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Adsorption / desorption

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Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Metal-EDTA chelates in aqueous and solid phases were determined by GC-NPD after one month's contact time under static conditions
GLP compliance:
no
Type of method:
batch equilibrium method
Media:
sediment
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
Sodium and iron complexes were tested by preparing solutions containing equimolar amounts of metal and EDTA (0.66E-5 mol/dm3), which were left overnight to make sure that the corresponding metal complexes were quantitatively formed.
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
Pore water and sediment samples were taken after one month contact time.
Details on matrix:
- Details on collection (e.g. location, depth, contamination history, procedure: Surface sediment sample was taken at depths of between 5 and 10 m using Ekman bottom sampler at Lake Saimaa, Finland)
Details on test conditions:
TEST SYSTEM
- Type, size and further details on reaction vessel: flasks
- Soil/sediment/sludge-water ratio: 12g sediment and 500 mL distilled water
Remarks on result:
not measured/tested
Sample no.:
#1
Duration:
1 mo
% Adsorption:
9
Remarks on result:
other: NA-EDTA
Sample no.:
#2
Duration:
1 mo
% Adsorption:
24.8
Remarks on result:
other: Fe(III)-EDTA
Transformation products:
not measured
Validity criteria fulfilled:
not applicable
Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Metal-EDTA chelates in aqueous and solid phases were determined by scintillation after 48h contact time under static conditions
GLP compliance:
no
Type of method:
batch equilibrium method
Media:
sediment
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
[14C] EDTA ( 9.4 Ci mo1-1, radiochemical purity 98%) was obtained from Sigma. This was converted into its Fe complex by reaction with a slight stoichiometric excess of Fe before use.
Radiolabelling:
yes
Test temperature:
22 °C
Analytical monitoring:
yes
Details on test conditions:
TEST CONDITIONS
- pH: 7.2

TEST SYSTEM
- Type, size and further details on reaction vessel: 30 ml screw-cap tubes
- Water filtered (i.e. yes/no; type of size of filter used, if any): yes (distilled)
- Amount of soil/sediment/sludge and water per treatment: 1g sediment and 10 mL distilled water
Key result
Sample No.:
#1
Type:
Koc
Value:
3.35 L/kg
Temp.:
22 °C
Matrix:
Sediment
Remarks on result:
other: Fe(III)-EDTA

In the partition experiments using 14C-labelled EDTA (Fe) there was a loss of radioactivity into the sediment phase within 1 h, but this could be accounted for by the presence of known radiochemical impurities in the substrates (halogenated acetic acids). Thereafter, the concentrations in the aqueous phase diminished slowly during 48h to values that were >98% of the initial values. From the differences between the initial and final concentration in the aqueous phase, the Koc value (1 kg-lorganic carbon) was calculated to be 3.35 L/kg for the Fe complex and 1.7 L/kg for the Mn complex.

Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
Movement and reaction of EDTA were evaluated using the miscible displacement technique
GLP compliance:
no
Media:
soil
Radiolabelling:
yes
Matrix no.:
#1
Matrix type:
clay loam
% Clay:
29.3
% Silt:
43.3
% Sand:
27.4
% Org. carbon:
4.9
pH:
7.35
Bulk density (g/cm³):
1.33
Matrix no.:
#2
Matrix type:
silt loam
% Clay:
18.4
% Silt:
30.8
% Sand:
50.8
% Org. carbon:
3.6
pH:
7.3
Bulk density (g/cm³):
1.4
Remarks on result:
not measured/tested
Endpoint:
adsorption / desorption, other
Remarks:
influence of water hardness to the complexation of trace metals
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
EDTA (19 µg/L) labelled with C-14 was added to suspensions of representative solids and the proportion remaining in solution was determined at intervals.
GLP compliance:
no
Type of method:
batch equilibrium method
Media:
other: particulate humic acid (300 mg/L), kaolin (650 mg/L) and silica (500 mg/L)
Specific details on test material used for the study:
RADIOLABELLING INFORMATION
Test substance: [14C]-EDTA
Supplier: Radiochemical Centre, Amersham
Radiopurity: no data
Radiolabelling:
yes
Analytical monitoring:
yes
Matrix no.:
#1
Matrix type:
other: humic acid
Matrix no.:
#2
Matrix type:
other: kaolin
Matrix no.:
#3
Matrix type:
other: silica
Details on matrix:
Particulate humic acid (300 mg/L), kaolin (650 mg/L) and silica (500 mg/L) werte suspended separately in hard ground water, river sediment (7.0 g/L) suspended in river water (both from R. Hiz, Arlesey, Herts) and a sample of effluent containing 40 mg solids/Lt from a percolating filter.
Remarks on result:
not measured/tested

The extent of adsorption of EDTA on container walls and on humic acid, silica, kaolin, river sediment and humus solids (in effluent from a percolating filter treating domestic sewage) was measured and was found  to be negligible, even after contact periods of up to 48 h. The EDTA was almost entirely present in the form of negatively-charged complexes with alkaline earth and trace metals, and neither of these complexes nor the free or protonated ligand itself could have been significantly adsorbed on the surfaces of the solids.

