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Environmental fate & pathways

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Members of the butenes category are considered to be readily biodegradable on the basis of a weight of evidence approach using data from QSARs and studies that have isolated but-1-ene degrading micro-organisms. The butenes are also expected to have low potentials for bioaccumulation and adsorption to soil and sediment based on their measured log Kow of 2.31 to 2.4. Structural analysis of the butene molecules indicates that they are not expected to undergo hydrolysis in the environment due to the lack of hydrolysable functional groups. The physico-chemical properties of butenes indicate that the majority of the substances will ultimately be released to the atmosphere where they are quickly photo-oxidised in approximately 0.5 days to 0.75 days.

The butenes are not expected to persist in the environment because they are predicted to degrade rapidly, have a low potential for adsorption to organic matter and have a low potential for bioaccumulation. Therefore, in the PBT assessment, butenes are considered to be not P/vP and not B/vB.