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Biodegradation in soil

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Endpoint:
biodegradation in soil: simulation testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
05 Apr 1995 to 09 Aug 1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: US EPA Pesticide Assessment Guidelines, Subdivision N, Chemistry, Environmental Fate, Series 164-1
Deviations:
no
Qualifier:
according to
Guideline:
other: BBA Guidelines "Richtlinien fiir die Priifung von Pflanzenschutzmitteln im Zulassungsverfahren" Teil IV 4-1
Version / remarks:
December 1986
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test type:
field trial
Radiolabelling:
yes
Remarks:
14C-labelled at position 2 of thiazole ring
Oxygen conditions:
aerobic
Soil classification:
not specified
Year:
1995
Soil type:
other: not reported
% Clay:
21
% Silt:
31.6
% Sand:
47.4
% Org. C:
3.1
pH:
7.2
CEC:
17.1 meq/100 g soil d.w.
Details on soil characteristics:
SOIL COLLECTION AND STORAGE
- Geographic location: The plot was located at in Switzerland.
- Pesticide use history at the collection site: In the year 1993 the original soil was removed and replaced by fresh, untreated soil. Until preparation of the plot prior to application, grass was grown (no pesticide treatments).
- Plot preparation prior to application: Three soil cores (depth 30 cm, diameter of 5cm) were taken before application, analyzed according to standard procedures and compared with background samples. No radioactivity beyond background level was found. The plot was leveled and hand-weeded before application.

PROPERTIES OF THE SOILS
- Water capacity: 49% (0.05 bar)
Duration:
492 d
Initial conc.:
207 g/ha d.w.
Based on:
test mat.
Remarks:
See 'Details on experimental conditions'.
Parameter followed for biodegradation estimation:
CO2 evolution
radiochem. meas.
Details on experimental conditions:
PESTICIDE APPLICATION
- On April 5, 1995, plot 1.2aN (6 m2) was treated with 300 ml of spraying suspension using a small plot sprayer KFA1 with 4 TeeJet nozzles (even flat spray tip #8001E) with a flow of ca 0.39 I/min each at ca 3 bar overpressure. In order to ensure that the total amount of radioactivity was applied onto the plot, the vessel was washed with 300 ml of water sprayed and the washing was sprayed onto the plot. A total amount of 124 mg [thiazol-2-14C] test substance (124 MBq) were applied, corresponding to a rate of 20.7 mg a.i./m2 or 207 g a.i. / ha.
- Post treatment crop maintenance: The field was surrounded with a fence and marked with appropriate labels. The bareground plot was divided into six sections in which the rotational crops were subsequently planted and harvested according to the schedule given in. From October 25, 1995 until December 11, 1995, i.e. part time of the growing period of spring wheat_2, the plot was covered with a plastic roof equipped with a heating to prevent the plant culture from freeze.

SAMPLING
- Samplng intervals: Soil samples were taken 1 hour, 29, 63, 89, 119, 180, 362, and 492 days after treatment.
- Sampling method for soil samples: Soil samples (diameter of 5cm) were taken at various intervals (systematically in the spraying direction at the position of the nozzles) throughout the area of the plot using a Humax2
electrical sample collector. Five soil cores 00 - 30 cm were taken at interval 1 to 6. Five cores 00 - 60 cm were taken at the last two intervals.
- Sample handling: The soil cores were divided into three to six 10 cm layers, 00-10 cm, 10-20 cm, 20-30 cm, 30 - 40 cm, 40 - 50 cm, 50 - 60 cm and. At interval 1 and 2 the top soil layers (00-10 cm) were extracted after sampling without drying. The total residues in these soil layers were determined by the sum of extractable and non-extractable radioactivity. All other soil samples were air dried and homogenized in a disk mill before analysis.
- Sample retention: The soil samples are kept at location for one year after the testing period.
- Storage stability: To evaluate the stability of the test substance and its metabolites during air drying (RT) and storage (-20°C), soil fortifications were prepared using fresh untreated soil from the control plot and soil extract of interval 4.
Key result
DT50:
51 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: field study; no standard temperature
Transformation products:
yes
Details on transformation products:
Results on the radioactivity of the transformation prodcuts thoughout the study are tabulated in 'Any other information on materials and methods incl. tables'

CHARACTERISATION IN RADIOACTIVITY IN SOIL
- 0 - 10 cm soil layer: Analysis of the extracts by 2-dim TLC (ss 160 / ss 79) revealed apart unchanged test substance at least 6 different metabolite fractions. The parent content in the 0 - 10 cm soil layer declined from 0.186 ppm just after treatment to 0.002 ppm at interval 8, i.e 492 days later. A DT50 of 51 days and a DT 90 of 170 days were determined assuming first order kinetics. M4 was found to be the major metabolite throughout the study. Its amount in percent of recovered radioactivity continuously increased and reached 36% after 492 days. M4 reached its maximum concentration (16.2 ppb or 8.7% of total residues at day 0) at Day 180 and thereafter declined to 10.3 ppb after 492 days after application. M1 accounted for 4.1 % of total radioactivity (5.9 ppb or 3.2% of total residues at day 0) at interval 2, i.e. 29 days after treatment and thereafter continuously declined to 0.2 ppb after 492 days. In addition minor amounts of M8 were detected. Its maximum concentration was found between Day 180 and Day 492, accounting for 1.1 - 1.4 ppb. Non-extractable residues in the 0 - 10 cm soil layer expressed in percent of recovered radioactivity continuously increased to 49% at the end of the experimental period. Maximum concentration of non-extractable residues (21.5 ppb) was found after 119 days and declined to 13.9 ppb at the end of the study.
- 10 - 20 cm soil layer: The metabolite pattern in the 10 - 20 cm soil layer, analyzed 492 days after treatment, was similar to the pattern of the top layer. M2 was found as major metabolite, accounting for 62% of total radioactivity or 4.5 ppb. No thiazol specific metabolite fractions were detected so far in relevant amounts, whereas one oxadiazin specific metabolite was found in minor amounts.
Evaporation of parent compound:
no
Volatile metabolites:
not specified
Residues:
yes
Remarks:
See 'Details on results'
Details on results:
Results on dissipation and storage stability are tabulated in 'Any other information on results incl. tables'.

