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Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
EPI Suite v4.11 Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.

2. MODEL (incl. version number)
KOCWIN v2.00, Log Kow based model

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.
Qualifier:
according to
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: EPI Suite v4.11
- Model(s) used: KOCWIN v2.00
Full reference and details of the used formulas can be found in:
1. Doucette, W.J. 2000. Soil and sediment sorption coefficients.  In: Handbook of Property Estimation Methods, Environmental and Health Sciences. R.S. Boethling & D. Mackay (Eds.): Lewis Publishers (ISBN 1-56670-456-1). 
2. US EPA. [2012]. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11 or insert version used]. United States Environmental Protection Agency, Washington, DC, USA.
- Model description: see field 'Justification for non-standard information', 'Attached justification' and 'any other information on Material and methods'
- Justification of QSAR prediction: see field 'Justific ation for type of information', 'Attached justification' and/or 'overall remarks'
GLP compliance:
no
Type of method:
other: calculation
Media:
soil
Details on test conditions:
BASIS FOR CALCULATION OF Koc:
- Estimation software: EPI Suite™ v4.11, KOCWIN v2.00, Log Kow based method
- Result based on measured log Pow of: 2.73
Type:
Koc
Value:
399.9 L/kg
Temp.:
25 °C
Type:
log Koc
Value:
2.602 dimensionless
Temp.:
25 °C

For detailed information on the results please refer to the attached report.

Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
EPI Suite v4.11 Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.

2. MODEL (incl. version number)
KOCWIN v2.00

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.
Qualifier:
according to
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: EPI Suite v4.11
- Model(s) used: KOCWIN v2.00, MCI based method
Full reference and details of the used formulas can be found in:
Meylan, W., P.H. Howard and R.S. Boethling, "Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients", Environ. Sci. Technol. 26: 1560-7 (1992)
- Model description: see field 'Justification for non-standard information', 'Attached justification' and 'any other information on Material and methods'
- Justification of QSAR prediction: see field 'Justific ation for type of information', 'Attached justification' and/or 'overall remarks'
GLP compliance:
no
Type of method:
other: calculation
Media:
soil
Details on test conditions:
BASIS FOR CALCULATION OF Koc:
- Estimation software: EPI Suite™ v 4.11, KOCWIN v2.00, MCI based method
Type:
Koc
Value:
491.8 L/kg
Temp.:
25 °C
Type:
log Koc
Value:
2.692 dimensionless
Temp.:
25 °C

For detailed information on the results please refer to the attached report.

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12 Dec 2006 - 27 Jan 2007
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.18 (Adsorption / Desorption Using a Batch Equilibrium Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
no
Test temperature:
25 °C
Analytical monitoring:
yes
Matrix no.:
#1
Matrix type:
loamy sand
% Clay:
>= 12.8 - <= 17
% Org. carbon:
>= 2.14 - <= 2.58
pH:
>= 5.2 - <= 6
Matrix no.:
#2
Matrix type:
sand
% Clay:
>= 7.7 - <= 9.1
% Org. carbon:
>= 0.86 - <= 1.44
pH:
>= 5.3 - <= 6.7
Matrix no.:
#3
Matrix type:
clay loam
% Clay:
>= 63.4 - <= 67
% Org. carbon:
>= 1.51 - <= 2.15
pH:
>= 6.5 - <= 7.1
Matrix no.:
#4
Matrix type:
other: Eurosoil 3
% Clay:
17
% Org. carbon:
3.3
pH:
5.9
Details on matrix:
COLLECTION AND STORAGE
- Soil preparation (e.g.: 2 mm sieved; air dried etc.): The tests were run using air-dried fine sieved soil(< 2 mm).

