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Adsorption / desorption

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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

Description of key information

According to REACh regulation EG Nr. 1907/2006 Annex VIII Column 2, the study does not to be conducted if based in physicochemical properties the substance can be expected to have a low potential for adsorption (log Kow).

This requirement is met by the test item with a log Kow of -2.28.  The Log Koc is expected to be in the range of 1.

Key value for chemical safety assessment

Additional information

The substance has not been tested as a study is scientifically not justified.


The substance is a high molecular weight complex, self-assembled via organized network of hydrogen bonds and aromatic ring stacking. The molecules of melamine and cyanuric acid are strongly bound in the crystal lattice and require considerable energy to remove them. The absence of a melting point, the high decomposition temperature and the poor solubility in any solvent is a consequence of this complexation behaviour. The substance is only defined through the solid state. In such a case, water solubility is the composition of the aqueous solution formed at equilibrium under a defined set of conditions. Due to the measurement of solubility, the composition consists of dissolved melamine and dissolved cyanuric acid. Therefore read-across it is justified from the supporting substances melamine or cyanuric acid.


For the component 108 -78 -1(melamine):

The QSAR-estimated logKoc is low, i.e. in the range of 1.1 to 1.5, depending on the 2 methods used. A relevant adsorption of melamine to soil is therefore not expected.


For the component cyanuric acid (CAS 108-80-5):

The QSAR-estimated logKoc is low, i.e. in the range of 0.7 to 1.9, depending on the 2 methods used. A relevant adsorption of cyanuric acid to soil is therefore not expected.