About this Research Topic
Metalloids are elements that possess physical and chemical properties that are intermediate between metals and nonmetals. Six elements are commonly recognized as metalloids; arsenic (As), antimony (Sb), boron (B), germanium (Ge), silicon (Si) and tellurium (Te). Certain other elements, like selenium (Se), are sometimes added to the list. The natural abundance of metalloids in the environment varies greatly. Si is the second most common element in the Earth's crust and constitutes approximately 28% of its mass. In contrast, Te is one of the rarest elements, present only in trace levels. Some metalloids have been in use since ancient times for medicinal purposes. Today, metalloids are mainly used in semiconductor devices, ceramics, solar batteries, and certain polymers. Beside geological sources, mining activities and industrial applications may result in high local concentrations of metalloids, rising concerns for human and environmental health. It is estimated that more than 100 million people worldwide are exposed to As concentrations above the WHO guideline with increased risks of developing cancer and other As-associated diseases. The situation is particularly alarming in Bangladesh and West Bengal (India), where As-contamination of the ground water has been called the largest mass poisoning of a population in history.
Metalloids affect living organisms in various ways. B, Si and Se have either essential or important functions in most organisms including humans. In contrast, As, Sb, Te and Ge are highly toxic and exposure can cause a range of human diseases. Also essential elements like B and Se are toxic when present in high concentrations. As and Sb have a long history of usage as chemotherapeutic agents and are important constituents of currently used pharmacological drugs. The impact of metalloids on the environment, agriculture and human health underscores the importance of elucidating toxicity and tolerance mechanisms.
The aim of this Research Topic is to bring together articles of the type Original Research, Methods, Hypothesis & Theory, Reviews and Perspectives that highlight the molecular mechanisms of metalloid transport, toxicity and tolerance. Contributions may focus on these mechanisms in individual cells or whole organisms including microbes, plants, parasites and mammals. Contributions that deal with the pathophysiology of metalloids, the use of metalloids in medical therapy as well as environmental aspects including phytoremediation are also welcome. We are convinced that this Research Topic is a timely milestone in this exciting and rapidly growing field, and be of great interest to a broad readership.
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