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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 February 2018 to 22 March 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Reliable experimental study following OECD 301 guidelines (1992) and EC No. 440/2008 Method C.4-C adopted 2008, U.S. EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph (m)), and GLP standards.
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
1992
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Version / remarks:
440/2008
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Version / remarks:
Paragraph (m)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
The test substance is listed as 2-Hydroxyethyl Ricinoleate . The test substance is a clear yellow viscous liquid. The test substance was obtained from the Sponsor, Vertellus Holdings LLC and stored at room temperature in the dark.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
A mixed population of activated sewage sludge micro-organisms was obtained on 19 February 2018 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.
Duration of test (contact time):
28 d
Initial conc.:
14.3 mg/L
Based on:
test mat.
Initial conc.:
10 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (CO2 evolution)
Value:
100
Sampling time:
28 d
Results with reference substance:
Sodium benzoate attained 87% biodegradation after 14 days with greater than 60% degradation being attained in a 10-day window. After 28 days 104% biodegradation was attained. Biodegradation values in excess of 100% were considered to be due to sampling/analytical variation. 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:
yes
Remarks:
IC content < 5% (protocol ≤ 5%); CO2 emitted by controls 28.18 mg/L (protocol <70 mg/L; difference reps <20% (protocol ≤20 %); degradation positive control 87% at 14 d (protocol ≤14 d to achieve >60%); degradation toxicity d 14, 71% (protocol > 25%).
Interpretation of results:
readily biodegradable
Conclusions:
The test item attained 100% biodegradation after 28 days and satisfied the 10-day window, whereby 60% biodegradation must be attained within 10 days of the biodegradation exceeding 10%. The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of the guideline.

Description of key information

The key study was a CO2 evolution test conducted in accordance with OECD Guideline 301B. The test item attained 100% biodegradation after 28 days and satisfied the 10-day window, whereby 60% biodegradation must be attained within 10 days of the biodegradation exceeding 10%. The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of the guideline.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information