What is the risk of drinking water downstream from sites polluted with polycyclic aromatic hydrocarbons (PAHs) ? Comparative toxicity of oxygenated polycyclic aromatic compounds (O-PACs) to associated PAHs
Résumé
Introduction: In industrialized countries, a lot of PAH-contaminated sites can be identified. PAH high toxicity has already been demonstrated. However, other polycyclic aromatic compounds (PACs) can be found at these sites and may therefore contribute to the risk for humans and the environment such as oxygenated PACs (O-PACs). O-PACs are emitted from the same sources as PAHs and can be formed by oxidation of the parent PAHs. They show a higher mobility and persistence in soils than PAH, and thus, a possible risk for human by drinking groundwater. In order to better assess the health risk associated to PAH-contaminated sites (former coking plants, gasworks or wood preservation facilities), 11 O-PACs were selected for their frequency of occurrence in groundwater and structural diversity. Method: A literature review summarizing existing data was performed on various toxicological endpoints for all 11 O-PACs. All results were gathered and analyzed in order to compare their toxicity to the associated PAH with the most similar structure. Since O-PACs are not extensively described in the databases, results were completed with (Q)SAR predictions and Threshold Toxicological Concern (TTC) safety assessment. Results: 3 of these compounds were already investigated. Anthraquinone (ANTQ), dibenzofuran (DBF) and 9H-fluorenone (9HF) were compared to their respectively associated PAH: anthracene, acenaphthene and fluorene. In the overall toxicity comparison of ANTQ to its parent compound anthracene, ANTQ seams to represent a greater danger based on a more important carcinogenicity. On the other hand, DBF and 9HF present the same level of toxicity on every studied endpoint compared to acenaphthene and fluorene. Conclusion: This preliminary work demonstrated that O-PACs present at least the same level of toxicity than their associated PAH, suggesting that a follow-up of those molecules could be implemented for groundwater in order to assess its quality.