Metals and Metalloids in Wild Asparagus at Uncontaminated and Mining-Contaminated Sites

Wild edible plants are often considered healthier than crops because they are unaffected by fertilizers, herbicides, and pesticides. However, the occurrence of potentially toxic elements in wild plants is poorly known and needs to be assessed. In this study, 22 elements were determined by inductively coupled plasma mass spectrometry in wild asparagus ( L.). Asparagus shoots were collected in uncontaminated environments (20 sites) and in areas contaminated by past mining (15 sites) in Sardinia, Italy. Beryllium, Bi, Te, Tl, and U were not detected in asparagus (<0.03 μg g); Ag, As, Co, Cd, Li, and Sb were detected at very low levels (median, 0.01-0.05 μg g); B, Cu, Fe, Mn, Rb, and Zn were relatively abundant (median, 10-58 μg g); and Ba, Mo, Ni, Pb, and Sr showed large variations (median, 0.4, 0.3, 3, 0.1, and 0.5 μg g, respectively). Median concentrations of detected elements were similar in asparagus collected in uncontaminated environments or previously mined areas. An exception was Cd in asparagus collected in mined areas (median, 1.4 μg g), whose levels were much higher than in asparagus from uncontaminated environments (median, 0.01 μg g), indicating that high Cd in bedrocks affect contents in asparagus shoots. Also, Sb- and As-rich substrates in mined areas resulted in asparagus with Sb and As concentrations much higher than asparagus samples from areas mined predominantly for Pb and Zn. Results of this study indicate potential health hazards to residents living worldwide in areas affected by past mining.