Why Heavy Metals are a Hazard to Your Health

Toxic metals are toxic because at high concentrations can produce a break-down in some very basic body functions.

Some metals are naturally found in the body and are essential to human health. Iron, for example, prevents anemia, and zinc is a cofactor in over 100 enzyme reactions. They normally occur at low concentrations and are known as trace metals. In high doses, they may be toxic to the body or produce deficiencies in other trace metals; for example, high levels of zinc can result in a deficiency of copper, another metal required by the body. A table listing these trace metals can be found here.

Heavy or toxic metals are trace metals with a density at least five times that of water. As such, they are stable elements (meaning they cannot be metabolized by the body) and bio-accumulative (passed up the food chain to humans). These include: mercury, nickel, lead, arsenic, cadmium, aluminum, platinum, and copper (the metallic form versus the ionic form required by the body). Heavy metals have no function in the body and can be highly toxic.

Once liberated into the environment through the air, drinking water, food, or countless human-made chemicals and products, heavy metals are taken into the body via inhalation, ingestion, and skin absorption. If heavy metals enter and accumulate in body tissues faster than the body's detoxification pathways can dispose of them, a gradual buildup of these toxins will occur. High- concentration exposure is not necessary to produce a state of toxicity in the body, as heavy metals accumulate in body tissues and, over time, can reach toxic concentration levels

Heavy metal exposure is not an entirely modern phenomenon: historians have cited the contamination of wine and grape drinks by lead-lined jugs and cooking pots as a contributing factor in the "decline and fall" of the Roman Empire; and the Mad Hatter character in Alice in Wonderland was likely modeled after nineteenth-century hat makers who used mercury to stiffen hat material and frequently became psychotic from mercury toxicity.

Human exposure to heavy metals has risen dramatically in the last 50 years, however, as a result of an exponential increase in the use of heavy metals in industrial processes and products. Today, chronic exposure comes from mercury-amalgam dental fillings, lead in paint and tap water, chemical residues in processed foods, and "personal care" products (cosmetics, shampoo and other hair products, mouthwash, toothpaste, soap). In today's industrial society, there is no escaping exposure to toxic chemicals and metals.

In addition to the hazards at home and outdoors, many occupations involve daily heavy metal exposure. Over 50 professions entail exposure to mercury alone. These include physicians, pharmaceutical workers, any dental occupation, laboratory workers, hairdressers, painters, printers, welders, metalworkers, cosmetic workers, battery makers, engravers, photographers, visual artists, and potters.

In my clinical nutrition practice, when I discuss with patients my concerns regarding heavy metal toxicity, I often get the response, "That isn't a problem for me." Most are astonished to learn that we are all being exposed to and absorbing these harmful substances to some degree in our daily lives. The astonishment turns to alarm when they hear what heavy metals do in the body.

The Effects of Heavy Metal Toxicity Studies confirm that heavy metals can directly influence behavior by impairing mental and neurological function, influencing neurotransmitter production and utilization, and altering numerous metabolic body processes. Systems in which toxic metal elements can induce impairment and dysfunction include the blood and cardiovascular, detoxification pathways (colon, liver, kidneys, skin), endocrine (hormonal), energy production pathways, enzymatic, gastrointestinal, immune, nervous (central and peripheral), reproductive, and urinary.

Breathing heavy metal particles, even at levels well below those considered nontoxic, can have serious health effects. Virtually all aspects of animal and human immune system function are compromised by the inhalation of heavy metal particulates. In addition, toxic metals can increase allergic reactions, cause genetic mutation, compete with "good" trace metals for biochemical bond sites, and act as antibiotics, killing both harmful and beneficial bacteria.

Much of the damage produced by toxic metals stems from the proliferation of oxidative free radicals they cause. A free radical is an energetically unbalanced molecule, composed of an unpaired electron, that "steals" an electron from another molecule to restore its balance. Free radicals result naturally when cell molecules react with oxygen (oxidation) but, with a heavy toxic load or existing antioxidant deficiencies, uncontrolled free-radical production occurs. Unchecked, free radicals can cause tissue damage throughout the body; free-radical damage underlies all degenerative diseases. Antioxidants such as vitamins A, C, and E curtail free-radical activity.

