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Environmental fate & pathways

Phototransformation in soil

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Reference
Endpoint:
phototransformation in soil
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: SETAC-EUROPE Procedures for Assessing the Environmental Fate and Ecotoxicity of Pesticides: Section 2 (Soil Photolysis)
Qualifier:
according to
Guideline:
other: EPA Guideline Series, OPPTS 835.2410: Photodegradation in Soil
Version / remarks:
November 2008
GLP compliance:
yes
Radiolabelling:
yes
Remarks:
14C-labelled at position 2 of thiazole ring or position 4 of the oxadiazine ring
Analytical monitoring:
yes
Analytical method:
liquid chromatography
high-performance liquid chromatography
mass spectrometry
other: Liquid Scintillation Counting (LSC), Thin-Layer Chromatography (TLC), combustion analysis
Details on sampling:
- Sampling intervals: 0, 1, 5, 7, 10, 13, 15 days after treatment (duplicates)
- Sampling procedures: Complete treated samples were removed at each sampling time
- Collection of CO2 and volatile organics: Traps replaced with fresh media at 1, 5, 7, 10, 13 days after treatment. Weight of solutions measured and duplicate aliquots taken for LSC analysis.
- Sample storage before analysis: All samples were stored at -20 °C before further analysis.
Details on soil:
COLLECTION AND STORAGE
- Sampling location: CH-1896 Vouvry, Switzerland
- Date of collection: November 2013
- Date of reception: November 2013
- Sampling depth (cm): 5 - 20 cm ground depth
- Storage conditions: 4 ºC, aerobic
- Duration of storage (days): 78

PROPERTIES
- Soil classification system: USDA
- Soil texture: Silt loam
- Clay (%, w/w) (< 2 µm): 7.8
- Silt (%, w/w) (50-2 µm): 64.8
- Sand (%, w/w) (2000-50 µm): 27.3
- pH (water): 7.06
- pH (0.01M CaCl2): 7.37
- Organic matter (%): 4.50
- Organic carbon (%): 2.61
- CEC (mmol/kg): 76.90
- Moisture at pF2 (% w/w): 38.54
- Initial biomass (mg carbon/100 g soil): 31.5
- Final biomass (mg carbon/100 g soil): 38.5

PREPARATION OF SOIL
- Condition of soil: Fresh soil, passed through 2 mm sieve prior to use
Light source:
Xenon lamp
Light spectrum: wavelength in nm:
>= 290 - <= 800
Details on light source:
- Filters used: Cut off filter (ensures min. λ ≥ 290 nm)
- Relationship to natural sunlight: Similar spectral distribution
- Continuous irradiation: Yes
- Nominal light intensity (300-800 nm): 330 W/m2
Details on test conditions:
EXPERIMENTAL DESIGN
- Soil sample weight: 20 g (dry weight) per replicate
- Control conditions: Darkness
- Number of replicates: 2 (irradiated and darkness)
- Test apparatus: Irradiated: quartz glass cuvettes, quartz lids with inlet and outlet; darkness: aluminium cuvettes, perforated foil
- Traps for CO2 and organic volatiles: One cyclohexylamine, one ethylene glycol (organic volatiles) and one 2 M NaOH (14CO2)
- Moisture content: At day 0 soil adjusted to pF2 moisture tension
- Moisture maintenance method: Control of moisture loss by weight and compensation by water addition

TEST MATERIAL APPLICATION
- Identity of solvent: Dosed in acetonitrile
- Volume of test solution used/treatment: 478-494 µL
- Application method: Pipette; Small droplets over the soil
- Evaporation of application solvent: 30 min

CALCULATIONS
- Mass balance: A mass balance for each sample was determined by summation of the radioactivity recovered in the soil extracts, the total 14CO2 and other volatiles evolved and the bound residues (total non-extractables).
- Half lives: The half-lives (DegT50) of the radiolabelled test substance in each soil (from the HPLC analysis) were determined using a Single First Order (SFO) kinetic model.
Duration:
15 d
Temp.:
20 °C
Initial conc. measured:
2.5 mg/kg soil d.w.
Reference substance:
no
Dark controls:
yes
% Degr.:
>= 41 - <= 55.7
Sampling time:
15 d
Test condition:
dry soil condition
Remarks on result:
other: mean degradation of the was 41% and 55.7 for the [thiazole-2-14C]- and [guanidine-4-14C]-labelled test substance, respectively.
% Degr.:
>= 48.5 - <= 49.3
Sampling time:
15 d
Test condition:
moist soil condition
Remarks on result:
other: mean degradation of the was 48.5 and 49.3 for the [thiazole-2-14C]- and [guanidine-4-14C]-labelled test substance, respectively.
DT50:
25.27 d
Test condition:
Irradiated dry soil; [thiazole-2-14C] labelled test substance
Key result
DT50:
51.15 d
Test condition:
Irradiated dry soil; [thiazole-2-14C] labelled test substance
Remarks on result:
other: Corrected DT50 to equivalent Summer Sunlight days 30-50ºN (OECD)
DT50:
22.22 d
Test condition:
Irradiated moist soil; [thiazole-2-14C] labelled test substance
DT50:
45.05 d
Test condition:
Irradiated moist soil; [thiazole-2-14C] labelled test substance
Remarks on result:
other: Corrected DT50 to equivalent Summer Sunlight days 30-50ºN (OECD)
DT50:
18.53 d
Test condition:
Irradiated dry soil; [guanidine-4-14C] labelled test substance
DT50:
37.55 d
Test condition:
Irradiated dry soil; [guanidine-4-14C] labelled test substance
Remarks on result:
other: Corrected DT50 to equivalent Summer Sunlight days 30-50ºN (OECD)
DT50:
18.65 d
Test condition:
Irradiated moist soil; [guanidine-4-14C] labelled test substance
DT50:
37.79
Test condition:
Irradiated moist soil; [guanidine-4-14C] labelled test substance
Remarks on result:
other: Corrected DT50 to equivalent Summer Sunlight days 30-50ºN (OECD)
Transformation products:
yes
No.:
#1
No.:
#2
No.:
#3
No.:
#4
No.:
#5
No.:
#6
Details on results:
The results are tabulated in 'Any other information on results incl. tables'.

