Methyl O-(4-amino-3,5-dichloro-6-fluoropyridin-2-yloxy)acetate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24 Jan - 1Mar 1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Adopted in 1981

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Methyl O-(4-amino-3,5-dichloro-6-fluoropyridin-2-yloxy)acetate

EC Number:

407-550-4

EC Name:

Methyl O-(4-amino-3,5-dichloro-6-fluoropyridin-2-yloxy)acetate

Cas Number:

69184-17-4

Molecular formula:

Hill formula: C8 H7 Cl2 F N2 O3 CAS formula: C8 H7 Cl2 F N2 O3

IUPAC Name:

methyl 2-[(4-amino-3,5-dichloro-6-fluoropyridin-2-yl)oxy]acetate

Details on test material:

- Name of test material (as cited in study report): Fluroxypyr methyl ester technical
- Substance type: technical product
- Physical state: solid, fine, black, crystalline powder
- Analytical purity: 90.8% w/w
- Lot/batch No.: C-3B
- Storage condition of test material: stored at approximately 13 °C until required and then stored at ambient temperature during the testing period

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum: the activated sludge was collected on the day of the test from a sewage treatment works, treating predominantly domestic waste
- Preparation of inoculum for exposure: once in the laboratory it was aerated for 4 hours. A sample of the mixed liquor was then homogenised in a mechanical blender and allowed to settle for 45 minutes. An aliquot of the supernatant was passed through a filter paper to remove coarse solids and
the filtrate used as the inoculum for the test

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

10 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
Stock 1:
Iron (III) chloride hexahydrate 0.25 g/L
Stock 2:
Magnesium sulphate heptahydrate 22.5 g/L
Stock 3:
Calcium chloride dihydrate 36.40 g/L
Stock 4:
Potasslum dihydrogen phosphate 8.5 g/L
di-Potassium hydrogen phosphate 21.75 g/L
di-Sodium monohydrogen phosphate dihydrate 33.4 g/L
Ammonium chloride 1.70 g/L
Stock 5:
Ammonium sulphate 40 g/L

The test medium was prepared by adding 4 mL of Stock 1, 1 mL of Stock 2, 1 mL of Stock 3, 2 mL of Stock 4 and 1 mL of Stock 5 per 1 L distilled water

- Test temperature: 14-23 °C
- pH: 6.86-7.34

TEST SYSTEM
- Culturing apparatus: 5 L brown glass vessels, containing 3.5 L test medium
- Number of culture flasks/concentration: 1
- Method used to create aerobic conditions: test vessels were aerated overnight prior to test initiation with air that had been passed through cylinders containing Carbosorb AS followed by 12 one-litre bottles containing 10N sodium hydroxide and one containing 0.25 barium hydroxide to remove CO2
- Details of trap for CO2 and volatile organics if used: the CO2 produced by each culture was trapped in a series of Dreschel bottles containing barium hydroxide which were connected to the outlet from each test vessel. The residual barium hydroxide was determined at intervals by titration with hydrochloric acid using phenolphthalein indicator


SAMPLING
- Sampling frequency: samples were collected at 2, 3, 4, 5, 6, 7, 9, 12, 16, 20, 27 and 28 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: 1
- Toxicity control: prior to the test an additional assay was performed in order to assess the potential of the test substance to inhibit bacterial activity. In this assay, mineral salts medium inoculated with sewage effluent (1 drop/L), with and without sodium benzoate (2 mg/L), was added to groups of 4 bottles containing the test material, to give nominal Fluroxypyr methyl ester concentrations of 2 and 10 mg/L. Control groups of bottles contained mineral salts medium alone, inoculated mineral salts medium or inoculated mineral salts containing sodium benzoate. The concentrations of dissolved oxygen in duplicate bottles from each group were measured at the start of the test and after incubation in darkness for five days at 20 °C.
Temperature: 19.6-20.4 °C
pH: 6.68-7.14

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (CO2 evolution)

Value:

20

Sampling time:

28 d

Remarks on result:

other: 10 mg/L test concentration

% Degradation 2

Parameter:

% degradation (CO2 evolution)

Value:

15

Sampling time:

28 d

Remarks on result:

other: 20 mg/L test concentration

Details on results:

The test substance did not reach the pass level of 60% biodegradation within the test period. Therefore, it can not be considered as readily biodegradable. The inhibition assay conducted additionally to the main test showed that the substance is not inhibitory to bacteria. The level of degradation of sodium benzoate after 5 days of incubation was 54%, and in the presence of 2 and 10 mg/L test substance, this degradation was unaffected (57% and 54% biodegradation respectively)

BOD5 / COD results

Results with reference substance:

Sodium benzoate reached 61% biodegradation within 6 days, and a final degradation value of 84% on day 28

Any other information on results incl. tables

Table 1. Degradation as a percentage of TCO2 in reference and test mixtures

Day	Reference substance %	Test substance 10 mg/L %	Test substance 20 mg/L %
2	3	0	1
3	29	6	4
3	42	-	-
4	51	10	6
5	57	12	6
6	61	12	6
7	65	-	-
9	69	-	-
12	73	12	6
16	78	17	10
20	81	17	13
27	84	20	15
28	84	20	15

Applicant's summary and conclusion

Interpretation of results:

other: not readily biodegradable