Heavy metals in the environment: Detection techniques and toxicity

Heavy metals are characterized by their relevance, toxicity, and capacity to accumulate in the natural environment. Therefore, their emission into the air can cause long-term environmental hazards. In addition, they can be transported in the atmosphere over long distances and deposited in regions far from the emission location. Among the pollutants currently implicated by their toxicity in the environment, we can cite, in order of importance, mercury, cadmium and lead, which are currently a matter of concern. Mercury is transported over long distances in the atmosphere, and its biotransformation into toxic methylated compounds and bioaccumulation in the trophic chain have made it a major pollutant. Cadmium, which is relatively rare and is mainly found in ores, is considered one of the most toxic metals. Its accumulation in different types of sediment and its capacity for remobilization constitute particularly worrying risks. Finally, although Pb is less toxic than Hg and Cd, it is very abundant in its natural state and is used in large quantities in industry, which makes this ubiquitous toxin a permanent threat to the health of populations. This review provides an analysis of the occurrence of heavy metals in the environment, including Cu, Pb, Ni, Hg, Cr, Zn, Fe, and Cd, their toxicity potential, their impact on human health, and detection technologies using Field-Effect Transistor (FET) sensors.