Uptake of heavy metals by vegetable plants grown on contaminated soil and their bioavailability in the human gastrointestinal tract

Abstract

Lettuce, spinach, radish and carrot were grown on compost that had previously been contaminated at different concentrations of Cd, Cu, Mn, Pb and Zn. Control plants of each vegetable were also grown on unadulterated compost. The experiment was carried out under greenhouse conditions. Mature plants were harvested and their roots and leaves collected. Soil samples from each growing pot and plant materials were acid digested and analysed to determine total metal concentration. Flame-Atomic Absorption Spectroscopy (FAAS) was employed to determine metal concentrations in soil and plant samples (Mn and Zn), while Cd, Cu and Pb in plant materials were analysed by Differential Pulse Anodic Stripping Voltammetry (DP-ASV). Soil (BCR 146R and GBW 07310) and plant (tea leaves, INCT-TL-1) certified reference materials were used to assess accuracy and precision. The edible part of plants, i.e. the leaves of lettuce and spinach and the roots of radish and carrot, were also extracted using an in vitro gastrointestinal (GI) extraction to assess metal bioavailability. The results showed that the uptake of Cd, Cu, Mn and Zn by plants corresponded to the increasing level of soil contamination, while the uptake of Pb was low. Soil-to-plant transfer factor (TF) values decreased from Mn ) Zn > Cd > Cu > Pb. Moreover, it was observed from this investigation that individual plant types greatly differ in their metal uptake, e.g. spinach accumulated a high content of Mn and Zn, while relatively lower concentrations were found for Cu and Pb in their tissues. From the in vitro gastrointestinal (GI) study, results indicate that metal bioavailability varied widely from element to element and according to different plant types. The greatest extent of metal releasing was found in lettuce (Mn, 63.7%), radish (Cu, 62.5%), radish (Cd, 54.9%), radish (Mn, 45.8%) and in lettuce (Zn, 45.2%).

Detection of heavy metals in common vegetables at Varaždin City Market, Croatia

“…The concentrations of heavy metals in plants largely depend on the concentrations of heavy metals in the soil (9,10). In our study, the overstepping of maximum levels for Cd and Pb in vegetable samples was most likely due to soil contamination with these heavy metals.…”

“…A phytosanitary strategy has been created to set guidelines for the development of plant-health national policy in Croatia (60). Although various factors may contribute to elevated concentrations of heavy metals in food, soil contamination is one of the most important (9,10). A programme for permanent monitoring of the soil in Croatia has been developed; however, data regarding the state of the soil has still not been collected (61,62).…”

IDENTIFICATION OF LEAD AND CADMIUM LEVELS IN WHITE CABBAGE (Brassica rapa L.), SOIL, AND IRRIGATION WATER OF URBAN AGRICULTURAL SITES IN THE PHILIPPINES

“…Pb mainly reaches leaves by aerial deposition. Likewise, the aerosol-deposited Pb particles do not penetrate the cuticle of leaves but tend to adhere to leaf surfaces (Caselles 1998;Intawongse and Dean 2006;Nabulo et al 2006;Kuang et al 2007). Basically, Pb content in crops grown in uncontaminated areas as cited by Umali (1999) and Flynn (1999) ranged from 0.1 to 10 ppm dry weight.…”

Mn- and Cd-Contaminated Wild Water Spinach: in vitro Human Gastrointestinal Digestion Studies, Bioavailability Evaluation, and Health Risk Assessment

“…It was shown that the total metal content was different among the digestion phases (HNO₃, gastric, intestinal, and residual). For example, the Mn bioaccessibility in the lettuce (Lactuca sativa L.) leaves decreased in the order of gastric > residual > intestinal [98], while [99] revealed that the solubility of Cd in the cock's comb (Celosia argentea L.) followed the order gastric > residual > intestinal. The bioaccessibility of metals from the different digestion phases is dependent on several factors such as the digestion and release of the ingested food matrix [100].…”