on the results of the structural analogue, the target substance is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information