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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to solid soil phase is not expected.

Key value for chemical safety assessment

Additional information

In accordance with Annex VIII, Column 2 a study on adsorption/desorption does not need to be conducted since based on PC parameters of the substance (logPow -0.74) adsorption is not expected. In accordance to Annex XI of Regulation (EC) No 1907/2006 the standard testing regime may be adapted, if test does not appear scientifically necessary. The present compound exhibits a conjugated system with a core structure of completely delocalized electrons. A delocalized electron system results in thermodynamically very stable molecules which at least partially prevents the interaction with neighboring surfaces. Due to the limited interaction caused by the lack of functional groups and the high stability of the substance, significant adsorption/desorption is not expected.
Furthermore, according to Appendix R7-1 for nanomaterials applicable to Chapter R7a, nanoparticles strive to reduce their surface energy by attaching to each other. This attachment can be homoagglomeration/aggregation between the nanoparticles, heteroagglomeration/aggregation with other particles or organic matter or to the interface between phases. In Regulation (EC) No 2018/1881 which amends Regulation (EC) No 1907/2006 it is stated, that data about dispersion stability may significantly influence the endpoint adsorption and estimations of exposure to nanoforms. In this case an OECD 318 study concerning dispersion stability resulted in a quick agglomeration and sedimentation of the substance, meaning homoagglomeration. Thus, stability of discrete particles in the nano size scale in the water phase is unlikely. Hence, existence of nanoforms in environmental systems is unlikely and due to agglomeration, an adsorption effect based on its nano scale properties can be excluded. Thus, sorption of the substance to soil particles is very unlikely and no study deemed necessary.