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Environmental fate & pathways

Biodegradation in water: screening tests

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biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed according to relevant guidelines and compliant to GLP

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)
GLP compliance:

Test material

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
Inocolum microbial concentration, in the experimental conditions of evaluation: it was, at the minimum, included between 0.5 x 10^6 and 0.7 x 10^6 micro-organisms per millilitre (to be compared with 1 x 10e6 cells/mL minimum)
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
10 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradationopen allclose all
% degradation (CO2 evolution)
Sampling time:
28 d
Remarks on result:
other: 10 mg/L test material
% degradation (CO2 evolution)
Sampling time:
28 d
Remarks on result:
other: 20 mg/L test material

BOD5 / COD results

Results with reference substance:
biodegradation of reference substance (sodium acetate): 87% in 28 days

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
other: not readily biodegradable
Taking into account the results obtained under the experimental conditions employed, the evaluation
of the biotic degradability of the test substance using the modified Stunn test showed :
Biodegradation of the test substance in 28 days :
4% at 10 mg/l
5 % at 20 mg/l
Executive summary:

- The study was performed using two concentrations (10 and 20 mg of test substance per litre) .

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- The CO2 released and incorporated as BaC03 was measured every 2 days over a I O-day period and then

every 4 or 5 days until the end of the study (28 days).

- A control assay, without test substance, was perfonned in the same conditions.

- An assay using a reference substance (sodium acetate) was also performed in the same conditions.

- The degradation of the test substance was evaluated by comparing the quantity of COo generated in the

test medium with that in the control assay, and in relation to the total CO2 that the test substance could

have theoretically produced (based on the carbon content of the test substance).

- The quality criteria for the study, notified in the E.E.C. protocol and relative to the biodegradation of the

reference substance and to the total production of CO2 in the control assay, were respected.