MASS BALANCE DRY SOIL
The mass balances in all dry soil samples (both radiolabels, irradiated and dark) ranged from 85.0 to 111.3 % AR, with an overall mean of 99.6 % AR.
- Total radioactivity: Sum of activity in soil extracts, residue on combustion, that trapped as 14CO2 in the 2M sodium hydroxide traps and that trapped in the cyclohexylamine traps.
- Recovery at 0 days after treatment: Irradiated soil: Range 99.5 to 105.1 % AR - Average 102.3 % AR; Dark control: Range 99.1 to 99.7 % AR - Average 99.4 % AR*
- Overall recovery (all samples): Irradiated: Range 85.0 to 105.7 % AR - Average 97.9 % AR; Dark control: Range 94.6 to 111.3 % AR - Average 101.3 % AR
* Dark controls: no separate sampling at 0 days after treatment; additional values for recovery are given for 1 day after treatment

MASS BALANCE MOIST SOIL
The mass balances in all moist soil samples (both radiolabels, irradiated and dark) ranged from 88.7 to 101.8 % AR, with an overall mean of 97.0 % AR.
- Total radioactivity: Sum of activity in soil extracts, residue on combustion, that trapped as 14CO2 in the 2M sodium hydroxide traps and that trapped in the cyclohexylamine traps.
- Recovery at 0 days after treatment: Irradiated: 98.2 and 101.8 % AR to Average 100.0 % AR; Dark control: 98.5 and 98.6 % AR - Average 98.6 % AR*
- Overall recovery (all samples): Irradiated: Range 88.7 to 101.8 % AR - Average 95.8 % AR; Dark control: Range 95.5 to 101.0 % AR - Average 98.1 % AR
* Dark controls: no separate sampling at 0 days after treatment; additional values for recovery are given for 1 day after treatment

BOUND AND EXTRACTABLE RESIDUES DRY SOIL
Extractable residues in the irradiated samples declined with time for both labels
- at 0 days after treatment (extractions E1 - E3): Irradiated soil: 95.5 % (thiazole) and 99.7 % (guanidine); Dark control: 94.7 % (thiazole) and 94.6 % (guanidine)*
- at end of study (15 days after treatment): (extractions E1 - E3): Irradiated soil: 61.2 % (thiazole) and 70.1 % (guanidine); Dark control: 94.7 % (thiazole) and 97.5 % (guanidine)

Bound residues in the irradiated samples increased throughout the irradiation period
- at 0 days after treatment (extractions E1 - E3): Irradiated soil: 4.0 % (thiazole) and 5.4 % (guanidine); Dark control: 4.4 % (thiazole) and 5.0 % (guanidine)*
- at end of study (15 days after treatment): (extractions E1 - E3): Irradiated soil: 13.5 % (thiazole) and 23.0 % (guanidine); Dark control: 4.9 % (thiazole) and 5.4 % (guanidine)
* Dark controls: no separate sampling at 0 days after treatment; additional values for recovery are given for 1 day after treatment.

BOUND AND EXTRACTABLE RESIDUES MOIST SOIL
Extractable residues in the irradiated samples declined with time for both labels
- at 0 days after treatment (extractions E1 - E3): Irradiated soil: 98.4 % (thiazole) and 94.3 % (guanidine); Dark control: 94.8 % (thiazole) and 93.8 % (guanidine)*
- at end of study (15 days after treatment): (extractions E1 - E3): Irradiated soil: 58.6 % (thiazole) and 69.1 % (guanidine); Dark control: 96.3 % (thiazole) and 93.7 % (guanidine)

Bound residues in the irradiated samples increased throughout the irradiation period
- at 0 days after treatment (extractions E1 - E3): Irradiated soil: 3.4 % (thiazole) and 3.9 % (guanidine); Dark control: 3.7 % (thiazole) and 4.6 % (guanidine)*
- at end of study (15 days after treatment): (extractions E1 - E3): Irradiated soil: 22.5 % (thiazole) and 24.9 % (guanidine) Dark control: 4.3 % (thiazole) and 5.5 % (guanidine)
* Dark controls: no separate sampling at 0 days after treatment; additional values for recovery are given for 1 day after treatment.

VOLATILISATION DRY SOIL
Carbon dioxide evolution was modest throughout the incubation and without temporal trend
- 14CO2 evolved at end of study (15 days after treatment): Irradiated soil: 1.8 % (thiazole) and 0.5 % (guanidine); Dark control: < 0.1 %
Other volatiles increased throughout the test period.
- Other volatiles evolved at end of study (15 days after treatment): Irradiated soil: 8.5 % (thiazole) and 2.2 % (guanidine); Dark control: 0.1 % (thiazole) and 0.0 % (guanidine)

VOLATILISATION MOIST SOIL
Carbon dioxide evolution was modest throughout the incubation and without temporal trend
- 14CO2 evolved at end of study (15 days after treatment): Irradiated soil: 0.7 % (thiazole) and 0.2 % (guanidine); Dark control: ≤ 0.3 %
Other volatiles increased throughout the test period.
- Other volatiles evolved at end of study (15 days after treatment): Irradiated soil: 7.6 % (thiazole) and 1.6 % (guanidine); Dark control: 0.3 % (thiazole) and 0.9 % (guanidine). The identity of these residues was not investigated but in former photolysis studies with test substance these residues were identified to be carbonyl sulphide and isocyanic acid.

TRANSFORMATION OF PARENT MATERIAL
- Overall degradation in dry soils: In dry soil samples the amounts of test substance decreased with the study duration by the end of the study to 59.0 % AR (thiazole label) and 44.3 % AR (guanidine label) at 15 days after treatment. There was no significant evolution of 14CO2 and the levels of bound residues (total non extractables) radioactivity reached up to 13.5 % (thiazole label) and 23.0 % (guanidine label) at the end of the study. Several minor degradation products were observed at low level, all less than 5 % of the applied.
- Overall degradation in moist soils: In moist irradiated soil samples the level of test substance decreased with the study duration to 51.6 % AR (thiazole label) and 50.7 % AR (guanidine label) at 15 days after treatment. There was no significant evolution of 14CO2 and the levels of bound residues (total non extractables) radioactivity reached up to 22.5 % (thiazole label) and 24.9 % (guanidine label). Several minor degradation products were observed at low level, all didn’t exceeded 5 % of the applied
- Transformation products in dry soils: In irradiated dry soil samples treated with [guanidine-4-14C] labelled test substance, an guanidine specific metabolite, M5, was detected at levels > 10 % AR. M5 occurred in concentrations up to 13.2 % AR (Extracts 1-3) and 6.3 % AR (Extract 4) at 15 days after treatment. M5 reached maximum mean value of 19.5 % AR in the dry soil conditions at 15 days after treatment. It was confirmed by high resolution LC-MS-MS.
- Transformation products in moist soils: Also in irradiated moist soil samples treated with [guanidine-4-14C] labelled test substance, an guanidine specific metabolite, M5, was detected exceeding 5 % AR (10 and 15 days after treatment). M5 was quantified in concentrations up to 8.4 % AR (Extracts 1-3) and 4.6 % AR (Extract 4) at 15 days after treatment. M5 reached maximum mean value of 13.0 % AR in the moist soil conditions at 15 days after treatment. It was also confirmed by LC-MS-MS.
- Degradation rates: The degradation rate (DegT50) of the parent was determined for both soils and both labels using non-linear regression and a single first order kinetic model (SFO, CAKE, version 1.4). SFO kinetics describes the degradation of the test substance very well with a Chi-square (X2) value better than 10 in all cases

