Heterocyclic polyaromatic hydrocarbons (heterocyclic PAHs) are frequently found in the environment yet, compared to homocyclic PAHs, little attention has been paid to their environmental behavior and a comprehensive hazard assessment has not been undertaken. Surprisingly, the physicochemical data necessary to perform at least a screening-level assessment are also limited. To address this, we began by experimentally determining the physicochemical properties of heterocyclic PAHs, namely, water solubility (Sw), n-octanol-water partition coefficients (Kow), and organic carbon-water partition coefficients (Koc). The physicochemical data obtained in this study allowed for the development of clear structure-property relationships and evaluation of the predictive power of in silico models including conductor-like screening model for realistic solvation, the poly-parameter linear solvation energy relationship, and the quantitative structure-property relationship. Finally, heterocyclic and homocyclic PAHs were evaluated in terms of persistence, bioaccumulation, mobility, and toxicity to perform a screening-level comparative hazard assessment by integrating the data and evidence from multiple sources.
Keywords: environmental hazard screening; heterocyclic PAHs; hydrophobicity; mobility; water solubility.