PROPERTIES
- Soil #1
origin: LUFA Speyer

- Soil #2
origin: LUFA Speyer

- Soil #3
origin: LUFA Speyer

- Soil #4
origin: IRMM Geel
Details on test conditions:
TEST SYSTEM
Soil / Solution Ratio: 1: 2.5
Test Item Solution: Approximately 50 mg of the test item were dissolved in methanol and it was filled up to 50 mL using a volumetric flask. For performance of the test the stock solution was diluted to 100 mg/L in 0.01 M CaCl2 solution. The concentration of the test item in 0.01 M CaCl2 solution was below the water solubility of the test item
Preparation of the test soils: The air dried soil samples were equilibrated by shaking with 22.5 mL of 0.01 M CaCl2 solution overnight. Afterwards 2.5 mL of the diluted test item solution (100 mg/L) were added in order to adjust the final volume to 25 mL. The volume of the added stock solution did not exceed 10% of the final 25 mL volume.
Performance of the test: The mixtures were shaken. After a period of 8h, 24h and 48h the contact time was finished and samples were collected. Therefore, the suspensions were centrifuged and filtered to obtain a clear solution. The aqueous solutions were analysed.
Control: yes (incl. blank control)
Replicates: Two replicates per each test soil/volume ratio and one replicate per control and blank sample were run.

Screening desorption test
Soil / Solution Ratio: 10 g of the soil in combination with 25 mL aqueous phase was used
Test Item Solution: Approximately 50 mg of the test item were dissolved in methanol and it was filled up to 50 mL using a volumetric flask. For performance of the test the stock solution was diluted to 100 mg/L in 0.01 M CaCl2 solution.
Preparation of the test soils: The air dried soil samples were equilibrated by shaking with 22.5 mL of 0.01 M CaCl2 solution overnight. Afterwards 2.5 mL of the stock solution of the test item was added in order to adjust the final volume.
Performance of the test: The mixtures were shaken until adsorption equilibrium was reached (the same time interval as in the adsorption kinetic experiment). After this time the phases were separated by centrifugation. The aqueous phase was removed as much as possible. The volume of solution removed was replaced by an equal volume of 0.01 M CaCl2. The new mixtures were shaken again. After defined time intervals (8h, 24h and 48h) the suspension was filtered. The aqueous phases were recovered and were analysed.
Control: yes (incl. blank control)
Replicates: In case of each experiment (one soil and one test item concentration) 6 samples were prepared allowing duplicate sampling after the specified time intervals.

Freundlich adsorption test
Soil / Solution Ratio: 10 g of the soil and 25 mL aqueous phase were used.
Test Item Solution: Approximately 500 mg of the test item were dissolved in methanol and it was filled up to 50 mL using a volumetric flask. For performance of the test the stock solution was diluted to 100 mg/L, 250 mg/L, 500 mg/L and 750 mg/L in 0.01 M CaCl2 solution. The concentrations did cover two orders of magnitude. The test item was dissolved in methanol.
Preparation of the test soils: The air dried soil samples were equilibrated by shaking with 22.5 mL of 0.01 M CaCl2 solution overnight. Afterwards 2.5 mL of the solution of the test item were added in order to adjust the final volume. The volume of the added stock solution did not exceed 10% of the final volume.
Performance of the test: The mixtures were shaken until equilibrium was reached. After 48h samples were collected. The suspension was centrifuged and filtered to obtain a clear solution. The aqueous solutions were analysed
Control: yes (incl. blank control)
Replicates: Each experiment (one soil and one test item concentration) was done at least in duplicate.

Freundlich desorption test
Preparation of the test soils: The air dried soil samples were equilibrated by shaking with 22.5 mL of 0.01 M CaCl2 solution overnight. Afterwards 2.5 mL of the solution of the test item were added in order to adjust the final volume. The volume of the added stock solution did not exceed 10% of the final volume.
Performance of the test: After end of the adsorption step the supernatant was removed from the soil by decanting. The volume of supernatant was measured and replaced by an equal volume of 0.01 M CaCl2. The new mixtures was shaken again until desorption equilibrium was reached. Afterwards the aqueous phases were recovered and were analysed.
Control: yes (incl. blank control)
Replicates: Each experiment (one soil and one test item concentration) was done at least in duplicate.


Computational methods:
The Freundlich adsorption isotherms equation relates the amount of test item adsorbed on soil to the concentration of test item in solution at equilibrium. The equations in linear form were calculated. The adsorption coefficients Ka (adsorption) and Kd (desorption) were derived from the screening test and the adsorption isotherm according to Freundlich.
Sample No.:
#1
Type:
Koc
Value:
160.9 L/kg
pH:
5.6
Temp.:
20 °C
Matrix:
Lufa 2.1- sand
% Org. carbon:
1.2
Sample No.:
#2
Type:
Koc
Value:
497.9 L/kg
pH:
6
Temp.:
20 °C
Matrix:
Lufa 2.2 - loamy sand
% Org. carbon:
2.4
Sample No.:
#3
Type:
Koc
Value:
508.2 L/kg
pH:
6.8
Temp.:
20 °C
Matrix:
Lufa 6S - clayey loam
% Org. carbon:
1.8
Sample No.:
#4
Type:
Koc
Value:
230.3 L/kg
pH:
5.9
Temp.:
20 °C
Matrix:
Eurosoil 3 - loam
% Org. carbon:
3.3
Sample No.:
#1
Type:
Kd
Value:
1.9 L/kg
pH:
5.6
Temp.:
20 °C
Matrix:
Lufa 2.1- sand
% Org. carbon:
1.2
Sample No.:
#2
Type:
Kd
Value:
11.8 L/kg
pH:
6
Temp.:
20 °C
Matrix:
Lufa 2.2 - loamy sand
% Org. carbon:
2.4
Sample No.:
#3
Type:
Kd
Value:
9.3 L/kg
pH:
6.8
Temp.:
20 °C
Matrix:
Lufa 6S - clayey loam
% Org. carbon:
1.8
Sample No.:
#4
Type:
Kd
Value:
7.6 L/kg
pH:
5.9
Temp.:
20 °C
Matrix:
Eurosoil 3 - loam
% Org. carbon:
3.3
Adsorption and desorption constants:
Please refer to "Any other information on results incl. tables".
Transformation products:
not specified

Table 1: Results of the batch equilibrium experiment

Soil

Adsorption

Desorption

Kd/KF*

Koc(mL/g)

1/n

KF*

1/n

Screening test: adsorption kinetic

Sand

1.9

160.9

n.a.

n.r.

n.a.

Loamy sand

11.8

497.9

n.a.

n.r.

n.a.

Clay

9.3

508.2

n.a.

n.r.

n.a.

Loam

7.6

230.3

n.a.

n.r.

n.a.

Freundlich adsorption isotherm

Sand

3

270

0.611

1.2

0.659

Loamy sand

14

598

0.596

1.5

0.996

Clay

18

981

0.448

1.7

0.967

Loam

11

322

0.747

0.5

1.192

* Values: Kd(mL/g) after 48 hours, KFfor the adsorption and desorption (µg1-1n(cm3)1/ng-1)
n.r. = not reported; n.a. = not applicable

Table 2: Mass balance of the screening test after 2 extraction with CaCl2-solution for all soil types

 

Mass nominal in solution [µg]

Mass measured in solution [µg]

1stextraction – Mass found [µg]

2ndextraction – Mass found [µg]

Total mass adsorbed on soil [µg]

Mass balance

[%]

Lufa 2.1

253.7

145.7

18.0

31.6

49.6

77

Lufa 2.1

253.4

148.5

17.9

28.5

46.4

76.9

Lufa 2.2

253.8

51.2

0.3

24.9

25.2

30.1

Lufa 2.2

253.7

49.5

-1.0

23.8

22.8

28.5

Lufa 6S

254.0

35.6

-9.3

16.1

6.8

16.7

Lufa 6S

253.5

41.2

4.8

35.6

40.4

32.2

Eurosoil 3

253.5

57.4

28.6

152.8

181.4

94.2

Eurosoil 3

253.4

53.0

24.7

181.3

206.0

102.2

Validity criteria fulfilled:
not applicable
Conclusions:
The calculated distribution coefficients were in the range of 1.9 to 11.8 mL/g. The corresponding adsorption coefficients related to organic carbon were in the range of 160.9 to 508.2 mL/g.
Executive summary:

Meinerling (2007) investigated the adsorption behaviour of p-chloro-m-cresol in a batch equilibrium test with four soils according to OECD Guideline No. 106 and Commission Directive 2001/59/EC, Method C.18. In a preliminary study the soil/solution ratio as well as the equilibrium time, the potential adsorption of p-chloro-m-cresol on surfaces of the test vessels and the stability of the test item were estimated. Two soils and three soil to solution ratios (1:1, 1:5 and 1:25) were used. In a screening test the adsorption kinetic of p-chloro-m-cresol at four different soil types was studied using a single concentration (approx. 10 µg/mL) and determining the distribution coefficients Kd and Koc after different time points (8, 24, 48 h). The desorption kinetics were performed to investigate whether the test item was reversibly or irreversibly adsorbed on the soil. In the test for determination of the Freundlich adsorption isotherm the influence of the concentration (0, 100, 220, 500, 750 and 1000 mg/L) on the extent of adsorption was investigated. The Freundlich desorption isotherm was determined on the soils used in the adsorption isotherms experiment.

The preliminary test an adequate adsorption of p-chloro-m-cresol at a soil/solution ratio of 1:25 was achieved. An equilibrium time of 48 h was considered for the screening test. P-chloro-m-cresolwas stable under the test conditions and did not adsorb on the surface of the test vessel. From analysis of the control soils no interfering compounds were detected. 28 % and 96 % of the nominal test item amount could be analytically recovered after adsorption. The calculated distribution coefficients were in the range of 1.9 to 11.8 mL/g. The corresponding adsorption coefficients related to organic carbon were in the range of 160.9 to 508.2 mL/g. Desorption of adsorbed p-chloro-m-cresol from the different soil types ranged from negligible desorption up to 22% desorption. The Freundlich adsorption coefficients (KF values) varied between 3 and 18 µg 1-1n(cm3)1/ng-1. Related to organic carbon, adsoption coefficients between 270 and 981 mL/g had been calculated. The slope of the isotherm was below 0.75 for all four soils. Freundlich coefficients determined for the desorption were lower as those determined for the adsorption, i.e. 0.5 to 1.7 µg1-1n(cm3)1/ng-1, indicating that the compound, once adsorbed, is restrictedly or delayed transferred back to the soil pore water.

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
23 Aug - 13 Sep 2001
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Test temperature:
40 °C
Details on study design: HPLC method:
EQUIPMENT
- Type: HPLC system
- Type, material and dimension of analytical (guard) column: Column: LiChrospher 100 CN, 5 µm, 250 x 4 mm; Detector: UV, 220 nm
- Detection system: UV, 220 nm

MOBILE PHASES
- Type: 400 mL acetonitrile : 85 mL buffer solution
- Experiments with additives carried out on separate columns: yes / no
- pH: 6

DETERMINATION OF DEAD TIME
- Method: with sodium nitrate the dead time is 1.652 min

REFERENCE SUBSTANCES
- Identity: Calibration substances for assessing the adsorption:
Sodium nitrate (assessment of the dead time of the HPLC system)
2-Nitrobenzamide
N,N-Dimethylbenzamide
Acetanilide
Naphthalene
1,2,3-Trichlorobenzene
Fenthion

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 5 µL

EVALUATION
From the retention times of the reference substances and the dead time of the HPLC column, a capacity factor for each of the substances was calculated. The retention time and capacity factor of the test substance was brought into relation to those of the reference substances.
Sample No.:
#1
Type:
log Koc
Value:
2.2 dimensionless
pH:
6.4
Temp.:
40 °C
Sample No.:
#1
Type:
Koc
Value:
158.5 L/kg
pH:
6.4
Temp.:
40 °C
Details on results (HPLC method):
The dead time (t0) with sodium nitrate is 1.652 min.
The linear regression of measured k’ against Koc values yielded a line with a slope of 0.33215, an intercept of -0.48334 and a correlation coefficient of r2 = 0.97979.
For further details please refer to “Any other information on results incl. tables”.

Table 1: Retention times and Koc values for p-chloro-m-cresol and reference substances

Substance

Retention time (tr) in min*

Capacity factor k’*

Log k’

Log Koc

2-Nitrobenzamide

3.002

0.818

-0.087

1.45

N,N-Dimethylbenzamide

3.298

0.997

-0.001

1.52

Acetanilide

3.391

1.053

0.022

1.25

Naphthalene

6.479

2.923

0.466

2.75

1,2,3-Trichorobenzene

7.121

3.312

0.520

3.16

Fenthion

8.929

4.406

0.644

3.31

p-Chloro-m-cresol

4.597

1.783

0.251

2.21

* mean value form 3 single values; the dead time (t0) with sodium nitrate is 1.652 min

Validity criteria fulfilled:
not applicable
Executive summary:

Erstling & Feldhues (2001b) investigated the adsorption of p-chloro-m-cresol in a screening test using High Performance Liquid Chromatography (HPLC). The test was performed according to OECD guideline 121 (proposal for new test guideline 121, 2001). Six reference standards of known Koc were analysed by HPLC to determine their retention times. Sodium nitrate was used to define the system’s dead time (t0). From the retention times and the dead time of the HPLC column, the capacity factor (k’) of each substance was calculated and a plot of the tabulated log Koc values of the calibration substances versus log k’ (measured) was developed using linear regression.