TOTAL RESIDUE LEVELS IN THE FIELD SOIL
- 0 - 10 cm soil layer: The total residue level in the 0 - 10 cm layer decreased from 0.186 ppm after application to 0.072 ppm 89 days later. After that time the decrease proceeded slower and finally reached 0.029 ppm 492 days after application. Curve fitting was achieved using a two compartment model, assuming slow and fast first order reactions contributing to the dissipation of radioactivity. On the basis of this model an overall DT so for the dissipation of total radioactivity in the 0 - 10 cm soil layer of about 92 days was calculated.
- 10 - 20 and 20 - 30 cm soil layers: Some downward movement of radioactivity with time was observed. Radioactivity in the 10 - 20 cm and 20 - 30 cm soil layers was below 0.001 ppm until interval 4, i.e. 89 days after treatment. Total radioactivity in the 10 - 20 cm layer increased to 0.003 ppm at interval 5, i.e. 119 days after treatment, reached 0.007 ppm at Day 362 and remained at 0.007 ppm until the end of the experimental period (492 days after treatment). The amount of radioactivity found in the 10 - 20 cm at 362 days and 492 days after application corresponded to about 4.5% of the radioactivity found in the 0 - 10 cm layer just after treatment. Total radioactivity in the 20 - 30 cm soil layer never exceeded 0.002 ppm and was found to be 0.001 ppm after 492 days.
- 30 - 40 cm, 40 - 50 cm and 50 - 60 cm soil layers: At the end of the experimental period the radioactivity in the 30 - 40 cm, 40 - 50 cm and 50 - 60 cm soil layers was below 0.001 ppm.

STORAGE STABILITY
To evaluate the stability of the test substance and its metabolites during air drying (room temperature) and storage (-20°C), soil fortifications were prepared using fresh untreated soil from the control plot. Fresh soil aliquots were treated with a concentrate of soil extract of interval 4. Two samples were extracted just after fortification and analyzed by 1-dim TLC. Stability of parent and its metabolites during air drying was evaluated after drying period of 7 and 14 days at room temperature. Freezer storage stability was demonstrated after a storage period of one, 6 and 12 months, respectively. No significant changes in the TLC pattern were observed during air drying or freezer storage.

Table: Dissipation of Radioactivity and Residual Test Substance in Soil after Bareground Application 

Days after Treatment

Soil Layers

Total Residues

Parent [ppm](1)

Extr. Radioactivity [%](3)

NE Rad. [%](3)

Total [%](3)

[ppm](1)

sd[%]

[%](2)

0

SOIL

 

 

 

 

 

 

 

00-10 cm

0.186

20.6

100

n.a.

87.6

12.4

100

29

SOIL

 

 

 

 

 

 

 

00-10cm

0.143

47.7

98.7

0.107

87.7

12.3

100

10-20cm

<0.001

56.1

0.7

n.a.

n.a.

n.a.

 

20-30 cm

<0.001

31.2

0.6

n.a.

n.a.

n.a.

 

SOIL TOTAL

 

 

100

 

 

 

 

63

SOIL

 

 

 

 

 

 

 

00-10 cm

0.134

30.5

99.2

0.101

90.4

12.8

103.2

10-20 cm

<0.001

43

0.4

n.a.

n.a.

n.a.

 

20-30 cm

<0.001

70.7

0.4

n.a.

n.a.

n.a.

 

SOIL TOTAL

 

 

100

 

 

 

 

89

SOIL

 

 

 

 

 

 

 

00-10 cm

0.072

25.9

98.7

0.045

83.9

20

103.9

10-20 cm

<0.001

43

0.9

n.a.

n.a.

n.a.

 

20-30 cm

<0.001

39.1

0.4

n.a.

n.a.

n.a.

 

SOIL TOTAL

 

 

100

 

 

 

 

119

SOIL

 

 

 

 

 

 

 

00-10cm

0.086

35.8

96.2

0.042

78.9

24.9

103.8

10-20 cm

0.003

181.1

3.7

n.a.

n.a.

n.a.

 

20-30 cm

<0.001

136.9

0.1

n.a.

n.a.

n.a.

 

SOIL TOTAL

 

 

100

 

 

 

 

180

SOIL

 

 

 

 

 

 

 

00-10 cm

0.055

26.1

86.6

0.012

63.8

39.1

102.9

10-20 cm

0.006

35.8

9.6

n.a.

n.a.

n.a.

 

20-30 cm

0.002

27.9

3.8

n.a.

n.a.

n.a.

 

SOIL TOTAL

 

 

100

 

 

 

 

362

SOIL

 

 

 

 

 

 

 

00-10 cm

0.041

37.7

76.3

0.006

56

43.2

99.1

10-20cm

0.007

94.3

13.5

n.a.

n.a.

n.a.

 

20 30cm

0.002

35.1

3.9

n.a.

n.a.

n.a.

 

30-40cm

0.001

26.7

3

n.a.

n.a.

n.a.

 

40-50cm

0.001

47.5

2

n.a.

n.a.

n.a.

 

50-60cm

<0.001

41.6

1.3

n.a.

n.a.

n.a.

 

SOIL TOTAL

 

 

100

 

 

 

 

492

SOIL

 

 

 

 

 

 

 

00-10 cm

0.029

28.2

71.8

0.002

54.6

48.5

103.1

10-20 cm

0.007

33

20.7

0.0001

79.3

26.3

105.6

20-30 cm

0.001

14.6

3.2

n.a.

n.a.

n.a.

 

30-40cm

<0.001

20.4

1.7

n.a.

n.a.

n.a.

 

40-50cm

<0.001

21.1

1.7

n.a.

n.a.

n.a.

 

1) In equivalents of test substance combustion

2) In % of the total radioactivity found in the sub-balanced soil layer, determined by combustion

3) In % of the total radioactivity found in the soil layer, determined by combustion

Limit of quantification for combustion: 0.001 ppm

Table: Quantitation of metabolites as a function of time (expressed in % of the radioactivity totally found in the soil layers)

Interval /Soil layer (Days after Treatment)

Metabolite Fractions(%)

 

NE

(%)

Total

(%)

Unidentified compound 1

M8

M4

Unidentified compound 2

Test substance

Unidentified compound 3

M1

unres.

subtot.

29 d: 0 - 10 cm

n.d.

n.d.

3.4

n.d.

74.6

1.9

4.1

3.7

87.7

12.3

100.0

63 d: 0 - 10 cm

n.d.

n.d.

6.0

n.d.

75.4

1.2

2.8

5.0

90.4

12.8

103.2

89 d: 0 - 10 cm

1.2

0.6

11.7

0.8

62.9

1.5

3.0

2.2

83.9

20.0

103.9

119 d: 0 -10 cm

3.0

1.0

17.0

1.8

49.3

1.1

2.2

3.4

78.8

24.9

103.7

180 d: 0 - 10 cm

1.6

2.5

29.7

1.2

22.6

1.6

1.0

3.6

63.8

39.1

102.9

362 d: 0 - 10 cm

0.5

2.7

32.0

0.8

14.6

2.0

0.8

2.7

56.1

43.2

99.3

492 d: 0 - 10 cm

n.d.

4.4

35.8

0.5

8.4

1.5

0.6

3.4

54.6

48.5

103.1

492 d: 10 - 20 cm

n.d.

9.9

62.3

n.d.

1.8

0.5

n.d.

