Spatial variations, origins, and risk assessments of polycyclic aromatic hydrocarbons in French soils

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants produced by anthropogenic activities that contaminate all environmental spheres, including soils. This study focused on PAHs measured in 2154 soils in France, covering the entire territory based on a regular sampling grid. The quantified concentrations in the Sigma 15 PAHs ranged from 5.1 to 31 200 mu g kg(-1), with a median value of 32.6 mu g kg(-1), and PAHs were detected in 70% of the soil samples. The map of Sigma 15 PAH concentrations revealed strong spatial variations in soil contamination throughout France, with larger concentrations in soils of industrial regions and near major cities. PAH molecular diagnostic ratios support the historical origin of PAHs in the northern part of France being linked to the significant emissions of PAHs in Europe during the industrial period of 1850-1950, in particular with the contribution of coal and/or biomass combustion and iron-steel production. A health risk assessment conducted for the residential population resulted in a median value of 1.07 x 10(-8) in total lifetime cancer risk, with only 20 sites above the limit of 10(-6) and one above the limit of 10(-5) adopted by the French government. These results reveal the need to conduct large-scale studies on soil contamination to determine the fate of PAHs and evaluate the risks induced by soil pollution at a country-level scale.