- Indication of test material adsorbing to walls of test apparatus: No

Table: Mass Balance and distribution of radioactivity in irradiated [thiazole-2-14C]-test substance treated [Dry Soil] – individual replicates (values as percentage of the applied radioactivity)

[thiazole-2-14C]-test substance

 

Replicate

Percentage of Applied Radioactivity by Incubation time(days)

0

1

5

7

10

13

15

Extract 1+2

irradiated

A

85.6

76.2

69.0

75.2

61.4

61.0

53.1

B

85.4

79.7

67.6

64.2

62.8

62.8

59.2

Mean

85.5

77.9

68.3

69.7

62.1

61.9

56.2

Extract 3

irradiated

A

10.5

9.7

8.9

8.1

8.3

6.2

5.3

B

9.6

9.8

7.0

8.0

7.6

8.2

4.7

Mean

10.0

9.7

8.0

8.1

8.0

7.2

5.0

Total Extractable

irradiated

Mean

95.5

87.6

76.2

77.8

70.1

69.1

61.2

Non-Extractable

irradiated

A

3.8

7.0

10.9

9.7

11.3

13.4

12.0

B

4.1

7.3

11.5

13.5

11.2

12.4

15.0

Mean

4.0

7.2

11.2

11.6

11.3

12.9

13.5

14CO2

irradiated

A

ND

0.1

2.4

1.0

4.9

1.2

0.1

B

ND

ND

3.0

3.2

1.9

2.8

3.5

Mean

ND

ND

2.7

2.1

3.4

2.0

1.8

Other Volatiles

irradiated

A

ND

0.8

6.0

2.0

6.1

9.2

4.0

B

ND

0.8

8.3

11.3

4.5

10.1

13.0

Mean

ND

0.8

7.1

6.7

5.3

9.6

8.5

Total recovery (%)

irradiated

A

99.9

93.8

97.1

96.0

92.1

90.9

74.5

B

99.1

97.6

97.3

100.1

88.0

96.4

95.5

Mean

99.5

95.7

97.2

98.1

90.1

93.7

85.0

Overall Mean ± SD

94.2 ± 5.1

ND - not detectable; SD - standard deviation

 

Table: Mass Balance and distribution of radioactivity in [thiazole-2-14C]-test substance treated [Dry Soil] dark controls – individual replicates (values as percentage of the applied radioactivity)

[thiazole-2-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)      

0

1

5

7

10

13

15

Extract 1+2

dark

A

NA

84.8

88.2

87.1

82.6

81.1

84.8

B

NA

84.2

86.9

86.1

83.8

84.7

87.2

Mean

NA

84.5

87.5

86.6

83.2

82.9

86.0

Extract 3

dark

A

NA

9.7

9.0

9.5

9.8

11.2

8.4

B

NA

10.7

9.8

9.2

10.0

10.6

9.0

Mean

NA

10.2

9.4

9.3

9.9

10.9

8.7

Total Extractable

dark

Mean

NA

94.7

96.9

95.9

93.1

93.9

94.7

Non-Extractable

dark

A

NA

4.1

3.8

4.5

4.6

5.8

5.0

B

NA

4.8

4.1

5.6

4.2

3.8

4.9

Mean

NA

4.4

4.0

5.1

4.4

4.8

4.9

14CO2

dark

A

NA

ND

0.05

0.02

0.04

0.09

0.06

B

NA

ND

0.05

0.02

0.04

0.09

0.06

Mean

NA

ND

0.05

0.02

0.04

0.09

0.06

Other Volatiles

dark

A

NA

0.05

0.08

0.11

0.00

0.11

0.12

B

NA

0.05

0.08

0.11

0.00

0.11

0.12

Mean

NA

0.05

0.08

0.11

0.00

0.11

0.12

Total recovery (%)

dark

A

NA

98.6

101.1

101.2

97.1

98.4

98.4

B

NA

99.7

100.8

101.1

98.0

99.4

101.2

Mean

NA

99.1

101.0

101.1

97.5

98.9

99.8

Overall Mean ± SD

99.6 ± 1.4

NA - not applicable; ND - not detectable; SD - standard deviation

 

Table: Mass Balance and distribution of radioactivity in irradiated [guanidine-4-14C]-test substance treated [Dry Soil] – individual replicates (values as percentage of the applied radioactivity)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

1

5

7

10

13

15

Extract 1+2

irradiated

A

89.2

81.9

82.9

77.6

83.7

74.8

61.4

B

87.0

79.4

81.9

79.8

83.4

60.6

62.6

Mean

88.1

80.6

82.4

78.7

83.5

67.7

62.0

Extract 3

irradiated

A

11.8

8.8

9.5

8.8

8.8

9.6

8.1

B

11.4

10.7

9.0

8.2

8.7

8.0

8.2

Mean

11.6

9.8

9.2

8.5

8.8

8.8

8.1

Total Extractable

irradiated

Mean

99.7

90.4

91.6

87.2

92.3

76.5

70.1

Non-Extractable

irradiated

A

5.5

11.0

13.1

12.8

12.4

15.2

24.0

B

5.4

10.4

12.8

14.1

13.2

21.9

22.0

Mean

5.4

10.7

13.0

13.4

12.8

18.5

23.0

14CO2

irradiated

A

ND

ND

ND

0.3

0.2

0.1

0.9

B

ND

0.1

ND

0.2

0.0

1.0

0.2

Mean

ND

ND

ND

0.2

0.1

0.5

0.5

Other Volatiles

irradiated

A

ND

0.1

0.2

0.7

0.4

0.3

3.7

B

ND

0.3

0.0

0.5

0.6

2.7

0.7

Mean

ND

0.2

0.1

0.6

0.5

1.5

2.2

Total recovery (%)

irradiated

A

106.4

101.7

105.7

100.2

105.5

100.0

98.0

B

103.7

100.9

103.7

102.7

105.9

94.2

93.7

Mean

105.1

101.3

104.7

101.5

105.7

97.1

95.9

Overall Mean ± SD

 

101.6 ± 3.9

ND - not detectable; SD - standard deviation

 

Table: Mass Balance and distribution of radioactivity in [guanidine-4-14C]-test substance treated [Dry Soil] dark controls – individual replicates (values as percentage of the applied radioactivity)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

