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Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
05 Aug 1999 - 17 Aug 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Version / remarks:
1981
Qualifier:
according to guideline
Guideline:
other: EPA Pesticide Assessment Guidelines, Subdivision N, Section 163-1
Version / remarks:
1982
Qualifier:
according to guideline
Guideline:
other: EC Directive 95/36/EC, Active Substances, Section 7.1.2
Version / remarks:
1995
Qualifier:
according to guideline
Guideline:
other: Environmental Chemistry and Fate Guidelines for Registration of Pesticides in Canada, Section B
Version / remarks:
1987
GLP compliance:
yes (incl. QA statement)
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
yes
Test temperature:
20 ± 1 °C
Analytical monitoring:
yes
Details on sampling:
- Concentrations:
Adsorption: Portions (5 mL and 1 mL) of the 5.0 µg/mL solution were diluted with 0.01 M calcium chloride solution (120 mL and 124 mL) to produce 0.2 µg/mL and 0.04 µg/mL solutions respectively. The initial concentrations of all solutions were verified by taking triplicate weighed aliquots for LSC.
Eight samples (10 g dry weight equivalent) of each soil were dispensed and preconditioned. Portions of each dosing solution (10 mL) were added to each soil in duplicate to achieve a soil to aqueous phase ratio of 1:1 w/v. The samples were mixed for ca 49 h then centrifuged.
Radioactivity in the supernatants was determined by taking duplicate weighed aliquots (100 µL or 200 µL) for LSC. The pH of each supernatant was then measured, supernatants were decanted, and their weights were determined. The conductivity of each supernatant was measured.
Desorption: The calcium chloride solution decanted at the end of the adsorption study was replaced with fresh 0.01 M calcium chloride solution (10 mL) and each unit was shaken vigorously to break up the soil packed at the bottom of the vessel. The exact weight of calcium chloride solution added was determined. After mechanical shaking for 24 h, samples were centrifuged and supernatant radioactivity, pH and conductivity were recorded as described for the adsorption phase.
The soils treated at the 5.0 µg/mL level were re-equilibrated with fresh 0.01 M calcium chloride solution (10 mL) for a further 24 h. Supernatants and soil were separated by centrifugation and supernatant radioactivity was determined as described above.
A third re-equilibration with fresh calcium chloride solution was performed. Methods used were as described for the second re-equilibration.
- Sampling interval: In the prestudy the times used for the equilibrium time determination were 2, 4, 8, 24, 49 and 72 h after commencement of mixing.

Matrix no.:
#1
Matrix type:
loamy sand
% Clay:
4
% Silt:
20
% Sand:
76
% Org. carbon:
0.4
pH:
8.4
CEC:
3 meq/100 g soil d.w.
Bulk density (g/cm³):
1.32
Matrix no.:
#2
Matrix type:
sandy loam
% Clay:
16
% Silt:
25
% Sand:
59
% Org. carbon:
1.2
pH:
7.6
CEC:
12.7 meq/100 g soil d.w.
Bulk density (g/cm³):
1.08
Matrix no.:
#3
Matrix type:
clay loam
% Clay:
30
% Silt:
43
% Sand:
27
% Org. carbon:
1.2
pH:
6.6
CEC:
6.8 meq/100 g soil d.w.
Bulk density (g/cm³):
0.99
Matrix no.:
#4
Matrix type:
sandy loam
% Clay:
14
% Silt:
16
% Sand:
70
% Org. carbon:
2.1
pH:
6.8
CEC:
7.4 meq/100 g soil d.w.
Bulk density (g/cm³):
1.03
Matrix no.:
#5
Matrix type:
sand
% Clay:
4
% Silt:
3
% Sand:
93
% Org. carbon:
0.5
pH:
4.1
CEC:
7.4 meq/100 g soil d.w.
Bulk density (g/cm³):
1.03
Details on matrix:
COLLECTION AND STORAGE
- Geographic location: The Quincy (#1), Elder (#2) and Crosby (#3) soils were collected from a 0 to 6 inches horizon of untreated areas associated with Terrestrial Field Dissipation Studies for TI-435. The Crosby soil was also used in the Aerobic Soil Metabolism Study. The soils Laacherhof (#4) and BBA 2.1 (#5) were collected in Germany from the 0 to 20 cm horizon.
- Storage conditions: After receipt the soils were air dried, thoroughly mixed, 2 mm sieved and stored in the dark in an incubator routinely maintained at 4 ± 2°C in loosely tied plastic bags.
- Soil preparation (e.g.: 2 mm sieved; air dried etc.): Prior to dispensing, the moisture contents of the stored soils were determined by drying a portion at ca 105°C. This allowed the dry weight equivalent of the dispensed soil to be calculated from the wet weight. All calculations were based upon soil dry weight.

