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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):The effluent of the municipal activated sludge plant of Pforzheim/Germany.
- Pretreatment: The inoculum was filtered, the first 200 mL being discarded, and was aerated by shaking one week in an Erlenmeyer flask.
- Initial cell/biomass concentration: 2.96 x 10E1 cells per mL in the test vessel.
- Water filtered: yes
- Type and size of filter used, if any: coarse filter.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
2 mg/L
Based on:
other: nominal test concentration.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
0.3
Sampling time:
7 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
4.4
Sampling time:
11 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
9.7
Sampling time:
14 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
13.7
Sampling time:
21 d
Parameter:
% degradation (O2 consumption)
Value:
38.2
Sampling time:
28 d

BOD5 / COD results

BOD5 / COD
Parameter:
BOD5
Value:
0 g O2/g test mat.
Results with reference substance:
With Na benzoate as reference substance a BOD5 value of 0.85 g O2/g was obtained. A BOD value of 1.18 g O2/g was obtained at day 28.

Any other information on results incl. tables

BOD mean values (mg O2/mg).

  DAY
   5  7  11  14 21   28
 Prednisolone  -0.01  0.01  0.10  0.22  0.31  0.86
 Na-benzoate  0.85  0.96  1.18  1.17  1.18  1.18

Individual calculations of the percentage degradation rates and mean values.

    DAY
 Substance  Bottle  5  7  11  14  21  28
 Prednisolone  1  0.44  0.88  7.96  -1.77  38.50  50.00
 Prednisolone  2  -0.88  0.44  0.88  1.77  0.44  28.76
 Prednisolone  3    -0.44    29.20  2.21  38.84
 Prednisolone  Mean  -0.2  0.3  4.4  9.7  13.7  38.2
 Na-benzoate  1  50.30  60.48  70.06  69.46  70.66  70.06
 Na-benzoate  2  50.90  60.48  71.26  73.65  72.46  71.86
 Na-benzoate  3    50.90    67.07  69.46  69.46
 Na-benzoate  Mean  50.6  57.3  70.7  70.1  70.9  70.5

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
The ready biodegradability of Prednisolone was determined with the Closed Bottle Test according to the OECD guideline 301 D. Prednisolone was tested at a nominal concentration of 2 mg/L.
The following biodegradation was determined at the end of the 28 -d period:
- Prednisolone 2 mg/L:       38.2%
- Na benzoate 2 mg/L:       70.5%
- Toxicity control:              41.6%

The test item is considered as not readily biodegradable.