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Heavy metal poisoning, or more properly metal toxicity is the toxic effect of certain metals in certain forms and doses on life. Some metals are toxic when they form poisonous soluble compounds. Certain metals have no biological role, i.e. are not essential minerals, or are toxic when in a certain form. In the case of lead, any measurable amount may have negative health effects. Often heavy metals are thought as synonymous, but lighter metals may also be toxic in certain circumstances, such as beryllium, and not all heavy metals are particularly toxic, and some are essential, such as iron. The definition may also include trace elements when considered in abnormally high, toxic doses.

Toxic metals sometimes imitate the action of an essential element in the body, interfering with the metabolic process to cause illness. Many metals, particularly heavy metals are toxic, but some heavy metals are essential, and some, such as bismuth, have a low toxicity. Most often the definition of “heavy metals” includes cadmium, lead, mercury and the radioactive metals. Metalloids (such as arsenic, polonium) may be included in the definition. Radioactive metals have both radiological toxicity and chemical toxicity. Metals in an oxidation state abnormal to the body may also become toxic: chromium(III) is an essential trace element, but chromium(VI) is a carcinogen.

Toxicity is a function of solubility. Insoluble compounds as well as the metallic forms often exhibit negligible toxicity. The toxicity of any metal depends on the molecules it is bound to. In some cases, organometallic forms, such as methylmercury and tetraethyl lead, can be extremely toxic. In other cases, organometallic derivatives are less toxic such as the cobaltocenium cation.

Decontamination for toxic metals is different from organic toxins. Because toxic metals are elements, they cannot be destroyed. Toxic metals may be made insoluble or collected, possibly by the aid of [[chelation|chelating agents. The standard practice to deal with large amounts of metal contaminated material is to keep it in one place, such as a tailings pond or hardzardous waste landfill and hope the engineered barriers do not allow the contaminants to dilute into the environment. Small increases in fat soluble contaminants lead to much larger increases in animals including humans.

Toxic metals can bioaccumulate in the body and in the food chain, Therefore, a common characteristic of toxic metals is the chronic nature of their toxicity. This is particularly notable with radioactive heavy metals such as radium, which imitates calcium to the point of being incorporated into human bone, although similar health implications are found in lead poisoning| or mercury poisoning. The exceptions to this are barium and aluminium, which can be removed efficiently by the kidneys.

The only part of the body that is not adversely affected by metal toxicity is the bones, although strontium and cadmium can weaken bones because they are both chemically similar to calcium.  

Heavy metal toxicity is, in most cases, a zebra diagnosis – the condition itself is rare and the variety of symptoms mimic many other diseases. As a result, metal toxicity has a very high mortality rate even when victims seek timely medical treatment. In many other cases, the diagnosis is delayed long enough for permanent damage to occur. However, it is often found in clusters as from an epidemiological standpoint, the two most likely reasons for heavy metal toxicity are environmental contamination and occupational exposure. However, iron and lead exposure are fairly common and are usually diagnosed in a timely manner.  However, the link between metal and mortality is ancient in origin, having been first described by Hippocrates who saw consistent symptoms in men who ran smelting operations. There is also a strong link between metal exposure and certain types of cancer

In some cases, metal toxicity has been traced to food or nutritional supplements which were either tainted or were in and of themselves toxic.  For example, Maria Palko poisoned her husband with a folk medicine that contained gold salts, and Arlene Cuddy used a folk remedy that contained a lead salt.  Many athletes have deliberately injected themselves with mercury in the mistaken belief that it builds muscle mass. In one infamous case, cardiomyopathy among beer drinkers was traced to cobalt used to stabilize the head of foam. Toxic metals have also been found in illegal drugs. 

Toxic metals[]

Aluminum has no known biological role and its classification into toxic metals is controversial. Significant toxic effects and accumulation to tissues have been observed in renally impaired patients. However, individuals with healthy kidneys can be exposed to large amounts of aluminium with no ill effects. Thus, aluminium is not considered dangerous to persons with normal elimination capacity.

Vanadium poisoning is notable as it is an anti-corrosive component of automotive steel, fragments of which can be left in passengers during an automobile accident.

Trace elements with toxicity[]


Some heavy nonmetals may be erroneously called "metals", because they have some metallic properties.

Heavy metal poisoning is usually diagnosed by doing gas chromatography of a blood, hair or tissue sample. Heavy metals all have a distinct spectrum that is easy to distinguish from the normal chemicals found in human tissue. In addition, they are usually found in people who work in particular industries or with particular products, so an environmental scan of the patient's home and workplace can provide valuable clues.

Heavy metal poisoning is usually treated with chelation, the use of chemicals that bind to the heavy metal which are then processed through the kidney and allow the metals to be lost in urine or feces.  However, chelation will only stop further damage to tissue – it cannot repair existing damage.