Heavy metals can also increase the acidity of the blood. The body draws calcium from the bones to help restore the proper blood pH. Further, toxic metals set up conditions that lead to inflammation in arteries and tissues, causing more calcium to be drawn to the area as a buffer. The calcium coats the inflamed areas in the blood vessels like a bandage, patching up one problem but creating another, namely the hardening of the artery walls and progressive blockage of the arteries. Without replenishment of calcium, the constant removal of this important mineral from the bones will result in osteoporosis (loss of bone density leading to brittle bones).

Current studies indicate that even minute levels of toxic elements have negative health consequences, however, these vary from person to person. Nutritional status, metabolic rate, the integrity of detoxification pathways (ability to detoxify toxic substances), and the mode and degree of heavy metal exposure all affect how an individual responds. Children and the elderly, whose immune systems are either underdeveloped or age-compromised, are more vulnerable to toxicity.

Aluminum, arsenic, cadmium, lead, mercury, and nickel are the most prevalent heavy metals. The specific sources of exposure, body tissues in which the metal tends to be deposited, and health effects of each metal are identified below.

Sources: Aluminum cookware, aluminum foil, antacids, antiperspirants, baking powder (aluminum containing), buffered aspirin, canned acidic foods, food additives, lipstick, medications and drugs (anti- diarrheal agents, hemorrhoid medications, vaginal douches), processed cheese, "softened" water, and tap water.

Target Organs: Bones, brain, kidneys and stomach.

Signs/Symptoms: Colic, dementia, esophagitis, gastroenteritis, kidney damage, liver dysfunction, loss of appetite, loss of balance, muscle pain, psychosis, shortness of breath, and weakness, Alzheimer's disease, Parkinson's disease, senile and presenile dementia, clumsiness of movements, staggering when walking, and inability to pronounce words properly, behavioral difficulties among school children.

Discussion: Among the patients I see in my practice, the highest aluminum exposure is most frequently due to the chronic consumption of aluminum- containing antacid products and the use of aluminum cookware. Research shows that aluminum builds up in the body over time; thus, the health hazard to older people is greater.

D.R. McLaughlin, M.D., F.R.C.P. (C), professor of physiology and medicine and director of the Centre for Research in Neurodegenerative Diseases at the University of Toronto, states, "Concentrations of aluminum that are toxic to many biochemical processes are found in at least ten human neurological conditions." Recent studies suggest that aluminum contributes to neurological disorders such as Alzheimer's disease, Parkinson's disease, senile and presenile dementia, clumsiness of movements, staggering when walking, and inability to pronounce words properly. Behavioral difficulties among schoolchildren have also been correlated with elevated levels of aluminum and other neurotoxic heavy metals. ⁶⁶

A disturbing pattern of aluminum accumulation and interference with normal neurological function appears to be supported in the literature. Dyslexic children were shown to have higher levels of aluminum in their hair compared with controls, and other behavioral difficulties in school also correlated with elevated levels of this element.^17,18 Urine levels of aluminum are observed to be elevated in people with a history of antacid intake.¹⁹ The estimated half-life of aluminum found in the urine is 7.5 hours; however, the excretion kinetics vary according to the form in which the element was present in a worker’s environment. ²⁰

There are geographical links between Alzheimer's disease and high aluminum in drinking water. Elevated hair aluminum has been observed in Alzheimer's patients, and some Alzheimer's patients experience stabilization of their symptoms following treatment with the aluminum- chelating agent desferrioxamine. Amyotrophic lateral sclerosis, another neurodegenerative disease, may also be linked to aluminum content of water supplies.

Aluminum is ubiquitous, being the most prevalent heavy metal in the Earth's crust. Sources of exposure may include drinking water (especially from areas exposed to acid rain), aluminum cookware, and aluminum- containing medications such as Maalox. ^21,22 The health and educational ramifications of these observations are of much current concern.

Sources: Arsenic toxicity has been recognized for centuries, and hair shows significant correlation with intake.⁵⁸ Arsenic toxicity manifests with various symptoms including macrocytosis and neuropathy. Data show that cereals are a major source of arsenic during infancy and that changes in hair arsenic levels during infancy correspond to the introduction of cereals into the diet. ⁵⁹

Air pollution, antibiotics given to commercial livestock, certain marine plants, chemical processing, coal-fired power plants, defoliants, drinking water, drying agents for cotton, fish, herbicides, insecticides, meats (from commercially raised poultry and cattle), metal ore smelting, pesticides, seafood (fish, mussels, oysters), specialty glass, and wood preservatives. The labels of treated wood and insecticides may be checked for arsenic content.

