3- Hydroxy-4-methyoxypyrdine-2-carboxylic acid

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.4100 (Aerobic Soil Metabolism)

Deviations:

no

GLP compliance:

yes

Test type:

laboratory

Test material

Test material information

Constituent 1

Reference substance name:

3-hydroxy-4-methoxypyridine-2-carboxylic acid

Cas Number:

210300-09-7

Molecular formula:

C7H7NO4

IUPAC Name:

3-hydroxy-4-methoxypyridine-2-carboxylic acid

Specific details on test material used for the study:

Substance name: X696476
Lot #: XS9-109113-80
Purity: 100%

Radiolabelling:

no

Study design

Oxygen conditions:

aerobic

Soil classification:

other: USDA Textural Class (hydrometer method)

Soil properties

Soil properties 1

Soil no.:

#1

Soil type:

clay loam

% Clay:

29

% Silt:

38

% Sand:

33

% Org. C:

3.7

pH:

6.5

CEC:

11.2 meq/100 g soil d.w.

Bulk density (g/cm³):

1

% Moisture content:

25.3

Soil properties 2

Soil no.:

#2

Soil type:

loam

% Clay:

25

% Silt:

50

% Sand:

25

% Org. C:

4.6

pH:

6

CEC:

16.2 meq/100 g soil d.w.

Bulk density (g/cm³):

0.91

% Moisture content:

41.9

Soil properties 3

Soil no.:

#3

Soil type:

clay loam

% Clay:

39

% Silt:

36

% Sand:

25

% Org. C:

4

pH:

7.5

CEC:

27 meq/100 g soil d.w.

Bulk density (g/cm³):

1.1

% Moisture content:

23.6

Soil properties 4

Soil no.:

#4

Soil type:

clay

% Clay:

47

% Silt:

22

% Sand:

31

% Org. C:

1.7

pH:

7.9

CEC:

11.8 meq/100 g soil d.w.

Bulk density (g/cm³):

1.13

% Moisture content:

16.3

Duration of test (contact time)

Duration of test (contact time) 1

Soil No.:

#1

Duration:

120 d

Duration of test (contact time) 2

Soil No.:

#2

Duration:

120 d

Duration of test (contact time) 3

Soil No.:

#3

Duration:

120 d

Duration of test (contact time) 4

Soil No.:

#4

Duration:

120 d

Initial test substance concentration

Initial test substance concentration 1

Soil No.:

#1

Initial conc.:

0.25 mg/kg soil d.w.

Based on:

test mat.

Initial test substance concentration 2

Soil No.:

#2

Initial conc.:

0.25 mg/kg soil d.w.

Based on:

test mat.

Initial test substance concentration 3

Soil No.:

#3

Initial conc.:

0.25 mg/kg soil d.w.

Based on:

test mat.

Initial test substance concentration 4

Soil No.:

#4

Initial conc.:

0.25 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Experimental conditions

Experimental conditions 1

Soil No.:

#1

Temp.:

20 ± 2°C

Microbial biomass:

Initial: 492 μg C/g soil
Final: 274 μg C/g soil

Experimental conditions 2

Soil No.:

#2

Temp.:

20 ± 2°C

Microbial biomass:

Initial: 551 μg C/g soil
Final: 403 μg C/g soil

Experimental conditions 3

Soil No.:

#3

Temp.:

20 ± 2°C

Microbial biomass:

Initial: 853 μg C/g soil
Final: 710 μg C/g soil

Experimental conditions 4

Soil No.:

#4

Temp.:

20 ± 2°C

Microbial biomass:

Initial: 416 μg C/g soil
Final: 282 μg C/g soil

Results and discussion

Half-life / dissipation time of parent compound

Half-life / dissipation time of parent compound 1

Key result

Soil No.:

#1

DT50:

> 1 000 d

Type:

other: SFO

Temp.:

20 °C

Remarks on result:

other: RefSol (clay loam)

Half-life / dissipation time of parent compound 2

Key result

Soil No.:

#2

DT50:

