N-[2,5-dichloro-4-(1,1,2,3,3,3-hexafluoropropoxy)-phenyl-aminocarbonyl]-2,6-difluorobenzamide

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:

14 Mar 1990 to 11 Apr 1990

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:

12 May 1981

Deviations:

yes

Remarks:

See deviations in 'Any other information on materials and methods incl. tables'

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Bacteria collected from activated sludge of the sewage treatment plant of CH-4153 Reinach on 13/03/90. The preparation was carried out according to the methods described in the guideline.

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

test mat.

Initial conc.:

20.1 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST SYSTEM
- Culturing apparatus: 2 Litre flasks (dark brown glass) equipped with gas inlet and magnetic stirrer.
- Air: 25 mL/min purified from carbon dioxide.
- Details of trap for CO2: Absorbers filled with 200 mL 0.05 N sodium hydroxide

TEST CONDITIONS
- Apply of test substance: 1200 mL of the mineral solution with the inoculum were aerated for 24 hours in the test vessel. In 300 mL mineral solution 15 mL Polyoxyethylene—Sorbitan—Monooleate (solution of 30 mg in 100 mL bidist. water) and 15.0 rsp. 30.1 mg of test substance were added and homogenized. This solution was given to the test vessel which was immediately connected to the CO2 traps.
- Number of culture flasks/concentration (test substance): 1
- Number of culture flasks/reference: 2
- Continuous darkness: Yes

SAMPLING
- Sampling frequency: Day 0, 2, 5, 9, 12, 16, 19, 23, 27 and 28.

Reference substance:

aniline

Remarks:

20 mg/L

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Remarks on result:

other: 10.0 mg/L treatment

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Remarks on result:

other: 20.1 mg/L treatment

Details on results:

An overview of the results is provied in Table 2 in 'Any other information on results incl. tables'.
After 28 days incubation, 16.5 and 15.9 mg of CO2 evolute from 10.0 mg/L treatment and 20.1 mg/L treatment groups, respectively. These values are lower than the theoretical carbon dioxide evolution, 20.90 mg CO2/1.5 L for 10.0 mg/L treatment and 41.64 mg CO2/1.5 L for 20.1 mg/L treatment. The theoretical carbon dioxide evolution was calculated based on the chemical formula of the substance and also the 95.2% purity of the test material. Regarding the amount of evolute CO2, the biodegradation of the test substance in these treatments was calculated to be -1 % (10.0 mg/L) and -2% (20.1 mg/L) at day 28. The negative degradation values are within the variation of the method. Thus, it is concluded that the test substance is not biodegradable under the test condition.

Results with reference substance:

An overview of the results is provied in Table 1 in 'Any other information on results incl. tables'.
After 28 days of incubation, 94% of the reference substance was biodegradaded.

Table 1. Results of the reference substance

	CO2 evolution measured					Biodegradation
	Blank			Reference		reference
Day	Replicate 1 (mg)	Replicate 2 (mg)	Mean (mg)	Replicate 1 (mg)	Replicate 2 (mg)	Replicate 1 (%)	Replicate 2 (%)	Mean (%)
2	4.3	3.8	4.0	3.1	4.4	-1	0	0
5	8.3	7.8	8.0	13.0	46.2	6	45	25
9	11.6	11.2	11.4	64.2	77.6	62	78	70
12	12.7	12.5	12.6	71.8	82.9	70	83	76
16	13.7	13.5	13.6	77.1	86.8	75	86	80
19	14.3	13.9	14.1	79.4	88.7	77	88	82
23	15.9	15.6	15.7	86.7	94.3	83	92	88
27	16.4	16.4	16.4	88.6	96.2	85	94	89
28	16.7	16.9	16.8	93.2	99.8	90	98	94

 

Table 2. Results of the test substance

	CO2 evolution measured		Biodegradation
Day	10 mg/L Treated group (mg)	20.1 mg/L treated group (mg)	10 mg/L Treated group (%)	20.1 mg/L treated group (%)
2	3.9	3.7	-1	-1
5	7.6	7.3	-2	-2
9	10.9	10.3	-2	-3
12	11.9	11.4	-3	-3
16	13.4	12.8	-1	-2
19	13.9	13.2	-1	-2
23	15.5	15.0	-1	-2
27	16.2	15.8	-1	-1
28	16.5	15.9	-1	-2

The negative degradation values are within the variation of the method.

 

 

 

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

In a 28-day ready biodegradability study in accordance with OECD TG 301B, no biodegradation of the test substance was observed. Thus, it is concluded that the test substance is not biodegradable under the test conditions.

Executive summary:

The ready biodegradability of the test item was investigated using aerobic activated sludge incubated at 22 ± 2 °C for 28 days under continuous stirring. The test was conducted in accordance with OECD TG 301 B, and in compliance with GLP criteria. The tested sludge was sampled from a sewage plant (Reinach-Switzerland). The sludge was aerated for 24 hours in the test vessel and was then homogenized. After that, the test vessel was immediately connected to the CO2 traps. The test sludge was incubated with 10.0 mg/L and 20.1 mg/L of test substance (1 replicate/concentration). In addition, a reference substance, Aniline, was included in the study (2 replicates). The released CO2 from the test materials was trapped and analysed on day 0, 2, 5, 9, 12, 16, 19, 23, 27 and 28. The biodegradation was calculated on the basis of the theoretical carbon content of the test substance and the quantities of carbon dioxide determined on the days of measurements.

After 28 days incubation, 94% of the reference substance was biodegraded. While, 16.5 and 15.9 mg of CO2 evolute from 10.0 mg/L treatment and 20.1 mg/L treatment groups, respectively, these values were lower than the theoretical carbon dioxide evolution, 20.90 mg CO2/1.5 L for 10.0 mg/L treatment and 41.64 mg CO2/1.5 L for 20.1 mg/L treatment. Regarding the amount of evolute CO2, the biodegradation of the test substance in these treatments was calculated to be -1 % (10.0 mg/L) and -2% (20.1 mg/L) at day 28. The negative degradation values are within the variation of the method. Thus, it is concluded that the test substance is not biodegradable under the test conditions.

Description of key information

The test substance is concluded to be "not biodegradable" under the conditions of the test, freshwater, OECD TG 301B, Bader 1990

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

There is one OECD TG 301 B followed and GLP complied study (Reliability 1) available for this endpoint. The test item was investigated using aerobic activated sludge incubated at 22 ± 2 °C for 28 days under continuous stirring. The tested sludge was sampled from a sewage plant (Reinach-Switzerland). The test sludge was incubated with 10.0 mg/L and 20.1 mg/L of test substance (1 replicate/concentration). In addition, a reference substance, Aniline, was included in the study (2 replicates). The released CO2 from the test materials was trapped and analysed on day 0, 2, 5, 9, 12, 16, 19, 23, 27 and 28. The biodegradation was calculated on the basis of the theoretical carbon content of the test substance and the quantities of carbon dioxide determined on the days of measurements. After 28 days incubation, regarding the amount of evolute CO2, the biodegradation of the test substance in these treatments was calculated to be -1 % (10.0 mg/L) and -2% (20.1 mg/L) at day 28. The negative degradation values are within the variation of the method. Thus, it is concluded that the test substance is not biodegradable under the test condition.