1

5

7

10

13

15

Extract 1+2

dark

A

NA

85.1

97.5

81.4

104.0

85.7

87.6

B

NA

83.8

88.3

81.2

90.0

87.0

87.2

Mean

NA

84.4

92.9

81.3

97.0

86.4

87.4

Extract 3

dark

A

NA

9.7

9.2

9.5

9.5

9.8

10.0

B

NA

10.7

10.0

8.7

10.2

9.9

10.1

Mean

NA

10.2

9.6

9.1

9.8

9.8

10.1

Total Extractable

dark

Mean

NA

94.6

102.5

90.4

106.8

96.2

97.5

Non-Extractable

dark

A

NA

4.7

5.6

4.2

4.3

5.2

5.3

B

NA

5.4

4.1

4.3

4.5

5.4

5.6

Mean

NA

5.0

4.8

4.2

4.4

5.3

5.4

14CO2

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

Other Volatiles

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

Total recovery (%)

dark

A

NA

99.4

112.3

95.1

117.9

100.7

102.9

B

NA

99.9

102.4

94.2

104.6

102.3

102.9

Mean

NA

99.7

107.3

94.6

111.3

101.5

102.9

Overall Mean ± SD

102.9 ± 5.8

NA - not applicable; ND - not detectable; SD - standard deviation

 

Table: Mass Balance and distribution of radioactivity in irradiated [thiazole-2-14C]-test substance treated [Moist Soil] – individual replicates (values as percentage of the applied radioactivity)

[thiazole-2-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

1

5

7

10

13

15

Extract 1+2

Irradiated

A

94.8

86.4

77.0

72.4

65.9

61.8

50.5

B

86.7

84.3

77.3

75.0

66.9

67.7

56.3

Mean

90.8

85.3

77.2

73.7

66.4

64.7

53.4

Extract 3

Irradiated

A

7.2

7.6

7.2

7.0

8.7

4.8

4.9

B

8.2

7.6

6.9

6.4

8.9

5.9

5.4

Mean

7.7

7.6

7.0

6.7

8.8

5.4

5.1

Total Extractables

Irradiated

Mean

98.4

93.0

84.2

80.4

75.2

70.1

58.6

Non-Extractables

Irradiated

A

3.2

4.1

6.6

8.5

11.2

15.1

25.1

B

3.5

4.8

6.7

7.5

10.2

12.0

20.0

Mean

3.4

4.4

6.6

8.0

10.7

13.6

22.5

14CO2

Irradiated

A

ND

0.1

0.4

1.0

1.2

0.6

0.9

B

ND

0.2

0.3

0.9

2.1

0.9

0.5

Mean

ND

0.1

0.4

1.0

1.7

0.8

0.7

Other Volatiles

Irradiated

A

ND

0.6

2.5

4.5

6.1

4.8

6.0

B

ND

0.8

2.0

5.0

5.1

3.7

9.2

Mean

ND

0.7

2.2

4.7

5.6

4.3

7.6

Total recovery (%)

Irradiated

A

105.2

98.7

93.6

93.4

93.1

87.1

87.4

B

98.4

97.7

93.2

94.7

93.3

90.2

91.4

Mean

101.8

98.2

93.4

94.0

93.2

88.7

89.4

Overall Mean ± SD

94.1 ± 4.6

ND - not detectable; SD - standard deviation

 

Table: Mass Balance and distribution of radioactivity in [thiazole-2-14C]-test substance treated [Moist Soil] dark controls – individual replicates (values as percentage of the applied radioactivity)

[thiazole-2-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

1

5

7

10

13

15

Extract 1+2

dark

A

NA

89.2

83.7

84.8

75.2

86.5

89.4

B

NA

84.8

84.0

85.9

81.4

84.1

88.7

Mean

NA

87.0

83.9

85.3

78.3

85.3

89.1

Extract 3

dark

A

NA

7.9

7.6

7.6

10.8

6.9

7.3

B

NA

7.7

7.7

7.7

9.8

6.6

7.2

Mean

NA

7.8

7.6

7.6

10.3

6.8

7.3

Total Extractables

dark

Mean

NA

94.8

91.5

93.0

88.6

92.0

96.3

Non-Extractables

dark

A

NA

3.7

3.7

4.3

6.9

5.4

4.3

B

NA

3.7

3.8

4.2

5.9

5.4

4.3

Mean

NA

3.7

3.7

4.2

6.4

5.4

4.3

14CO2

dark

A

NA

ND

ND

0.1

0.1

0.2

0.1

B

NA

ND

ND

0.1

0.1

0.2

0.1

Mean

NA

ND

ND

0.1

0.1

0.2

0.1

Other Volatiles

dark

A

NA

0.1

0.2

0.5

1.0

0.7

0.3

B

NA

0.1

0.2

0.5

1.0

0.7

0.3

Mean

NA

0.1

0.2

0.5

1.0

0.7

0.3

Total recovery (%)

dark

A

NA

100.9

95.2

97.3

94.0

99.8

101.5

B

NA

96.3

95.8

98.3

98.3

97.0

100.5

Mean

NA

98.6

95.5

97.8

96.1

98.4

101.0

Overall Mean ± SD

97.2 ± 2.0

ND - not detectable; SD - standard deviation

 

Table: Mass Balance and distribution of radioactivity in irradiated [guanidine-4-14C]-test substance treated [Moist Soil] – individual replicates (values as % of the applied radioactivity)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

1

5

7

10

13

15

Extract 1+2

Irradiated

A

85.9

82.0

80.4

78.9

68.6

70.9

69.7

B

86.9

82.5

75.7

77.2

67.4

68.8

56.3

Mean

86.4

82.3

78.1

78.0

68.0

69.9

63.0

Extract 3

Irradiated

A

7.8

8.3

7.7

6.9

7.5

7.3

7.0

B

7.8

8.4

8.0

7.9

7.2

6.1

5.3

Mean

7.8

8.3

7.8

7.4

7.4

6.7

6.1

Total Extractables

Irradiated

Mean

94.3

90.6

85.9

85.4

75.4

76.5

69.1

Non-Extractables

Irradiated

A

3.9

5.9

9.3

12.2

18.8

15.9

17.0

B

3.9

5.4

11.7

12.4

18.9

19.3

32.7

Mean

3.9

5.6

10.5

12.3

18.9

17.6

24.9

14CO2

Irradiated

A

ND

ND

0.2

0.2

0.2

0.5

0.1

B

ND

ND

0.1

0.4

0.2

0.6

0.2

Mean

ND

ND

0.2

0.3

0.2

0.6

0.2

Other Volatiles

Irradiated

A

ND

0.1

0.7

0.8

1.5

1.5

1.2

B

ND

0.1

0.7

1.4

1.6

7.3

2.0

Mean

ND

0.1

0.7

1.1

1.5

4.4

1.6

Total recovery (%)

Irradiated

A

97.7

96.3

98.3

99.0

96.7

96.1

95.1

B

98.7

96.4

96.2

99.3

95.4

102.1

96.5

Mean

98.2

96.4

97.3

99.1

96.0

99.1

95.8

Overall Mean ± SD

97.4 ± 1.4

ND - not detectable; SD - standard deviation

 

