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Adsorption / desorption

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Description of key information

A measured Koc is not available for alkenes C24 - 28. A log Koc of >6.56 has been calculated using a QSAR. 

Key value for chemical safety assessment

Additional information

A measured Koc is not available for alkenes C24 - 28. Based on read across their measured log Kow is >3 so the adsorption/desorption endpoint cannot be waived. However, ECHA's Guidance on Information Requirements and Chemical Safety Assessment R7a Endpoint Specific Guidance (2008) indicates that before commissioning a new study alternative sources of data (e.g. QSARs) on the adsorption/desorption potential of a chemical should used. If the calculated Koc proves to be influential in the risk assessment then it may be necessary to conduct a new study.

Soil sorption of non-ionic substances can be estimated from their log Kow. Several QSARs have been developed that calculate the Koc of non-polar hydrocarbons on the basis of their log Kow (e.g. Sabljic and Gusten, 1995). The log Kow range of alkenes C24 - 28 falls outside the applicability domain of this model. There is a clear trend across this category of increasing log Koc with increasing carbon number. Therefore, on the basis of read across from hexadecene the log Koc is >6.56.