4.8

79.3

26.3

105.6

 

Table: Storage Stability

Initial pattern in spiked soil(1) [%](2)

Pattern after air drying [%](2)

Pattern after freezer storage [%](2)

Fractions/Time

0 Days

7 Days

14 days

1 Month

6 Months

12 Months

1 = start

3.9

2.9

2.9

3.8

4.1

3.6

2

0.9

0.7

1.0

0.9

0.8

0.9

3

3.1

3.1

3.3

3.1

3.1

2.8

4

13.4

13.0

14.0

13.0

13.1

12.8

5 = test substance

71.1

74.9

73.1

73.7

73.4

70.0

6

1.4

1.0

1.2

1.0

1.4

2.0

7

4.9

4.2

4.5

4.2

3.7

5.2

8

1.2

0.2

0.2

0.3

0.4

3.0

1) The soil was extracted just after spiking

2) Given in % of extracted

Conclusions:
The total residue level in the 0 - 10 cm soil layer decreased from 0.186 ppm (immediately after application) to 0.029 ppm within 492 days. The DT50 and DT90 values for the test substance in the 0 - 10 cm layer were 51 days and 170 days, respectively.
Executive summary:

The degradation of the test substance in soil was investigated in a field study according to US EPA 164-1 and BBA part IV, 4-1 and in compliance with GLP criteria. The dissipation of the parent compound in soil (47.4% sand, 31.6% silt, 21.0% clay) under field conditions was determined along with the rate of formation and dissipation of major metabolites and the downward movement of parent as a function of time. Therefore, a bareground spray application of formulated [Thiazol-2-14C]-radiolabelled test substance at a rate of 207 g a.i. / ha was performed on a plot which was conjointly used to grow the rotational crops. The soil was subject to realistic environmental conditions with a pH of 7.2, an organic carbon content of 3.1%, a CEC potential of 17.1 meq/100g soil and a water capacity of 49%. Soil samples were taken 1 hour, 29, 63, 89, 119, 180, 362, and 492 days after treatment. Five soil cores at 00 - 30 cm were taken at interval 1 to 6. Five cores at 00 - 60 cm were taken at the last two intervals. Samples were extracted and radioactivity of the combusted samples or in extracts and silica gel removed from TLC was measured by liquid scintillation counting. Total radioactivity in soil samples, as well as non-extractable radioactivity was determined by combustion with subsequent liquid scintillation counting of the evolved carbon dioxide.

The total residue level in the 0 - 10 cm soil layer decreased from 0.186 ppm (immediately after application) to 0.029 ppm within 492 days. The DT50 and DT90 values for the test substance in the 0 - 10 cm layer were 51 days and 170 days, respectively. Some downward movement of radioactivity with time was observed. Total radioactivity in the 10 - 20 cm layer increased to 0.003 ppm at Day 119 and reached 0.007 ppm at Day 362 and remained at 0.007 ppm until the end of the experimental period (492 days after treatment). Total radioactivity in the 20 - 30 cm soil layer never exceeded 0.002 ppm and was found to be 0.001 ppm after 492 days. At the end of the experimental period the radioactivity in the 30 - 40 cm, 40 - 50 cm and 50 - 60 cm soil layers was below 0.001 ppm. M4 and M1 were found as major metabolites. The concentration of M1 amounted to 5.9 ppb at interval 2, i.e. 29 days after treatment and thereafter continuously declined to 0.2 ppb after 492 days. Maximum concentration of M4 (16.2 ppb) was found after 180 days and declined to 10.3 ppb after 492 days. Non-extractable residues in the 0 - 10 cm soil layer expressed in percent of recovered radioactivity continuously increased to 49% at the end of the experimental period. Maximum concentration of non-extractable residues (21.5 ppb) was found after 119 days and declined to 13.9 ppb at the end of the study.

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
Qualifier:
according to
Guideline:
other: Richtlinie für die amtliche Prüfung von Pflanzenschutzmitteln, Teil IV, 4-1: “Verbleib von Pflanzenschutzmitteln im Boden: Abbau, Umwandlung und Metabolismus.” Biologische Bundesanstalt für Land und Forstwirtschaft, Bundesrepublik Deutschland
Version / remarks:
December 1986
Deviations:
no
GLP compliance:
yes
Test type:
laboratory
Radiolabelling:
yes
Remarks:
14C-labelled at position 2 of thiazole ring
Oxygen conditions:
aerobic
Soil classification:
USDA (US Department of Agriculture)
Year:
1995
Soil no.:
#1
Soil type:
loamy sand
% Clay:
6.2
% Silt:
15.2
% Sand:
78.6
% Org. C:
1.7
pH:
7.4
CEC:
14.3 meq/100 g soil d.w.
Soil no.:
#2
Soil type:
sand
% Clay:
4.1
% Silt:
7.6
% Sand:
88.3
% Org. C:
0.6
pH:
8.2
CEC:
6 meq/100 g soil d.w.
Soil no.:
#3
Soil type:
sandy loam
% Clay:
6.2
% Silt:
31.5
% Sand:
62.3
% Org. C:
1.3
pH:
7.55
CEC:
14.5 meq/100 g soil d.w.
Soil no.:
#4
Soil type:
sandy loam
% Clay:
4.4
% Silt:
31.8
% Sand:
63.8
% Org. C:
1.3
pH:
7.5
CEC:
8.2 meq/100 g soil d.w.
Soil no.:
#5
Soil type:
loamy sand
% Clay:
2.9
% Silt:
22.7
% Sand:
74.4
% Org. C:
1.1
pH:
7.6
CEC:
6.5 meq/100 g soil d.w.
Details on soil characteristics:
Five soils were used for the study. The study was performed with three soils stored in a greenhouse under field conditions (soils #1-#3) and two soils taken directly from the field (soils #4 and #5). For a full listing of test soil specifics, see the data table at 'Any other information on materials and methods'.
Soil No.:
#1
Duration:
181 d
Soil No.:
#2
Duration:
181 d
Soil No.:
#3
Duration:
181 d
Soil No.:
#4
Duration:
121 d
Soil No.:
#5
Duration:
121 d
Soil No.:
#1
Initial conc.:
0.496 mg/kg soil d.w.
Based on:
test mat.
Remarks:
corresponding to 0.322 kg a.s./ha / Dose concentration based on 5 cm soil depth incorporation, average soil bulk density of 1.3 g/mL
Soil No.:
#2
Initial conc.:
0.496 mg/kg soil d.w.
Based on:
test mat.
Remarks:
corresponding to 0.322 kg a.s./ha / Dose concentration based on 5 cm soil depth incorporation, average soil bulk density of 1.3 g/mL
Soil No.:
#3
Initial conc.:
0.496 mg/kg soil d.w.
Based on:
test mat.
Remarks:
corresponding to 0.322 kg a.s./ha / Dose concentration based on 5 cm soil depth incorporation, average soil bulk density of 1.3 g/mL
Soil No.:
#4
Initial conc.:
0.492 mg/kg soil d.w.
Based on:
test mat.
Remarks:
corresponding to 0.320 kg a.s./ha / Dose concentration based on 5 cm soil depth incorporation, average soil bulk density of 1.3 g/mL
Soil No.:
#5
Initial conc.:
0.492 mg/kg soil d.w.
Based on:
test mat.
Remarks:
corresponding to 0.320 kg a.s./ha / Dose concentration based on 5 cm soil depth incorporation, average soil bulk density of 1.3 g/mL
Parameter followed for biodegradation estimation:
CO2 evolution
radiochem. meas.
Soil No.:
#1
Temp.:
20 ± 2°C
Humidity:
The soil moisture was 40 % of the maximum water holding capacity, corresponding to 18.7 g water per 100 g dry soil
Microbial biomass:
Not reported
Soil No.:
#2
Temp.:
20 ± 2°C
Humidity:
The soil moisture was 40 % of the maximum water holding capacity, corresponding to 9.4 g water per 100 g dry soil
Microbial biomass:
Not reported
Soil No.:
#3
Temp.:
20 ± 2°C
Humidity:
The soil moisture was 40 % of the maximum water holding capacity, corresponding to 18.9 g water per 100 g dry soil
Microbial biomass:
Not reported
Soil No.:
#4
Temp.:
20 ± 2°C
Humidity:
The soil moisture was 40 % of the maximum water holding capacity, corresponding to 18.9 g water per 100 g dry soil
Microbial biomass:
Not reported
Soil No.:
#5
Temp.:
20 ± 2 °C
Humidity:
The soil moisture was 40 % of the maximum water holding capacity, corresponding to 15.8 g water per 100 g dry soil
Microbial biomass:
Not reported
Details on experimental conditions:
EXPERIMENTAL DESIGN
- Duration between collection and dosing: Depending on soil between 0 days and 80 months before use in the study. See 'Any other information on materials and methods incl. tables'.
- Storage conditions: The greenhouse soils were stored under natural conditions in a greenhouse until use. The field soils were collected freshly from the field.
- Sieving mesh size: 2 mm
- Soil incubation sample weight (g, dry weight equivalent): 75 g (100 g for microbial biomass samples)
- Test apparatus: 150 mL crystallisation dishes (incubated in a common chamber), moist air flow through system at 60 to 100 mL/min.
- Traps for organic volatiles and CO2: Ethylene glycol trap (for organic volatiles) followed by 0.1N H2SO4 (for volatile bases) and two flasks with 2N NaOH traps (for carbon dioxide).
- Frequency of trap collection/replenishment: Adsorption solutions were collected after 1 and 3 days, then in intervals of about 1 week during the first month, thereafter in about 2 week intervals.
- Moisture maintenance/frequency and sample handling: Chambers were continuously ventilated with moistened air. No soil moisture maintenance procedures were reported
- Control (untreated) samples handling: Received only equivalent volume of co-solvent; for microbial biomass.
- Sterile Samples: Not required
- Bulk density: Average soil bulk density of 1.3 g/mL, no soil-specific data.

