5-Brom-2-[(3,4,5-trifluorphenoxy)-difluormethyl]-1,3-difluorbenzene

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:

12 Dec 2006 - 27 Feb 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: activated sludge, micro organisms from a domestic waste water treatment plant (supplied by sewage plant Rossdorf, Germany)
- Treatment: Activated sludge used for this study was washed by centrifugation ans the supernatant liquid phase was decanted. the solid material was re-suspended in tap water and centrifuged again. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 1.5 g dry material/L were mixed with test water ans the aerated until use overnight.
- Concentration in the reaction mixture: 1.5 g/L (on dry matter base) stock suspension, final concentration 30 mg/L
- Preparation/Conditioning: Aeration overnight

Duration of test (contact time):

28 d

Initial conc.:

1 000 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Test temperature: 22°C in the dark
- pH: 7.6 (7.7 - 7.9)

TEST SYSTEM
- Preparation of test flasks:
The amounts of test item and reference item were directly weighed into the test flasks (flask 1: 25.1 mg; flask 2 25.0 mg test item). No emulsifiers or solvents were used, but the solutions were dispersed by stirring to achieve a homogenous solution of the test item.
Incubation:
The closed test flasks were incubated in a climatic chamber under continuous stirring. The consumption of oxygen was determined by measuring the change of the pressure in the flasks. Evolved carbon dioxide was absorbed in an aqueous solution (45%) of potassium hydroxide.
The change of pressure was measured in the test flasks by means of a manometric method (BSB/BOD Sensor System, Aqualytic, Neu Isenburg. Germany) each day.
Themperature was measured each working day in the climatic chamber.
pH values were measured in all flasks at the start and and of the test using a pH electrode WTW pH 340i.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Details on results:

Unter the test conditions, no biodegradation of the test item could be observed. The degradation rate of the test item did not reach 60 % within the 10-day window and after 28 days of incubation. Therefore the test item is considered not to be readily biodegradable.
The reference item sodium benzoate was sufficiently degraded to 87% after 14 days and 90 % after 28 days of incubation. The percentage of degradation confirms the suitability of the used activated sludge inoculum.
In the toxicity control containing both, the test item and the reference item, 54 % biogedradation was noted within 14 days and 57 % biodegradation was noted after 28 days of incubation. According to the test guidelines the test item can be assumed to be not inhibitory on the activated sludge micro organisms because the degradation was >25 % within 14 days.
The oxygen demand in the abiotic control was zero, no correction of the test item degradation rates had to be done.

Results with reference substance:

Degradation of reference item (sodium benzoate): 87 % after 14 days and 90 % after 28 days of incubation.

Tab 1: Biodegradation [%] of test item, reference and toxicity control

Time (d)	Test material flask 1	Test material flask 2	Sodium benzoate	Toxicity control
1	0	0	28	21
2	-6	-6	40	28
3	-5	-6	51	36
4	-5	-7	61	44
5	-4	-8	69	45
6	-4	-8	74	48
7	-3	-8	74	48
8	-3	-8	79	50
9	-3	-8	79	50
10	-3	-8	83	52
11	-3	-8	84	53
12	-3	-8	85	54
13	-4	-8	87	54
14	-2	-7	87	54
15	-1	-7	87	56
16	-2	-8	86	55
17	-2	-7	86	55
18	-2	-7	87	55
19	-2	-6	87	55
20	-2	-7	87	56
21	-2	-4	90	57
22	-3	-5	89	56
23	-4	-5	90	56
24	-5	-7	90	56
25	-4	-5	90	57
26	-5	-6	89	56
27	-5	-6	89	57
28	-5	-5	90	57

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item is not readily biodegradable according to the criteria of the OECD guideline 301 F.

Executive summary:

Purpose

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The GLP study was performed according to OECD TG 301F.

Result

Biodegradation of test item

The degradation rate of the test item did not reach 60 % within the 10 day window and after 28 days of incubation of incubation. Therefore, the test item is not considered to be readily biodegradable.

Biodegradation of Sodium Benzoate

The reference item sodium benzoate was sufficiently degraded to 87 % after 14 days and to a mean of 90 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum.

Biodegradation in the Toxicity Control

In the toxicity control containing both, the test item and the reference item sodium benzoate, a mean of 54% biodegradation was noted within 14 days and 57% biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms because degradation was >25% within 14 days.

Conclusion

The test item is not considered to be readily biodegradable.

Description of key information

The test item is not readily biodegradable according to the criteria of the OECD guideline 301 F.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The GLP study was performed according to OECD TG 301F.

Biodegradation of test item

The degradation rate of the test item did not reach 60 % within the 10 day window and after 28 days of incubation of incubation. Therefore, the test item is not considered to be readily biodegradable.

Biodegradation of Sodium Benzoate

The reference item sodium benzoate was sufficiently degraded to 87 % after 14 days and to a mean of 90 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum.

Biodegradation in the Toxicity Control

In the toxicity control containing both, the test item and the reference item sodium benzoate, a mean of 54% biodegradation was noted within 14 days and 57% biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms because degradation was >25% within 14 days.

The test item is not considered to be readily biodegradable.