Target Organs: Most organs of the body, especially the gastrointestinal system, lungs, and skin.

Signs/Symptoms: Abdominal pain, burning of the mouth and throat, cancer (especially lung and skin), coma, diarrhea, nausea, neuritis, peripheral vascular problems, skin lesions, and vascular collapse; macrocytosis and neuropathy.

Lower levels of exposure to inorganic arsenic may cause nausea, vomiting, and diarrhea, decreased production of red and white blood cells, abnormal heart rhythm, blood vessel damage, a "pins and needles" sensation in hands and feet, painful and profuse diarrhea, shock, coma, convulsions and death, irritation, inflammation, ulceration of mucous membranes and skin, kidney damage. Direct skin contact may cause redness and swelling.

Chronic toxic effects are fatigue, loss of energy, G.I. disturbance, nasal septum perforation, ulceration in folds of skin, increased pigmentation of skin, appearance of small "corns" or "warts" on the palms, soles, and torso, exfoliative dermatitis, rashes, muscular paralyses and atrophy, sensory disturbances, visual disturbances and blindness, degeneration of liver (cirrhosis) and kidneys, garlic odor to breath, noncirrhotic portal hypertension.

Discussion: The greatest dangers from chronic arsenic exposure are lung and skin cancers and gradual poisoning, most frequently from living near metal smelting plants or arsenic factories. Arsenic toxicity has been recognized for centuries, and hair shows significant correlation with intake.⁵⁸

Cadmium is an element that occurs naturally in the earth's crust. Pure cadmium is a soft, silver-white metal; however cadmium is not usually found in the environment as a metal. It is usually found as a mineral combined with other elements such as oxygen (cadmium oxide), chlorine (cadmium chloride), or sulfur (cadmium sulfate, cadmium sulfide). These compounds are solids that may dissolve in water but do not evaporate or disappear from the environment. All soils and rocks, including coal and mineral fertilizers, have some cadmium in them. Cadmium is often found as part of small particles present in air. You cannot tell by smell or taste that cadmium is present in air or water, because it does not have any definite odor or taste.

Most cadmium used in this country is extracted during the production of other metals such as zinc, lead, or copper. Cadmium has many uses in industry and consumer products, mainly batteries, pigments, metal coatings, and plastics.

Sources: Air pollution, art supplies, bone meal, cigarette smoke, food (coffee, fruits, grains, and vegetables grown in cadmium-laden soil, meats [kidneys, liver, poultry, or refined foods), freshwater fish, fungicides, highway dusts, incinerators, mining, nickel-cadmium batteries, oxide dusts, paints, phosphate fertilizers, power plants, seafood (crab, flounder, mussels, oysters, scallops), sewage sludge, "softened" water, smelting plants, tobacco and tobacco smoke, and welding fumes.

Cadmium can enter the environment in several ways. It can enter the air from the burning of coal and household waste, and metal mining and refining processes. It can enter water from disposal of waste water from households or industries. Fertilizers often have some cadmium in them and fertilizer use causes cadmium to enter the soil. Spills and leaks from hazardous waste sites can also cause cadmium to enter soil or water. Cadmium attached to small particles may get into the air and travel a long way before coming down to earth as dust or in rain or snow. Cadmium does not break down in the environment but can change into different forms. Most cadmium stays where it enters the environment for a long time. Some of the cadmium that enters water will bind to soil but some will remain in the water. Cadmium in soil can enter water or be taken up by plants. Fish, plants, and animals take up cadmium from the environment.

Target Organs: Appetite and pain centers (in brain), brain, heart and blood vessels, kidneys, and lungs.

Signs/Symptoms: Anemia, dry and scaly skin, emphysema, fatigue, hair loss, heart disease, depressed immune system response, hypertension, joint pain, kidney stones or damage, liver dysfunction or damage, loss of appetite, loss of sense of smell, lung cancer, pain in the back and legs, and yellow teeth.

Discussion: Current studies are attempting to determine if cadmium-induced bone and kidney damage can be prevented (or made less likely) by adequate calcium, protein (amino acids), vitamin D, and zinc in the diet.