TEST MATERIAL APPLICATION
- Dosing solution concentration: Greenhouse: 39.23 mg/L; Field: 38.63 mg/L
- Test solution: Greenhouse: 960 µL of application solution (water with 3.7 % residual acetonitrile) corresponding to 37.19 µg of test substance; Field: 970 µL of application solution (water with 3.9 % residual acetonitrile) corresponding to 36.9 µg of test substance.
- Application method: the test substance was uniformly applied with a 1000 µL Hamilton-syringe.
- Percentage of co-solvent per sample (mL/g X 100 %): Not reported (but <0.1 % based on above dilutions)

CALCULATIONS
The DT50 and DT90 values were calculated by one and two compartment single first order (SFO) models. In general the two compartment models fit the degradation plots more accurately than the one compartment models, with the exception of Weide soil where the one compartment models produce a better fit.
Soil No.:
#1
% Recovery:
98.7
St. dev.:
1.88
Remarks on result:
other:
Remarks:
Sum of activity in soil extracts and that trapped in adsorption vessels
Soil No.:
#2
% Recovery:
100
St. dev.:
1.85
Remarks on result:
other: Recovery reported as 100.72%
Remarks:
Sum of activity in soil extracts and that trapped in adsorption vessels
Soil No.:
#3
% Recovery:
98.97
St. dev.:
2.11
Remarks on result:
other:
Remarks:
Sum of activity in soil extracts and that trapped in adsorption vessels
Soil No.:
#4
% Recovery:
95.65
St. dev.:
4.13
Remarks on result:
other:
Remarks:
Sum of activity in soil extracts and that trapped in adsorption vessels
Soil No.:
#5
% Recovery:
96.24
St. dev.:
2.59
Remarks on result:
other:
Remarks:
Sum of activity in soil extracts and that trapped in adsorption vessels
Soil No.:
#1
% Degr.:
46.3
Parameter:
radiochem. meas.
Remarks:
dissapearance of parent compound at day 181
Sampling time:
181 d
Soil No.:
#2
% Degr.:
38.9
Parameter:
radiochem. meas.
Remarks:
disappearance of parent compound at day 181
Sampling time:
181 d
Soil No.:
#3
% Degr.:
53
Parameter:
radiochem. meas.
Remarks:
disappearance of parent compound at day 181
Sampling time:
181 d
Soil No.:
#4
% Degr.:
63.71
Parameter:
radiochem. meas.
Remarks:
disappearance of parent compound at day 120
Sampling time:
120 d
Soil No.:
#5
% Degr.:
45.35
Parameter:
radiochem. meas.
Remarks:
disappearance of parent compound at day 121
Sampling time:
121 d
Soil No.:
#1
DT50:
184 d
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Remarks on result:
other: two compartment model
Soil No.:
#2
DT50:
272 d
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Remarks on result:
other: two compartment model
Soil No.:
#3
DT50:
143 d
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Remarks on result:
other: one compartment model
Soil No.:
#4
DT50:
164 d
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Remarks on result:
other: two compartment model
Soil No.:
#5
DT50:
80 d
Type:
(pseudo-)first order (= half-life)
Temp.:
20 °C
Remarks on result:
other: one compartment model
Transformation products:
yes
No.:
#1
No.:
#2
No.:
#3
No.:
#4
Details on transformation products:
- Formation and decline of each transformation product during test: The main metabolite was M4 as was determined by co-chromatography with reference substances and confirmed by mass spectrometry. It was formed in all soils studied approximately 3 days after application of the test substance and the amounts increased until the end of the study (greenhouse soils, average of duplicates: 12.91 % in soil #1, 4.62 % in soil #2 and 15.1 % in soil #3; field soils: 12.92 % in soil #4 and 18.92 % in soil #5). An additional metabolite that could be identified by co-chromatography was M1. It was built in all soils except in the sandy standard soil in amounts ≤ 2.35 % of the applied dose. In the greenhouse soils, M1 was formed only after 153 days of incubation. Additionally up to five unknown metabolites (depending on soil type) were found in low amounts (≤ 5.90 % of the dose applied). Another prominent metabolite was 14CO2 amounting to 13.49 %, 12.11 % and 21.09 % for the green- house soils #1, #2 and #3, respectively, and to 12.10 % and 14.24 % in the field soils #4 and #5 (121 days of incubation compared to 181 days for greenhouse soils).
Evaporation of parent compound:
no
Volatile metabolites:
no
Remarks:
Non-CO2 volatiles were not detected
Residues:
yes
Remarks:
bound residues represented 7.6-16.6% of added radioactivity
Details on results:
MASS BALANCE
- Total radioactivity: Sum of activity in soil extracts and that trapped as in adsorption vessels
- Mean Recovery at 0 DAT: Range 97.93 to 102.3 % of the applied radioactivity (AR)

