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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:
From June 09 to July 09, 2010
1 (reliable without restriction)

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guidelineopen allclose all
according to guideline
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
according to guideline
EPA OPPTS 835.3110 (Ready Biodegradability)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
1-benzyl-1,2-dihydro-3H-indazol-3-one, sodium salt
EC Number:
EC Name:
1-benzyl-1,2-dihydro-3H-indazol-3-one, sodium salt
Cas Number:
Molecular formula:
sodium 1-benzyl-3-oxo-2,3-dihydro-1H-indazol-2-ide
Details on test material:
Name: 1-benzyl-3-hydroxy-1H-indazole sodium salt
Batch no. 09-749

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
The study was performed using aerobic activated sludge from ALSI (Alto Lambro Servizi Idrici) wastewater treatment plant treating civil wastewater. The sludge was washed by centrifugation and the supernatant liquid phase decanted. A homogenized aliquot of the final sludge suspension was weighted, thereafter dried and the ratio of wet to dry weight was calculated as 10.1%.
Based on this ratio, calculated amounts of wet sludge were suspended in the test water to get a concentration equivalent to 3 g dry material/L. During holding, the sludge was aerated at room temperature in dark conditions. Before using, the sludge inoculum was diluted with test water to obtain a final concentration of 15 mg/L (dry weight).
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
100 mg/L
Based on:
test mat.
Details on study design:
The assay on test item has been run in parallel with a ready biodegradable reference item, i.e. sodium benzoate, the inoculum control, the abiotic control containing the test item and a sterilizing agent (HgCl2) and the toxicity control, containing test item, reference compound and inoculums.
BOD flasks of 500 mL capacity, equipped with pressure sensors fitted on the bottle mouth, have been used as test units.
- Test temperature: 21- 22°C
- Light condition: darkness
- Stirring: continuous
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
% degradation (O2 consumption)
Sampling time:
10 d
% degradation (O2 consumption)
24.2 - 24.3
Sampling time:
28 d
Details on results:
The test item is considered to be stable at the test conditions for a time corresponding to the exposure time (28 days). Therefore, all reported results are related to the nominal concentration of the test item.
The ThODNH3 values were calculated to be equal to 1.67 mg O2/mg for reference item and 2.47 mg O2/mg for test item.
The test complies with the validity criteria since the mean oxygen uptake in the inoculum control at the end of test period was 25 mg O2/L and the difference between duplicate values of test item degradation at the end of the test period was 16.8 % . Moreover, the reference item reached the biodegradation pass level (60%) on the fourth day (64.8%)

The oxygen consumption due to nitrification was measured at the start and at the end of the test. The oxygen amount used in oxidising ammonium process was determined to be equal to 0.152 mg O2. Then, the corrected value of biodegradation at the end of the test period (28 days) obtained by subtraction of oxygen uptake due to nitrification (0.152 mg O2) to the oxygen uptake at the end of the test, was 24.2% (mean value between two replicates).
The biodegradation value at the end of the test without nitrification correction was 24.3%.
Since the oxygen uptake due to nitrification was very low (0.152 mg O2), the corrected values reported in the following tables were equal to the uncorrected values except for the biodegradation percentage corresponding to 24.2% as corrected value and 24.3% as uncorrected value.
The test item did not show any inhibitory effect on the microorganism activity at the tested concentration, as demonstrated by the 25% of biodegradation exceeded in the toxicity control already at the fourth day of test period (25.4%)

Any other information on results incl. tables

BOD values and % biodegradation for the test item 1-benzyl-3-hydroxy-1-h-indazole sodium salt in a Manometric Respirometry


* this value was estimated as 0 being negative(< 0) as per calculation

** start of 10-d window

*** end of 10-d window

**** corrected value due to nitrification values

 Day ofmeasurement  BOD  % of biodegradation
 1  0.01  0.4
 5  -0.02  0*
 10  -0.06  0*
 14  0.20  7.9
 17  0.26  10.5**
 26  0.59 23.9***
 28  0.60****  24.2****

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
not inherently biodegradable
The test item has showed to be not ready biodegradable under the conditions applied in a Manometric Respirometry test, having not reached the pass level (60% biodegradation) in the 10-day window, but showing a maximum value of degradation of 23.9% during this period.
Moreover. the test item did not show any inhibitory effects on the microorganism activity at the tested concentration as demonstrated by the 25% of biodegradation exceeded in the toxicity control already at the fourth day of test period.

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