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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

A measured BCF is not available for alkenes C20 - 24. Log BCFs have been calculated using a QSAR for icos-2-ene and docos-2-ene. Calculated log BCFs are 1.6-2.1.

Key value for chemical safety assessment

Additional information

A measured BCF is not available for alkenes C20 - 24. Based on read across the measured log Kow is >3, so the bioaccumulation endpoint cannot be waived. However, ECHA's Guidance on Information Requirements and Chemical Safety Assessment R7c Endpoint Specific Guidance (2008) indicates that before commissioning a new vertebrate test alternative sources of data on the bioaccumulation potential of a chemical should used.

Non-polar substances have been shown to have a linear relationship between log Kow and BCF in the log Kow range 1 - 6. However, at log Kow >6 a decreasing relationship is observed. Several QSARs have been developed that calculate the BCF of non-polar, hydrophobic compounds on the basis of their log Kow (e.g. Connell and Hawker; 1988, USEPA, 2008). Icos-2-ene and docos-2-ene fall within the applicability domain of the USEPA QSAR, but slightly outside that of Connell and Hawker. The calculated log BCFs range from 1.6 - 2.1.

The log Kow of icos-2-ene and docos-2-ene have been calculated in KOWWIN (log Kow 9.95 and 10.93 respectively) and SPARC (log Kow 11.68 and 12.85 respectively). ECHA's Guidance on Information Requirements and Chemical Safety Assessment - Part C: PBT assessment (2008) states that the aquatic BCF of a substance is probably lower than 2000 l/kg if the calculated log Kow is higher than 10. As none of the log Kow models have experimental data in this log Kow range the reliability of modelled log Kow values >10 is not known. However, as both models indicate a log Kow >10 we can conclude that icos-2 -ene, docos-2 -ene and any substance with a higher carbon number are unlikely to bioaccumulate.

Taken together, this information indicates that alkenes C20-24 are not expected to bioaccumulate or pose a risk of secondary poisoning.