Estimating Koc for persistent organic pollutants: limitations of correlations with Kow

The n-octanol/water partition coefficient (Kow) is commonly used to predict the soil or aquatic particle water partition coefficient normalized to organic carbon (Koc). Many correlations are available covering several chemical classes and ranges of hydrophobicity. This work indicates the Kow may not be a strong predictor for persistent organic pollutants (POPs) which are defined here as chemicals with logKow>5.0. In addition, the correlation developed in this work for POPs will still result in a predicted value which is of by a factor of 15. Accordingly, care must be taken when applying Koc estimations using Kow for POPs until more suitable correlations are developed.