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Environmental fate & pathways

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:
June 19th 2018 - July 23rd 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
Version / remarks:
2014
GLP compliance:
yes
Specific details on test material used for the study:
Batch 0400
Manufacturing date: 04/2018
Expiry date: 04/2019
Oxygen conditions:
aerobic
Inoculum or test system:
other: Aerobic sludge
Details on inoculum:
- Source of inoculum/activated sludge: Aerobic sludge was collected from the mixed treatment plant of urban(about 66%) and industrial (about 34%) liquid sewage situated at San Rocco-Monza (MB) Italia. The treatment plant is managed by Brianzacque Srl (Monza)
Duration of test (contact time):
28 d
Initial conc.:
23.78 other: mgC/L
Based on:
TOC
Parameter followed for biodegradation estimation:
TOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: See tables 1 -4 below
- Test temperature: 20°C ± 1 °C
- Suspended solids concentration: 4 mg/L
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: Glass bottels with hermetic seal
- Measuring equipment: Determination of total inorganic carbon was made using an automatic TOC analyzer. It is a high sensitivity instrument based on the combustion catalytic oxidation method (680°C). The carbon dioxide generated by oxidation is detected using an infrared gas analyzer (NDIR).


SAMPLING
- Sampling frequency: The concentration of inroganic carbon (TIC) was measured weekly0, 1, 7, 14 21 and 28 days
- Sampling method: At least 12 hour before every determination of inorganic carbon (TIC) the reaction in one bottle of blank, one of reference susbtance and one of test item were stopped with the addition of 6 ml of sodium hydroxide (1 M).


CONTROL AND BLANK SYSTEM
- Inoculum blank: The blank used water contaning culture medium added with the inoculum of the muds.
- Abiotic sterile control: the test item was put together with 50 mg/L HgCl2 in order to check a possible abiotic degradation.


Reference substance:
other: Sodium benzoate
Remarks:
Supplier: Sigma Aldrich, Batch: SLBP6327V, Exp date: Mar 2019
Key result
Parameter:
% degradation (test mat. analysis)
Value:
16
Sampling time:
28 d

Biodegradation results:

Check point (days)

% of biodegradation (reference substance)

% of biodegradation (test item)

% of biodegradation (reference substance + test item)

0

0

0

0

1

11

5

8

7

82

4

-

14

84

3

-

21

89

6

-

28

92

16

41

The trend of the inorganic carbon and related biodegradation percentages in the bottle containing both the test sample and the reference substance confirm the absence of an inhibitory effect of the test sample on the inoculum.

The quality criteria of the test were satisfied.

The mean amount of TIC present in the blank controls at the end of the test was < 3 mg C/L. The test item resulted not inhibitory to the inoculum at the concentration at which it was applied in the test. Abiotic degradation had not occurred because the amount of TIC during the test in the abiotic bottles was less than 10%.

TIC T – 1 gg (ppm)

TIC T = 28 gg (ppm)

% INCREASE (<10%)

CONFORMITY

2.730

2.690

- 1.47

CONFORM

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The test substance Balsalazide was considered to be 'not biodegradable' in aerobic conditions.

Description of key information

The ready biodegradability of Balsalazide acid was determined in accordance with OECD Guideline 310. On the basis of the results obtained, the test item Balsalazide acid is considered to be not biodegradable under aerobic conditions.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information