Table: Mass Balance and distribution of radioactivity in [guanidine-4-14C]-test substance treated [Moist Soil] dark controls – individual replicates (values as % of the applied radioactivity)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

1

5

7

10

13

15

Extract 1+2

dark

A

NA

85.1

82.9

86.4

84.7

83.6

86.3

B

NA

85.0

81.3

85.2

84.6

82.2

85.9

Mean

NA

85.1

82.1

85.8

84.6

82.9

86.1

Extract 3

dark

A

NA

8.5

8.8

7.6

7.9

8.3

7.5

B

NA

8.9

9.0

8.6

8.3

9.2

7.9

Mean

NA

8.7

8.9

8.1

8.1

8.8

7.7

Total Extractables

dark

Mean

NA

93.8

91.0

93.9

92.7

91.7

93.7

Non-Extractables

dark

A

NA

4.3

5.2

4.8

5.1

5.7

5.3

B

NA

4.8

5.9

5.4

5.0

5.8

5.6

Mean

NA

4.6

5.5

5.1

5.1

5.7

5.5

14CO2

dark

A

NA

ND

0.2

0.1

0.1

0.5

0.3

B

NA

ND

0.2

0.1

0.1

0.5

0.3

Mean

NA

ND

0.2

0.1

0.1

0.5

0.3

Other Volatiles

dark

A

NA

0.2

0.4

0.4

0.6

1.5

0.9

B

NA

0.2

0.4

0.4

0.6

1.5

0.9

Mean

NA

0.2

0.4

0.4

0.6

1.5

0.9

Total recovery (%)

dark

A

NA

98.1

97.5

99.4

98.4

99.7

100.3

B

NA

98.9

96.8

99.7

98.6

99.3

100.5

Mean

NA

98.5

97.1

99.5

98.5

99.5

100.4

Overall Mean ± SD

98.9 ± 1.1

ND - not detectable; SD - standard deviation

 

Table: Phototransformationof[thiazole-2-14C]-labelled test substancein Extracts (E1-E3) of [Dry Soil], expressed as percentage of the applied radioactivity (HPLC quantification)

[thiazole-2-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

0

1

5

7

10

13

15

Test substance

irradiated

A

96.0

84.4

76.6

83.1

69.5

64.1

56.2

B

95.0

88.1

72.4

69.1

68.9

70.7

61.7

Mean

95.5

86.2

74.5

76.1

69.2

67.4

59.0

M3

irradiated

A

ND

ND

ND

ND

ND

ND

ND

B

ND

ND

ND

ND

ND

ND

ND

Mean

ND

ND

ND

ND

ND

ND

ND

M2

irradiated

A

ND

ND

ND

ND

ND

0.9

0.2

B

ND

ND

ND

ND

ND

ND

ND

Mean

ND

ND

ND

ND

ND

0.5

0.1

M4

irradiated

A

ND

1.5

1.3

ND

ND

1.9

2.0

B

ND

1.4

1.9

2.0

ND

ND

2.2

Mean

ND

1.4

1.6

1.0

ND

0.9

2.1

M1

irradiated

A

ND

ND

ND

ND

ND

ND

ND

B

ND

ND

ND

ND

ND

ND

ND

Mean

ND

ND

ND

ND

ND

ND

ND

Unknown (Rt 1.95 min)

irradiated

A

ND

ND

ND

0.2

0.3

0.3

ND

B

ND

ND

0.3

1.1

1.5

0.4

ND

Mean

ND

ND

0.1

0.7

0.9

0.3

ND

*Calculated as the addition of data from analysis of E1 and 2 combined and E3

ND - not detectable

Table: Transformation of [thiazole-2-14C]-labelled test substance in Extracts (E1-E3) of [Dry Soil] dark controls, expressed as percentage of the applied radioactivity (HPLC quantification)

[thiazole-2-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

0

1

5

7

10

13

15

Test substance

dark

A

NA

94.5

97.1

96.5

92.4

92.4

93.3

B

NA

94.9

96.6

95.3

93.8

95.4

96.2

Mean

NA

94.7

96.9

95.9

93.1

93.9

94.7

M3

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M2

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M4

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M1

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

Unknown (Rt 1.95 min)

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

*Calculated as the addition of data from analysis of E1 and 2 combined and E3

NA - not applicable; ND - not detectable

 

Table: Phototransformation of [guanidine-4-14C]-labelled test substance in Extracts (E1-E3) of [Dry Soil], expressed as percentage of the applied radioactivity (HPLC quantification)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

0

1

5

7

10

13

15

Test substance

irradiated

A

101.0

75.0

71.2

76.2

72.2

67.2

39.3

B

98.4

78.7

68.8

74.2

73.1

45.8

49.4

Mean

99.7

76.8

70.0

75.2

72.7

56.5

44.3

M3

irradiated

A

ND

1.1

2.9

0.9

3.0

2.0

3.6

B

ND

1.0

1.6

1.2

2.5

2.2

2.0

Mean

ND

1.1

2.2

1.1

2.7

2.1

2.8

M6

irradiated

A

ND

1.3

0.5

0.1

0.1

1.4

1.9

B

ND

0.0

1.8

0.1

0.4

1.6

1.5

Mean

ND

0.6

1.2

0.1

0.2

1.5

1.7

M2

irradiated

A

ND

ND

ND

ND

ND

ND

ND

B

ND

ND

ND

ND

ND

ND

ND

Mean

ND

ND

ND

ND

ND

ND

ND

M4

irradiated

A

ND

1.5

0.9

0.1

0.6

1.3

1.4

B

ND

ND

1.9

ND

ND

1.0

1.0

Mean

ND

0.7

1.4

0.0

0.3

1.1

1.2

M1

irradiated

A

ND

2.0

2.9

ND

1.7

1.8

1.7

B

ND

2.6

ND

1.4

0.2

2.3

1.6

Mean

ND

2.3

1.4

0.7

1.0

2.0

1.7

Unknown** (Rt 1.66 min)

irradiated

A

ND

9.9

14.0

9.1

14.9

10.7

21.5

B

ND

7.8

16.7

11.1

15.9

15.8

15.3

Mean

ND

8.8

15.4

10.1

15.4

13.2

18.4

*Calculated as the addition of data from analysis of E1 and E2 combined and E3.

