2-chloro-N-[[[4-(trifluoromethoxy)phenyl]amino]carbonyl]benzamide

Biodegradation in soil

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

In-life initiated/completed: 20-Feb-2009 to 06-May-2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Version / remarks:

April 24, 2002

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Commission Directive 95/36/EC (Annexes II and III, Fate and Behaviour in the Environment)

Version / remarks:

July 14, 1995 - amending Council Directive 91/414/EEC

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

laboratory

Radiolabelling:

not specified

Oxygen conditions:

aerobic

Soil classification:

USDA (US Department of Agriculture)

Year:

2009

Soil no.:

#1

Soil type:

loam

% Clay:

21

% Silt:

30

% Sand:

49

% Org. C:

1.7

pH:

5.8

CEC:

10.3 meq/100 g soil d.w.

Bulk density (g/cm³):

1.13

% Moisture content:

54.6

Soil no.:

#2

Soil type:

clay loam

% Clay:

33

% Silt:

46

% Sand:

21

% Org. C:

5.4

pH:

7.4

CEC:

20.6 meq/100 g soil d.w.

Bulk density (g/cm³):

0.96

% Moisture content:

94.8

Soil no.:

#3

Soil type:

clay loam

% Clay:

31

% Silt:

45

% Sand:

24

% Org. C:

0.9

pH:

7.8

CEC:

11.4 meq/100 g soil d.w.

Bulk density (g/cm³):

1.14

% Moisture content:

43.1

Details on soil characteristics:

Soil #1: Laacher Hof "Wurmwiese" (Soil ID: WW)
Soil #2: Dollendorf II (Soil ID: DD)
Soil #3: Les Cayades (Soil ID: LC)

Soil No.:

#1

Duration:

32 d

Soil No.:

#2

Duration:

32 d

Soil No.:

#3

Duration:

32 d

Soil No.:

#1

Initial conc.:

240 other: µg a.s./kg soil d.w.

Based on:

other: single maximum field use rate

Soil No.:

#2

Initial conc.:

240 other: µg a.s./kg soil d.w.

Based on:

other: single maximum field use rate

Soil No.:

#3

Initial conc.:

240 other: µg a.s./kg soil d.w.

Based on:

other: single maximum field use rate

Soil No.:

#1

Temp.:

19.7°C

Humidity:

55 ± 5 % MWHC

Microbial biomass:

Study start, without/with application solvent: 503/550 mg C/kg soil.
Study end, without/with application solvent: 471/488 mg C/kg soil.

Soil No.:

#2

Temp.:

19.7°C

Humidity:

55 ± 5 % MWHC

Microbial biomass:

Study start, without/with application solvent: 3568/3678 mg C/kg soil.
Study end, without/with application solvent: 3363/3234 mg C/kg soil.

Soil No.:

#3

Temp.:

19.7°C

Humidity:

55 ± 5 % MWHC

Microbial biomass:

Study start, without/with application solvent: 217/231 mg C/kg soil.
Study end, without/with application solvent: 228/250 mg C/kg soil.

Key result

Soil No.:

#1

DT50:

3.5 d

Temp.:

19.7 °C

Key result

Soil No.:

#2

DT50:

1.7 d

Temp.:

19.7 °C

Key result

Soil No.:

#3

DT50:

7.3 d

Temp.:

19.7 °C

Transformation products:

not specified

Details on results:

During study incubation the concentration of the test item decreased rapidly in all soils, dropping below 10 % of the applied 7 to 32 days after application. At study termination, the residue levels were 5.0, 3.5 and 2.2 % of the applied amount for soils Laacher Hof "Wurmwiese", Dollendorf II and Les Cayades, respectively.

Conclusions:

The test item Triflumuron was found to degrade rapidly in a typical soil environment under aerobic laboratory conditions. The decline occurred with calculated DT50 values of 1.7 to 7.3 days in the three soils tested. Due to its short half-life, Triflumuron is unlikely to accumulate in viable soils. The present study demonstrated Triflumuron to be rapidly degraded in typical agricultural soils under aerobic laboratory conditions. Therefore, the compound will not persist in a viable soil environment.

