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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The testing for adsoption coefficient has been assessed as unnecessary for this substance based on a number of factors as discussed below

Key value for chemical safety assessment

Additional information

No experimental determination of the adsorption coefficient of the test material was considered to be justified based on a combination of factors.The test item is determined to be essentially insoluble in water at normal environmental pH range of 4-9. The test item is a synthetic version of naturally occurring clay derivative (hectorite) which is essentially a mineral fraction of soil already.Therefore the regulatory end point of distribution coefficient and/or organic carbon normalised adsorption coefficient may not be valid or relevant for this test item. Although it must be recognised that the physical and chemical characteristics of a soil would be altered by the accidental release of a significant quantity of the test item, physical recovery would probably be feasible in the absence of significant disturbance, and certainly equilibration between an aqueous dissolved fraction and an organic carbon content absorbed fraction as addressed by the method guideline would not be anticipated be a significant mechanism for transport through the soil and water tables. The past environmental application of the test item and related substances must be recognised without evidence of recorded, significant adverse effects. Laponite®, which is a commercial product of this substance, has applications in agriculture and horticulture as an inert ingredient in formulations applied to growing crops or to raw agricultural crops after harvest. It is used as a medium for seed germination and a rooting medium and also as a non-toxic antistatic and barrier coating for seeds