**Contains M5 (13.3 % AR as determined by TLC), the remaining residue was multicomponent.

NA - not applicable; ND - not detectable

 

Table: Transformationof [guanidine-4-14C]-labelled test substance in Extracts (E1-E3) of [Dry Soil] dark controls, expressed as percentage of the applied radioactivity (HPLC quantification)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

0

1

5

7

10

13

15

Test substance

dark

A

NA

94.8

106.6

86.8

113.3

95.5

97.6

B

NA

94.2

98.3

85.2

100.1

96.9

97.3

Mean

NA

94.5

102.5

86.0

106.7

96.2

97.5

Unknown (Rt 1.66 min)

dark

A

NA

ND

ND

4.1

ND

ND

ND

B

NA

ND

ND

4.6

ND

ND

ND

Mean

NA

ND

ND

4.3

ND

ND

ND

M3

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M6

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M2

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M4

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M1

dark

A

NA

ND

ND

ND

0.3

ND

ND

B

NA

0.3

ND

0.1

0.0

ND

ND

Mean

NA

0.1

ND

0.1

0.1

ND

ND

*Calculated as the addition of data from analysis of E1 and E2 combined and E3

NA - not applicable; ND - not detectable

 

Table:Phototransformation of [guanidine-4-14C]-labelled test substance in Extracts (E1-E3) of [Dry Soil], expressed as percentage of the applied radioactivity (TLC quantification)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

5

10

15

Test substance

Irradiated

A

77.4

76.3

45.5

B

74.6

77.1

51.4

Mean

76.0

76.7

48.4

Origin Rf 0.00

Irradiated

A

0.6

0.3

0.5

B

0.5

0.4

0.4

Mean

0.5

0.3

0.4

M5

Irradiated

A

7.7

9.5

14.8

B

7.2

8.5

11.7

Mean

7.5

9.0

13.2

Unknown Rf 0.42

Irradiated

A

0.4

0.6

0.4

B

0.6

0.5

0.4

Mean

0.5

0.5

0.4

Unknown Rf 0.49

Irradiated

A

0.4

0.3

1.2

B

0.0

0.3

0.5

Mean

0.2

0.3

0.8

Unknown Rf 0.54

Irradiated

A

0.6

0.6

0.0

B

0.9

0.5

1.0

Mean

0.8

0.6

0.5

M2

Irradiated

A

0.4

0.4

0.5

B

0.6

0.4

0.6

Mean

0.5

0.4

0.5

Unknown Rf 0.78

irradiated

A

1.9

1.8

3.1

B

2.9

1.7

2.6

Mean

2.4

1.7

2.9

M1

irradiated

A

3.0

2.7

2.7

B

3.6

2.7

2.3

Mean

3.3

2.7

2.5

* Calculated as the addition of data from analysis of E1 and 2 combined and E3

 

Table: Phototransformation of [thiazole-2-14C]-labelled test substance in Extract4 of [Dry Soil], expressed as percentage of the applied radioactivity (TLC quantification)

[thiazole-2-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

15

Test substance

irradiated

A

0.8

B

0.7

Mean

0.8

Origin Rf 0.00

irradiated

A

0.5

B

0.3

Mean

0.4

Unknown Rf 0.21

irradiated

A

0.4

B

0.3

Mean

0.3

Unknown Rf 0.45

irradiated

A

0.8

B

1.2

Mean

1.0

M2

irradiated

A

0.3

B

0.5

Mean

0.4

M1

irradiated

A

0.1

B

0.3

Mean

0.2

  

Table: Phototransformation of [guanidine-4-14C]-labelled test substance in Extract4 of [Dry Soil], expressed as percentage of the applied radioactivity (TLC quantification) 

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

5

15

 

Test substance

irradiated

A

0.7

0.7

B

ND

1.4

Mean

NA

1.0

Origin Rf 0.00

irradiated

A

0.3

0.8

B

ND

0.4

Mean

NA

0.6

M5

irradiated

A

4.0

6.4

B

ND

6.2

Mean

NA

6.3

Unknown Rf 0.44

irradiated

A

0.7

0.2

B

ND

0.4

Mean

NA

0.3

M2

irradiated

A

0.5

0.1

B

ND

0.3

Mean

NA

0.2

*Calculated as the addition of data from analysis of E1 and E2 combined and E3.

ND - not detectable

  

Table:Phototransformation of[thiazole-2-14C]-labelled test substance in Extracts (E1-E3) of [Moist Soil], expressed as percentage of the applied radioactivity (HPLC quantification)

[thiazole-2-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

0

1

5

7

10

13

15

Test substance

irradiated

A

97.4

87.4

83.1

76.5

71.9

61.7

47.7

B

93.4

85.4

82.3

78.7

71.4

71.6

55.4

Mean

95.4

86.4

82.7

77.6

71.7

66.7

51.6

M3

irradiated

A

ND

ND

ND

ND

0.0

0.5

0.7

B

ND

ND

ND

ND

0.6

0.0

0.7

Mean

ND

ND

ND

ND

0.3

0.3

0.7

M2

irradiated

A

ND

1.6

ND

ND

0.9

ND

0.8

B

ND

1.7

ND

ND

0.0

ND

0.7

Mean

ND

1.6

ND

ND

0.5

ND

0.8

M4

irradiated

A

ND

ND

0.0

1.0

1.1

0.9

1.4

B

ND

ND

0.6

0.7

1.2

0.5

1.2

Mean

ND

ND

0.3

0.8

1.2

0.7

1.3

M1

irradiated

A

4.5

5.0

1.2

2.0

1.6

3.4

4.0

B

1.5

4.9

1.2

1.9

2.6

1.4

3.3

Mean

3.0

4.9

1.2

2.0

2.1

2.4

3.7

Unknown (Rt 1.95 min)

irradiated

A

ND

ND

ND

ND

ND

ND

0.7

B

ND

ND

ND

ND

ND

ND

0.3

Mean

ND

ND

ND

ND

ND

ND

0.5

*Calculated as the addition of data from analysis of E1 and E2 combined and E3.

ND - not detectable

 

Table: Transformation of [thiazole-2-14C]-labelled test substance in Extracts (E1-E3) of [Moist Soil] dark controls, expressed as percentage of the applied radioactivity (HPLC quantification)

[thiazole-2-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

0

1

5

7

10

13

15

Test substance

dark

A

NA

93.4

90.2

88.8

82.0

86.1

92.2

B

NA

89.9

90.1

90.2

88.5

87.9

92.8

Mean

NA

91.6

90.2

89.5

85.3

87.0

92.5

M3

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M2

dark

A

NA

0.3

ND

ND

ND

ND

ND

 

B

NA

0.1

ND

ND

ND

ND

ND

 

Mean

NA

0.2

ND

ND

ND

ND

ND

M4

dark

A

NA

ND

0.1

0.1

1.2

1.4

ND

B

NA

ND

ND

0.9

0.9

ND

ND

Mean

NA

ND

0.0

0.5

1.0

0.7

ND

M5

dark

A

NA

3.5

1.0

3.6

2.8

6.0

4.5

B

NA

2.5

1.6

2.5

1.8

2.8

3.1

Mean

NA

3.0

1.3

3.0

2.3

4.4

3.8

Unknown (Rt 1.95 min)

