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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:
supporting study
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: old manufacturing process

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guidelineopen allclose all
according to guideline
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Version / remarks:
OCDE n° 301 B Dir. 92/69/CEE : C.4
according to guideline
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Reference substance name:
EC Number:
EC Name:
Molecular formula:
C5H11O5 [C6H10O5]1.45 and C5H10O4 and C5H12O5
D-glucopyranose, oligomers, xylityl glycosides and 1,4 anhydro D-xylitol and D-xylitol
Details on test material:
Sponsor's identification : AQUAXYL
Description : yellow solid gel
Batch number : 4359 MP
Date received : 9 July 2003
Storage conditions : room temperature in the dark

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
The sample of effluent was filtered through coarse filter paper (first approximate 200 ml
discarded) and the filtrate maintained on continuous aeration in a temperature controlled room at
21°C prior to use.
Duration of test (contact time):
ca. 28 d
Initial test substance concentration
Initial conc.:
ca. 3 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
% degradation (O2 consumption)
ca. 35
Sampling time:
28 d
Details on results:
Points of degradation plot (test substance):
15 % degradation after 3 d
17 % degradation after 6 d
24 % degradation after 9 d
28 % degradation after 12 d
29 % degradation after 14 d
30 % degradation after 18 d
31 % degradation after 21 d
34 % degradation after 24 d
35 % degradation after 28 d

BOD5 / COD results

Results with reference substance:
Points of degradation plot (reference substance):
48 % degradation after 3 d
48 % degradation after 6 d
52 % degradation after 9 d
59 % degradation after 12 d
63 % degradation after 14 d
65 % degradation after 18 d
66 % degradation after 21 d
65 % degradation after 24 d
67 % degradation after 28 d

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
other: not readily biodegradable
The test material (old manufacturing process) attained 35% degradation after 28 days and therefore cannot be considered as readily biodegradable under the strict terms and conditions of OECD Guideline No 301D.
Executive summary:

Introduction. A study was performed to assess the ready biodegradability of the test material in an aerobic aqueous medium. The method followed that described in the OECD Guidelines for Testing of Chemicals (1992) No 301D, "Ready Biodegradability; Closed Bottle Test” referenced as Method C.4-E of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC), and US EPA Fate, Transport, and Transformation Test Guidelines OPPTS 835.3110 Paragraph (o). This study complies with the GLP.

Methods. The test material, at a concentration of 3.0 mg/l, was exposed to sewage treatment micro-organisms with culture medium in sealed culture vessels in the dark at 20 ± 0.2°C for 28 days. The degradation of the test material was assessed by the determination of the amount of oxygen consumed. Control solutions with inoculum and the standard material, sodium benzoate, together with a toxicity control were used for validation purposes.

Results. The test material attained 35% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301D.