1-acetyl-4-(3-dodecyl-2,5-dioxo-1-pyrrolidinyl)-2,2,6,6-tetramethylpiperidine

Biodegradation in water: screening tests

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:

1991-03-21 to 1991-04-19

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study performed according to relevant guidelines and compliant with GLP; however, the test was performed according to the old version of OECD guideline 301 B (1981), which was less detailed on test performance and requirements than the updated version (adopted 1992).

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Version / remarks:

(1981)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.5 (Degradation: Biochemical Oxygen Demand)

Version / remarks:

adopted 1948: 84/449/EEC, C.5 (Mod. Sturm)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

CHARACTERISATION OF INOCULUM
The inoculum consisted of activated sludge originating from the municipal water-treatment plant in Marl-West. The clarified sludge was taken on March 21, 1991 and treated in the laboratory as described in the guideline. The number of bacteria in the inoculum was determined with the Koch plate-casting method. The inoculum had a bacterial count of 11 x 10^5 CFU/mL (colony-forming units).

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
The test substance was placed into a liquid nutrient medium that was inoculated with the activated sludge and ventilated at 20.5 to 21.4°C. The evolved CO2 was bound in a lyme (sodium hydroxide) solution in the form of sodium carbonate. The decomposition was tracked over the course of the 28 days of the test, i.e. after 3, 6, 12, 17, 20, 24 and 28 days by means of TIC analysis of bound CO2.

- Composition of medium: according to the guideline

TEST SYSTEM
- Vessel: 5000 mL glass vessel
- Test batch: substance and inoculum, 2 replicates
- Inoculum blank: 1 replicate
- System control: 1 replicate (reference substance)
- Abiotic sterile control: no
- Toxicity control: no
- Measuring equipment: TIC analyzer

SAMPLING
- Sampling frequency: days 0, 3, 6, 12, 17, 20, 24, 28

Reference substance:

benzoic acid, sodium salt

Remarks:

(sodium benzoate)

Parameter:

% degradation (CO2 evolution)

Value:

21

Sampling time:

28 d

Remarks on result:

other: at test item concentration of 20 mg/L corresponding to 14.46 mg C/L

Parameter:

% degradation (CO2 evolution)

Value:

20

Sampling time:

28 d

Remarks on result:

other: at test item concentration of 10 mg/L corresponding to 7.23 mg C/L

Details on results:

RESULTS ON THE READY BIODEGRADABILITY OF THE TEST SUBSTANCE
The test substance reached a level of decomposition of 20% (10 mg/L treatment group) and 21% (20 mg/L treatment group) within 28 days. Since this was below 60% biodegradation, the test substance could neither be regarded as readily biodegradable nor inherently biodegradable.

For result table see: any other information on results

CO2 EVOLUTION IN THE INOCULUM BLANK
The cumulative CO2 evolution in the inoculum control was 52.29 mg CO2/3 L. This value approximately met the related quality criterion of the OECD 301 B (adopted 1981) (max. 50 mg CO2/3L) and fulfilled the same but revised validity criterion of OECD 301 B (adopted 1992) (max. 70 mg CO2/L).

For result table see: any other information on results

Results with reference substance:

RESULTS ON THE READY BIODEGRADABILITY OF THE REFERENCE SUBSTANCE
The reference substance (sodium benzoate) reached a level of decomposition of >= 60% by day 14. Thus, the validity criterion of OECD 301 B (adopted 1981; 1992) was met, and the inoculum used had a sufficient biological activity.

Appendix 3:

              Concentration:  10 mg/L => 7.23 mg C/L

              Theor. CO₂production: 26.53 mg/L

Test duration (days)	TAC mg/L			CO2mg/L	Decomposition %
Test substance Blind value Diff./3
30 min.	1.37	1.54	- 0.06	- 0.21	- 1
3	3.31	3.05	0.09	0.32	1
6	5.06	4.23	0.28	1.02	4
12	9.49	7.56	0.64	2.36	9
17	15.06	10.61	1.48	5.44	21
20	15.75	12.89	0.95	3.50	13
24	18.38	14.55	1.28	4.69	18
28 after acidification	20.17	15.87	1.43	5.26	20

Appendix 4

              Concentration:  20 mg/L => 14.46 mg C/L

              Theor. CO₂production:  53.07 mg/L

Test duration (days)	TAC mg/L			CO2mg/L	Decomposition %
Test substance Blind value Diff./3
30 min.	1.46	1.54	- 0.03	- 0.10	0
3	3.84	3.05	0.26	0.97	2
6	5.63	4.23	0.47	1.71	3
12	11.42	7.56	1.29	4.72	9
17	14.96	10.61	1.45	5.32	10
20	18.97	12.89	2.03	7.44	14
24	22.56	14.55	2.67	9.80	18
28 after acidification	25.15	15.87	3.09	11.35	21

Validity criteria fulfilled:

yes

Remarks:

according to the guideline adopted 1981; however, w.r.t. the new added criteria of the adopted version from 1992, the inorganic carbon was > 5% of the total carbon.

Interpretation of results:

other: not readily biodegradable

Conclusions:

The test substance was not readily biodegradable under the test conditions; i.e. 20% biodegradation within 28 days.

Executive summary:

A study was conducted to investigate the ready biodegradability of the test substance according to the OECD guideline 301 B (Modified Sturm Test; adopted 1981) and EEC Commission Directive 84/449/EEC, C.5, and was performed in compliance with GLP.

The study included two treatment groups of test item concentrations of nominal 10 mg/L and 20 mg/L, an inoculum control and a system control (reference substance sodium benzoate), each in replicates of two. The percentage biodegradation was measured with respect to CO2 evolution in the course of 28 days. Measurements of the inorganic carbon content took place on days 0, 3, 6, 12, 17, 20, 24 and 28. The inorganic carbon was measured with a TIC-analyzer (Shimadzu).

After 28 days, the test substance reached a level of decomposition of 20% (10 mg/L) or 21% (20 mg/L). As the amount biodegradation was below 60%, the test item could not be considered readily biodegradable. The reference substance, sodium benzoate, reached a level of decomposition of >= 60% within 14 days and thus met the related validity criterion of OECD 301 B (adopted 1981; 1992). The cumulative CO2 evolution in the inoculum control was 52.29 mg CO2/3L. This value did not agree with the related quality criterion of OECD 301 B adopted 1981 (max. 50 mg CO2/3L), however, it did fulfill the revised criterion in OECD 301 B adopted 1992 (max. 70 mg/L).

In conclusion, the test substance was not readily biodegradable under the given test conditions. The study fulfilled the validity criteria of the guideline, and the obtained results were considered reliable.

Description of key information

The test substance is not readily biodegradable; after 28 days of exposure to activated sludge, degradation of the test substance was 20% of the initial concentration.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

A reliable study was conducted to investigate the ready biodegradability of the test substance according to the OECD guideline 301 B (Modified Sturm Test; adopted 1981) and EEC Commission Directive 84/449/EEC C.5, and was performed in compliance with GLP.

The study was performed under aerobic conditions using activated domestic sludge as inoculum. The study included two treatment groups of test item concentrations of nominal 10 mg/L and 20 mg/L, an inoculum control and a system control (reference substance sodium benzoate). The percentage biodegradation was measured with respect to CO2 evolution in the course of 28 days. After 28 days, the test substance reached a level of decomposition of 20% (10 mg/L) or 21% (20 mg/L). As the amount biodegradation was below 60%, the test item could not be considered readily biodegradable under the given test conditions.

The study fulfilled the validity criteria of the guideline, and the obtained results were considered reliable.