In USEtox, persistent and bioaccumulative chemicals are considered and included in the chemical database. These compounds typically have large characterization factors due to the significant potential for exposure through multiple pathways. If such substances are moderately soluble, this will yield lower eco-exposure factors. However, due to the generally large fate factors (i.e. long persistence in the environment) and higher bioaccumulation potential (reflected in high effect factors), overall characterization factors for such substances are typically large as compared to other chemicals.