Risk of contamination for edible vegetables growing on soils polluted by polycyclic aromatic hydrocarbons

Former industrial sites represent a potential source for food chain contamination if they are converted to residential use where garden practices may be undertaken. In order to assess the risk for human health through vegetable consumption, two research programs were initiated to evaluate the bioavailability of selected PAHs and their potential transfer to edible parts of different vegetables. With this intention, we tested four methods to predict the potential contamination of vegetables growing on polluted soils (wild plant analysis, cropping of vegetables on polluted soils, models of organic pollutant transfer soil selective chemical extractions). Various wild plant species colonized naturally the contaminated soils of former industrial sites and edible vegetables grew on these soils without symptoms of phytotoxicity. When soils presented concentrations ofpollutants compatible with residential land use, no significant concentration of PAHs was measured in the different tissues. Moreover, in soils highly polluted by PAHs significant soil-root-leaf transfers of pollutants were showed, but no PAHs were found in fruits and in storage organs. We noted a similar behavior of cultivated vegetables and of their wild analogous plants facing organic pollutants. In another way, two selective chemical extraction methods correctly evaluated the soil PAH bioavailable fraction for plants growing on low-polluted soil. This would allow the use of wild plants naturally present on polluted soils in parallel with soil chemical extraction methods to assess the risk of contamination of the food chain.