EXTRACTABLE RESIDUES
- Total extractable residues at 0 days after treatment: #1: Mean 99.0 % AR; #2: Mean 101.2 % AR; #3: Mean 97.8 % AR; #4: Mean 97.8 % AR; #5: Mean 98.6 % AR
- Total extractable residues at end of study: #1: Mean 72.8 % AR; #2: Mean 71.1 % AR; #3: Mean 69.4 % AR; #4: Mean 62.84 % AR; #5: Mean 71.13 % AR

BOUND RESIDUES
- Bound residues were measured at the beginning and end of the study
- Bound residues at 0 days after treatment: #1: Mean 2.2 % AR; #2: Mean 1.1 % AR; #3: Mean 2.5 % AR; #4: Mean 0.1 % AR #5: Mean 0.1 % AR.
- Bound residues at end of study: #1: Mean 10.2 % AR; #2: Mean 16.6 % AR; #3: Mean 12.5 % AR; #4: Mean 9.6 % AR; #5: Mean 7.6 % AR

VOLATILISATION
Radioactivity in the form of evolved 14CO2 was found throughout the study. No other volatiles were found
- 14CO2 evolved at the end of the study: #1: Mean 13.5 % AR; #2: Mean 12.1 % AR; #3: Mean 21.1 % AR; #4: Mean 14.24 % AR; #5: Mean 12.10 % AR

Table: Mass balance and distribution of radioactivity in extracts of soil #1 – individual replicates (values as percentage of the applied radioactivity)

Radiolabelled test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

59

90

120

153

181

Extraction at room temperature

A

102.15

96.42

94.65

92.28

90.98

91.22

87.04

83.44

79.53

75.35

70.31

69.20

B

95.85

97.94

96.58

93.50

91.02

90.51

87.15

85.56

78.83

76.80

72.48

67.12

Mean

99.0

97.2

95.6

92.9

91.0

90.9

87.1

84.5

79.2

76.1

71.4

68.2

Soxhlet extraction

A

n.d.

2.63

2.82

3.31

3.44

3.17

4.42

4.75

4.26

4.83

5.42

5.59

B

n.d.

2.70

2.98

3.64

3.17

3.53

4.27

4.68

4.49

5.08

5.23

5.54

Mean

n.d.

2.7

2.9

3.5

3.3

3.4

4.3

4.7

4.4

5.0

5.3

5.6

Bound residue

A

2.16

0.57

1.23

1.62

2.23

2.31

2.99

4.45

6.02

7.25

8.12

10.56

B

2.26

0.53

1.14

1.54

2.39

2.31

2.96

4.36

5.67

6.75

7.94

9.82

Mean

2.2

0.6

1.2

1.6

2.3

2.3

3.0

4.4

5.8

7.0

8.0

10.2

Volatiles

A

n.d.

0.30

0.70

1.41

1.71

2.28

3.91

5.16

7.73

9.50

11.72

13.49

B

n.d.

0.30

0.70

1.41

1.71

2.28

3.91

5.16

7.73

9.50

11.72

13.49

Mean

n.d.

0.3

0.7

1.4

1.7

2.3

3.9

5.2

7.7

9.5

11.7

13.5

Total recovery (%)(1)

A

104.31

99.92

99.40

98.62

98.36

98.98

98.36

97.80

97.54

96.93

95.57

98.84

B

98.11

101.47

101.40

100.09

98.29

98.63

98.29

99.76

96.72

98.13

97.37

95.97

Mean

101.2

100.7

100.4

99.4

98.3

98.8

98.3

98.8

97.1

97.5

96.5

97.4

Overall Mean ± RSD

98.70 ± 1.88

1) Total recovery was calculated by summing up amounts in extracts, Soxhlet extract, non-extractable and adsorption traps. Mean total recovery is the mean of total recovery of replicate A and B.

n.d. - not determined RSD - relative standard deviation

Table: Mass balance and distribution of radioactivity in extracts of soil #2 – individual replicates (values as percentage of the applied radioactivity)

Radiolabelled test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

59

90

120

153

181

Extraction at room temperature

A

100.93

99.05

97.48

88.62

90.10

87.61

84.11

80.18

76.42

70.79

69.64

64.58

B

101.44

93.64

95.48

89.51

90.50

86.83

83.99

77.52

76.16

73.38

68.45

62.83

Mean

101.2

96.3

96.5

89.1

90.3

87.2

84.1

78.9

76.3

72.1

69.0

63.7

Soxhlet extraction

A

n.d.

n.d.

2.47

4.30

3.87

5.00

6.45

6.32

5.61

8.63

7.21

7.38

B

n.d.

n.d.

2.80

3.93

5.01

5.90

7.55

6.01

5.52

8.38

6.61

7.47

Mean

n.d.

n.d.

2.6

4.1

4.4

5.5

7.0

6.2

5.6

8.5

6.9

7.4

Bound residue

A

1.15

3.58

2.94

3.98

4.68

5.26

5.75

9.39

11.85

11.93

15.81

17.13

B

1.04

3.76

2.91

4.34

5.09

5.08

5.93

8.52

11.36

11.77

12.47

15.97

Mean

1.1

3.7

2.9

4.2

4.9

5.2

5.8

9.0

11.6

11.9

14.1

16.6

Volatiles

A

n.d.

0.41

0.79

1.31

1.94

2.55

3.93

5.00

7.11

8.95

10.81

12.11

B

n.d.

0.41

0.79

1.31

1.94

2.55

3.93

5.00

7.11

8.95

10.81

12.11

Mean

n.d.

0.4

0.8

1.3

1.9

2.6

3.9

5.0

7.1

9.0

10.8

12.1

Total recovery (%)(1)

A

102.08

103.04

103.68

98.21

100.59

100.42

100.24

100.89

100.99

100.30

103.47

101.20

B

102.48

97.81

101.98

99.09

102.54

100.36

101.40

97.05

100.15

102.48

98.34

98.38

Mean

102.3

100.4

102.8

98.7

101.6

100.4

100.8

99.0

100.6

101.4

100.9

99.8

Overall Mean ± RSD

100.72 ± 1.85

1) Total recovery was calculated by summing up amounts in extracts, Soxhlet extract, non-extractable and adsorption traps. Mean total recovery is the mean of total recovery of replicate A and B.

n.d. - not determined; RSD - relative standard deviation

 

Table: Mass balance and distribution of radioactivity in extracts of soil #3 – individual replicates (values as percentage of the applied radioactivity)

Radiolabelled test substance

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

59

90

120

153

181

Extraction at room temperature

A

98.30

96.84

94.96

91.05

89.94

85.39

84.49

78.10

71.81

67.92

64.94

66.14

B

97.37

92.87

96.03

89.60

90.05

87.00

83.43

81.18

73.12

69.75

62.13

61.40

Mean

97.8

94.9

95.5

90.3

90.0

86.2

84.0

79.6

72.5

68.8

63.5

63.8

Soxhlet extraction

A

n.d.

