Ozonized sunflower oil

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

GLP compliance:

yes

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

The microbial inoculum was obtained on 22 June 2022 from the activated sludge of the biological urban wastewater treatment plant of Conselve (Padova, Italy). The microbial cells count at test start was 2.6 × 109 CFU/L. The suspended solids of the sludge were 5,130 mg/L, so it was diluted to have 28 mg/L of suspended solids in the of final reaction medium (volume of the reaction vessel: 250 mL). According to the OECD test guidelines, the concentration of suspended solids in the reaction medium must be < 30 mg/L and microbial cells should be 107-108 CFU/L.
Before being used for test, the inoculum was conditioned by aerating it for 5 days at the test temperature.

Duration of test (contact time):

28 d

Initial conc.:

27.2 mg/L

Based on:

ThOD

Remarks:

78 mgO2/L

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

BOD

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

47.4

Sampling time:

10 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

67.9

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Based on results of the present study, the maximum average degradation percentage of the test substance is 67.9% (after 28 days), thus the test substance can be deemed as rapidly (readily) biodegradable.

Executive summary:

The method used during the test is the OECD/OECD 301:1992 “Ready biodegradability” (Test F, Manometric Respirometry Test).
A measured volume of inoculated mineral medium, containing a known concentration of test substance (e.g. 100 mg test substance/l giving at least 50-100 mg ThOD/L) as the nominal sole source of organic carbon, is stirred in a closed flask at a constant temperature (± 1°C) for up to 28 days. The continuous stirring creates a suspension of the sample which is acceptable for water-insoluble samples (§ 4, OECD 301:1992).
The consumption of oxygen is determined by measuring the decrease of partial pressure due to the consumption of O2, with a sensor hosted in the cap of the vessel. Evolved carbon dioxide does not add to the pressure in the headspace of the vessel, since it is absorbed by a solution of sodium hydroxide. The amount of oxygen taken up by the microbial population during biodegradation of the test substance (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of the ThOD (Theoretical Oxygen Demand) calculated stoichiometrically or COD (Chemical Oxygen Demand) measured in the laboratory. Whenever possible ThOD should be preferred over COD (§§ 2 and 22, OECD 301:1992).
PASS LEVEL: to define a readily biodegradable substance, the pass level for biodegradability is 60% with reference to ThOD or COD.

 

The “REGULATION (EC) No 1272/2008 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 16 December 2008 on classification, labelling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006” reports the evaluation criteria for the rapid degradability of organic substances at § 4.1.2.9.5:
“Substances are considered rapidly degradable in the environment if one of the following criteria holds true:
(a) if, in 28-day ready biodegradation studies, at least the following levels of degradation are achieved:
(i) tests based on dissolved organic carbon: 70%;
(ii) tests based on oxygen depletion or carbon dioxide generation: 60% of theoretical maximum.
These levels of biodegradation must be achieved within 10 days of the start of degradation which point is taken as the time when 10% of the substance has been degraded, unless the substance is identified as an UVCB or as a complex, multi-constituent substance with structurally similar constituents. In this case, and where there is sufficient justification, the 10-day window condition may be waived and the pass level applied at 28 days. …”.

 

Based on results of the present study, the maximum average degradation percentage of the test substance is 67.9% (after 28 days), thus the test substance can be deemed as rapidly (readily) biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable