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Diss Factsheets

Administrative data

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

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report date:
2014

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Deviations:
yes
Remarks:
Desorption coefficients were not determined as they are not required for ground water risk assessment.
Qualifier:
according to guideline
Guideline:
other: OPPTS 835.1230 Adsorption/Desorption (Batch Equilibrium)
Deviations:
yes
Remarks:
Desorption coefficients were not determined as they are not required for ground water risk assessment.
GLP compliance:
yes
Type of method:
batch equilibrium method
Media:
soil

Test material

Constituent 1
Chemical structure
Reference substance name:
3-hydroxy-4-methoxypyridine-2-carboxylic acid
Cas Number:
210300-09-7
Molecular formula:
C7H7NO4
IUPAC Name:
3-hydroxy-4-methoxypyridine-2-carboxylic acid
Specific details on test material used for the study:
Substance ID: 14C-X696872
Lot #: INV303815
Radiochemical purity: 99.4%
Specific activity: 26.1 μCi/mmol

Substance ID: 14C- X696476
Lot #: INV303736
Radiochemical purity: 96.5%
Specific activity: 26.7 μCi/mmol

Substance ID: 14C- X12264475
Lot #: INV303784
Radiochemical purity: 98.4%
Specific activity: 11.3 μCi/mmol

Substance ID: 14C- X12313581
Lot #: INV303854
Radiochemical purity: 99.5%
Specific activity: 26.5 μCi/mmol

Substance ID: 14C- X763024
Lot #: INV304984
Radiochemical purity: 98.0%
Specific activity: 28.9 μCi/mmol

Substance ID: X11963422
Lot #: INV304033
Radiochemical purity: 99.8%
Specific activity: 28.8 μCi/mmol
Radiolabelling:
yes

Study design

Test temperature:
Ambient

Batch equilibrium or other method

Analytical monitoring:
yes
Matrix propertiesopen allclose all
Matrix no.:
#1
Matrix type:
clay loam
% Clay:
31
% Silt:
26
% Sand:
43
% Org. carbon:
0.8
pH:
6.9
CEC:
19.2 meq/100 g soil d.w.
Bulk density (g/cm³):
1.19
Matrix no.:
#2
Matrix type:
silt loam
% Clay:
15
% Silt:
55
% Sand:
30
% Org. carbon:
3.9
pH:
5.8
CEC:
23 meq/100 g soil d.w.
Bulk density (g/cm³):
1
Matrix no.:
#3
Matrix type:
loam
% Clay:
19
% Silt:
35
% Sand:
46
% Org. carbon:
4.4
pH:
7.2
CEC:
26.6 meq/100 g soil d.w.
Bulk density (g/cm³):
1.14
Matrix no.:
#4
Matrix type:
other: Light clay
% Clay:
41
% Silt:
23
% Sand:
36
% Org. carbon:
1.7
pH:
7.6
CEC:
9.2 meq/100 g soil d.w.
Bulk density (g/cm³):
1.13
Matrix no.:
#5
Matrix type:
silt loam
% Clay:
17
% Silt:
57
% Sand:
26
% Org. carbon:
3.9
pH:
5.8
CEC:
14.5 meq/100 g soil d.w.
Bulk density (g/cm³):
0.95
Details on test conditions:
Test concentrations:
Tier 1 and Tier 2 tests of X696872 were conducted at nominal concentrations of 0.05 μg/mL and 0.01 μg/mL. Freundlich adsorption coefficients were established at nominal concentrations of 0.001 μg/mL, 0.002 μg/mL, 0.01 μg/mL, 0.02 μg/mL and 0.1 μg/mL.
All Tier 1 tests of X696476 were conducted at nominal concentrations of 0.1, 0.3 and 1.5 μg/mL. Tier 2 of X696476 was performed at a nominal concentration of 0.3 μg/mL for M830 and M852 soil samples and at 1.5 μg/mL for M849, M850 and M853 soil samples. Freundlich adsorption coefficients were established at nominal concentrations of 0.01 μg/mL, 0.02 μg/mL, 0.1 μg/mL, 0.2 μg/mL and 1.0 μg/mL.
All Tier 1 tests of X12264475 were conducted at a nominal concentration of 0.1 μg/mL except that Teir 1 stability test was performed at 1.0 μg/mL. Tier 2 of X12264475 was performed at a nominal concentration of 0.1 μg/mL. Freundlich adsorption coefficients were established at nominal concentrations of 0.03 μg/mL, 0.09 μg/mL, 0.3 μg/mL, 0.9 μg/mL and 3.0 μg/mL.
Tier 1 and Tier 2 tests of X12313581 were conducted at a nominal concentration of 0.1 μg/mL and Freundlich adsorption coefficients were established at nominal concentrations of 0.01 μg/mL, 0.05 μg/mL, 0.1 μg/mL, 0.5 μg/mL and 1.0 μg/mL.
All Tier 1 tests of X763024 were conducted at a nominal concentration of 0.1 μg/mL except that Teir 1 stability test was performed at 0.5 μg/mL. Tier 2 of X763024 was performed at a nominal concentration of 0.1 μg/mL. Freundlich adsorption coefficients were established at nominal concentrations of 0.01 μg/mL, 0.05 μg/mL, 0.1 μg/mL, 0.5 μg/mL and 1.0 μg/mL.
Tier 1 and Tier 2 tests of X11963422 were conducted at a nominal concentration of 0.1 μg/mL and Freundlich adsorption coefficients were established at nominal concentrations of 0.03 μg/mL, 0.09 μg/mL, 0.3 μg/mL, 0.9 μg/mL, 3.0 μg/mL.