2.63

3.26

3.96

3.54

4.38

5.21

5.00

5.46

5.66

5.65

5.74

B

n.d.

2.56

3.34

4.24

3.31

4.11

5.01

5.45

5.15

6.42

5.58

5.43

Mean

n.d.

2.6

3.3

4.1

3.4

4.2

5.1

5.2

5.3

6.0

5.6

5.6

Bound residue

A

2.52

0.64

1.30

1.79

2.94

2.99

3.84

5.80

7.19

8.60

10.09

12.22

B

2.57

0.67

1.33

1.89

2.84

3.08

4.01

5.92

7.84

8.98

9.93

12.70

Mean

2.5

0.7

1.3

1.8

2.9

3.0

3.9

5.9

7.5

8.8

10.0

12.5

Volatiles

A

n.d.

0.45

0.58

1.68

2.76

3.15

5.82

7.89

12.00

15.31

18.60

21.09

B

n.d.

0.45

0.58

1.68

2.76

3.15

5.82

7.89

12.00

15.31

18.60

21.09

Mean

n.d.

0.5

0.6

1.7

2.8

3.2

5.8

7.9

12.0

15.3

18.6

21.1

Total recovery (%)(1)

A

100.82

100.56

100.10

98.48

99.18

95.91

99.36

96.79

96.46

97.49

99.28

105.19

B

99.94

96.55

101.28

97.41

98.96

97.34

98.27

100.44

98.11

100.46

96.24

100.62

Mean

100.4

98.6

100.7

97.9

99.1

96.6

98.8

98.6

97.3

99.0

97.8

102.9

Overall Mean ± RSD

98.97 ± 2.11

1) Total recovery was calculated by summing up amounts in extracts, Soxhlet extract, non-extractable and adsorption traps. Mean total recovery is the mean of total recovery of replicate A and B.

n.d. – not determined; RSD - relative standard deviation

  

Table: Mass balance and distribution of radioactivity in extracts of soil #4 – individual replicates (values as percentage of the applied radioactivity)

Radiolabelled test substance

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

62

90

121

Extraction at room temperature

95.53

95.29

91.66

88.62

89.39

81.95

79.12

73.27

64.81

56.89

Soxhlet extraction

2.30

3.25

3.64

4.11

3.52

4.49

4.75

3.36

4.86

5.95

Bound residue

0.10

0.74

1.16

1.86

2.51

3.71

4.89

6.31

8.49

9.56

Volatiles

n.d

0.62

1.35

2.83

4.37

5.23

8.00

10.45

13.31

14.24

Total recovery (%)(1)

97.93

99.90

97.81

97.42

99.79

95.38

96.76

93.39

91.47

86.64

Overall Mean ± RSD

95.65 ± 4.13

1 Total recovery was calculated by summing up amounts in extracts, Soxhlet extract, non-extractable and adsorption traps.

n.d. - not determined; RSD - relative standard deviation

  

Table: Mass balance and distribution of radioactivity in extracts of soil #5 – individual replicates (values as percentage of the applied radioactivity)

Radiolabelled test substance

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

62

90

121

Extraction at room temperature

96.62

96.17

90.34

87.82

89.16

81.67

79.57

77.87

69.29

63.29

Soxhlet extraction

1.99

2.90

4.06

4.29

3.55

6.04

5.48

3.76

6.73

7.84

Bound residue

0.13

0.78

1.24

1.63

2.36

3.89

4.07

5.13

7.67

7.61

Volatiles

n.d.

0.37

0.99

2.19

3.36

4.41

6.59

8.57

10.87

12.10

Total recovery (%)(1)

98.74

100.22

96.63

95.93

98.43

96.01

95.71

95.33

94.56

90.84

Overall Mean ± RSD

96.24 ± 2.59

1) Total recovery was calculated by summing up amounts in extracts, Soxhlet extract, non-extractable and adsorption traps.

n.d. - not determined; RSD - relative standard deviation

 

Table: Summary of product distribution in extracts of soil #1 (values as percentage of the applied radioactivity)

14C-Residues

Soil: Collembey Radiolabel:

[thiazole-2-14C]

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

59

90

120

153

181

Test substance

A

102.15

96.30

95.75

88.97

87.82

87.48

79.46

76.26

67.50

62.15

61.56

55.65

B

95.85

99.14

97.04

92.62

88.38

85.57

79.01

78.11

67.41

61.15

54.26

51.80

Mean

99.0

97.7

96.4

90.8

88.1

86.5

79.2

77.2

67.5

61.9

54.8

53.7

M4

A

<LD

1.46

1.72

1.14

4.55

4.16

7.49

8.66

11.62

11.94

14.56

12.59

B

<LD

0.85

1.92

1.03

4.48

4.73

8.20

7.64

11.01

12.77

14.12

13.22

Mean

<LD

1.2

1.8

1.1

4.5

4.4

7.8

8.2

11.3

12.4

14.3

12.9

M1

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.96

1.58

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

1.62

0.83

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

1.3

1.2

Unidentified metabolite 1

A

<LD

1.29

<LD

5.47

0.87

0.77

1.74

1.23

0.95

3.02

2.51

1.81

B

<LD

0.66

0.61

3.48

0.70

1.88

1.56

1.24

1.02

1.75

2.80

2.87

Mean

<LD

1.0

0.3

4.5

0.8

1.3

1.7

1.2

1.0

2.4

2.7

2.3

Unidentified metabolite 2

A

<LD

<LD

<LD

<LD

1.19

2.00

2.77

2.03

3.70

1.95

1.97

1.84

B

<LD

<LD

<LD

<LD

0.60

1.84

2.64

2.52

3.05

4.09

2.01

0.98

Mean

<LD

<LD

<LD

<LD

0.9

1.9

2.7

2.3

3.4

3.0

2.0

1.4

Unidentified metabolite 3

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

1.11

0.73

0.74

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.70

0.83

1.04

0.85

0.98

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.4

0.4

1.1

0.8

0.9

Unidentified metabolite 4

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.76

<LD

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.93

0.90

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.8

0.5

Unidentified metabolite 5

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.58

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.68

<LD

1.08

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.3

<LD

0.8

Total extractables

A

102.15

99.05

97.47

95.58

94.43

94.41

91.46

88.18

83.77

80.17

75.75

74.79

B

95.85

100.65

99.57

97.13

94.16

94.02

91.41

90.21

83.32

81.89

77.70

72.66

Mean

99.0

99.9

98.5

96.4

94.3

94.2

91.4

89.2

83.5

81.0

76.7

73.7

<LD = below limit of detection

 

