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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data is from peer reviewed journal
Justification for type of information:
Data is from peer reviewed journal
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Remarks:
Activated sludge collected from municipal sewage treatment plant in Downingtown (PA, USA) and wastewater treatment plant located in Winston-Salem (NC, USA).
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Two activated sludge test systems were included. The first system was collected from a municipal sewage treatment plant in Downingtown (PA, USA) that received primarily domestic sewage and was considered to be unacclimated to test chemical. The second system was collected from a wastewater treatment plant located in Winston-Salem (NC, USA) that received wastewater from a cigarette manufacturing facility and was considered to be acclimated to test chemical.
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST SYSTEM
- Measuring equipment: The evolved CO2 was captured using a serial barium hydroxide trapping system in which the CO2 reacted with Ba(OH)2 to form an insoluble BaCO3 precipitate. The amount of CO2 produced was calculated indirectly by titration of the remaining hydroxide with 0.05 N standardized HCl.

CONTROL AND BLANK SYSTEM
- Abiotic sterile control: Nonspecific production of CO2 was indicated by an abiotic sterile control that contained test chemical (10 mg C/L) and 0.01% HgCl2 but no inocula.
- Toxicity control: a toxicity control containing both test chemical (10 mg C/L) and sodium benzoate (10 mg C/L) was included to ensure the test substance was not adversely affecting the inocula.
- Other: A procedural control in which sodium benzoate (10 mg C/L) was used as the sole source of organic carbon was included to confirm the activity of the inocula.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (CO2 evolution)
Value:
84.5
Sampling time:
28 d
Remarks on result:
other: 84.5 % degradation of test chemical by using unacclimated activated sludge.
Key result
Parameter:
% degradation (CO2 evolution)
Value:
82.1
Sampling time:
28 d
Remarks on result:
other: %degradation of test chemical by using acclimated activated sludge.
Details on results:
In the activated sludge test system considered to be unacclimated to nicotine, the final TCO2 results for the two flasks dosed with test chemical averaged 86.8%, and the 60% pass value was achieved within a 10-d window despite a 3-d lag in CO2 evolution. The TCO2 result for the toxicity control was 81% at day 14, with a final value of 87.3%, indicating the test substance was noninhibitory at the concentration tested (24.0 mg/L).

For the activated sludge test system acclimated to nicotine, the final TCO2 results for the two flasks dosed with test chemical averaged 82.2% and the 60% pass value was achieved within a 10-d window following a lag of approximately 1 d in CO2 evolution. The TCO2 result for the toxicity control for the acclimated test system was 58.9% at day 14 with a final value of 70.1%, indicating that 24.0 mg/L test chemical also was non-inhibitory in this test system.

Thus, based on the result, it indicates that the chemical 3-[(2S)-1-methylpyrrolidin-2-yl]pyridine; sulfuric acid was determined to be readily and ultimately biodegradable in both the unacclimated and acclimated activated sludge test systems.

Table: Biodegradation of chemical by aquatic microorganisms under aerobic conditions as indicated by the percentage of theoretical CO2 produced.

 

Test substance

Test conc. (mg/l)

Test system inopculuma

Final pH

Final TCO2 (%)b

Lag (d)

Control

NAc

Unacclimated

 

 

Acclimated

6.5

6.0

 

6.3

6.3

NA

NA

 

NA

NA

NA

NA

 

NA

NA

Test chemical

10

Unacclimated

Acclimated

5.7

5.1

 

5.9

5.8

86.8

82.2

 

79.6

84.5

3.4 ± 0.1

2.4 ± 0.1

 

1.3 ± 0.2

0.9 ± 0.2

Procedure controld

10

Unacclimated

Acclimated

5.9

6.0

79.1

92.0

0.8 ± 0.1

0.0 ± 0.4

Toxicity controlc

10 + 10

Unacclimated

Acclimated

5.7

6.0

87.3

70.1

1.4 ± 0.2

0.2 ± 0.3

ASCf

10 (S-NHS)

NA

5.9

20.3

0.0 ± 1.4

 

Where,

a - Two activated sludge test systems were used as sources for inocula, which were considered as either unacclimated or acclimated to nicotine based on the source of the wastewater received by each of the treatment facilities.

b - TCO2 theoretical carbon dioxide.

c – (NA) not available.

d - Sodium benzoate was included as a procedural control to confirm activity of the inocula.

e- Toxicity control was 10 mg C/L for each of the test substance and the procedural control.

f – (ASC) abiotic sterile control (10 mg C/L S-NHS plus 0.01% HgCl2).

