Heavy Metals Definition

Heavy metal is a broad term that describes a group of naturally occurring metallic elements of high molecular weight and density compared to water. At low concentrations, certain heavy metals, such as iron, zinc, copper, and manganese, are essential for human survival but can become toxic agents at higher concentrations. Other heavy metals, such as arsenic, cadmium, lead, thallium, and mercury, serve no biological role. However, they will inevitably enter the human body due to their presence in the environment. Similarly to essential metals, they induce toxicity once specific concentrations are reached.
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Fisher, Richard M. and Vikas Gupta. “Heavy Metals.” StatPearls, StatPearls Publishing, 27 February 2024.