PROPERTIES
- Soil texture: All data on the properties of each soil are provided in table “Matrix properties”.
Details on test conditions:
TEST SYSTEM
- Type, size and further details on reaction vessel: Unless otherwise stated, soils were dispensed into pre-weighed plastic centrifuge tubes (50 mL, Nalgene polypropylene co-polymer) and were re-equilibrated by tumbling with approximately twice their weight of water for a minimum of 24 hours. The soils were then centrifuged (5000 g, 15 min) and the excess water was decanted to waste. The vessels were re-weighed to determine the weight of the wet soil prior to test article application.
- Method of preparation of test solution: The acetonitrile solvent was removed from a portion (450 µL) of a stock [14C]-labelled test substance solution (1.34 mg/mL) and the [14C]-labelled test substance was dissolved in a 0.01 M calcium chloride solution (120.6 mL) to produce a 5.0 µg/mL solution. A 1.0 µg/mL solution was similarly prepared from 92 µL of the stock solution. Portions (5 mL and 1 mL) of the 5.0 µg/mL solution were diluted with 0.01 M calcium chloride solution (120 mL and 124 mL) to produce 0.2 µg/mL and 0.04 µg/mL solutions respectively.
- Other: All studies were performed in a temperature controlled room (20 ± 1 °C) in the dark. Soils and solutions were mixed mechanically using a Stuart Scientific Rotator Drive STR4 set at speed 3. This speed ensured efficient mixing of the soils and solution.
Centrifugation was performed in a Sorvall RC-3B centrifuge at 5000 g for 15 min. These conditions separated the soil from the supernatant.
Duration:
49 h
Initial conc. measured:
5 other: µg/mL
Temp.:
20 °C
Duration:
49 h
Initial conc. measured:
1.2 other: µg/mL
Temp.:
20 °C
Duration:
49 h
Initial conc. measured:
0.2 other: µg/mL
Temp.:
20 °C
Duration:
49 h
Initial conc. measured:
0.04 other: µg/mL
Temp.:
20 °C
Sample No.:
#1
Type:
Koc
Value:
129 L/kg
pH:
8.4
Temp.:
20 °C
Matrix:
loamy sand; soil identification: Quincy
% Org. carbon:
0.4
Sample No.:
#2
Type:
Koc
Value:
345 L/kg
pH:
7.6
Temp.:
20 °C
Matrix:
sandy loam; soil identification: Elder
% Org. carbon:
1.2
Sample No.:
#3
Type:
Koc
Value:
123 L/kg
pH:
6.6
Temp.:
20 °C
Matrix:
clay loam; soil identification: Crosby
% Org. carbon:
1.2
Sample No.:
#4
Type:
Koc
Value:
84 L/kg
pH:
6.8
Temp.:
20 °C
Matrix:
sandy loam; soil identification: Laacherhof
% Org. carbon:
2.1
Sample No.:
#5
Type:
Koc
Value:
119 L/kg
pH:
4.1
Temp.:
20 °C
Matrix:
sand; soil identification: BBA 2.1
% Org. carbon:
0.5
Recovery of test material:
Mean recoveries of applied radioactivity from each soil type were in the range 97.3 to 98.6%.
Sample no.:
#1
Duration:
49 h
% Adsorption:
47.9
Remarks on result:
other:
Remarks:
Soil identification: Quincy (#1)
Sample no.:
#2
Duration:
49 h
% Adsorption:
11.8
Remarks on result:
other:
Remarks:
Soil identification: Elder (#2)
Sample no.:
#3
Duration:
49 h
% Adsorption:
28.4
Remarks on result:
other:
Remarks:
Soil identification: Crosby (#3)
Sample no.:
#4
Duration:
49 h
% Adsorption:
24.2
Remarks on result:
other:
Remarks:
Soil identification: Laacherhof (#4)
Sample no.:
#5
Duration:
49 h
% Adsorption:
48.5
Remarks on result:
other:
Remarks:
Soil identification: BBA 2.1 (#5)
Sample no.:
#1
Duration:
24 h
% Desorption:
21.2
Remarks on result:
other:
Remarks:
% Recovery after desorption phase 1; Soil identification: Quincy (#1)
Sample no.:
#2
Duration:
24 h
% Desorption:
9.2
Remarks on result:
other:
Remarks:
% Recovery after desorption phase 1; Soil identification: Elder (#2)
Sample no.:
#3
Duration:
24 h
% Desorption:
17.4
Remarks on result:
other:
Remarks:
% Recovery after desorption phase 1; Soil identification: Crosby (#3)
Sample no.:
#4
Duration:
24 h
% Desorption:
15.8
Remarks on result:
other:
Remarks:
% Recovery after desorption phase 1; Soil identification: Laacherhof (#4)
Sample no.:
#5
Duration:
24 h
% Desorption:
20.8
Remarks on result:
other:
Remarks:
% Recovery after desorption phase 1; Soil identification: BBA 2.1 (#5)
Transformation products:
no
Remarks:
Degradation of the test substance during the study was insignificant (<1%).
Details on results (Batch equilibrium method):
PRELIMINARY TEST
- Ratio of soil to aqueous phase: From the acquired data a ratio of 1:1 w/w was chosen for all soils. At this ratio, the amount adsorbed was in the range of 19 to 71% of the applied radioactivity.
- Equilibrium time: From the acquired data adsorption and desorption equilibrium times of 49 h and 24 h respectively were chosen. The rate of change of supernatant concentration with time was <5% (based on supernatant radioactivity) in all soils at these times.
- Preliminary stability: None of the HPLC chromatograms of 24 h adsorption supernatants or of 8 or 24 h desorption supernatants from any of the soils showed evidence of the test substance degradation. Similarly, no degradation of [14C]-labelled test substance was detected in the acetonitrile extracts of any of the soils following the 72 h adsorption and desorption phases. This experiment strongly suggested that the test substance would be stable during the definitive study.