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

*Calculated as the addition of data from analysis of E1 and E2 combined and E3

NA - not applicable; ND - not detectable

 

Table: Phototransformation of [guanidine-4-14C]-labelled test substance in Extracts (E1-E3) of [Moist Soil], expressed as percentage of the applied radioactivity (HPLC quantification)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

0

1

5

7

10

13

15

Test substance

irradiated

A

93.8

86.0

82.3

76.4

58.1

64.4

63.1

B

94.8

89.5

75.4

76.7

59.3

60.8

38.3

Mean

94.3

87.7

78.8

76.5

58.7

62.6

50.7

M3

irradiated

A

ND

0.1

1.6

0.9

2.1

1.1

1.0

B

ND

ND

2.0

0.5

1.2

ND

2.2

Mean

ND

ND

1.8

0.7

1.7

0.6

1.6

M6

irradiated

A

ND

ND

ND

1.0

1.3

1.1

0.3

B

ND

ND

ND

0.5

0.5

0.9

1.1

Mean

ND

ND

ND

0.8

0.9

1.0

0.7

M2

irradiated

A

ND

ND

ND

ND

ND

ND

0.0

B

ND

ND

ND

ND

ND

ND

2.8

Mean

ND

ND

ND

ND

ND

ND

1.4

M4

irradiated

A

ND

ND

0.1

0.9

0.6

1.1

1.2

B

ND

ND

1.2

1.1

0.9

1.4

1.2

Mean

ND

ND

0.6

1.0

0.8

1.2

1.2

M1

irradiated

A

ND

3.2

1.4

1.5

1.8

2.1

2.2

B

ND

1.4

1.2

2.3

2.0

1.6

4.2

Mean

ND

2.3

1.3

1.9

1.9

1.9

3.2

Unknown** (Rt 1.66 min)

irradiated

A

ND

1.0

2.6

5.0

12.3

8.4

8.9

B

ND

0.0

3.9

4.0

10.8

10.2

11.8

Mean

ND

0.5

3.3

4.5

11.6

9.3

10.4

*Calculated as the addition of data from analysis of E1 and E2 combined and E3

**Contains M5, 8.4 % AR by TLC

NA - not applicable; ND - not detectable

 

Table: Transformation of [guanidine-4-14C]-labelled test substance in Extracts (E1-E3) of [Moist Soil] dark controls, expressed as percentage of the applied radioactivity (HPLC quantification)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

0

1

5

7

10

13

15

Test substance

dark

A

NA

93.7

89.3

93.8

90.2

88.3

90.7

B

NA

93.9

89.3

91.7

90.1

87.1

90.5

Mean

NA

93.8

89.3

92.8

90.2

87.7

90.6

M3

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M6

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M2

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

M4

dark

A

NA

ND

0.9

0.1

0.7

2.3

1.7

B

NA

ND

ND

0.8

1.0

2.6

1.5

Mean

NA

ND

0.4

0.5

0.9

2.5

1.6

M1

dark

A

NA

ND

1.4

0.1

1.6

1.3

1.3

B

NA

ND

1.2

1.3

1.7

1.7

1.7

Mean

NA

ND

1.3

0.7

1.7

1.5

1.5

Unknown (Rt 1.66 min)

dark

A

NA

ND

ND

ND

ND

ND

ND

B

NA

ND

ND

ND

ND

ND

ND

Mean

NA

ND

ND

ND

ND

ND

ND

*Calculated as the addition of data from analysis of E1 and E2 combined and E3

NA - not applicable; ND - not detectable

 

Table: Phototransformation of [guanidine-4-14C]-labelled test substance in Extracts (E1-E3) of [Moist Soil], expressed as percentage of the applied radioactivity (TLC quantification)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity* by Incubation time (days)

5

10

15

Test substance

irradiated

A

84.1

60.5

65.1

B

78.2

60.9

40.3

Mean

81.1

60.7

52.7

Origin Rf 0.00

irradiated

A

0.1

0.5

0.3

B

0.2

0.3

0.3

Mean

0.2

0.4

0.3

M5

irradiated

A

1.9

8.2

6.6

B

3.0

7.5

10.2

Mean

2.4

7.8

8.4

Unknown Rf 0.49

irradiated

A

0.0

1.7

0.5

B

0.0

1.3

0.5

Mean

0.0

1.5

0.5

Unknown Rf 0.54

irradiated

A

0.0

0.4

0.3

B

0.0

0.3

0.6

Mean

0.0

0.3

0.4

M2

irradiated

A

0.1

0.5

0.4

B

0.2

0.4

2.9

Mean

0.2

0.4

1.6

Unknown Rf 0.78

irradiated

A

0.7

2.4

1.6

B

0.9

2.1

2.7

Mean

0.8

2.2

2.2

M1

irradiated

A

1.2

2.0

2.0

B

1.3

1.9

3.9

Mean

1.2

1.9

2.9

*Calculated as the addition of data from analysis of E1 and E2 combined and E3

 

Table: Phototransformation of [thiazole-2-14C]-labelled test substance in Extract 4 of [Moist Soil], expressed as percentage of the applied radioactivity (TLC quantification)

[thiazole-2-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

15

Test substance

irradiated

A

2.0

B

2.4

Mean

2.2

Origin Rf 0.00

irradiated

A

0.9

B

0.9

Mean

0.9

Unknown Rf 0.21

irradiated

A

0.0

B

0.7

Mean

0.4

Unknown Rf 0.44

irradiated

A

0.5

B

0.6

Mean

0.6

M2

irradiated

A

0.1

B

0.5

Mean

0.3

M1

irradiated

A

0.6

B

1.3

Mean

1.0

 

Table: Phototransformation of [guanidine-4-14C]-labelled test substance in Extract 4of [Moist Soil], expressed as percentage of the applied radioactivity (TLC quantification)

[guanidine-4-14C]-test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

15

Test substance

irradiated

A

0.4

B

0.5

Mean

0.5

Origin Rf 0.00

irradiated

A

0.1

B

0.1

Mean

0.1

M5

irradiated

A

2.8

B

6.4

Mean

4.6

Unknown Rf 0.44

irradiated

A

0.1

B

0.2

Mean

0.1

Unknown Rf 0.76

irradiated

A

0.2

B

0.4

Mean

0.3

M1

irradiated

A

0.0

B

0.2

Mean

0.1

 

Table: DegT50 and DegT90 values for [thiazole-2-14C]-test substance under irradiated conditions

Soil Gartenacker

[thiazole-2-14C] label

SFO Experimental Days

DegT50 (days)

DegT90 (days)

K

χ2

R2

Prob > t

Irradiated Dry Soil

25.27

83.93

0.02743

3.220

0.8550

1.254E-06

Irradiated Moist Soil

22.22

73.82

0.03119

4.167

0.8778

5.675E-07

Corrected DT50to equivalent Summer Sunlight days 30-50ºN (OECD)

