Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016-11-04 to 2017-02-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
July 1992
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
White powder.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Activated sludge, municipal wastewater treatment plant Breisgauer Bucht, 30 mg dry solids per litre; Sampling date of activated sludge was on 21 November 2016. Dry solid of the activated sludge was determined as 4.6 g/L by weight measurements after drying at 105 °C (mean of triplicate measurements).
- Storage length: 1 d
- Preparation of inoculum for exposure: The activated sludge was washed twice with tap water by settling the sludge, decanting the supernatant and re-suspending the sludge.
- Pretreatment: Dry solid of the activated sludge was determined as 4.6 g/L by weight measurements after drying at 105 °C (mean of triplicate measurements). The activated sludge was washed twice with tap water by settling the sludge, decanting the supernatant and re-suspending the sludge.
- Initial cell/biomass concentration: 10 - 20 mg TOC/L
- Water filtered: no
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: CO2-absorption medium: 52.27 g NaOH was dissolved in 6500 mL deionised water in closed vessels (0.2 M NaOH). The inorganic carbon concentration of the 0.2 M NaOH was determined (IC = 6.0 mg/L).
- Test temperature: 20.4 – 23.1°C
- Suspended solids concentration: A solution or suspension of the test item in a mineral medium, corresponding to 10-20 mg TOC/L, is inoculated with activated sludge (30 mg d.s./L).

TEST SYSTEM
- Culturing apparatus: In total three reactors containing the test item, three reactors containing only inoculum (blank), three reactors containing the reference compound, one reactor containing test item and reference compound (toxicity control) and one reactor without inoculum containing test item and a toxicant (abiotic control) were set up.
- Method used to create aerobic conditions: The system was sealed and aerated with CO2-free air overnight.
- Degradation is followed by determining the carbon dioxide produced and absorbed to sodium hydroxide via IC-measurement (IC = inorganic carbon). The amount of carbon dioxide produced from the test item less the amount derived from the blank inoculum is expressed as a percentage of ThCO2 (theoretical amount of CO2).
- Measuring equipment: The CO2 produced in the reactors was absorbed in two 250 mL gas wash bottles in series each filled with 200 mL 0.2 M NaOH. Sampling was performed through the lateral connecting pieces through the butyl rubber septum using 5 mL PE syringes.


SAMPLING
- Sampling frequency: T = 0, 2, 7, 10, 14, 21, 28 days
- Sampling method: Sampling was performed through the lateral connecting pieces through the butyl rubber septum using 5 mL PE syringes


CONTROL AND BLANK SYSTEM
- Inoculum blank: three reactors containing only inoculum (blank)
- Abiotic sterile control: one reactor; 4.78 mL of the test item stock solution (10 g/L) and 22.5 g of Sodium azide (corresponding to a concentration of 15 g/L) were added into the abiotic control vessel. No inoculum was added.
- Toxicity control: one reactor; 4.78 mL of the test item stock solution (10 g/L) and 5.15 mL of the reference stock solution (10 g/L) were added to the toxicity control vessel corresponding to a concentration of 40 mg/L organic carbon.
- Other: Reference substance: A stock solution of 10 g/L sodium benzoate in water was prepared. 5.15 mL of this stock solution were added into the reference vessels corresponding to a concentration of 20 mg/L organic carbon.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (CO2 evolution)
Value:
89.7
Sampling time:
28 d
Details on results:
In two of three test vessels a degradation process was observed (see table 1, vessel 11 and 12), whereas there were no degradation activities in test vessel 13 at all until the end of the test. On principal the degradation process of the test item started very different. This is obviously caused by a long and varying lag-phase in the different test vessel replicates.
Another reason could be an inadequate bioavailability of the test item in vessel 13. Therefore test vessel 13 is regarded as an outlier and will be reported but not counted into the evaluation of the results of the study.
The degradation extent of the test item at the end of the test was 89.7% (28 d after acidification, mean of two replicates, see table°1 and fig°1). The 10-d-window in test vessel 11 starts between day 7 and 10 whereas in test vessel 12 the start of the 10-d-window was later than day 14. Nevertheless the fulfilment of the 10-d-window was given in both test vessels (see table 1 and figure 1).
The criterion for ready biodegradation (degradation ≥ 60% and fulfilment of 10-d-window) was met in two of three replicates, therefore the test item is ready biodegradable according to the OECD criteria.

The degradation extent of the test item during the test, as well as for the reference and the abiotic control are shown in table 1 and figure 1, attached to the illustration part of the present substance.

Table 1: Theoretical CO2 Evolution during the test

Ultimate biodegradation after x days [% of ThCO2]

Reactor

Day

 

0

2

7

10

14

21

28

11

Test flask

0

1.9

2.8

38.9

79.9

89.0

93.1

92.6

12

 

0

1.6

1.7

3.3

4.9

69.7

86.5

86.8

13 (regarded as outlier, hence, excluded from evaluation)

 

0

2.4

4.3

4.5

5.4

5.8

7.0

6.7

4

Reference flask

0

56,3

75,5

82,2

90,2

89,7

93,6

95,7

5

 

0

54,4

79,5

84,9

90,1

93,1

94,9

93,9

6

 

0

48,7

76,8

82,5

88,4

93,3

93,9

94,4

 

Toxicity control

 

 

 

 

 

 

 

 

14

Test item

0

29,2

41,2

43,8

49,5

86,5

91,9

93,4

 

Reference item

 

 

 

 

 

 

 

 

15

Abiotic control

0

-3,3

-15,0

-18,4

-21,0

-26,8

-30,9

-31,8

 

 

 

 

 

 

 

 

 

 

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
1-Benzyl-3-carbamoyl-pyridinium, chloride is readily biodegradable.
Executive summary:

The ready biodegradability of 1-Benzyl-3-carbamoyl-pyridinium, chloride was investigated in accordance with OECD Guideline 301 B (July 1992). The test substance was applied at an initial concentration of 20 mg TOC/L. Biodegradation was followed by measurement of CO2 evolution.

The degradation extent of the test item at the end of the test was 89.7% (28 d after acidification, mean of two replicates, see table°1 and fig°1).

The criterion for ready biodegradation (degradation ≥ 60% and fulfilment of 10-dwindow) was met in two of three replicates, therefore the test item is ready biodegradable according to the OECD criteria. The test item is considered to be readily biodegradable according to the OECD criteria.

Description of key information

The degradation extent of 1-Benzyl-3-carbamoyl-pyridnium, chloride after 28 days under the conditions of OECD test 301 B was 89.7%. The criterion for ready biodegradation (degradation ≥ 60% and fulfilment of 10-d-window) was met, and the test item is considered readily biodegradable according to the OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information