MAIN TEST: PERFORMANCE
- Test material stability during adsorption/desorption phase: HPLC and TLC chromatograms of adsorption and desorption supernatants from the samples treated at the 5.0 µg/mL concentration showed no evidence of test article instability. Similarly, insignificant degradation of test article was observed in acetonitrile extracts of the soil after the third desorption step. The most significant degradate accounted for <1% of sample radioactivity. These results show that the test substance was stable during both adsorption and desorption and that radioactivity was a true measure of the test substance levels.

RESIDUES
- Extractable residues (% of applied amount at end of study period): The per cent adsorbed for Quincy (#1), Elder (#2), Crosby (#3), Laacherhof (#4) and BBA 2.1 (#5) soils was 24 to 42%, 74 to 90%, 47 to 70%, 53 to 76% and 28 to 43% respectively. Although >80% of the test article bound to Elder soil at the three lowest concentrations, the accuracy of the determination of the adsorption and desorption constants and coefficients was considered acceptable. Adsorption and desorption isotherms were constructed for each soil from the adsorbed concentrations of the test substance and the concentrations of the test substance in the adsorption and desorption supernatants. There was a good correlation (r2>0.99) between the log of the concentrations adsorbed and in solution over the concentration range studied (0.04 µg/mL to 5 µg/mL). Adsorption Koc values (84 to 345 mL/g) were in a tighter band than Kf values (0.52 to 4.14 mL/g) indicating that the organic carbon content of soil is an important property in determining adsorption.
- Other: Using mobility classes as defined by McCall, the test substance has high mobility in Quincy, Crosby, Laacherhof, and BBA 2.1 soils and medium mobility in Elder soil and the average of the five soils. Using mobility classes defined by Hollis the test substance is classified as 'moderately mobile' in all five soils.
Desorption Kocdes constants (95 to 382 mL/g, mean 188 mL/g, median 154 mL/g) were higher than adsorption constants (84 to 345 mL/g, mean 160 mL/g, median 123 mL/g) for all soils indicating partial irreversible adsorption of the test substance to soil.
Conclusions:
The test substance was shown to be 'moderately mobile' (adsorption Koc 84 to 345 mL/g) in five soils. The lowest value was in Laacherhof soil and the highest value was in Elder soil. The mole fraction Freundlich adsorption coefficients (Kmf) were in the range 3.98 E-06 to 1.30 E-04 moles/g. Although >80% of the test substance was adsorbed on to Elder soil at the three lowest concentrations, this did not prevent adsorption and desorption constants and coefficients from being determined.
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
23 Dec 1996 - 30 Nov 1998
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
other: Environmental Fate Data Requirement, 40 CFR 158, Subdivision N, Series 163-1, "Leaching and Adsorption/Desorption Studies"
Version / remarks:
1982
Qualifier:
according to guideline
Guideline:
other: Environmental Chemistry and Fate Guidelines for Registration of Pesticides in Canada, Section 6.2, B, 1 "Mobility, Adsorption/Desorption Measurements"
Version / remarks:
1987
GLP compliance:
yes (incl. QA statement)
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
yes
Test temperature:
25 °C
Analytical monitoring:
yes
Matrix no.:
#1
Matrix type:
other: sandy loam, soil identification: 635W-3
% Clay:
8
% Silt:
32
% Sand:
60
% Org. carbon:
0.7
pH:
8
CEC:
7.7 meq/100 g soil d.w.
Bulk density (g/cm³):
1.4
Matrix no.:
#2
Matrix type:
other: clay, soil identification: 635W-5A
% Clay:
42
% Silt:
40
% Sand:
18
% Org. carbon:
3.5
pH:
7.5
CEC:
17.2 meq/100 g soil d.w.