Cadmium is another toxic metal with a long history of detrimental effects. Hair analysis is useful for evaluating cadmium in smoker and nonsmoker populations of industrially non-exposed urban and rural areas.⁵¹ Smoking itself causes significant elevation of toxic element levels in hair, particularly cadmium, lead, and nickel.⁵² The urine level of cadmium is also a good measure of body stores.⁵³Under most circumstances, measurement of urine levels is a clinically useful technique. Once the renal threshold has been exceeded, however, urine levels become less trustworthy.⁵⁴

Cadmium exposure has been associated with hypertension, and studies show that hair levels of hypertensives are higher than controls.⁵⁵ Hair cadmium has also been shown to be significantly and inversely related to the activity of erythrocyte Na+/K+ ATPase among a group of male smokers. This enzymatic inhibition by cadmium was noted at levels far below toxic levels and may provide additional insight into the link between hypertension and cadmium exposure. ⁵⁶ Cadmium appears to inhibit sulfhydryl-containing enzymes so that relatively low doses depress levels of norepinephrine, serotonin, and acetylcholine. ⁵⁷

Cadmium has no known good effects on your health. Breathing air with very high levels of cadmium severely damages the lungs and can cause death. Breathing lower levels for years leads to a build-up of cadmium in the kidneys that can cause kidney disease. Other effects that may occur after breathing cadmium for a long time are lung damage and fragile bones. Workers who inhale cadmium for a long time may have an increased chance of getting lung cancer. No proof has been found that mice or hamsters that breathe in cadmium get lung cancer. However, some rats that breathe in cadmium do develop lung cancer. We do not know if breathing cadmium can affect your ability to have children or can harm unborn babies. Female rats and mice that breathe high levels of cadmium have fewer litters and the pups may have more birth defects than usual. Breathing cadmium causes liver damage and changes in the immune system in rats and mice. We do not know if breathing cadmium harms the liver, heart, nervous system, or immune system in humans.

Eating food or drinking water with very high cadmium levels severely irritates the stomach, leading to vomiting and diarrhea. The only people who have died from drinking cadmium are people who used cadmium to commit suicide. Eating lower levels of cadmium over a long period of time leads to a build-up of cadmium in the kidneys. This cadmium build-up causes kidney damage, and also causes bones to become fragile and break easily. We know that if female rats or mice eat or drink cadmium, their litters may be harmed. We do not know if eating cadmium affects your ability to have children or harms unborn babies. Animals eating or drinking cadmium sometimes get high blood pressure, iron poor blood, liver disease, and nerve or brain damage. We do not know if humans eating or drinking cadmium get any of these diseases. Studies of humans or animals that eat or drink cadmium have not found increases in cancer. These studies were not strong enough to show that eating or drinking cadmium definitely does not cause cancer. The Department of Health and Human Services has determined that cadmium and cadmium compounds may reasonably be anticipated to be carcinogens. The International Agency for Research on Cancer has determined that cadmium is probably carcinogenic to humans. The EPA has determined that cadmium is a probable human carcinogen by inhalation. Skin contact with cadmium is not known to cause health effects in humans or animals.

Sources: Air pollution, ammunition (shot and bullets), bathtubs (cast iron, porcelain, steel), batteries, canned foods, ceramics, chemical fertilizers, cosmetics, dolomite, dust, foods grown around industrial areas, gasoline, hair dyes and rinses, leaded glass, newsprint and colored advertisements, paints, pesticides, pewter, pottery, rubber toys, soft coal, soil, solder, tap water, tobacco smoke, and vinyl 'mini-blinds'.

Target Organs: Bones, brain, heart, kidneys, liver, nervous system, and pancreas.

Signs/Symptoms: Abdominal pain, {anemia} anemia, anorexia, anxiety, auto exhaust, bone pain, brain damage, confusion, {constipation} constipation, convulsions, dizziness, drowsiness, fatigue, {headaches} headaches, {hypertension1} hypertension, inability to concentrate, {heart_burn}indigestion, irritability, loss of appetite, loss of muscle coordination, memory difficulties, miscarriage, muscle pain, pallor, tremors, vomiting, and weakness.