Results and discussion

Adsorption coefficientopen allclose all
Key result
Type:
Kd
Value:
24.7 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X696872
Key result
Type:
Kd
Value:
701 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X696476
Key result
Type:
Kd
Value:
9.38 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X12264475
Key result
Type:
Kd
Value:
25.6 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X12313581
Key result
Type:
Kd
Value:
14 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X763024
Key result
Type:
Kd
Value:
2.93 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X11963422
Key result
Type:
Koc
Value:
1 180 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X696872
Key result
Type:
Koc
Value:
33 572 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X696476
Key result
Type:
Koc
Value:
424 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X12264475
Key result
Type:
Koc
Value:
1 320 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X12313581
Key result
Type:
Koc
Value:
608 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X763024
Key result
Type:
Koc
Value:
150 dimensionless
Matrix:
Soil
Remarks on result:
other: average value of all 5 soils for the test substance X11963422

Results: Batch equilibrium or other method

Adsorption and desorption constants:
X696872 adsorption Kd and Koc values averaged 25 ± 8 and 1180 ± 846, respectively. The X696872 Freundlich adsorption KF constants ranged between 12 and 26 with 1/n values of 0.90 to 1.03.
X696476 adsorption Kd and Koc values averaged 701 ± 397 and 33572 ± 31452, respectively. The X696476 Freundlich adsorption KF constants ranged between 94 and 495 with 1/n values of 0.77 to 0.85.
X12264475 adsorption Kd and Koc values averaged 9.4 ± 2.9 and 424 ± 267, respectively. The X12264475 adsorption KF constants ranged between 5.9 and 12 with 1/n values of 0.90 to 0.97.
X12313581 adsorption Kd and Koc values averaged 26 ± 10 and 1320 ± 791, respectively. The X12313581 adsorption KF constants ranged between 11 and 31 with 1/n values of 0.84 to 0.90.
X763024 adsorption Kd and Koc values averaged 14 ± 7.8 and 608 ± 400, respectively. The X763024 adsorption KF constants ranged between 6.2 and 20 with 1/n values of 0.90 to 0.94.
X11963422 adsorption Kd and Koc values averaged 2.9 ± 1.1 and 150 ± 118, respectively. The X11963422 adsorption KF constants ranged between 1.3 and 3.7 with 1/n values of 0.84 to 0.93.
Concentration of test substance at end of adsorption equilibration period:
The average mass balance of X696872 in all five soils at the end of the adsorption phase was 97.1 ± 3.7% of the applied. After 4 hours of equilibration between 23.3% and 57.3% (average 38.2 ± 8.7%) of the applied X696872 was adsorbed across all tested soil types.
The average mass balance of X696476 in all five soils at the end of the adsorption phase was 95.3 ± 2.9% of the applied. After 6 hours of equilibration between 54.5% and 94.0% (average 79.5 ± 8.7%) of the applied X696476 was adsorbed across all tested soil types.
The average mass balance of X12264475 in all five soils at the end of the adsorption phase was 100.9 ± 3.1% of the applied. After 24 hours of equilibration between 31.2% and 62.6% (average 45.0 ± 8.3%) of the applied X12264475 was adsorbed across all tested soil types.
The average mass balance of X12313581 in all five soils at the end of the adsorption phase was 96.1 ± 4.0% of the applied. After 24 hours of equilibration between 32.1% and 63.9% (average 46.3 ± 8.3%) of the applied X12313581 was adsorbed across all tested soil types.
The average mass balance of X763024 in all five soils at the end of the adsorption phase was 100.0 ± 3.7% of the applied. After 24 hours of equilibration between 36.9% and 75.9% (average 54.2 ± 10.3%) of the applied X763024 was adsorbed across all tested soil types.
The average mass balance of X11963422 in all five soils at the end of the adsorption phase was 96.7 ± 3.9% of the applied. After 2 or 6 hours of equilibration between 33.7% and 71.6% (average 51.5 ± 8.6%) of the applied X11963422 was adsorbed across all tested soil types.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
No correlation was observed between soil pH and the sorption coefficients of any of the six XDE-777 aerobic soil metabolites tested.
Executive summary:

The adsorption characteristics of six aerobic soil metabolites of XDE-777 (X696872, X696476, X12264475, X12313581, X763024 and X11963422) were studied in five soil types, a Yolo sandy clay (pH 6.9, 0.8% organic carbon) from the US, a Site E1 - Farditch Farm loam (pH 5.8, 3.9% organic carbon) from the UK, a Site K - Woodside Farm clay loam (pH 7.2, 4.4% organic carbon) from the UK, a Site J3 - Hareby House light clay (pH 7.6, 1.7% organic carbon) from the UK and a RefSol 03-G clay loam (pH 5.8, 3.9% organic carbon) from the Germany. To minimize microbial degradation during sorption tests, soil samples were sterilized by gamma radiation prior to equilibration with test materials. No desorption isotherms were calculated.