Bulk density (g/cm³):
1.08
Matrix no.:
#3
Matrix type:
other: sand, soil identification: 635W-6
% Clay:
2
% Silt:
8
% Sand:
90
% Org. carbon:
1
pH:
5.8
CEC:
3.9 meq/100 g soil d.w.
Bulk density (g/cm³):
1.5
Matrix no.:
#4
Matrix type:
other: sandy loam, soil identification: 635W-7A
% Clay:
10
% Silt:
28
% Sand:
62
% Org. carbon:
6.6
pH:
6.4
CEC:
22.8 meq/100 g soil d.w.
Bulk density (g/cm³):
1.11
Matrix no.:
#5
Matrix type:
other: loam, soil identification: 635W-8A
% Clay:
12
% Silt:
48
% Sand:
40
% Org. carbon:
3
pH:
5.7
CEC:
10.7 meq/100 g soil d.w.
Bulk density (g/cm³):
1.22
Matrix no.:
#6
Matrix type:
other: silt loam, soil identification: 635W-11
% Clay:
15
% Silt:
56
% Sand:
29
% Org. carbon:
2.7
pH:
7.1
CEC:
9.4 meq/100 g soil d.w.
Bulk density (g/cm³):
1.19
Sample No.:
#1
Type:
Koc
Value:
382.5 L/kg
Temp.:
25 °C
Matrix:
sandy loam, soil identification: 635W-3
% Org. carbon:
0.4
Sample No.:
#2
Type:
Koc
Value:
70.5 L/kg
Temp.:
25 °C
Matrix:
clay, soil identification: 635W-5A
% Org. carbon:
2.1
Sample No.:
#3
Type:
Koc
Value:
176.7 L/kg
Temp.:
25 °C
Matrix:
sand, soil identification: 635W-6
% Org. carbon:
0.6
Sample No.:
#4
Type:
Koc
Value:
205.1 L/kg
Temp.:
25 °C
Matrix:
sandy loam, soil identification: 635W-7A
% Org. carbon:
3.9
Sample No.:
#5
Type:
Koc
Value:
113.3 L/kg
Temp.:
25 °C
Matrix:
loam, soil identification: 635W-8A
% Org. carbon:
1.8
Sample No.:
#6
Type:
Koc
Value:
93.1 L/kg
Temp.:
25 °C
Matrix:
silt loam, soil identification: 635W-11
% Org. carbon:
1.6
Validity criteria fulfilled:
not applicable
Conclusions:
Adsorption/Desorption isotherms of the test substance were determined using 6 soils (sandy loam, clay, sand, Rignold sandy loam, loam and silt loam). Adsorption Koc values ranged from 70.5 to 382.5. These Koc values predict [trade name] to exhibit high to medium mobility in the six soils studied. The desorption Koc values were higher than the adsorption Koc values, ranging from 157.6 to 1002.5 which indicates that, once adsorbed to soil, [trade name] is less likely to be removed with water or to leach.
Endpoint:
adsorption / desorption: screening
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
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Version / remarks:
1981
Qualifier:
according to guideline
Guideline:
other: European Community Commission Directive 95/36/EC of 22 July 1995 amending Council Directive 91/414/EEC: Annex II : 7.1.2
Version / remarks:
1995
GLP compliance:
yes (incl. QA statement)
Type of method:
batch equilibrium method
Media:
soil
Test temperature:
20 °C
Matrix no.:
#1
Matrix type:
other: loamy sand; soil identification: Collombey
% Clay:
4.2
% Silt:
18.3
% Sand:
77.5
% Org. carbon:
0.8
pH:
7.3
CEC:
6.1 meq/100 g soil d.w.
Matrix no.:
#2
Matrix type:
other: sand; soil identification: Speyer 2.1
% Clay:
5.2
% Silt:
6.1
% Sand:
88.7
% Org. carbon:
0.3
pH:
6.8
CEC:
3.9 meq/100 g soil d.w.
Matrix no.:
#3
Matrix type:
other: loam; soil identification: Gartenacker
% Clay:
11.9
% Silt:
48
% Sand:
40.1
% Org. carbon:
2
pH:
7.1
CEC:
12.7 meq/100 g soil d.w.
Matrix no.:
#4
Matrix type:
other: silt loam; soil identification: Vetroz
% Clay:
23.3
% Silt:
58.5
% Sand:
18.2
% Org. carbon:
4.7
pH:
7.2
CEC:
28.1 meq/100 g soil d.w.
Matrix no.:
#5
Matrix type:
other: humic soil; soil identification: Illarsaz
% Org. carbon:
19.8
pH:
6.7
CEC:
102.8 meq/100 g soil d.w.
Sample No.:
#3
Type:
Koc
Value:
73.5 other: µg/g
Temp.:
20 °C
Matrix:
loam; soil identification: Gartenacker
% Org. carbon:
2
Sample No.:
#4
Type:
Koc
Value:
62.5 other: µg/g
Temp.:
20 °C
Matrix:
silt loam; soil identification: Vetroz
% Org. carbon:
4.7
Sample No.:
#5
Type:
Koc
Value:
73.5 other: µg/g
Temp.:
20 °C
Matrix:
humic soil; soil identification: Illarsaz
% Org. carbon:
19.8