Endpoint:
adsorption / desorption: screening
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance has a low octanol water partition coefficient and the adsorption potential of this substance is related to this parameter
the study does not need to be conducted because the physicochemical properties of the substance indicate that it can be expected to have a low potential for adsorption
Endpoint:
adsorption / desorption: screening
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, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
QMRFs and QPRFs are attached.
Principles of method if other than guideline:
Calculation based on KOCWIN v2.00, Estimation Programs Interface Suite™ for Microsoft® Windows v 4.10. US EPA, United States Environmental Protection Agency, Washington, DC, USA.
GLP compliance:
no
Type of method:
other: calculation
Media:
soil
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Smiles code: O([Na])C(=O)CN(CCN(CC(=O)(O([Na])))CC(=O)(O([Na])))CC(=O)(O([Na]))
- Molecular weight: 380.17 g/mol
Test temperature:
25 °C
Key result
Type:
Koc
Value:
312.7 dimensionless
Temp.:
25 °C
Remarks on result:
other: MCI method; The substance is not fully within the applicability domain of the model.
Key result
Type:
log Koc
Value:
2.49 dimensionless
Temp.:
25 °C
Remarks on result:
other: MCI method; The substance is not fully within the applicability domain of the model.
Type:
Koc
Value:
0 dimensionless
Temp.:
25 °C
Remarks on result:
other: log Kow method; The substance is not fully within the applicability domain.
Type:
log Koc
Value:
-7.25 dimensionless
Temp.:
25 °C
Remarks on result:
other: log Kow method; The substance is not fully within the applicability domain.

Koc Estimate from MCI:

---------------------

First Order Molecular Connectivity Index ........... : 9.201

Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 5.3964

Fragment Correction(s):

6  Nitrogen to Carbon (aliphatic) (-N-C).. : -1.2764

*  Organic Acid (-CO-OH) ............... : -1.6249

Corrected Log Koc .................................. : 2.4952

 

Estimated Koc: 312.7 L/kg  <===========

 

Koc Estimate from Log Kow:

-------------------------

Log Kow (Kowwin estimate) ......................... :-13.17

Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : -6.3596

Fragment Correction(s):

6  Nitrogen to Carbon (aliphatic) (-N-C).. : -0.1307

*  Organic Acid (-CO-OH) ............... : -0.7694

Corrected Log Koc .................................. : -7.2597

 

Estimated Koc: 5.499e-008 L/kg  <===========

 

Endpoint:
adsorption / desorption: screening
Remarks:
adsorption
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Justification for type of information:
Read across justification document is attached in chapter 13.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Key result
Sample No.:
#1
Type:
Koc
Value:
3.35 L/kg
Temp.:
22 °C
Matrix:
Sediment
Remarks on result:
other: Fe(III)-EDTA
Sample no.:
#1
Duration:
1 mo
% Adsorption:
9
Remarks on result:
other: Na-EDTA
Sample no.:
#2
Duration:
1 mo
% Adsorption:
24.8
Remarks on result:
other: Fe(III)-EDTA

Description of key information

The adsorption potential of Tetrasodium ethylenediaminetetraacetate is low.

Key value for chemical safety assessment

Koc at 20 °C:
312.7

Additional information

No study investigating the adsorption potential of Tetrasodium ethylenediaminetetraacetate is available. In accordance with column 2 of REACH Annex VIII, an Adsorption-/Desorption-Screening test (required in chapter 9.3.1) does not need to be conducted, since the log Pow value is very low (-3.86, caused by the ionic nature under environmentally relevant pH conditions, low stability constant) and thus adsorption onto the organic fraction of soil or sediment is not a relevant process in the environment (see also EU Risk Assessment 2004). This is confirmed by experimental results where EDTA was almost entirely present in the form of negatively-charged complexes with alkaline earth and trace metals, and neither of these complexes nor the free or protonated ligand itself could have been significantly adsorbed on the surfaces of the solids (Gardiner 1976). QSAR calculations for undissociated EDTA-Na4 using KOCWin v2.00 resulted in KOC values of 312.7 based on MCI method and 5.4E-8 based on the log KOW method, respectively. The test substance did not completely fall into the applicability domains of both methods, but results are considered sufficiently reliable to support the assumption of low adsorption potential in a Weight-of evidence approach. Taken all available data into account a KOC of 312.7 L/kg was used for the risk assessment of Tetrasodium ethylenediamintetraacetate. This value was chosen, since it is the highest value in the data set and thus enable the most conservative risk assessment for the terrestrial compartment for which relevant effects were determined.