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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Members of this category are not expected to be bioaccumulative.

Key value for chemical safety assessment

Additional information

Experimental data on Kow are available for several members of this category. For 68649-11-6 log Kow is measured as >6.5 (Walker and Mullee, 2006) and > 4.82 (Hogg and Bartlett, 1995). For 68649-12-7, experimental data measures log Kow as > 5 (Howard, 1982), > 7.6 (Seary, 2000) and > 3.87 (Hogg and Bartlett, 1995). For 68037-01-4 an experimental value of >6.5 (Walker and Mullee, 2006) is given. As the majority of the experimental log Kow for substances in this category are greater than 4.5 this indicates that an estimate of the bioaccumulation potential is required.

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. 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. All of the experimental log Kow values for substances in this category are unbounded due to limitations of the experimental method, so do not allow us to conclude if the log Kow is greater than 10. Calculated partition coefficients have been obtained from EPIWEB 4.0 (USEPA, 2008) and SPARC (Karickhoff et al, 2009) for dec-1-ene dimer, hydrogenated (CAS 68649-11-6) and dec-1-ene trimer, hydrogenated (CAS 157707-86-3) as these are the only two members of this category being registered as substances with predominantly a single carbon number. The calculated log Kow for 68649-11-6 is 10.09 and 11.71 and for 157707-86-3 is 14.93 and 17.21 (USEPA, 2008 and Karickhoff et al, 2009 respectively). All of the calculated log Kow values are greater than 10.

There is a clear trend of increasing log Kow with increasing carbon number in the alkanes and olefins. Dec-1 -ene dimer hydrogenated (CAS 68649 -11 -6) is the category member with the lowest carbon number, and therefore will be the category member with the lowest partition coefficient. This therefore indicates that the calculated log Kow of all category members would be >10. As QSAR models do not have experimental data in this Kow range the reliability of modelled Kow values > 10 is not known. However, as two models indicate a log Kow >10 for the category member with the lowest carbon number we can conclude that members of this category are unlikely to be bioaccumulative and therefore that conducting a study to determine an experimental BCF is not scientifically justified.