The linear regression of log Koc values against measured log k’ values yielded a line with a slope of 0.33215, an intercept of –0.48334 and a correlation coefficient of r2 = 0.97979. The estimated log Koc value for p-chloro-m-cresol was 2.2, corresponding to a Koc of 158.5.

Endpoint:
adsorption / desorption: screening
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Refer to analogue justification document provided in IUCLID section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Sample No.:
#1
Type:
Koc
Value:
160.9 L/kg
pH:
5.9
Temp.:
20 °C
Matrix:
Lufa 2.1-sand
% Org. carbon:
1.2
Remarks on result:
other: source, CAS 59-50-7, key rel 2, Meinerling 2007
Sample No.:
#2
Type:
Koc
Value:
497.9 L/kg
pH:
6
Temp.:
20 °C
Matrix:
Lufa 2.2 - loamy sand
% Org. carbon:
2.4
Remarks on result:
other: source, CAS 59-50-7, key rel 2, Meinerling 2007
Sample No.:
#3
Type:
Koc
Value:
508.2 L/kg
pH:
6.8
Temp.:
20 °C
Matrix:
Lufa 6S - clayey loam
% Org. carbon:
1.8
Remarks on result:
other: source, CAS 59-50-7, key rel 2, Meinerling 2007
Sample No.:
#4
Type:
Koc
Value:
230.3 L/kg
pH:
5.9
Temp.:
20 °C
Matrix:
Eurosoil 3 - loam
% Org. carbon:
3.3
Remarks on result:
other: source, CAS 59-50-7, key rel 2, Meinerling 2007
Sample No.:
#1
Type:
Kd
Value:
1.9 L/kg
pH:
5.6
Temp.:
20 °C
Matrix:
Lufa 2.1 - sand
% Org. carbon:
2.4
Remarks on result:
other: source, CAS 59-50-7, key rel 2, Meinerling 2007
Sample No.:
#2
Type:
Kd
Value:
11.8 L/kg
pH:
6
Temp.:
20 °C
Matrix:
Lufa 2.2 - loamy sand
% Org. carbon:
2.4
Remarks on result:
other: source, CAS 59-50-7, key rel 2, Meinerling 2007
Sample No.:
#3
Type:
Kd
Value:
9.3 L/kg
pH:
6.8
Temp.:
20 °C
Matrix:
Lufa 6S - clayey loamm
% Org. carbon:
1.8
Remarks on result:
other: source, CAS 59-50-7, key rel 2, Meinerling 2007
Sample No.:
#4
Type:
Kd
Value:
7.6 L/kg
pH:
5.9
Temp.:
20 °C
Matrix:
Eurosoil 3 - loam
% Org. carbon:
3.3
Remarks on result:
other: source, CAS 59-50-7, key rel 2, Meinerling 2007
Sample No.:
#1
Type:
log Koc
Value:
2.2 dimensionless
pH:
6.4
Temp.:
40 °C
Remarks on result:
other: source, CAS 59-50-7, rel 2, Erstling & Feldbusch 2001
Sample No.:
#1
Type:
Koc
Value:
158.5 L/kg
pH:
6.4
Temp.:
40 °C
Remarks on result:
other: source, CAS 59-50-7, rel 2, Erstling & Feldbusch 2001

Description of key information

KOC = 195.6 mL/g (OECD 106)

Log KOC = 2.3

Key value for chemical safety assessment

Additional information

No studies investigating the adsorption behavior of sodium p-chloro-m-cresolate (CAS 15733-22-9)are available. Therefore, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read-across to the source substance (p-chloro-m-cresol, CAS 59-50-7) which is the main transformation product of the target substance sodium p-chloro-m-cresolate (CAS 15733-22-9) is applied.

