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Endpoint:
adsorption / desorption: screening
Type of information:
other: expert statement
Adequacy of study:
key study
Study period:
November-December 2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Cross-reference
Reason / purpose for cross-reference:
reference to other study
Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 August 1995 - 13 October 1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-compliant study in accordance with EC A.6 and OECD 105.
Qualifier:
according to guideline
Guideline:
EU Method A.6 (Water Solubility)
Version / remarks:
(1992)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 105 (Water Solubility)
Version / remarks:
(1981)
Deviations:
no
GLP compliance:
yes
Type of method:
other: column elution method and chemical analysis
Water solubility:
< 2.4 mg/L
Temp.:
20 °C
Remarks on result:
other: pH: not measured
Details on results:
- Column 1: The concentration of the test substance decreased in time. No steady state was reached. The samples probably contained undissolved test substance particles.
- Column 2: The results of the low and high flow rates were not in agreement with each other. The concentration of the test substance (based on Al) at the highest flow rate was below the detection limit of 3.7 mg test substance/L, whereas at the lowest flow rate high values were measured (between 7.7 and 30.5 mg test substance/L).
- Additional stirring experiment: No significant differences were found after the ultracentrifuge step and after the ultracentrifuge+filtration step (see the table below). However, it is possible that particles with a diameter <0.2 µm were present. Therefore it was concluded that the water solubility of the test substance is best described as the mean of the 4 samples, by a lower than value: < 2.4 mg/L.
- As the LOD of the column elution method with the substance was 3.7 mg test substance/L, calculated based on Al concentration, it was concluded that it was not possible to obtain a more accurate value.

Additional stirring experiment:

Sample description

Measured concentration of Mg

[mg/L]

Measured concentration of Al

[mg/L]

Concentration of the test substance, calculated based on Al concentration

[mg/L]

Mean

[mg/L]

Blank

0.20

<0.078

<0.85

Blank

0.108

<0.078

<0.85

After ultracentrifuge

143

0.29

3.26

2.4

After ultracentrifuge

144

0.18

1.96

After ultracentrifuge + filtration

147

0.22

2.40

After ultracentrifuge + filtration

149

0.17

1.85

 

Conclusions:
Interpretation of results (migrated information): other: < 2.4 mg/L
In a GLP-compliant study in accordance with EC A.6 and OECD 105 using the column elution method and an additional experiment in which the substance was stirred with water followed by (ultra)centrifugation and filtration, the water solubility of the substance at 20°C has been estimated as < 2.4 mg/L. The substance is not stable in water, releasing a Mg-salt upon contact with water. The water solubility of the substance was calculated based on measured Aluminium concentrations.

Data source

Reference
Reference Type:
other: Expert statement
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The suitability/applicability of available test guidelines for adsorption/desorption was theoretically assessed in relation to the inorganic nature of the substance.
GLP compliance:
no
Type of method:
other: theoretical assessment of the suitability/applicability of available test guidelines (HPLC, QSAR and batch equilibrium)

Test material

Constituent 1
Chemical structure
Reference substance name:
-
EC Number:
422-150-1
EC Name:
-
Molecular formula:
Hill formula: Mg4.3 Al2(OH)12.6 (CO3)0-0.75 (ClO4)0.5-2.0 . (0-5)H2O CAS formula: Mg4.3 Al2(OH)12.6 (CO3)0-0.75 (ClO4)0.5-2.0 . (0-5)H2O
IUPAC Name:
carbonic acid perchloric acid alumane dihydrate magnesium dihydride
Test material form:
solid: particulate/powder
Details on test material:
- Appearance: White powder
- Storage condition of test material: At room temperature

Results and discussion

Adsorption coefficientopen allclose all
Key result
Type:
log Koc
Remarks on result:
not determinable
Remarks:
- HPLC screening method not applicable for inorganic substances
Key result
Type:
log Koc
Remarks on result:
not determinable
Remarks:
- QSAR (based on log Pow) not applicable due to lack of Pow data (not possible/meaningful to determine for inorganic substances)

Any other information on results incl. tables

Column 2 of the REACH Annex VIII endpoint point 9.3.1. (Adsorption/desorption screening) provides 2 specific adaptation rules from the standard information requirements. However, these adaptation rules cannot be applied to inorganic substances for the following reasons:

- the potential for adsorption based on e.g. a low octanol water partition coefficient cannot be assessed for inorganic substances because the octanol water partition coefficient of inorganic substances can usually not be determined (e.g. due to solubility issues).

- rapid decomposition of degradation products is not applicable because inorganic substances do not degrade in a similar fashion as organic substances.

Proposed screening methods, such as the HPLC estimation method or QSAR, are not deemed applicable due to the inorganic nature of the substance, its poor solubility in water and commonly used solvents in the HPLC screening test as well as expected detection issues. In addition, the HPLC estimation method is not validated for inorganic substances, as pointed out in the test guidelines (OECD 121 and EU C.19). Furthermore, no valid QSAR models are available for inorganic substances to predict physico-chemical properties, so it is not possible to provide e.g. a calculated log Pow value (nor details of the calculation method, or details on the applicability domain of the model), and thus calculation of log Koc (based on log Pow) is also not possible.

Finally, the applicability of performing a batch equilibrium method was assessed. Considering that, due to the inorganic nature of the substance in combination with its poor solubility in water, most of the parameters required as a pre-requisite for performing an OECD 106 test (abiotic degradation, log Pow, ready biodegradability, pKa and direct photolysis in water) cannot be acquired, and taking into account that analytical monitoring of the substance as such (or dissolved ions) in test solutions at very low concentrations is not expected to be accurate and reliable, due to sensitivity issues, it was concluded that a batch equilibrium test very likely cannot be performed either.

Applicant's summary and conclusion

Conclusions:
Based on available physico-cemical information and in view of the inorganic nature of the substance it is concluded that it is considered scientifically justified to waive testing for adsorption/desorption of this inorganic substance.