Discussion: The toxicity of lead is widely acknowledged. The greatest risk for harm, even with only minute or short-term exposure, is to infants, young children, and pregnant women. A federal study conducted by the Centers for Disease Control and Prevention (CDCP) in 1984 estimated that three to four million American children have an unacceptably high level of lead in their blood. Dr. Suzanne Binder, a CDCP official, stated, "Many people believed that when lead paint was banned from housing [in 1978], and lead was cut from gasoline [in the late 1970s], lead- poisoning problems disappeared, but they're wrong. We know that throughout the country children of all races, and ethnicities and income levels are being affected by lead [already in the environment]." In their book, 'Toxic Metal Syndrome', Dr.'s R. Casdorph and M. Walker report that over 4 million tons of lead is mined each year and existing environmental lead levels are at least 500 times greater than pre-historic levels.

In 1989, the U.S. Environmental Protection Agency (EPA) reported that more than one million elementary schools, high schools, and colleges are still using lead-lined water storage tanks or lead-containing components in their drinking fountains. The EPA estimates that drinking water accounts for approximately 20% of young children's lead exposure. Other common sources are lead paint residue in older buildings (as in inner cities) and living in proximity to industrial areas or other sources of toxic chemical exposure, such as commercial agricultural land. All children born in the U.S. today have measurable traces of pesticides, a source of heavy metals and chlorine- based chemicals, in their tissues.

Lead is a known neurotoxin (kills brain cells), and excessive blood lead levels in children have been linked to learning disabilities, {conditionmentaladd} attention deficit disorder, hyperactivity syndromes, and reduced intelligence and school achievement scores.

Lead is the best-known example of problems associated with chronic low-level toxic element exposure. Studies show that lead toxicity is associated with deficits in {nervous_system_central}central nervous system functioning that can persist into young adulthood. ⁴⁷ Hair lead and cadmium are correlated with both reduced intelligence scores and lowered school achievement scores. ⁴⁸ A recent study of 277 1st-grade children gave some indication of the profound effects of lead on learning and behavior. There was a highly significant (p< .0001) relationship between hair lead and children with a high deficit rating in teacher questionnaires relating to concentration and task completion. ⁴⁹ One study on lead noted a seven-fold increase in failure to graduate from high school. ⁵⁰ The accepted level for lead-engendered neurotoxicity in children has declined steadily over the past decade as more sophisticated studies have demonstrated the harmful effects of much lower levels of lead.

In people with mercury amalgam fillings, measurements of the mercury level in the mouth ranges between 20 and 400 mcg/m3. Keep in mind that this is continuous exposure. The National Institute of Occupation Safety and Health places the safe limit of environmental exposure to mercury at 20 mcg/m3, but that is assuming a weekly exposure of 40 hours (the work week) and the mercury involved is outside the body. The Environmental Protection Agency's allowable limit for continuous mercury exposure is 1 mcg/m3 but, again, that is based on mercury sources outside the body. Neither figure addresses 24-hour-a-day exposure from mercury in one's mouth.

Hal Huggins, D.D.S., a specialist in the effect of mercury amalgams on health, reports that 90% of the 7,000 patients he tested showed immune system reactivity from exposure to low levels of mercury. In 1984, the American Dental Association (ADA), without providing scientific evidence, claimed that only 5% of the U.S. population is reactive to mercury exposure, and that this figure is insignificant. Meanwhile, the ADA mandates that dentists alert all dental personnel to the potential hazards of inhaling mercury vapors. The Environmental Protection Agency (EPA) goes further, instructing dentists to treat mercury amalgam as a toxic material while handling before insertion, and as toxic waste after removal.

Mark S. Hulet, D.D.S., who conducts research on amalgam fillings, wrote a pamphlet for his patients, in which he cites five categories of pathological reaction to mercury fillings, as identified by dentists, doctors, and toxicologists. The categories are:

- Neurological: emotional manifestations (depression, suicidal impulses, irritability, inability to cope) and motor symptoms (muscle spasms, facial tics, seizures, multiple sclerosis)

- Cardiovascular problems: nonspecific chest pain, accelerated heart beat o Collagen diseases: arthritis, bursitis, scleroderma, systemic lupus erythematosis

- Allergies: Airborne allergies, food allergies, and "universal" reactors. One of the keys to mercury's effects on health may be its ability to block the functioning of manganese, a key mineral required for physiological reactions in all five categories, notes Dr. Hulet.