> 1 000 d

Type:

other: SFO

Temp.:

20 °C

Remarks on result:

other: Chelmorton (loam)

Half-life / dissipation time of parent compound 3

Key result

Soil No.:

#3

DT50:

> 1 000 d

Type:

other: SFO

Temp.:

20 °C

Remarks on result:

other: Woodside Farm (clay loam)

Half-life / dissipation time of parent compound 4

Key result

Soil No.:

#4

DT50:

> 1 000 d

Type:

other: SFO

Temp.:

20 °C

Remarks on result:

other: Hareby (clay)

Applicant's summary and conclusion

Conclusions:

There was no apparent degradation of the test substance with the DT50 being calculated to be greater than 1000 days in all four soils. It can be concluded that the test substance may only degrade slowly in the environment.

Executive summary:

The rate of degradation of the test substance has been investigated under aerobic conditions at 20 ± 2°C in four soils in the dark. The soils were RefSol (Germany, clay loam) Chelmorton (UK, loam), Woodside Farm (UK, clay loam) and Hareby (UK, clay).

The study was conducted to fulfil the requirements of Commission Regulation (EU) No 283/2013 of 01 March 2013 setting out the data requirements for active substances, in accordance with Regulation (EC) No 1107/2009 of the European Parliament and of the Council concerning the placing of plant protection products on the market. The experiments were conducted in accordance with OECD 307, Aerobic and Anaerobic Transformation in Soil (April 2002) and OPPTS 835.4100 Aerobic Soil Metabolism (October 2008).

The study was conducted in accordance with the OECD Principles of Good Laboratory Practice, based on Section II of Annex I to the European Parliament and Council Directive 2004/10/EC and embodied in the UK Good Laboratory Practice Regulations 1999 (Statutory Instrument No. 3106) as amended by the UK Good Laboratory Practice (Codification Amendments Etc.) regulations 2004 (Statutory Instrument No. 994), and as accepted by Regulatory Authorities throughout the European Community, the United States of America and Japan.

The soils, sieved to 2 mm, were dispensed [50g oven-dried equivalent (ode)] into individual flasks, the water content of the soil was adjusted to 50% of the maximum moisture holding capacity and the samples were incubated at 20 ± 2°C. Each flask was treated at a nominal application rate of 17.5 μg of the test substance per 50 g of oven dried equivalent (ode) soil, this being equivalent to 0.35 mg/kg or 130 g/ha.

Duplicate flasks were removed after incubation for 0, 2, 6, 14, 30, 63, 90 and 120 days. Each soil sample was extracted using accelerated solvent extraction with a series of solvents and conditions and, following solid phase clean up and concentration, the test substance present in the extracts was quantified by LC-MS/MS.

At each time-point three 50g (ode) samples of each soil were prepared from a quantity of untreated soil designated for the purpose of method efficiency determinations. Duplicate samples were fortified at a level approximately equivalent to the expected concentration of the test substance in the samples under analysis whilst a single control sample was left untreated. These samples were then extracted and analysed alongside, and in the same manner, as the incubated samples.

The incubated study sample, fortification and control sample extracts were all analysed by LC-MS/MS with ESI tandem mass spectrometry. Two Multiple Reaction Monitoring (MRM) transitions were monitored to confirm the selectivity of the method. The first transition was used for quantification and the second for confirmation. For each analytical run a calibration curve using matrix matched standards of known concentration in the range ca 0.25 to 51.0 ng/mL was constructed to allow quantification of the test substance in the sample extracts.

The concentrations of extractable test substance remained essentially unchanged throughout the duration of the study. The nominal concentration was 0.35 mg/kg and the average measured concentration for the initial time point (zero-time) samples was 0.25 mg/kg or 73% of nominal which remained at 0.29 mg/kg or 81% of nominal after 120 days.

The degradation rate and the DT50/DT90 values of the test substance in the four test soils were determined according to the FOCUS guidance document on degradation kinetics using the KinGUI software. The test substance was shown to have no significant degradation with estimated DT50 values of greater than 1000 days in all soils.