Types of Heavy Metal Poisoning[]


Iron poisoning at Wikipedia

Also see – Iron toxicity

As seen in:

  •  Emancipation – Culo developed the condition from being given too many iron supplements by his brother.
  • The Jerk – Nate's iron levels were high due to his hemochromatosis and his recent switch to a diet containing meat.

Iron is the most commonly diagnosed form of metal toxicity.  Although it is a vital nutrient, critical to the formation of hemoglobin for red blood cells, it is also ubiquitous in the environment. Iron toxicity can be the result of ingestion of a diet too rich in iron (including the use of iron supplements, which were once a common sight on pharmacy shelves to fight "tired blood"), occupational exposure, and genetic conditions.  Although it is clear the body can process iron from the diet and dispose of excess iron in body waste, the mechanism by which this occurs to keep iron levels at an appropriate level is still poorly understood.  

Iron toxicity from hemochromatosis was also a factor in Who's Your Daddy? and Known Unknowns.


Lead poisoning at Wikipedia

As seen in The Itch – Stewart Nozick developed it from the lead in the bullet fragments that was lodged in one of his bones when he survived a mugging.

Lead and lead compounds are toxic to many of the body's tissues, including the heart, blood, reproductive system, digestive tract, kidneys, and nerves.  Because these tissues develop more quickly in children, lead poisoning is particularly severe in young patients.  Even non-lethal doses can have severe morbidity, leading to permanent problems with intellectual development.  Lead poisoning can present with abdominal pain, headache, anemiaperipheral neuropathy and irritability.  In severe cases, it can cause seizure, coma and death.

Lead is very common in the environment.  It is found in many compounds used in industry, such as solder, and is one of the primary elements used in automobile batteries.  Prior to 1970, lead was commonly used in the pigments of house paint, and homes built before that most likely have lead paint.  Lead is easy to ingest when it is in the environment and is often found in drinking water.  It is one of the most common employment related diseases.

Diagnosis of lead poisoning is fairly easy as it shows up clearly in blood tests

Also see Lead


Cadmium poisoning at Wikipedia

As seen in Sports Medicine – Both Hank Wiggen and his wife Lola Wiggen were poisoned by marijuana grown in soil contaminated by the metal.

Cadmium does not occur naturally in the human body and even very low doses are toxic.  In addition, the element tends to accumulate in the human body as it is not excreted in sweat, feces or urine.  It is generally found in individuals who work in industry as it is used in certain types of solder and in plating operations.  It can also be found in the air and soil around industrial facilities.  Batteries, coatings and plastics often use cadmium (it is, for example, one of the main ingredients in certain types of rechargeable batteries).  Cadmium causes symptoms that look like influenza, but more severe exposures can cause inflammation of the trachea and bronchial tubes, inflammation of the lungs, and pulmonary edema.  After the respiratory problems, the element damages the kidneys and liver.  It then starts to affect bone density leading to soft bones and osteoporosis.  It can lead to both gout and loss of the sense of smell. 


Mercury poisoning at Wikipedia

Mercury is a metallic element that is liquid at room temperature and vaporizes at a fairly low temperature. It also forms compounds with other elements rapidly. Although liquid mercury and solid mercury alloys (like dental amalgam) are not toxic and are readily passed through the digestive tract without harming human tissue, mercury vapors and mercury compounds are almost universally toxic to all life. All types of mercury poisoning can affect cognitive functions such as vision, hearing and speech, and can affect coordination. It's initial symptoms are peripheral neuropathy which manifests as burning, itching and edema. As mercury is not excreted from the body once it enters the bloodstream, it accumulates in animal tissue. Animals at the top of large food chains in mercury laden environments can have large amounts of mercury in their symptoms. This is particularly true of large carnivorous fish (e.g. swordfish), which are the main source of mercury in the human diet. Humans can also be exposed to mercury in many industries, such as mining and smelting. In the 19th century, mercury was often used to treat the felt in hats. Hat makers often suffered from mercury exposure which caused brain damage. The phrase "As mad as a hatter" and The Mad Hatter in Alice in Wonderland are two examples of this industrial illness having an effect on language well into the 21st century.

See also Mercury


Thallium poisoning at Wikipedia

As seen in Whatever It Takes – Casey Alfonso was deliberately poisoned by Travis Brennan to mimic polio so he could run a fake diagnostic trial.  

Thallium is a metallic element and its compounds and vapors are also toxic. Because thallium compounds dissolve easily in water, they can be absorbed easily through the skin. Thallium is particularly dangerous because it binds to the same chemical processes as the essential trace element potassium and therefore interferes with its processing in the body. It used to be used widely in rat and ant poisons, but because of the danger in using it, it is no longer used in those applications. Most exposure is due to its use in electronics and glass manufacturing, but it is also used in pharmaceutical manufacturing. Its key symptoms are loss of hair and damage to the peripheral nerves. Due to the fact that most of its compounds are tasteless and it can be easily administered, it has been used as a means of deliberate poisoning.