Sources: Appliances, buttons, ceramics, cocoa, cold-wave hair permanent, cooking utensils, cosmetics, coins, dental materials, food (chocolate, hydrogenated oils, nuts, food grown near industrial areas), hair spray, industrial waste, jewelry, medical implants, metal refineries, metal tools, nickel-cadmium batteries, orthodontic appliances, shampoo, solid-waste incinerators, stainless steel kitchen utensils, tap water, tobacco and tobacco smoke, water faucets and pipes, and zippers.

Target Organs: Areas of skin exposure, larynx (voice box), lungs, and nasal passages

Signs/Symptoms: Apathy, blue-colored lips, cancer (especially lung, nasal, and larynx), contact dermatitis, diarrhea, fever, headaches, dizziness, gingivitis, insomnia, nausea, rapid heart rate, skin rashes (redness, itching, blisters), shortness of breath, stomatitis, and vomiting.

Discussion: The greatest danger from chronic nickel exposure is lung, nasal, or larynx cancers, and gradual poisoning from accidental or chronic low-level exposure, the risk of which is greatest for those living near metal smelting plants, solid waste incinerators, or old nickel refineries.

Hair appears to be an accurate medium for evaluation of total tissue burden of nickel. Findings of elevated IgG, IgA, IgM, and decreased levels of IgE have been observed in patients with high hair levels. ²⁷ Most exposure leading to elevated hair levels is via dust from nearby industries including electrometallurgical emissions. ^28,29 Nickel accumulates with age and smoking, perhaps explaining why tissue levels are highest in patients who died of cardiovascular disease. ^30,31

Given nickel's ability to cause contact dermatitis, and its observed perturbation of immunoglobulin levels, elevated hair levels may serve as an indicator of possible immune dysfunction, as well as a potentially useful marker of cardiovascular problems.

Pure nickel is a hard, silvery white metal, which has properties that make it very desirable for combining with other metals to form mixtures called alloys. Some of the metals that nickel can be alloyed with are iron, copper, chromium, and zinc. These alloys have important uses such as in the making of metal coins and jewelry and in industry for making items such as valves and heat exchangers. Most nickel is used to make stainless steel. Compounds of nickel combined with many other elements, including chlorine, sulfur, and oxygen, exist. Many of these compounds dissolve fairly easily in water and have a characteristic green color. Nickel and its compounds have no characteristic odor or taste. Nickel compounds are used for nickel plating, to color ceramics, to make some batteries, and as substances known as catalysts to increase the rate of chemical reactions.

Nickel combined with other elements occurs naturally in the earth's crust, is found in all soils, and is also emitted from volcanos. Nickel is the 24th most abundant element, and in the environment it is found primarily as oxides or sulfides. Nickel is also found in meteorites and in lumps of minerals on the floor of the ocean, known as sea floor nodules. The earth's core is believed to contain large amounts of nickel. Nickel is released into the atmosphere during nickel mining and by industries that convert scrap or new nickel into alloys or nickel compounds or by industries that use nickel and its compounds. These industries may also discharge nickel in waste water. Nickel is also released into the atmosphere by oil-burning power plants, coal-burning power plants, and trash incinerators.

There is only one nickel mine in operation in the United States. The mine is located in Riddle, Oregon. Most of our new nickel is imported from Canada. Much of our domestic nickel comes from recycling nickel- containing alloys.

Fate & Transport: Nickel may be released to the environment from the stacks of large furnaces used to make alloys or from power plants and trash incinerators. The nickel that comes out of the stacks of the power plants is attached to small particles of dust that settle to the ground or are taken out of the air in rain. It will usually take many days for nickel to be removed from the air. If the nickel is attached to very small particles, removal can take longer than a month. Nickel can also be released in waste water. Most nickel will end up in the soil or sediment where it is strongly attached to particles containing iron or manganese. Under acidic conditions, nickel is more mobile in soil and may seep into groundwater. Nickel does not appear to concentrate in fish. Two recent studies indicate that it does not accumulate in plants growing on land that has been treated with nickel-containing sludge or in small animals living on that land.

