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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 Mar to 8 April 1991
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Principles of method if other than guideline:
The test evaluated ready and ultimate biodegradability.
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Test material form:
Specific details on test material used for the study:
Test material name (as stated in the report): Cervolide
Sample Code : R675
Purity : 98.00%

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
the inoculum used was 10% by volume of activated sludge plant secondary effluent, filtered through a Whatman filter paper (541) to remove coarse particulate matter. The level of dissolved inorganic carbon (DIC) was reduced by sparging the filtered effluent with nitrogen after prior adjustment of the PH to 6.5
Duration of test (contact time):
28 d
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
The test used was the 160mL sealed vessel containing 100 ml mineral salts medium inoculated with secondary effluent and the respective test or reference substance. The headspace in each vessel has a volume of 60 ml and filled with air. The sealed vessels are incubated at 20 on a rotary shaker. At intervals during the 28 day test period a vessel is removed and concentration of carbon dioxide in the headspace gas determined. The total inorganic carbon in the vessel is calculated and corrected by subtracting the total inorganic carbon produced in a control. The extent of mineralisation can by determined by the initial organic carbon concentration added as test substance

Results and discussion

% Degradation
Key result
% degradation (inorg. C analysis)
Sampling time:
28 d
Remarks on result:
other: 95% CL (82.8-110.2%)

Any other information on results incl. tables

The percentage biodgradation is given by:


TICt=total inorganic carbon in test bottle

TICc=total inorganic carbon in control bottle

TC=organic carbon after reference to the appropriate inorganic carbon standard curve

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
readily biodegradable
The test substance was assessed to have achieved 96.5 % (95 % CL of 82.8 to 110.2) degradation after 28 days. Therefore Rhubafuran can be considered to be readily and ulimately biodegradable.
Executive summary:

The ready and ultimate biodegradability of the test substance was examined in a CO2evolution test with similarities to OECD 301B and to GLP standard.

Biodegradation of Day 4,8,14,22,24 and 28 is determined as 35.8%, 71.4%, 92.6%, 80.7%, 89.0% and 96.5%, respectively. The test substance was assessed to have achieved 96.5 % (95 % CL of 82.8 to 110.2) degradation after 28 days. Therefore Rhubafuran can be considered to be readily and ulimately biodegradable.