 

 Table: Summary of environmental fate and effects test results.

 

Factors

Description

Value

Aqueous CO2 evolution

TCO2 (10 mg C/L, unacclimated)

TCO2 (10 mg C/L, acclimated)

TCO2 (10 mg C/L benzoate, unacclimated)

84.5%

82.1%

79.1%

 

 

 

 

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The percentage degradation of test substance was determined to be 84.5 % degradation of test chemical by using unacclimated activated sludge and 82.1% degradation of test chemical by using acclimated activated sludge. Thus, based on percentage degradation, test chemical was considered to be readily biodegradable in water.
Executive summary:

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance. The study was performed according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) under aerobic conditions.Two activated sludge test systems were included. The first system was collected from a municipal sewage treatment plant in Downingtown (PA, USA) that received primarily domestic sewage and was considered to be unacclimated to nicotine. The second system was collected from a wastewater treatment plant located in Winston-Salem (NC, USA) that received wastewater from a cigarette manufacturing facility and was considered to be acclimated to nicotine. In this test, mineral media containing test chemical (10 mg C/L) as the nominal sole source of organic carbon were aerated in CO2-free air for 28 d. Biodegradation of test chemical over the test period was indicated by production of CO2. The evolved CO2 was captured using a serial barium hydroxide trapping system in which the CO2 reacted with Ba(OH)2 to form an insoluble BaCO3 precipitate. The amount of CO2 produced was calculated indirectly by titration of the remaining hydroxide with 0.05 N standardized HCl. A procedural control in which sodium benzoate (10 mg C/L) was used as the sole source of organic carbon was included to confirm the activity of the inocula, and a toxicity control containing both test chemical (10 mg C/L) and sodium benzoate (10 mg C/L) was included to ensure the test substance was not adversely affecting the inocula. Nonspecific production of CO2 was indicated by an abiotic sterile control that contained test chemical (10 mg C/L) and 0.01% HgCl2 but no inocula. The percentage degradation of test substance was determined to be 84.5 % degradation of test chemical by using unacclimated activated sludge and 82.1% degradation of test chemical by using acclimated activated sludge. Thus, based on percentage degradation, test chemical was considered to be readily biodegradable in water.

Description of key information

The percentage degradation of test substance was determined to be 84.5 % degradation of test chemical by using unacclimated activated sludge and 82.1% degradation of test chemical by using acclimated activated sludge. Thus, based on percentage degradation, test chemical was considered to be readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance. The study was performed according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) under aerobic conditions.Two activated sludge test systems were included. The first system was collected from a municipal sewage treatment plant in Downingtown (PA, USA) that received primarily domestic sewage and was considered to be unacclimated to nicotine. The second system was collected from a wastewater treatment plant located in Winston-Salem (NC, USA) that received wastewater from a cigarette manufacturing facility and was considered to be acclimated to nicotine. In this test, mineral media containing test chemical (10 mg C/L) as the nominal sole source of organic carbon were aerated in CO2-free air for 28 d. Biodegradation of test chemical over the test period was indicated by production of CO2. The evolved CO2 was captured using a serial barium hydroxide trapping system in which the CO2 reacted with Ba(OH)2 to form an insoluble BaCO3 precipitate. The amount of CO2 produced was calculated indirectly by titration of the remaining hydroxide with 0.05 N standardized HCl. A procedural control in which sodium benzoate (10 mg C/L) was used as the sole source of organic carbon was included to confirm the activity of the inocula, and a toxicity control containing both test chemical (10 mg C/L) and sodium benzoate (10 mg C/L) was included to ensure the test substance was not adversely affecting the inocula. Nonspecific production of CO2 was indicated by an abiotic sterile control that contained test chemical (10 mg C/L) and 0.01% HgCl2 but no inocula. The percentage degradation of test substance was determined to be 84.5 % degradation of test chemical by using unacclimated activated sludge and 82.1% degradation of test chemical by using acclimated activated sludge. Thus, based on percentage degradation, test chemical was considered to be readily biodegradable in water.