Heavy Metal Poisoning

Heavy Metal Poisoning

Heavy metal poisoning is the toxic accumulation of heavy metals in the soft tissues of the body. Heavy metals are chemical elements that have a specific gravity at least five times that of water. The heavy metals most often implicated in human poisoning are lead, mercury, arsenic, and cadmium. Some heavy metals, such as zinc, copper, chromium, iron, and manganese, are required by the body in small amounts, but these same elements can be toxic in larger quantities.

Heavy metals may enter the body in food, water, or air, or by absorption through the skin. Once in the body, they compete with and displace essential minerals such as zinc, copper, magnesium, and calcium, and interfere with organ system functions. People may come into contact with heavy metals in industrial work, pharmaceutical manufacturing, and agriculture. Its even possible that children can be poisoned as a result of playing in contaminated soil.

Heavy metal poisoning may be detected using blood and urine tests, hair and tissue analysis, or x rays. In childhood, blood lead levels above 80 Ð'µg/dL generally indicate lead poisoning, however, significantly lower levels (>30 Ð'µg/dL) can cause mental retardation and other cognitive and behavioral problems in affected children. The Centers for Disease Control and Prevention considers a blood lead level of 10 Ð'µg/dL or higher in children a cause for concern. In adults, symptoms of lead poisoning are usually seen when blood lead levels exceed 80 Ð'µg/dL for a number of weeks. Another important factor is that blood levels containing mercury should not exceed 3.6 Ð'µg/dL, while urine levels should not exceed 15 Ð'µg/dL. Symptoms of mercury poisoning may be seen when mercury levels exceed 20 Ð'µg/dL in blood and 60 Ð'µg/dL in urine. An interesting way to test for the amount of mercury in someones system, is to test hair a follicle, and record the levels of mercury in order to gauge the severity of chronic mercury exposure. Furthermore, arsenic is rapidly cleared from the blood. Blood arsenic levels may not be very useful in diagnosis. Arsenic in the urine (measured in a 24-hour collection following 48 hours without eating seafood) may exceed 50 Ð'µg/dL in people with arsenic poisoning. If acute arsenic poisoning is suspected, an x ray may reveal ingested arsenic in the abdomen. It is visible because the arsenic appears solid on an x-ray. Arsenic may also be detected in the hair and nails for months following exposure.

Symptoms will vary, depending on the nature and the quantity of the heavy metal ingested. Patients may complain of nausea, vomiting, diarrhea, stomach pain, headache, sweating, and a metallic taste in the mouth. Depending on the metal, there may be blue-black lines in the gum tissues. In severe cases, patients exhibit obvious impairment of cognitive, motor, and language skills. The expression "mad as a hatter" comes from the mercury poisoning prevalent in 17th century France among hatmakers who soaked animal hides in a solution of mercuric nitrate to soften the hair.

The treatment available for most heavy metal poisoning is chelation therapy. A chelating agent specific to the metal involved is given orally, intramuscularly, or intravenously. The three most common chelating agents are calcium disodium edetate, dimercaprol (BAL), and penicillamine. The chelating agent encircles and binds to the metal in the body's tissues, forming a complex; that complex is then released from the tissue to travel in the bloodstream. The complex is filtered out of the blood by the kidneys and excreted in the urine.