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Environmental fate & pathways

Adsorption / desorption

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Description of key information

There are no adsorption/desorption test data for the test substance. It is assumed that equilibrium partitioning to soil and associated organic matter is an irrelevant fate mechanism. As the MDI substances will be rapidly reacted with associated pore water, adsorbed water, and organic matter associated with soil particles, no accumulation is expected in soil. Because of this reactivity, the migration of MDI substances through soil is not possible, and the substance cannot occur as a contaminant in groundwater. A Koc value of 8200 L/kg can be estimated with the Molecular Connectivity Index of the Estimation Program Interface Suite (v.4.00, 2009) for monomeric MDI. However, this value has no scientific meaning due to the reactivity of MDI substances with water (interstitial pore water).

Key value for chemical safety assessment

Additional information

The test substances of the methylenediphenyl isocyanate (MDI) category react quickly with water and hence will be rapidly hydrolysed in contact with aqueous media (T1/2 = 20h). As a result, persistence in soil is unlikely.