Toxic metals are individual metals and metal compounds that negatively affect people’s health. In very small amounts, many of these metals are necessary to support life. However, in larger amounts, they become toxic. They may build up in biological systems and become a significant health hazard making us very sick.
Although aluminum is not a heavy metal, it makes up about 8% of the surface of the earth and is the third most abundant element. It is readily available for human ingestion through the use of food additives, antacids, buffered aspirin, astringents, nasal sprays, and antiperspirants; from drinking water; from automobile exhaust and tobacco smoke; and from using aluminum foil, aluminum cookware, cans, ceramics, and fireworks. Studies began to emerge about 20 years ago suggesting that aluminum might have a possible connection with developing Alzheimer’s disease when researchers found what they considered to be significant amounts of aluminum in the brain tissue of Alzheimer’s patients. Target organs for aluminum are the central nervous system, kidney, and digestive system.
Testing Testing procedures measure aluminum levels in blood, urine, hair and fingernails, and feces. According to a spokesperson at the ATSDR in spring 2002, levels of aluminum that are recognized as average are less than 0.01 mg/L. However, blood testing might underestimate the total body level of aluminum; postmortem brain, lung, and bone measurements reveal much higher levels of aluminum than blood tests.
Arsenic- Sources of exposure usually include hazardous waste sites and areas with high levels naturally occurring in soil, rocks, and water. Arsine gas is a common byproduct produced by the manufacturing of pesticides that contain arsenic. Arsenic may be also be found in water supplies worldwide in turn leading to exposure of shellfish, cod, and haddock. Other sources are paints, rat poisoning, fungicides, and wood preservatives. Target organs are the blood, kidneys, and central nervous, digestive, and skin systems Exposure to high levels of arsenic can cause death.
Testing Arsenic levels can be measured in blood, urine, hair, and fingernails. Because arsenic clears fairly rapidly from the blood, blood tests are not always useful. Therefore, urine tests are the most reliable for arsenic exposure within the past few days; hair and fingernail testing are used to measure exposure over the past several months.
Beryllium- Exposure to this metal usually occurs in mining, extraction, and in the processing of alloy metals containing beryllium. Beryllium can cause sensitization, lung and skin disease in a significant percentage of exposed workers.
Cadmium- An extremely toxic metal commonly found in industrial workplaces, particularly where any ore is being processed or smelted. Several deaths from acute exposure have occurred among welders who have unsuspectingly welded on cadmium-containing alloys or with silver solders. It is used in nickel-cadmium batteries, PVC plastics, and paint pigments. It can also be found in soils because insecticides, fungicides, sludge, and commercial fertilizers that use cadmium are used in agriculture. Cadmium may be found in reservoirs containing shellfish. Cigarettes also contain cadmium. Lesser-known sources of exposure are dental alloys, electroplating, motor oil, and exhaust. Target organs are the liver, placenta, kidneys, lungs, brain, and bones.
Testing Laboratory testing procedures for cadmium toxicity include collection of a 24-hour urine specimen, CBC, and hair and fingernail clippings. Blood levels show recent exposure; urine levels show both recent and earlier exposure. Note: The ATSDR is unsure of the reliability of tests for cadmium levels.
Hexavalent Chronium- Calcium chromate, chromium trioxide, lead chromate, strontium chromate, and zinc chromate are known human carcinogens. An increase in the incidence of lung cancer has been observed among workers in industries that produce chromate and manufacture pigments containing chromate.
Lead- Lead accounts for most of the cases of pediatric heavy metal poisoning . In adults, occupational exposure is usually how someone is overexposured to lead. Industries with high potential exposures include construction work, most smelter operations, radiator repair shops, and firing ranges. Millions of homes built before 1940 still contain lead (e.g., in painted surfaces), leading to chronic exposure from weathering, flaking, chalking, and dust. Target organs are the bones, brain, blood, kidneys, and thyroid gland.
Testing: Blood lead levels in children higher than 10 mcg/dL are considered to be of concern . However, medical treatment is usually necessary in children who have levels of 45 mcg/dL. Significantly lower levels of 30 mcg/dL in children can cause mental retardation or cognitive and behavioral problems.A complete blood count (CBC) is also done to check for abnormalities on red blood cells . In children, long-bone x-rays may reveal bands called “lead lines” that indicate failure of the bone to rebuild. A less common test is measurement of lead in teeth (ATSDR ToxFAQs for Lead). All children with brain-related symptoms should be considered for lead toxicity.
Mercury- Common sources of mercury exposure include mining, production, and transportation of mercury, as well as mining and refining of gold and silver ores. Mercury is generated naturally in the environment from the degassing of the earth’s crust, from volcanic emissions. It exists in three forms: elemental mercury and organic and inorganic mercury. Mining operations, chloralkali plants, and paper industries are significant producers of mercury. Atmospheric mercury is dispersed across the globe by winds and returns to the earth in rainfall, accumulating in aquatic food chains and fish in lakes. Mercury compounds were added to paint as a fungicide until 1990. These compounds are now banned; however, old paint supplies and surfaces painted with these old supplies still exist. Mercury continues to be used in thermometers, thermostats, and dental amalgam. Many researchers suspect dental amalgam as being a possible source of mercury toxicity. Medicines, such as mercurochrome and merthiolate, are still available. Algaecides and childhood vaccines are also potential sources. Inhalation is the most frequent cause of exposure to mercury. Target organs are the brain and kidneys.High mercury exposure results in permanent nervous system and kidney damage.
Testing: A 24-hour urine specimen is collected for measurement of mercury levels. Chest x-rays can reveal a collection of mercury from exposure to elemental mercury or a pulmonary embolism containing mercury. Abdominal x-rays can reveal swallowed mercury as it moves through the gastrointestinal tract. Blood and urine samples are used to determine recent exposure, as well as exposure to elemental mercury and inorganic forms of mercury. Scalp hair is used in testing for exposure to methylmercury. Liver and kidney function tests are also important in severely exposed persons.
Therapies to remove heavy metals from humans include chelation and decontamination procedures, as well as supportive measures, often used in combination. The therapies can be very complex and highly individualized, tailored to the specific needs of each individual and requiring the expertise of trained and experienced professionals, sometimes a team of professionals. Self-diagnosis and treatment is not appropriate.
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