Plants absorb a number of elements from soil, some of which have no known biological
function and some are known to be toxic at low concentrations. As plants constitute
the foundation of the food chain, some concerns have been raised about the possibility
of toxic concentrations of certain elements being transported from plants to higher
strata of the food chain. Special attention has been given to the uptake and biotransformation
mechanisms occurring in plants and its role in bioaccumulation and impact on consumers,
especially human beings. While this review draws particular attention to metal accumulation
in edible plants, researched studies of certain wild plants and their consumers are
included. Furthermore, this review focuses on plant uptake of the toxic elements arsenic,
cadmium, chromium, mercury, and lead and their possible transfer to the food chain.
These elements were selected because they are well-established as being toxic for
living systems and their effects in humans have been widely documented. Arsenic is
known to promote cancer of the bladder, lung, and skin and can be acquired, for example,
through the consumption of As-contaminated rice. Cadmium can attack kidney, liver,
bone, and it also affects the female reproduction system. Cadmium also can be found
in rice. Chromium can produce cancer, and humans can be exposed through smoking and
eating Cr-laden vegetables. Lead and mercury are well known neurotoxins that can be
consumed via seafood, vegetables and rice.