IS IT SAFE TO GROW VEGETABLES IN SOILS SURROUNDING ESTARREJA CHEMICAL COMPLEX (PORTUGAL)?

Accumulation of hazardous elements in soils through anthropogenic activity may not only result in soil contamination but also affect food safety and quality and even human or animal health. This study was carried out in an urban area (Estarreja, NW Portugal) that is located around one of the most important portuguese poles of industrial chemical. Twenty-six small farms or kitchen gardens, all used by local inhabitants to grow edible vegetables for their own consumption, were selected to assess As, Cd, Hg and Pb concentration in soil and vegetables and to estimate daily intake doses from its consumption. Edible parts of cabbage, tomato and maize and the rizosphere soil of the respective crops were collected and analyzed by ICP/ES-MS after extraction with aqua regia (“near total” soil and foodstuffs concentration) and also after soil leaching with ammonium acetate (soil available fraction). The results show that 46%, 11.5% and 7.6% of the soil samples present total As, Hg and Pb concentrations that exceed protective Health Canadian Soil Quality Guidelines for agricultural purposes. The estimated soil available fractions were low for all elements (As< 12%; Hg< 0.4%; Pb< 23%) except for Cd that ranged between 20 and 96% of the total. The cabbage leaves concentrate more As, Hg, Pb and Cd (max.: 3.5, 0.08, 0.46 and 1.13 mg/kg dw, respectively) than the tomato fruit (max.: 0.4, 0.02, 0.4 and 0.5 mg/kg dw, respectively) or the maize ears (max.: 0.3, 0.004, 0.02 and 0.09 mg/kg dw, respectively). Daily intakes of the analysed elements from consumption of cabbage (50 g) and tomato (120 g) by an adult were 26 µg (As), 0.8 µg (Hg), 4.45 µg (Pb) and 12 µg (Cd). Although both vegetables contribute to exposure doses that were below the provisional tolerable weekly intake values set by WHO/FAO, it seems advisable to analyze other crops to ensure that is safe to grow and consume them, taking into account that some local soils are considered to be contaminated.