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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:
20 December 2002 to 17 January 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Reliable experimental study following OECD 306 guidelines and GLP standards.
Qualifier:
according to
Guideline:
OECD Guideline 306 (Biodegradability in Seawater)
Version / remarks:
Not Specified
Deviations:
yes
Remarks:
The temperature of the incubator in which the biodegradation bottles were held, was found to exceed the maximum limit of 20°C on the 24th December 2002 by 0.5°C.; this did not impact the integrity of the test.
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
natural water: marine
Details on inoculum:
Natural seawater was collected from Penrhyn Point in North Wales on the 6th December 2002. The temperature at collection was 14.0°C, pH 7.73, salinity 29.5 g H and the dissolved oxygen level 92.0%. After collection the seawater was coarse filtered and maintained in the dark. The seawater was aged prior to use by gentle aeration, at 20 ± 2°C.
Duration of test (contact time):
28 d
Initial conc.:
1.5 mg/L
Based on:
test mat.
Initial conc.:
2.5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Remarks:
Chemcial oxygen demand (COD) was calculated from direct measurements of dissolved oxygen concentrations.
Details on study design:
The test item, at concentrations of 1.50 mg/L and 2.50 mg/, was exposed to coarse filtered natural seawater as inoculum.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
Dissolved oxygen (DO) concentrations were measured.
Value:
74.3
Sampling time:
28 d
Remarks on result:
other:
Remarks:
Biodegradation calculated from test performed with 1.50 mg/L test item.
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
Dissolved oxygen (DO) concentrations were measured.
Value:
83.1
Sampling time:
28 d
Remarks on result:
other:
Remarks:
Biodegradation calculated from test performed with 2.50 mg/L test item.
Results with reference substance:
Sodium benzoate attained >100% biodegradation after 28 days. These results confirmed the suitability of the inoculum and test conditions and satisfied the validation criterion given in the OECD Test Guidelines.
Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Conclusions:
The test item attained 74.3% biodegradation at 1.50 mg/L and 83.1% biodegradation at 2.50 mg/L after 28 days., showing high potential for degradation in the marine environment. Therefore, the substance has been shown to be readily biodegradable (Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.7.b: Endpoint-specific guidance, Version 3.0, February 2016, Section R.7.9.4.1, p. 206) .

Description of key information

The key study was an aerobic biodegradation in seawater test using the closed bottle procedure and conducted in accordance with OECD Guideline 306.  The test item attained 74.3% biodegradation after 28 days at a test substance concentration of 1.50 mg/L, and 83.1% biodegradation aftter 28 days at a test substance concentration of 2.50 mg/L, showing high potential for degradation in the marine environment. Therefore, the substance has been shown to be readily biodegradable (Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.7.b: Endpoint-specific guidance, Version 3.0, February 2016, Section R.7.9.4.1, p. 206) .

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
marine water

Additional information