Table: Summary of product distribution in extracts of soil #2 (values as percentage of the applied radioactivity)

14C-Residues

Soil: Speyer 2.1

Radiolabel:

[thiazole-2-14C]

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

59

90

120

153

181

Test substance

A

100.93

98.34

97.55

85.68

88.84

88.19

81.67

79.03

73.54

67.69

67.06

61.92

B

101.43

92.10

95.89

88.44

89.23

87.33

85.56

76.76

73.73

73.64

66.05

60.28

Mean

101.2

95.2

96.7

87.1

89.0

87.8

83.6

77.9

73.6

70.7

66.6

61.1

M4

A

<LD

<LD

0.51

3.12

1.22

1.51

2.57

2.30

3.00

3.90

4.19

4.73

B

<LD

0.65

0.75

3.34

1.51

1.92

2.10

2.66

3.08

3.94

4.17

4.51

Mean

<LD

0.3

0.6

3.2

1.4

1.7

2.3

2.5

3.0

3.9

4.2

4.6

M1

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Unidentified metabolite 1

A

<LD

0.70

1.87

4.11

3.32

2.21

5.40

3.84

4.26

5.90

3.54

3.59

B

<LD

0.90

1.62

1.65

4.18

2.74

2.41

2.76

3.20

3.40

2.80

3.82

Mean

<LD

0.8

1.7

2.9

3.8

2.5

3.9

3.3

3.73

4.7

3.2

3.7

Unidentified metabolite 2

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Unidentified metabolite 3

A

<LD

<LD

<LD

<LD

0.58

0.68

0.92

1.33

1.22

1.94

2.06

1.71

B

<LD

<LD

<LD

<LD

0.57

0.73

1.45

1.35

1.65

0.77

2.04

1.70

Mean

<LD

<LD

<LD

<LD

0.6

0.7

1.2

1.3

1.4

1.4

2.1

1.7

Unidentified metabolite 4

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Unidentified metabolite 5

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Total extractables

A

100.93

99.04

99.93

92.91

93.96

92.59

90.56

86.50

82.02

79.43

76.85

71.95

B

101.43

93.65

98.26

93.43

95.49

92.72

91.52

83.53

81.66

81.75

75.06

70.31

Mean

101.2

96.3

99.1

93.2

94.7

92.7

91.0

85.0

81.8

80.6

76.0

71.1

<LD = below limit of detection

 

Table: Summary of product distribution in extracts of soil #3 (values as percentage of the applied radioactivity)

14C-Residues

Soil: Weide

Radiolabel:

[thiazole-2-14C]

Replicate

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

59

90

120

153

181

Test substance

A

98.30

98.02

96.47

88.64

87.07

81.54

78.54

69.85

58.69

55.27

47.97

51.39

B

96.86

93.66

97.80

87.28

86.74

83.14

76.32

72.61

60.01

56.40

47.01

42.66

Mean

97.6

95.8

97.1

88.0

86.9

82.3

77.4

71.2

59.4

55.8

47.5

47.0

M4

A

0.00

0.86

0.76

2.80

4.15

5.75

6.91

8.96

12.34

12.03

15.78

14.76

B

0.51

1.77

1.57

3.59

4.28

4.65

7.42

9.35

12.29

14.05

13.44

15.37

Mean

0.3

1.3

1.2

3.2

4.2

5.2

7.2

9.2

12.3

13.0

14.6

15.1

M1

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.81

1.33

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.87

1.00

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.8

1.2

Unidentified metabolite 1

A

<LD

0.59

1.00

3.58

1.13

1.37

1.31

0.82

2.05

3.41

2.21

0.87

B

<LD

<LD

<LD

1.99

1.61

1.45

2.15

0.76

3.26

1.35

2.64

3.18

Mean

<LD

0.3

0.5

2.8

1.4

1.4

1.7

0.8

2.7

2.4

2.4

2.0

Unidentified metabolite 2

A

<LD

<LD

<LD

<LD

1.13

1.11

1.95

2.46

3.17

1.15

1.52

1.79

B

<LD

<LD

<LD

0.99

0.73

1.11

1.56

2.39

1.33

2.30

1.43

1.41

Mean

<LD

<LD

<LD

0.5

0.9

1.1

1.8

2.4

2.3

1.7

1.5

1.6

Unidentified metabolite 3

A

<LD

<LD

<LD

<LD

<LD

<LD

0.99

1.01

1.01

0.85

1.17

0.94

B

<LD

<LD

<LD

<LD

<LD

0.77

0.97

1.52

1.36

1.04

1.19

1.21

Mean

<LD

<LD

<LD

<LD

<LD

0.4

1.0

1.3

1.2

0.95

1.2

1.1

Unidentified metabolite 4

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

1.13

0.81

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

1.13

1.07

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

1.1

0.9

Unidentified metabolite 5

A

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

0.88

<LD

<LD

B

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

1.02

<LD

0.92

Mean

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

1.0

<LD

0.5

Total extractables

A

98.30

99.47

98.23

95.02

93.48

89.77

89.70

83.10

77.26

73.59

70.59

71.89

B

97.37

95.43

99.37

93.85

93.36

91.12

88.42

86.63

78.25

76.16

67.71

66.82

Mean

97.8

97.5

98.8

94.4

93.4

90.4

89.1

84.9

77.8

74.9

69.2

69.4

<LD = below limit of detection

Table: Summary of product distribution in extracts of soil #4 (values as percentage of the applied radioactivity)

14C-Residues

Soil: Weide

Radiolabel: [thiazole-2-14C]

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

59

90

120

Test substance

96.98

96.33

91.40

86.38

80.64

72.80

66.20

55.08

44.58

36.29

M4

<LD

1.57

2.60

4.82

7.97

9.48

12.83

14.15

16.79

18.92

M1

0.85

0.63

0.64

0.76

0.99

0.75

<LD

1.20

0.78

<LD

Unidentified metabolite 1

<LD

<LD

0.67

<LD

2.35

2.79

3.46

3.83

5.38

5.51

Unidentified metabolite 2

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Unidentified metabolite 3

<LD

<LD

<LD

0.76

0.99

0.64

0.72

0.84

<LD

<LD

Unidentified metabolite 4

<LD

<LD

<LD

<LD

<LD

<LD

0.66

1.55

2.14

2.13

Unidentified metabolite 5

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Total extractables

97.83

98.53

95.31

92.72

92.94

86.46

83.87

76.65

69.67

62.85

<LD = below limit of detection

Table: Summary of product distribution in extracts of soil #5 (values as percentage of the applied radioactivity)

14C-Residues

Soil: Pappelacker

Radiolabel:[thiazole-2-14C]

Percentage of Applied Radioactivity by Incubation time (days)