Executive summary:

The degradation of the insecticidal compound Triflumuron was tested in three different soils of European origin. A loam (Laacher Hof "Wurmwiese": pH(CaCl₂) 5.6, 1.7 % OC) and two clay loam type soils (Dollendorf II: pH(CaCl₂) 7.3, 5.4 % OC; Les Cayades: pH(CaCl2) 7.6, 0.9 % OC) from Germany and France were applied with Triflumuron and studied for up to 32 days under aerobic laboratory conditions in the dark, at 20 ± 1°C and 55 ± 5 % of MWHC soil moisture. The experiment was conducted in accordance with the OECD Guideline for Testing of Chemicals No. 307 [1] and the Commission Directive 95/36/EC amending Council Directive 91/414/EEC. The study was conducted in compliance with the OECD Principles of Good Laboratory Practice, current version and the Principles of Good Laboratory Practice – German Chemical Law (Chemikaliengesetz), current version of Annex 1. The amount of the test item for the treatment of the incubation flasks was 240 μg Triflumuron per kg of soil dry weight. This trial application rate was based on the single maximum field use rate (180 g/ha). The calculation was performed according to OECD Test Guideline No. 307 for conversion of field application rate (FAR, kg/ha) into trial application rate (TAR, mg/kg soil), assuming a homogeneous distribution of Triflumuron in a topsoil layer of 5 cm depth at a generic soil bulk density of 1.5 g/cm³. The test systems consisted of open Erlenmeyer glass flasks each containing 100 g of soil dry weight equivalents (static test system design). Samples were analyzed after 0, 0.25, 1, 2, 4 and 7 days of incubation for all soils. In addition, samples for soil Laacher Hof "Wurmwiese" were analyzed on day 14 and for soil Les Cayades on days 14, 21 and 32. Duplicate test systems were taken per sampling interval. The entire soil per flask was processed two times at ambient temperature and once by microwave-accelerated solvent extraction using acetonitrile. The combined extracts were analysed for Triflumuron residues by reversed phase high performance liquid chromatography/mass spectrometry (HPLC-MS/MS) in multiple reaction monitoring (MRM) mode using matrix-matched non-labeled Triflumuron standards. Method development and validation was performed successfully within this study prior to soil sample analyses. In addition, recovery tests concurrent to all sample analyses were performed. The recovered mean amount of Triflumuron directly after soil treatment was 98.7, 96.0 and 97.2 % of the applied for soils Laacher Hof "Wurmwiese", Dollendorf II and Les Cayades, respectively. During study incubation the concentration of the test item decreased rapidly in all soils, dropping below 10 % of the applied 7 to 32 days after application. At study termination, the residue levels were 5.0, 3.5 and 2.2 % of the applied amount for soils Laacher Hof "Wurmwiese", Dollendorf II and Les Cayades, respectively. Triflumuron was found to rapidly dissipate from soils under aerobic laboratory conditions, with typical half-lives of 3.5, 1.7 and 7.3 days for soils Laacher Hof "Wurmwiese", Dollendorf II and Les Cayades, respectively. Therefore, the compound will not persist in a viable soil environment.

Description of key information

The test item Triflumuron was found to degrade rapidly in a typical soil environment under aerobic laboratory conditions. The decline occurred with calculated DT50 values of 1.7 to 7.3 days in the three soils tested. Due to its short half-life, Triflumuron is unlikely to accumulate in viable soils. The present study demonstrated Triflumuron to be rapidly degraded in typical agricultural soils under aerobic laboratory conditions. Therefore, the compound will not persist in a viable soil environment. The Half-life value  of 7.3 d at 20°C in soil has been converted to 15.5 d at 12°C using the Arrhenius equation.

Key value for chemical safety assessment

Half-life in soil:

15.5 d

at the temperature of:

12 °C