Tellurium dioxide

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Principles of method if other than guideline:

A detailed description of method is given under "Any other information on materials and methods".

GLP compliance:

no

Remarks:

Study was not conducted for REACH propose. But information and documentation is sufficient. A replication under GLP is not reasonable.

Media:

soil

Radiolabelling:

no

Analytical monitoring:

yes

Details on matrix:

A total of 4813 soils were sent to CSIRO by Eurometaux for this study. From these, a subset of samples were repeated or replicated by re-scanning.
A total of 492 soils were selected for IR analysis to be used in the development of calibration and validation models.
The FTIR spectral variability in the analysis of soils can be found in supplemental information. Soils were oven dried at 40oC for 12 h and cooled in a desiccator prior to MIR analysis or experimental log-Kd value determinations.
The soil pH in 0.01 M calcium chloride (CaCl2) was provided to CSIRO by Eurometaux (EU).

Type:

Kd

Value:

> 0.32 - <= 4 650 L/kg

Remarks on result:

other: For further details refer to executive summary

Results for the modelling of log-Kd for Te(VI) are shown for PLS modelling using only the DRIFT spectra, univariate regression from pH, and the composite PLS model (DRIFT plus soil pH). Statistics are described by coefficient of determination (R2), root mean square of error for cross validation (RMSECV), standard deviation (SD) and ratio of prediction to deviation (RPD). Statistics are also shown for prediction of the 200 sample validation soil set and the full set of unknown samples from the composite PLS model†.

		Log(Kd+1) PLS (DRIFT model)	Log(Kd+1) univariate model)	Log(Kd+1) PLS (DRIFT+pH model)	Log(Kd+1) (DRIFT+pH validation of the 200 sample Test set	Log(Kd+1) predictions
Min	0.121		0.121	0.121	0.121	-0.583
Max	3.388		3.388	3.388	3.388	4.060
R2	0.719		0.649	0.788	0.776
RMSECV	0.515		0.573	0.446	0.447
SD	0.968		0.968	0.968	0.945	0.910
RPD	1.879		1.690	2.170	2.114

†Min, Max, SD, and RMSECV are in L/kg units.

Validity criteria fulfilled:

yes

Executive summary:

• The aim of this project was to use mid-infrared (MIR) spectroscopic analysis of soils with experimental derived Kdvalues to develop calibration models to predict the solid- solution partitioning (log-Kd) values for tellurium(VI) (T e(VI)) in soils of the EuroGeoSurveys geochemical mapping of agricultural and grazing land soil of Europe (GEMAS).

• Experimental log-Kdvalues and a multivariate partial least squares (PLS) model was developed using 492 selected soils from the 4813 soils of the GEMAS sampling program. A composite PLS model was developed using a combination of both spectral and soil pH data and was found to predict with good accuracy the experimental log-Kdvalues for Te(VI) in calibration soils (n = 292, R2= 0.79).

• Validation of the model was carried out with the 492 soil samples being split into two subsets; the first 292 for calibration and the remaining 200 for validation. The composite PLS model (spectra plus soil pH) developed from the 292 calibration samples was found to predict with good accuracy the log-Kdvalues for Te(VI) in the validation soils (n = 200, R2= 0.78).

• The validated composite PLS model (spectra plus soil pH) was applied to the prediction of log-Kdvalues for Te(VI) in the remaining 4321 soils of the GEMAS sampling program.

The experimantal results for the kd values are between 0.32 and 4650. Based on the statistical calulation a log kd value of 2 - 3 seems to be realistic. For the enivronmental modelling by EUSES the log kd will be stated with 2.

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Justification for type of information:

see section 13.1 for read-across justification

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Principles of method if other than guideline:

A detailed description of method is given under "Any other information on materials and methods".

GLP compliance:

no

Remarks:

Study was not conducted for REACH propose. But information and documentation is sufficient. A replication under GLP is not reasonable.