0

3

7

14

21

28

45

62

90

121

Test

substance

97.25

96.82

91.52

87.53

86.62

78.73

73.35

67.99

60.82

54.65

M4

<LD

1.02

1.57

2.95

5.07

5.79

8.25

10.06

11.80

12.92

M1

1.35

1.22

1.32

1.64

<LD

2.35

1.01

1.30

0.97

<LD

Unidentified metabolite 1

<LD

<LD

<LD

<LD

<LD

<LD

1.45

1.40

1.75

2.59

Unidentified metabolite 2

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Unidentified metabolite 3

<LD

<LD

<LD

<LD

1.03

0.84

1.01

0.90

0.69

0.98

Unidentified metabolite 4

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Unidentified metabolite 5

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

<LD

Total extractables

98.60

99.06

94.41

92.12

92.72

87.71

85.07

81.65

76.03

71.14

<LD = below limit of detection

Table: DegT50 and DegT90 values for the test substance in soils

Soil

Single First Order Kinetics

DegT50 [days]

DegT90 [days]

Compartment model

#1

184

694

Two compartment model

#2

272

1013

Two compartment model

#3

143

475

One compartment model

#4

164

911

Two compartment model

#5

80

266

One compartment model

Conclusions:
The key findings after application of [thiazole-2-14C]-test substance at a dose rate of 0.496 mg/kg (greenhouse soil) and 0.492 mg/kg (field soil) to the test soil and subsequent aerobic incubation (20°C, dark and 40% maximum water holding capacity) for up to 181 days are summarised as follows: the mass balance from all individual soil samples ranged from range 86.64 to 105.19%. The main extractable metabolite observed was M4 in all soils. It reached maximum amounts corresponding to between 4.6% of applied radioactivity in the soil #2 after 181 days and 18.9% in the soil #4 after 121 days. An additional metabolite identified was the hydrolysis product M1, which was observed in all soils except soil #2 in amounts ≤2.4% of the applied dose. Unidentified chromatographic fractions consisted of up to 5 individual compounds reaching in sum 6.5% of the applied dose as a maximum.
Bound residues reached a maximum concentration between 10.2% and 16.6% after 181 days in the greenhouse soils and of 7.6% and 9.6% after 121 days in the field soils. Volatile radioactivity was identified as carbon dioxide. It reached between 12.1% and 21.1% after 181 days in the greenhouse soils and between 12.1% and 14.2% after 121 days in the field soils. The single first order (SFO) half-lives (DT50) ranged from 80 to 272 days.
Executive summary:

The biodegradation of the substance in soil was investigated in a study according to BBA part IV, 4-1 and in compliance with GLP criteria. The rate and route of degradation of [thiazole-2-14C]-test substance was investigated in five different soils. The study was performed with three soils stored in a greenhouse under field conditions (referred to as greenhouse soils) and with two soils directly taken from the field (referred to as field soils). The following soils were used: greenhouse soils - a loamy sand (Collombey, #1), a sandy German Standard Soil (Speyer 2.1, #2) and a sandy loam (Weide, #3); field soils - a sandy loam (Weide, #4) and a second loamy sand (Pappelacker, #5). The test substance was applied to the greenhouse soils at a concentration of 0.496 mg a.i./kg (dry weight soil) and to the field soils at a concentration of 0.492 mg a.i./kg (dry weight soil), equivalent to a single field application rate of 0.322 and 0.320 kg a.i./ha, respectively (assuming an average bulk density of the soil of 1.3 g/mL and a distribution of the test substance in the top 5 cm layer of the soil). The soils were incubated under aerobic conditions in the laboratory at 20 ± 2°C and a moisture content of 40 % maximum water holding capacity for up to 181 or 121 days for the greenhouse or field soils, respectively. For greenhouse soils duplicate samples were taken for analysis immediately after application (0 days), and at 3, 7, 14, 21, 28, 45, 59, 90, 120, 153 and 181 days after treatment. For field soils, the sampling times were the same, but the experiment was stopped after 121 days and was done without duplicates. All samples were subjected to exhaustive extraction with acetone, the extracts were concentrated and analysed by HPLC and the results verified by TLC. The recoveries of applied radioactivity (AR) were 98.70 ± 1.88 % for #1, 100.72 ± 1.85 % for #2, 98.97 ± 2.11 % for #3, 95.65 ± 4.13 % for #4 and 96.24 ± 2.59 % for #5. The DegT50 and DegT90 values were calculated using one and two compartment first-order kinetics (SFO) models.

The main extractable metabolite observed was M4 in all soils. It reached maximum amounts corresponding to between 4.6 % of applied radioactivity in the greenhouse soil #2 after 181 days and 18.9% in the field soil #4 after 121 days. An additional metabolite identified was the hydrolysis product M1. It was observed in all soils except in the Speyer 2.1 soil, in amounts 2.4 % of the applied dose. Unknown chromatographic fractions consisted of up to 5 individual compounds reaching in sum 6.5 % of the applied dose as a maximum. Bound residues reached a maximum concentration between 10.2 % and 16.6 % after 181 days in the greenhouse soils and of 7.6 % and 9.6 % after 121 days in the field soils. Volatile radioactivity was identified as carbon dioxide. It reached between 12.1 % and 21.1 % after 181 days in the greenhouse soils and between 12.1 % and 14.2 % after 121 days in the field soils.

Description of key information

DT50 = 51 days, in field soil under realistic environmental conditions, US EPA 164-1 and BBA IV, 4-1, Sandmeier 1997. The study by Sandmeier is considered representative of the soil degradation properties of the test substance.

Key value for chemical safety assessment

Half-life in soil:
51 d
at the temperature of:
20 °C

Additional information

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

Method

Guideline / GLP

Endpoint

Value (days)

Comment

Reference

Test medium

pH

CEC (meq/100g soil dw)

%OC

Crop field soil

7.2

17.1

3.1

US EPA 164-1 and BBA IV, 4-1 / GLP

DT50

51 d

Field study, realistic environmental conditions, reliable

Sandmeier, 1997

Soil dissipation

A large number of soil dissipation studies were conducted with the test material. As information on soil dissipation is outside the scope of REACH, the studies are not summarized as individual endpoint study entries, but briefly discussed here: The test material was tested for different application types in different crops and bare grounds with an application rate ranging from 26.3 to 336 g ai/ha for broadcast application and 70 to 200 g ai/ha for seed treatment. The DT50 values reported in the original reports as calculated with first order kinetic modelling were between 5.9 - 72 days for broadcast application and 5 - 31 days for seed treatment. The DT50 values as recalculated with first order kinetic modeling were between 7.15 - 109 days for broadcast application and 11.5 - 54.5 days for seed treatment. (Hayes, 2015a,b,c; Ford, 2015; Mair, 1996; Hardy, 2015; Pointurier, 1997a,b,c,d,e,f; Smith, 1998a,b; Mair, 1998a,b; Balluff, 2003; Sandmeier, 1997; Finger, 2015a,b,c,d; Gezahegne and Ahrens, 2015; Tribolet, 2001; Purdy, 2004; Speth, 1999a,b; Wiepke, 1999a,b; Wiepke, 1998; Stolze, 2001a,b,c; Nagra, 2004a,b; Nagra, 2007 and Gezahegne and Arhens, 2015).