This paper reviews the biotoxic effects of heavy metals on humans and the mechanisms of their biochemical activities. Heavy metals, including lead (Pb), cadmium (Cd), zinc (Zn), mercury (Hg), arsenic (As), and others, are naturally present in the Earth's crust but can be released into the environment through both natural and anthropogenic sources, such as mining and industrial activities. These metals can leach into groundwater and surface waters, leading to water and soil pollution. Ingestion of contaminated water and food can result in the accumulation of heavy metals in the body, where they interfere with normal biochemical processes by forming stable compounds with biomolecules like proteins and enzymes, leading to various health issues. The paper discusses the specific toxic effects of heavy metals, such as gastrointestinal disorders, neurological damage, and organ dysfunction, and highlights the importance of understanding their sources, leaching processes, and modes of deposition to mitigate environmental and human health risks. The authors emphasize the need for proper handling and occupational hygiene to prevent heavy metal pollution and its associated health hazards.This paper reviews the biotoxic effects of heavy metals on humans and the mechanisms of their biochemical activities. Heavy metals, including lead (Pb), cadmium (Cd), zinc (Zn), mercury (Hg), arsenic (As), and others, are naturally present in the Earth's crust but can be released into the environment through both natural and anthropogenic sources, such as mining and industrial activities. These metals can leach into groundwater and surface waters, leading to water and soil pollution. Ingestion of contaminated water and food can result in the accumulation of heavy metals in the body, where they interfere with normal biochemical processes by forming stable compounds with biomolecules like proteins and enzymes, leading to various health issues. The paper discusses the specific toxic effects of heavy metals, such as gastrointestinal disorders, neurological damage, and organ dysfunction, and highlights the importance of understanding their sources, leaching processes, and modes of deposition to mitigate environmental and human health risks. The authors emphasize the need for proper handling and occupational hygiene to prevent heavy metal pollution and its associated health hazards.