Media:

soil

Radiolabelling:

no

Analytical monitoring:

yes

Details on matrix:

A total of 4813 soils were sent to CSIRO by Eurometaux for this study. From these, a subset of samples were repeated or replicated by re-scanning.
A total of 492 soils were selected for IR analysis to be used in the development of calibration and validation models.
The FTIR spectral variability in the analysis of soils can be found in supplemental information. Soils were oven dried at 40oC for 12 h and cooled in a desiccator prior to MIR analysis or experimental log-Kd value determinations.
The soil pH in 0.01 M calcium chloride (CaCl2) was provided to CSIRO by Eurometaux (EU).

Type:

Kd

Value:

> 0.32 - <= 4 650 L/kg

Remarks on result:

other: For further details refer to executive summary

Results for the modelling of log-Kd for Te(VI) are shown for PLS modelling using only the DRIFT spectra, univariate regression from pH, and the composite PLS model (DRIFT plus soil pH). Statistics are described by coefficient of determination (R2), root mean square of error for cross validation (RMSECV), standard deviation (SD) and ratio of prediction to deviation (RPD). Statistics are also shown for prediction of the 200 sample validation soil set and the full set of unknown samples from the composite PLS model†.

		Log(Kd+1) PLS (DRIFT model)	Log(Kd+1) univariate model)	Log(Kd+1) PLS (DRIFT+pH model)	Log(Kd+1) (DRIFT+pH validation of the 200 sample Test set	Log(Kd+1) predictions
Min	0.121		0.121	0.121	0.121	-0.583
Max	3.388		3.388	3.388	3.388	4.060
R2	0.719		0.649	0.788	0.776
RMSECV	0.515		0.573	0.446	0.447
SD	0.968		0.968	0.968	0.945	0.910
RPD	1.879		1.690	2.170	2.114

†Min, Max, SD, and RMSECV are in L/kg units.

Validity criteria fulfilled:

yes

Executive summary:

• The aim of this project was to use mid-infrared (MIR) spectroscopic analysis of soils with experimental derived Kdvalues to develop calibration models to predict the solid- solution partitioning (log-Kd) values for tellurium(VI) (T e(VI)) in soils of the EuroGeoSurveys geochemical mapping of agricultural and grazing land soil of Europe (GEMAS).

• Experimental log-Kdvalues and a multivariate partial least squares (PLS) model was developed using 492 selected soils from the 4813 soils of the GEMAS sampling program. A composite PLS model was developed using a combination of both spectral and soil pH data and was found to predict with good accuracy the experimental log-Kdvalues for Te(VI) in calibration soils (n = 292, R2= 0.79).

• Validation of the model was carried out with the 492 soil samples being split into two subsets; the first 292 for calibration and the remaining 200 for validation. The composite PLS model (spectra plus soil pH) developed from the 292 calibration samples was found to predict with good accuracy the log-Kdvalues for Te(VI) in the validation soils (n = 200, R2= 0.78).

• The validated composite PLS model (spectra plus soil pH) was applied to the prediction of log-Kdvalues for Te(VI) in the remaining 4321 soils of the GEMAS sampling program.

The experimantal results for the kd values are between 0.32 and 4650. Based on the statistical calulation a log kd value of 2 - 3 seems to be realistic. For the enivronmental modelling by EUSES the log kd will be stated with 2.

Key value for chemical safety assessment

Other adsorption coefficients

Type:

log Kp (solids-water in sediment)

Value in L/kg:

100

at the temperature of:

21 °C

Other adsorption coefficients

Type:

log Kp (solids-water in soil)

Value in L/kg:

100

at the temperature of:

21 °C

Additional information

The experimantal results for the kd values are between 0.32 and 4650. Based on statistical calulation a log kd value of 2 - 3 seems to be realistic. For the enivronmental modelling by EUSES the log kd will be stated with 2.

Based on data from selenium, which is considered to be the most comparable element, in a first approach for the partition coefficients solids-water in sediment and solids-water in soil the same order of magnitude is assumed.