The source substance p-chloro-m-cresol is the common compound in this analogue approach and is solely responsible for the environmental fate behaviour. Thus, the source substance is considered a suitable representative for the evaluation of the adsorption behaviour. The read-across approach is justified in detail within the analogue justification in IUCLID section 13.

One key and one supporting study investigated the adsorption of p-chloro-m-cresol (CAS 59-50-07). The key study (Meinerling, 2007) investigated the adsorption behaviour of p-chloro-m-cresol in a batch equilibrium test with four soils according to OECD Guideline No. 106 and Commission Directive 2001/59/EC, Method C.18. In a preliminary study the soil/solution ratio as well as the equilibrium time, the potential adsorption of p-chloro-m-cresol on surfaces of the test vessels and the stability of the test item were estimated. Two soils and three soil to solution ratios (1:1, 1:5 and) were used. In a screening test the adsorption kinetic of p-chloro-m-cresol at four different soil types was studied using a single concentration (approx. 10 µg/mL) and determining the distribution coefficients Kd and Koc after different time points (8, 24, 48 h). The desorption kinetics were performed to investigate whether the test item was reversibly or irreversibly adsorbed on the soil. In the test for determination of the Freundlich adsorption isotherm the influence of the concentration (0, 100, 220, 500, 750 and 1000 mg/L) on the extent of adsorption was investigated. The Freundlich desorption isotherm was determined on the soils used in the adsorption isotherms experiment.

The preliminary test an adequate adsorption of p-chloro-m-cresol at a soil/solution ratio of was achieved. An equilibrium time of 48 h was considered for the screening test. P-chloro-m-cresol was stable under the test conditions and did not adsorb on the surface of the test vessel. From analysis of the control soils no interfering compounds were detected. 28 % and 96 % of the nominal test item amount could be analytically recovered after adsorption. The calculated distribution coefficients were in the range of 1.9 to 11.8 mL/g. The corresponding adsorption coefficients related to organic carbon were in the range of 160.9 to 508.2 mL/g. Desorption of adsorbed p-chloro-m-cresol from the different soil types ranged from negligible desorption up to 22% desorption. The Freundlich adsorption coefficients (KF values) varied between 3 and 18 µg1-1n (cm3)1/ng-1. Related to organic carbon, adsoption coefficients between 270 and 981 mL/g had been calculated. The slope of the isotherm was below 0.75 for all four soils. Freundlich coefficients determined for the desorption were lower as those determined for the adsorption, i.e. 0.5 to 1.7 µg1-1n(cm3)1/ng-1, indicating that the compound, once adsorbed, is restrictedly or delayed transferred back to the soil pore water. The estimated Koc value was expressed as arithmetic mean value 195.6 mL/g (mean of 160.9 and 230.3 (Lufa 2.1 + Eurosoil 3), log Koc = 2.3, where recovery was sufficient).

The supporting study (Erstling & Feldhues 2001b) investigated the adsorption of p-chloro-m-cresol in a screening test using High Performance Liquid Chromatography (HPLC). The test was performed according to OECD guideline 121 (proposal for new test guideline 121, 2001). Six reference standards of known Koc were analysed by HPLC to determine their retention times. Sodium nitrate was used to define the system’s dead time (t0). From the retention times and the dead time of the HPLC column, the capacity factor (k’) of each substance was calculated and a plot of the tabulated log Koc values of the calibration substances versus log k’ (measured) was developed using linear regression. The linear regression of log Koc values against measured log k’ values yielded a line with a slope of 0.33215, an intercept of –0.48334 and a correlation coefficient of r2 = 0.97979. The estimated log Koc value for p-chloro-m-cresol was 2.2, corresponding to a Koc of 158.5 (log Koc 2.2). This result is similar to the result of the key study.

Based on the available results from a structurally similar source substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which is the main transformation product of the target substance and is characterized by a similar environmental fate behavior and comparable structure, it can be concluded thatsodium p-chloro-m-cresolatehas a logKow in the same range as the target substance.

Moreover this result is supported by QSAR calculation using KOCWIN v2.00 based on log Kow estimation and the Molecular Connectivity Index (MCI). The model has no universally accepted definition of model domain and the Kow values are inside the domain. The calculated log Koc values of 2.6 (log Kow) and 2.7 (MCI) indicate a low potential for adsorption.