Trace Element Occurrence in Vegetable and Cereal Crops from Parts of Asia: A Meta-data Analysis of Crop-Wise Differences

In the present study, a systematic review along with a meta-analysis was conducted based on relevant studies from 11 Asian countries (1999–2022, Scopus, PubMed, MEDLINE, ScienceDirect, and Google Scholar) to evaluate the crop-wise differences in the accumulation of trace element (TE) in the edible part of different crops (vegetables: leafy (LV), root (RV), fruit (FV); cereal crops: rice (RIC), wheat (WHE), maize (MAZ)). Based on the median concentration of the compiled data, the TE accumulation in different vegetable crops was ranked in the decreasing order of Fe > Zn > Mn > Cu > Ni > Cr > Pb > Co > Se > Cd > As, and in cereal crops, this is followed as Fe > Zn > Cu > Ni > Cr > Co > Pb > As > Se > Cd > Hg. A clear difference was found between vegetable categories, with a higher accumulation of most of the elements in LV, especially spinach, coriander, radish leaves, mustard, amaranthus, and pakchoi than other vegetable types. Root vegetables displayed higher bioconcentration factors (BCF) than the other two vegetable types. For cereal crops, higher metal contents were found in WHE followed by RIC and MAZ, but RIC had relatively higher BCF for certain metals (As, Cd, Cu, Cr, Ni) and WHE dominated for the remaining metals. When compared with the prescribed safe limits of the non-essential metals (As, Cd, and Pb), this study revealed that the majority of the vegetable and cereal crop contaminations were from Bangladesh, China, India, Iran, and Pakistan.