Bioassays for evaluation of sanitary risks from food crops cultivated in potentially contaminated sites

Environmental pollution in agricultural contexts cannot be neglected since food crops can be an important exposure pathway for soil pollutants. In Italy the Law on the Environment (Law Decree 152/2006) is unclear with regard to agricultural areas, since the specific regulation provided for in Art. 241 has not been enacted. Current risk analysis is based only on direct risk (i.e. via ingestion and inhalation of soil particles), while indirect risk via food consumption is not considered. For defining potential risks for consumers, assessment of exposure to potentially toxic elements (PTEs) can be made through the analysis of their content in food crops and the estimation of the related hazard quotient (HQ) based on the ratio between PTE intake through food and the health risks due to PTE doses during a lifetime. In order to obtain a precautionary estimate, the worst case approach was followed by selecting species well known for their PTE accumulation capacity, such as chicory (Cichorium intybus L.), lettuce (Lactuca sativa L.), spinach (Spinacia oleracea L.), radish (Raphanus sativus L.) and rocket salad (Eruca vesicaria L.), and by cultivating these plants in hotspots with the highest PTE concentrations. The PTE contents in such crops show wide variability, with values from 0.005 to 0.054 mg kg–1 for arsenic (As), from 0.004 to 3.9 mg kg–1 for cadmium (Cd), from 0.17 to 0.79 mg kg–1 for chromium (Cr), from 0.22 to 1.18 mg kg–1 for copper (Cu), from 0.03 to 0.43 mg kg–1 for lead (Pb) and from 1.43 to 25.06 mg kg–1 for zinc (Zn). Lead and Cd contents in vegetables exceeded thresholds established by EC Reg. 1881/2006 in 14% and 25% of samples, respectively. By contrast, from HQ analysis, any potential risk of dietary exposure due to ingestion of As, Cr, Cu, Pb or Zn was excluded. Only Cd content in lettuce, spinach and chicory resulted in a potential health risk due to intake of such foodstuffs. The proposed method could resolve the lacuna in current Italian legislation regarding the evaluation of risks for human health due to the intake of contaminants through the food chain.