Lead: Lead has toxic effects on all human systems, mainly in the nervous system, hematopoietic system and blood vessel. In the nervous system, advanced neurological dysfunction can occur in the early stage, which can cause organic encephalopathy and nerve paralysis. The hematopoietic system, mainly lead interference with the synthesis of heme caused anemia. Lead has great effect on children's growth and development. The brain of children is more sensitive to lead pollution, which seriously affects children's intellectual development and behavior.
Mercury: Mercury through the food chain in the human body, accumulate in the most parts of the body for the bone marrow, kidney, liver, brain, lung, heart and so on. Mercury can cause irreversible damage to the nervous system, kidneys and liver of the human body. Mercury has a corrosive effect on tissue and binds to proteins to form loose protein compounds. Mercury has become a public health hazard in some parts of the world.
Arsenic: Arsenic in the environment due to chemical action and microbial action, mostly in the form of inorganic arsenic and alkyl arsenic exist. Arsenic in different forms has a great difference in toxicity. The toxicity of trivalent arsenic compounds is greater than five valence arsenic compounds, and arsenic hydride and arsenic trioxide (commonly known as arsenic) are the most toxic. Oral three arsenic trioxide 5-50mg can be poisoned, 60-100mg can be lethal. Long-term exposure to arsenic can cause cell poisonings, sometimes inducing malignant tumours, especially inorganic arsenic, which is carcinogenic to skin cancers and lung cancer. Arsenic can also damage the fetus through the placenta.