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Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
October-November 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic (adaptation not specified)
Details on inoculum:
Sample site: Water treatment plant "STEP de Lille", 33290 Blanquefort (France) Tank 1
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium:
Na2HPO4,2H2O: 334 mg/l
K2HPO4: 217.5 mg/l
NH4Cl: 5 mg/l
KH2PO4: 85 mg/l
CaCl2,2H2O:36.4 mg/l
MgSO4,7H2O: 22.5 mg/l
FeCl3,6H2O: 0.25 mg/l
- Test temperature: 22.5 to 22.9ºC
- pH: 7.5

TEST SYSTEM
- Culturing apparatus: WTW Oxitop (FCBA reference: ACQU 1030)
- Number of culture flasks:
Control flasks: 3 (inoculum only)
Test flasks: 3 (test item and inoculum)
Reference flasks: 2 (sodium benzoate and inoculum)
Toxicity control: 2 (test item, sodium benzoate and inoculum)
- Method used to create aerobic conditions: aerating sludge (in mineral medium) for 5-7 days before the test
- Measuring equipment: WTW Oxitop (FCBA reference: ACQU 1030)
- Test performed in closed vessels: yes, under continuous stirring
- Details of trap for CO2: releases CO2 were absorbed by soda lime pellets present in the headspace of flasks.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes
Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
10.94
Sampling time:
7 d
Parameter:
% degradation (O2 consumption)
Value:
19.61
Sampling time:
17 d
Parameter:
% degradation (O2 consumption)
Value:
21.87
St. dev.:
2.93
Sampling time:
28 d
Parameter:
ThOD
Value:
1.46 mg O2/g test mat.
Results with reference substance:
The reference item “Sodium benzoate” was degraded up to 99.50% and 88.13% after 14 days.
Therefore, it confirms the suitability of the used aerobic sludge inoculum.
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The test item is not considered to be readily biodegradable following the ThODNH4, after 28 days of incubation.
Under conditions of OECD Guideline 301F, the test item "MM212" is not considered to be readily biodegradable.
Executive summary:

All the validity criteria for OECD 301F were successful.

The % Biodegradation at 28 days is presented as follows:

% Biodegradation at 28 days (with ThODNH4): average: 21.87% (S.D. 2.93), pH 7.4

Based on ThODNH4, the degradation rate of the test item "MM212" do not reach 60% within the 10 -Day window and after 28 days of incubation the biodegradation was 21.87% (18.68% to 24.43%).

The results show that the test item is not considered to be readily biodegradable following the ThODNH4, after 28 days of incubation.

Under conditions of OECD Guideline 301F, the test item "MM212" is not considered to be readily biodegradable.

Description of key information

The degradation rate of the test item “MM212” reached 21.87% (18.68% to 24.43%), following the ThODNH4, after 28 days of incubation.

Under conditions of OECD Guideline 301F, the test item "MM212" is not considered to be readily biodegradable.

Key value for chemical safety assessment

Additional information