Risk assessment of urban soils contamination: The particular case of polycyclic aromatic hydrocarbons

The assessment of soil quality and characterization of potential risks to the environment and human health can be a very difficult task due to the heterogeneity and complexity of the matrix, the poor understanding about the fate of contaminants in the soilmatrix, scarcity of toxicological/ecotoxicological data and variability of guidelines. In urban soils these difficulties are enhanced by the patchy nature of urban areas and the presence of complex mixtures of organic and inorganic contaminants resulting from diffuse pollution caused by urban activities (e.g. traffic, industrial activity, and burning of carbon sources for heating). Yet, several tools are available which may help to assess the risks of soil contamination in a simpler, cost effective and reliable way. Within these tools, a tiered risk assessment (RA) approach, first based on a chemical screening in combination with geostatistical tools, may be very useful in urban areas. However, there is still much to improve and a long way to go in order to obtain a reliable RA, especially in the case of hydrophobic organic compounds such as polycyclic aromatic hydrocarbons (PAHs). This paper aims at proposing a RA framework to assess the environmental and human health risks of PAHs present in urban soils, based on existing models. In addition, a review on ecotoxicological, toxicological, and exposure assessment data was made, as well as of the existing soil quality guidelines for PAHs that can be used in the RA process. (C) 2016 Elsevier B.V. All rights reserved.