The experiment was conducted in accordance with the OECD Guideline for the Testing of Chemicals –Adsorption/Desorption-106 and the EPA OPPTS guideline. Sorptive characteristics of the test materials were determined in a batch equilibrium experiment.


The Tier 3 adsorption phase for all six metabolites was carried out by equilibrating sterilized soil with the desired test material at five nominal concentrations covering two orders of magnitude. Equilibration was conducted at ambient temperature and the equilibrating solution was 0.01 M CaCl2, with a soil: solution ratio determined in the Tier 1 tests. Samples were shaken on a horizontal shaker for an appropriate amount of time to maximize equilibration while minimizing hydrolysis of the test materials.


Soil and aqueous phases were separated by centrifugation after the adsorption steps. Soil samples of X696872, X12264475 and X11963422 were then subjected to an extraction procedure appropriate to remove the test compound from the soil. Radioactive residues in aqueous solution and organic extracts were assayed by LSC and analyzed by HPLC or LC-MS to determine the amount of test material present in each sample phase over the course of the study. As stability of X696476, X12313581 and X763024 during the adsorption phase was demonstrated in Tier 1 tests, soil samples of these three test materials were freeze-dried and portions were combusted to determine the amount of test material sorbed.


X696872 adsorption Kd and Koc values averaged 25 ± 8 and 1180 ± 846, respectively. The X696872 Freundlich adsorption KF constants ranged between 12 and 26 with 1/n values of 0.90 to 1.03.


X696476 adsorption Kd and Koc values averaged 701 ± 397 and 33572 ± 31452, respectively. The X696476 Freundlich adsorption KF constants ranged between 94 and 495 with 1/n values of 0.77 to 0.85.


X12264475 adsorption Kd and Koc values averaged 9.4 ± 2.9 and 424 ± 267, respectively. The X12264475 adsorption KF constants ranged between 5.9 and 12 with 1/n values of 0.90 to 0.97.


X12313581 adsorption Kd and Koc values averaged 26 ± 10 and 1320 ± 791, respectively. The X12313581 adsorption KF constants ranged between 11 and 31 with 1/n values of 0.84 to 0.90.


X763024 adsorption Kd and Koc values averaged 14 ± 7.8 and 608 ± 400, respectively. The X763024 adsorption KF constants ranged between 6.2 and 20 with 1/n values of 0.90 to 0.94.


X11963422 adsorption Kd and Koc values averaged 2.9 ± 1.1 and 150 ± 118, respectively. The X11963422 adsorption KF constants ranged between 1.3 and 3.7 with 1/n values of 0.84 to 0.93. The average mass balance of X696872 in all five soils at the end of the adsorption phase was 97.1 ± 3.7% of the applied. After 4 hours of equilibration between 23.3% and 57.3% (average 38.2 ± 8.7%) of the applied X696872 was adsorbed across all tested soil types.


The average mass balance of X696476 in all five soils at the end of the adsorption phase was 95.3 ± 2.9% of the applied. After 6 hours of equilibration between 54.5% and 94.0% (average 79.5 ± 8.7%) of the applied X696476 was adsorbed across all tested soil types.


The average mass balance of X12264475 in all five soils at the end of the adsorption phase was 100.9 ± 3.1% of the applied. After 24 hours of equilibration between 31.2% and 62.6% (average 45.0 ± 8.3%) of the applied X12264475 was adsorbed across all tested soil types.


The average mass balance of X12313581 in all five soils at the end of the adsorption phase was 96.1 ± 4.0% of the applied. After 24 hours of equilibration between 32.1% and 63.9% (average 46.3 ± 8.3%) of the applied X12313581 was adsorbed across all tested soil types.


The average mass balance of X763024 in all five soils at the end of the adsorption phase was 100.0 ± 3.7% of the applied. After 24 hours of equilibration between 36.9% and 75.9% (average 54.2 ± 10.3%) of the applied X763024 was adsorbed across all tested soil types.


The average mass balance of X11963422 in all five soils at the end of the adsorption phase was 96.7 ± 3.9% of the applied. After 2 or 6 hours of equilibration between 33.7% and 71.6% (average 51.5 ± 8.6%) of the applied X11963422 was adsorbed across all tested soil types.


No correlation was observed between soil pH and sorption of any of the test compounds.