Thallium poisoning can be treated with Prussian Blue, a pigment commonly used in artist's oil paints, which binds to thallium and allows it to be excreted.


As seen in Whatever It Takes –  "John" developed selenium poisoning by eating large numbers of nuts which had been grown in selenium rich soil. Unlike many heavy metals, the body does use selenium in trace amounts. However, excess selenium causes a condition known as selenosis, It is characterized by a garlic-like odor on the breath, gastro-instestinal problems, loss of hair and fingernails, fatigue, irritability and nerve damage. Food grown in selenium rich soil can often lead to selenosis.


Cobalt poisoning at Wikipedia

As seen in Family Practice – Arlene Cuddy developed the condition when her artificial hip joint broke down prematurely, releasing cobalt into her bloodstream.

Cobalt is also required by the body in small quantities. However, in larger quantities, it causes symptoms similar to intoxication. It is usually caused by exposure during the production of tungsten carbide, but can also be found in rechargeable batteries, industrial catalysts, glass coloring and paint pigments.


As seen in Clueless – Bob Palko is being deliberately poisoned by his wife Maria.

In its metallic form, gold is not toxic and is often added to specialty foods and drinks.  None of the body's natural processes can break gold down into its atomic form, and gold easily resists corrosion even by stomach acid.  However, most gold compounds, such as gold salts, are toxic as they break down in the body, releasing a gold ion.  These can damage the liver and kidneys.  One of the most common forms of gold poisoning is potassium gold cyanide, which is used in gold plating.  Both the gold and the cyanide are toxic and both must be treated separately.

In addition, some people have an allergy to gold, causing a rash when they wear gold jewellery.  However, gold allergies are rarer than similar allergies to other metals, such as nickel.


Copper toxicity and Symptoms at Wikipedia Wilson's Disease at Wikipedia

As seen is Damned If You Do Sister Mary Augustine was exposed to Copper Toxicity at her abbey and before she became a nun from copper pots she was washing and from a copper crucifix IUD placed in her uterus that was not changed and she got Copper toxicity from it.

As seen in The Socratic Method and Remorse the side effect of Copper Toxicity if not treated is Wilson's disease which Lucy Palmeiro and Valerie suffer from.

As a preservative copper is used to purify water, beverages, and foods. Copper can be absorbed by the body and is essential for life. However in it's raw form copper contains impurities and other trace metals like Molly, Lead, Zinc, and Uranium which must be refined out or it can lead to Copper Poisoning, and Copper Toxicity.

Copper Toxicity can cause vomiting, hematemesis, hypertension, melena, glaucoma, cataracts, jaundice, eye disorders, and gastrointestinal distress. It can also cause kidney and bladder damage, liver damage, ulcer, heart damage, and ovary and uterus damage in females.

Those exposed to this need to have the copper removed and the body flushed with Penicillamine, Dimercaprol, and alpha lipoic acid. Vinegar is not suppose to be used until after the drugs have run through the system or it will leave copper traces.

Copper is the leading cause of all known eye disorders and it can cause Wilson's disease, Alzheimer's disease, and Indian childhood cirrhosis among many known diseases that are traced to copper toxicity. Treatment for eye disorders caused by Copper Toxicity is surgery to remove the copper from the cornea they will also need a liver transplant to repair the damage but only if it is an extreme case.

Uranium, Plutonium, and Radioactive Metals[]

Acute Radiation Syndrome at Wikipedia

As seen in Daddy's Boy Carnell Hall, his father Ken, and his friend Taddy were exposed to a radioactive plumb bob used in a practice called borehole logging which is now banned. Because of exposure all three have acute radiation syndrome and had to undergo transfusions.

It is not uncommon for people to be exposed to radioactive metals uranium chief among them. Uranium, and Plutonium were used in the mining industry and the oil and gas industry but are now banned. Care must be taken when working in scrapyards, mines, processing mills, oil and gas industry, dentistry, power plants, and in hospital radiology labs because exposure to these elements can be life threatening. Radiation when controlled can treat cancer but it can also cause it. Anyone exposed to radiation needs treatment immediately. Radiation sickness also called Radiation Poisoning or Acute Radiation Syndrome to use the scientific term is a deadly condition anyone exposed to this can end up dead or can get cancer. Blood transfusions and bone marrow transplants can help but there is no cure to radiation and patients exposed are given a limited amount of time to live.

On the show[]

Different types of heavy metal poisoning are one of the most common diagnoses on the show, having been the final diagnosis five times.  Only cancer has more appearances, and only porphyria has as many.  In addition, it shows up commonly in the differential diagnosis and is a common excuse for doing an environmental scan.

Even clinic patients are not immune

  • Sheldon and George suffered from antimony poisoning from the sizing used on their cheap polyester uniforms.

External links[]

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