Soils Gartenacker (#3), Vetroz (#4) and lllarsaz (#5) have been selected for the final adsorption / desorption experiment because they adsorbed more than 10 % of the test substance in the pre-test.

Validity criteria fulfilled:
not applicable
Conclusions:
The adsorption/desorption characteristics and the Freundlich adsorption/desorption isotherms of the test substance, i.e. N-(2-Chloro-thiazol-5-ylmethyl)-N'-methyl-N"-nitro-guanidine, were determined in various soil types and compared to other pesticides. For the pre-test the following soil types were used: a loamy sand (Collombey), a loam (Gartenacker), a sand (Speyer 2.1; German Standard Soil), a silt loam (Vetroz) and a humic soil (lllarsaz). Soils Gartenacker, lllarsaz and Vetroz have been selected for the final adsorption / desorption experiment because they adsorbed more than 10 % of the test substance in the pre-test.
Five dilutions of the test substance were prepared in 0.01 M CaCl2 for each soil: 0.10, 0.20, 0.50, 1.00 and 2.00 mg/liter. The equilibrium time for adsorption and desorption experiments was set to 24 hours.
The Freundlich adsorption coefficient kF varied between 1.46 mL/g for the loam and 14.60 mL/g for the humic soil (the expression mL/g is equivalent to mg a.i./g soil for ce = 1 mg/mL). An average Koc value of 70 µL/g or, related to the organic matter, an average Kom (or Q value) of 41 µL/g was calculated.
The test substance is a compound with a low sorption capacity to most soils, it can be classified as slightly mobile in loamy and sandy soils.
The slopes 1/n for the adsorption isotherms ranged between 0.7501 (silty loam) and 0.8972 (humic soil) indicating that the Freundlich adsorption isotherms would not strongly follow the distribution law.
Desorption of the test substance from the soils was nearly equal to adsorption as shown by the very similar desorption coefficients (kdes1 = 1.14 to 16.27 µL/g) calculated after the first desorption step. The values after the second desorption step were in the same order of magnitude.
The 14C-material balance ranged between 94.37 and 100.33 % recovery of the applied dose for the three soils tested. Analysis of the acetone soil extracts after the adsorption step showed that the adsorbed radioactivity consisted entirely of parent compound.
Endpoint:
adsorption / desorption: screening
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
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Version / remarks:
2000
Qualifier:
according to guideline
Guideline:
other: Commission Directive 95/36/EC amending Council Directive 91/414/EEC (Annexes I and II, Fate and Behaviour in the Environment)
Version / remarks:
1995
GLP compliance:
yes (incl. QA statement)
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
yes
Test temperature:
20 ± 1 °C
Analytical monitoring:
yes
Matrix no.:
#1
Matrix type:
other: weak loamy sand
% Clay:
6
% Silt:
22.4
% Sand:
71.6
% Org. carbon:
0.9
pH:
6
CEC:
8 meq/100 g soil d.w.
Bulk density (g/cm³):
1.34
Sample No.:
#1
Type:
Koc
Value:
77.3 L/kg
Temp.:
20 °C
Matrix:
weak loamy sand
% Org. carbon:
0.9
Validity criteria fulfilled:
not applicable
Conclusions:
The adsorption of the test substance was investigated in loamy sand soil (Birkenheide, Germany).
