Currently, millions of people living in and around Bangladesh are at risk for organ dysfunction and cancer from chronic arsenic poisoning from the water supply. In an effort to bypass ground water sources rife with bacterial contamination, tube wells were sunk throughout that area, deep into the water table. Bedrock rich in arsenic gives these deeper water stores—and the crops they irrigate—a high concentration of arsenic, and toxicity is epidemic throughout the area. Childhood lead poisoning linked to the ingestion of old paint chips in the North American setting is another good example of environmental contamination.
Metals have been used as instruments of murder. Arsenic is perhaps more rightly classified as a metalloid, but it is consistently the single substance most commonly thought of as a poison. Metals have also been used in warfare as chemical weapons. Again, arsenic was the primary component of the spray known as Lewisite that was used by the British during trench warfare in World War I. Exposure produced severe edema of the eyelids, gastrointestinal irritation, and both central and peripheral neuropathies. The first antidote to heavy metal poisoning, and the basis for chelation therapy today, was British Anti-Lewisite (BAL, or dimercaprol), a large molecule with sulfhydryl groups that bind arsenic, as well as other metals, to form stable covalent bonds that can then be excreted by the body. BAL was developed by the Germans during World War II in anticipation of a reinitiation of gas warfare as had been waged earlier in the century.
In total, however, occupational exposure has probably accounted for the vast majority of heavy metal poisonings throughout human history. Hippocrates described abdominal colic in a man who extracted metals, and the pernicious effects of arsenic and mercury among smelters were known even to Theophrastus of Erebus (370-287 BC). The classic acute occupational heavy metal toxicity is metal fume fever (MFF), a self-limiting inhalation syndrome seen in workers exposed to metal oxide fumes. MFF, or “”brass founder’s ague,”” “”zinc shakes,”” or “”Monday morning fever”” as it is variously known, is characterized by fever, headache, fatigue, dyspnea, cough, and a metallic taste occurring within 3-10 hours after exposure. The usual culprit is zinc oxide, but MFF may occur with magnesium, cobalt, and copper oxide fumes as well.
Chronic occupational exposure to metal dusts has also been linked to the development of pneumoconioses, neuropathies, hepatorenal degeneration and a variety of cancers. These syndromes develop slowly over time and may be difficult to recognize clinically. In the United States, Occupational Safety and Health Administration (OSHA) regulations guide the surveillance of workers at risk and suggest exposure limits for metals of industrial importance
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