Heavy metals are elements that occur naturally on the surface of earth. These elements include heavy metals such as zinc, lead, mercury, copper, arsenic, and cadmium. These are widely used in many chemical industries for applications in agriculture, medicine and many other industries.
Our body naturally contains some heavy metals such as Zn, Fe and Cu for the natural function of body tissues. But their amount in excess leads to toxicity. The source of heavy metals is usually from the untreated wastes released by industries into land and water. Poisoning occurs when high concentration of metals from food, air or water pollution as well as medicine enter the tissues of body. Heavy metal poisoning is due to the presence of mercury, lead, cadmium, arsenic.
- Mercury poisoning– It is a naturally occurring element. The toxic form in which mercury occurs is as methylmercury. It is found in fish and shellfish through which it enters humans. Mercury in the air settles onto water bodies, some micro organisms change it to methylmercury and this enters fish. Symptoms include insomnia, weakness and headache. High exposure results in kidney, respiratory problems and death. Treatment includes the removal of mercury source, chelation therapy. Minamata is a disease in Japan which was due to mercury poisoning.
Lead poisoning– Exposure of lead is through inhaling of lead particles by burning of materials containing it and ingestion of
lead contaminateddust. Constipation, high blood pressure, anemia, headache are some of the symptoms. Chelation therapy is used as treatment. Chelating agents such as EDTA ( ethylenediammminetetraacetate) and DMSA bind to the lead metal that has accumulated in the body.
Arsenic poisoning– It is also called as arsenicosis. Arsenic is a
semi metallicchemical usually found in groundwater. Exposure includes swallowing ,absorbingor inhaling the arsenic contaminatedgroundwater and infected soil. Symptoms include red swollen skin, nausea, muscle cramps. Treatment includebowel irrigation and chelation therapy.
Cadmium poisoning– It usually occurs as cadmium chloride. Intake is through inhalation or ingestion. Smoking cigarettes is a significant source of cadmium exposure. Fever, muscle pain, breathing problems are some of the symptoms. Detoxification is carried out by chelation therapy using