Dry Soil

51.15

Moist soil

45.05

 

Table: DegT50 and DegT90 values for [guanidine-4-14C]-test substance under irradiated conditions

Soil Gartenacker

[guanidine-4-14C]-label

SFO Experimental Days

DegT50 (days)

DegT90 (days)

K

χ2

R2

Prob > t

Irradiated Dry Soil

18.53

61.55

0.03741

3.220

0.8550

1.254E-06

Irradiated Moist Soil

18.65

61.94

0.03718

4.167

0.8778

5.675E-07

Corrected DT50to equivalent Summer Sunlight days 30-50ºN (OECD)

Dry Soil

37.55

Moist soil

37.79

 

Validity criteria fulfilled:
not specified
Conclusions:
Photo-degradation of test substance was relatively fast with a half-life (DegT50) of 51.15 and 45.05 days under summer sunlight (UK/US) for the dry and wet soil layers, respectively, of the [thiazole-2-14C] labelled test item and 37.55 and 37.79 days under summer sunlight (UK/US) for the dry and wet soil layers of the [guanidine-4-14C] labelled test item.
Executive summary:

The photolysis of [thiazole-2-14C] and [guanidine-4-14C] labelled test substance was investigated on dry and moist soil surfaces in a study according to OPPTS 835.2410 and in compliace with GLP criteria. In this study, thiazole-2-14C and guanidine-4-14C labelled test substance were applied separately, at an application rate equivalent to 80 g a.s./ha, to thin layers ( 2 mm) of Gartenacker soil (Silt Loam) in individual photolysis vessels. The treated soils were continuously irradiated using light from a xenon arc lamp. The emitted light was filtered to give a spectral distribution close to that of natural sunlight at a mean light intensity of 50 W/m2 in the wavelength range of 300 - 400 nm. The samples were maintained at 20 ± 2 °C and were irradiated for periods up to the equivalent of 30 days summer sunlight at latitudes 30 - 50°N. In each test, duplicate samples were taken for analysis at up to 7 intervals during irradiation. ‘Dark control’ samples were also prepared and maintained at 20 ± 2°

C. Dark control samples were taken for analysis at the same intervals as the irradiation test. The mean mass balance for the irradiated samples (dry soil, both labels) was 97.9 % AR (range 85.0 to 105.7 % AR) and for the dark controls 101.3 % AR (range 94.6 to 111.3 % AR). The mean mass balance for the irradiated samples (moist soil, both labels) was 95.8 % AR (range 88.7 to 101.8 % AR) and for the dark controls 98.1 % AR (range 96.1 to 101.0 % AR). The test substance degraded relatively rapidly in the irradiated samples. For the dry soil condition, the mean level of test substance remaining after 15 days of irradiation was 59.0 % AR and 44.3 % AR in the [thiazole-2-14C] and [guanidine-4-14C] treatments respectively. For the moist soil condition, the mean level of test substance remaining after the same period of irradiation was 51.5 % AR and 50.7 % AR. No significant degradation was apparent in any of the ‘dark controls’ indicating that the degradation observed in the irradiated samples was due to photodegradation only. The DegT50 and DegT90 values were calculated using non-linear regression and first-order kinetics (SFO) and corrected to equivalent Summer Sunlight days 30-50ºN (OECD). The DegT50 values for the dry soils were determined to be 51.15 and 37.55 days for the [thiazole-2-C14]- and [guanidine-4-C14]-labelled test substance, respectively. DegT50 values for the moist soils were determined to be 45.05 and 37.79 days for the [thiazole-2-C14]- and [guanidine-4-C14]-labelled test substance, respectively. In this study, the major soil metabolite of the test substance was found to be M5 (specific to the guanidine label), which reached maximum mean values of 19.5 % and 13.0 % of applied radioactivity (AR) in the dry and moist soil conditions at the end of the study, respectively. These values were derived from the analysis of extracts performed at room temperature (Extracts 1-4). In addition, known metabolites M3, M2, M4, M1 and M6 were found in amounts < 5 % AR, in both the dry and the moist soil experiments. Carbon dioxide was a minor product of photolysis and only reached a maximum value of 1.8 %AR (guanidine label, moist soil) by the end of the irradiation period. Other volatile(s) were trapped in a cyclohexylamine containing trap. These reached values of 8.5 % (thiazole label, dry soil), 2.2 % (guanidine label, dry soil), 7.6 % (thiazole label, moist soil) and 1.6 % AR (guanidine label, moist soil) by the end of the irradiation period. The identity of these residues was not investigated but in former photolysis studies with test substance these residues were identified to be carbonyl sulphide and isocyanic acid. The bound residues [total non extractables including extract 4 (E4), extract 5 (E5), total OMF (total organic matter fraction] and combustion] increased during the incubation, reaching values of 13.5 % and 22.5 % AR in the thiazole irradiated (dry and moist soil) treatment by the end of the study. The corresponding levels for the guanidine irradiated condition (dry and moist soil) were 23.0 % and 24.9 % AR. The non-extractable residues (NER) in the final samples (15 days irradiation), were further characterised following an additional extraction at room temperature using 30 mL ammonium/acetate (Extract 4) followed by reflux (Extract 5) using 25 mL acetonitrile/water adjusted to pH 3. Extract 4 is therefore not considered as a true bound residue fraction. Test substance was found only at levels of 0.8 % AR and 2.2 % AR for the thiazole label (dry and moist soil) and 1.0 % AR and 0.5 % AR for guanidine (dry and moist soil). The level of M5 present in Extract 4 was 6.3 % AR and 4.6 % AR in the dry and moist soil conditions, respectively. Given the low levels of test substance present in Extract 4, subsequent kinetic calculations were done based on the analyses of Extracts 1-3.

Description of key information

DegT50 = of 51.15 and 37.55 days, dry soil layers for the [thiazole-2-14C] labelled and the [guanidine-4-14C] labelled test item, respectively, OPPTS 835.2410, Hüben, 2015

Key value for chemical safety assessment

Half-life in soil:
51.15 d

Additional information

Table: Overview of available data for the test item on phototransformation in soil

Method

Guideline / GLP

Endpoint

Value (days)

Comment

Reference

Radiolabel

Soil type

Duration

[thiazole-2-14C]-labelled

Dry soil

15 d

OPPTS 835.2410 / GLP

DegT50

 

51.15

DT50 values are corrected for Summer Sunlight days at 30-50ºN (OECD)

Hüben, 2015

[thiazole-2-14C]-labelled

Moist soil

15 d

DegT50

45.05

[guanidine-4-14C]-labelled

Dry soil

15 d

DegT50

37.55

[guanidine-4-14C]-labelled

Moist soil

15 d

DegT50

37.79