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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
Principles of method if other than guideline:
limited details provided
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Bayer water treatment plant
- Concentration of sludge: 250 mg/L

Duration of test (contact time):
28 d
Initial conc.:
262 mg/L
Based on:
test mat.
Initial conc.:
100 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Reference substance:
aniline
Parameter:
% degradation (DOC removal)
Value:
>= 70
Sampling time:
28 d
Remarks on result:
other: day 7-27
Remarks:
see table

Time

Blanc

Reference substance

Test substance

 

DOC (mg/L)

DOC (mg/L)

DOC corrected (mg/L)

% degradation

DOC (mg/L)

DOC corrected (mg/L)

% degradation

0 h

16

110

94

0

72

56

0

3 h

15

84

69

27

70

55

2

1

15

91

75

20

44

28

50

7

26

29

3

97

40

14

75

14

24

26

2

98

33

9

84

21

18

20

2

98

29

11

80

27

15

17

2

98

32

17

70

28

15

18

3

97

37

22

61

 

Validity criteria fulfilled:
not specified
Interpretation of results:
inherently biodegradable
Conclusions:
Under the conditions of the test the substance is considered inherently biodegradable
Executive summary:

In a Zahn-Wellens test the substance was inherently biodegradable over the 28 day exposure period.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
21 July 2017 to 28 August 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Remarks:
urban (about 66%) and industrial (about 34%) liquid sewage
Details on inoculum:
- Source of inoculum/activated sludge: urban (about 66%) and industrial (about 34%) liquid sewage situated at San Rocco - Monza (MB), Italia.
- Storage conditions: under aerobic conditions
- Storage length: no data
- Preparation of inoculum for exposure: centrifuged and washed
- Pretreatment: none
- Concentration of sludge: 4 mg/L SS
Duration of test (contact time):
28 d
Initial conc.:
10.41 mg/L
Based on:
TOC
Remarks:
determined by REDOX SnC using CHN analyser
Parameter followed for biodegradation estimation:
inorg. C analysis
Details on study design:
TEST CONDITIONS
- Composition of medium: according to OECD 310
- Test temperature: 20°C
- pH: not indicated
- pH adjusted: no
- Suspended solids concentration: 4 mg/L
- Continuous darkness: yes
- Other: contimuous stirring
TEST SYSTEM
- Culturing apparatus: 1000 mL volumteric flask
- Number of culture flasks: 3/sampling and 5 for the sampling after 28 days for test substance, blancs and reference substance
- Measuring equipment: TOC analyser
- Test performed in closed vessels: yes

SAMPLING
- Sampling frequency: on day 1, 7, 14, 21 and 28 in blanks, reference substance controls and test substance treated bottles (3 replicates per sampling time except at day 28 5 replicates)
- Sampling method: in individual bottles reaction stopped with the addition of 6 ml
of sodium hydroxide (1 M) (12 h before measuring)
- Sample storage before analysis: none

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Toxicity control: yes


STATISTICAL METHODS:
Reference substance:
benzoic acid, sodium salt
Remarks:
at 21.50 mg/L as C
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
4
Sampling time:
1 d
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
18
Sampling time:
7 d
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
15
Sampling time:
14 d
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
12
Sampling time:
21 d
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
12
Sampling time:
28 d
Details on results:
The substance is biodegradable, but does not meet the 10-day window criterion
Results with reference substance:
see table

 

CHECK POINT

(Days)

 

% OF BIODEGRADATION

Reference substance

 

% OF BIODEGRADATION

Test item

 

% OF BIODEGRADATION

Reference substance+

Test item

0

0

0

0

1

20

4

3

7

82

18

-

14

86

15

-

21

82

12

-

28

89

12

64

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
the substance is considered to be not biodegradable
Executive summary:

In a test according to OECD 310, the substance (10.41 mg C/L) degraded 12% over a period of 28 days. The substance is not readily biodegradable.

Description of key information

In a test according to OECD 310, the substance (10.41 mg C/L) degraded 12% over a period of 28 days. The substance is not readily biodegradable (Eurofins 2017). In a Zahn-Wellens test >70% degradation of a formulation of the substance was observed (Bayer 1987).

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, not fulfilling specific criteria
Type of water:
freshwater

Additional information

Based on the composition of the tested substance in this Zahn-Wellens test, which is similar to that of the substance subject to registration, the outcome of this test is considered representative for the substance subject to registration.