Based on the study plan and on the outcome of a preliminary test a soil/solution ratio of 1:1 corresponding to 20 g soil and 20 mL solution and shaking periods of 48 hours for adsorption, but 24 hours for desorption was used. When applying the test item at concentrations corresponding to 5.00, 1.00, 0.20, 0.04 and 0.01 mg/L in 0.01 M CaCl2 solution, the proportion of the test substance adsorbed on soil Birkenheide ranged from 36 % to 62 %.
The chromatographic analysis of the clear centrifuged supernatants, after establishment of the equilibrium, showed that more than 99 % of the measured radioactivity could be assigned to be the unchanged test item.
The adsorption constants Kd, determined by means of the Freundlich adsorption isotherm, as well as the soil carbon-based sorption Koc, were calculated. The Kd (expressed as mL/g) was 0.70 mL/g. The Koc for adsorption was calculated to be 77.3 mL/g.
Subsequent desorption tests showed that between 27% and 42% of the adsorbed test item were desorbed again in a first step and between 20% and 37% of the residue after first desorption in a second step. The resulting desorption constants were 0.83 mL/g for the first step and 0.99 mL/g for the second step. The respective Koc-values were calculated to be 92.4 mL/g and 109.6 mL/g.
In mass balance tests a mean recovery of 99.5 % of the applied radioactivity was found. The mass balances for the full test cycles (one adsorption and two desorptions) ranged between 94.4 and 101.1%.
Based on the results of this study and on the classification system of McCall et al. the test substance is classified to have a high mobility (McCall classification: for Koc-values within the range of 50-150 mL/g the mobility is considered to be "high").

Description of key information

logKoc = 1.92 – 2.54 L/kg

Key value for chemical safety assessment

Koc at 20 °C:
345

Additional information

In an experimental study following GLP and OECD Guideline 106, Freundlich adsorption constants of (E)-1-(2-chloro-1,3-thiazol-5-ylmethyl)-3-methyl-2-nitroguanidine related to organic carbon content (Koc) were 84 to 345 mL/g (mean 160 mL/g, median 123 mL/g) and mole fraction Freundlich adsorption constants (Kmf) were 3.98 E-06 to 1.30 E-04 moles/g respectively depending on soil type. Freundlich desorption constants related to organic carbon content (95 to 382 mL/g, mean 188 mL/g, median 154 mL/g) were higher than the corresponding adsorption constants (Koc) indicating partially irreversible adsorption of the test substance to soil. Degradation of the test substance during the study was insignificant (<1%).

This result is supported by three additional studies.

In the first study, conducted according to GLP, the adsorption of the test compound was studied in six different soils and Koc values ranged from 70.5 to 382.5 L/kg.

In the second study, the adsorption/desorption behaviour the test substance has been studied in loamy sand soil. The Koc for the adsorption was determined to be 77.3 L/kg, for the first desorption a value of 92.4 L/kg was calculated, for the second desorption step a value of 109.6 L/kg.

When related to the organic carbon content, Koc data of the test substance in the third study ranged from 62 to 74 µg/g of organic carbon with an average Koc value of 70 µg/g. The test substance was rather stable in the supernatants.