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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Using QSAR, the Koc value for C14-17 chlorinated paraffins was calculated to be 588,844 L/kg.
Log Koc values of 5.0 and 5.2 (and corresponding Koc values of 103,846 and 175,333 L/kg) were determined in sediment for two C16 chlorinated paraffins (34 and 69% chlorination, respectively).

Key value for chemical safety assessment

Additional information

Using the QSAR equation for predominantly hydrophobic chemicals given in the Technical Guidance Document (log Koc=0.81 log Kow + 0.10), and a log Kow value of 7.0, the Koc value for C14-17 chlorinated paraffins can be estimated as 588,844 (L/kg) (EU, 2005).

 

The organic carbon-water partition coefficients (Koc) for two C16 chlorinated paraffins (34 and 69% chlorinated) have been assessed in a study to determine their adsorption to sediment and their subsequent sediment-sorbed depuration by the oligochaete worm, Lumbriculus variegatus, using sediment spiked with 14C-labelled materials. Organisms were exposed to the spiked sediment for 14 or 21 days and depuration followed up to day 56 of the study. Concentrations of the C16 chlorinated paraffins in sediment, interstitial water and worms were determined by radiochemical analysis and the concentrations of freely dissolved and bound organic carbon in interstitial water by Sep-Pak chromatography. The log Koc values of 5.0 and 5.2 for the two C16 chlorinated paraffins (34 and 69% chlorination, respectively) were calculated from the sediment sorption partition coefficient (Kp) and the fraction of organic carbon in the sediment (foc) (Fisk et al. 1998).