Exposure Pathways: You may be exposed to nickel by breathing air, drinking water, eating food, and smoking tobacco and by skin contact with soil, water, and metals containing nickel as well as with metals plated with nickel. Stainless steel and coins contain nickel. Jewelry is often plated with nickel or made from nickel alloys. Patients may be exposed to nickel in artificial body parts made from nickel-containing alloys.

We do not always know to what form of nickel we are exposed. Much of the nickel found in sediment, soil, and rock is so strongly attached to dust and soil particles or embedded in minerals that it is not readily taken up by plants and animals and cannot easily affect your health. We do not know what forms of nickel are found at most hazardous waste sites.

Nickel in air is attached to small particles. In 1982, the average concentration of nickel in air in 111 U.S. cities ranged from 1 to 86 ng/m3 (1 ng/m3 is equivalent to 1 billionth of a gram in a cubic meter of air).

The concentration of nickel in water from rivers and lakes is very low. The average concentration of nickel is generally less than 10 parts in a billion parts (ppb) in rivers and lakes. The level of nickel in water is often so low that we cannot measure it unless we use very sensitive instruments. The average concentration of nickel in drinking water is about 2 ppb. However, you may be exposed to higher than average levels of nickel in drinking water if you live near industries that process or use nickel.

Soil generally contains between 4 and 80 parts of nickel in a million parts of soil (ppm; 1 ppm is 1,000 times greater than 1 ppb). The highest soil concentrations (up to 9,000 ppm) are found near industries where nickel is extracted from ore. High concentrations of nickel occur because dust released from stacks during processing settles out of the air. You may be exposed to nickel in soil by skin contact. Children may also be exposed to nickel by eating soil.

Food contains nickel and is the major source of nickel exposure for the general population. You eat about 170 micrograms (ug; 1 ug = 1,000 ng) of nickel in your food every day. Foods naturally high in nickel include chocolate, soy beans, nuts, and oatmeal. Our daily intake of nickel from drinking water is only about 2 ug. We breathe in between 0.1 and 1 ug nickel/day, excluding nickel in tobacco smoke. We are exposed to nickel when we handle coins and touch other metals containing nickel.

You may be exposed to higher than background levels of nickel if you work in industries that process or use nickel. You may be exposed to nickel by breathing dust or furmes (as from welding) or by skin contact with nickel-containing metal and dust or solutions containing dissolved nickel compounds. A national survey conducted from 1980 to 1983 estimated that 727,240 workers are potentially exposed to nickel metal, nickel alloys, or nickel compounds.

Metabolism: Nickel can enter your body when you breathe in air containing nickel, when you drink water or eat food that contains nickel, and when your skin is in contact with nickel. If you breathe in air that contains nickel dust, the amount of inhaled nickel that reaches your lungs and enters your blood depends on the size of the dust particles. If the particles are large, they stay in your nose; if the particles are small they can enter deep into your lungs. More nickel is absorbed from your lungs into your body when the dust particles are able to dissolve easily in water. When the particles do not dissolve easily in water, the nickel will tend to remain in your lungs for a long time. Some of these nickel particles can leave the lungs with mucus that you spit out or swallow. More nickel will pass into your body through your stomach and intestines if you drink water containing nickel than if you eat food containing the same amount of nickel. A small amount of nickel can enter your bloodstream after being placed on your skin. After nickel gets into your body, it can go to all organs, but it mainly goes to the kidneys. The nickel that gets into your bloodstream leaves in the urine. After nickel is eaten, almost all of it leaves quickly in the feces, and the small amount that gets into your body leaves in the urine.

Health Effects: Nickel is essential to maintain health in animals. Although a lack of nickel has not been found to effect the health of humans, a small amount of nickel is probably also essential for humans.

Much of our knowledge of nickel toxicity is based on animal studies. Rats and mice may die after eating large amounts of nickel. Eating levels of nickel very much greater than the levels normally found in food causes lung disease in dogs and rats and affects the stomach, blood, liver, kidneys, and immune system in rats and mice. Effects on reproduction and birth defects also were found in rats and mice eating or drinking very high levels of nickel. The studies in animals were completed using high levels of soluble nickel which is more readily absorbed by the gastrointestinal tract than the nickel compounds usually found in water and food.

The most common adverse health effect of nickel in humans is an allergic reaction to nickel. People can become sensitive to nickel when jewelry or other things containing nickel are in direct contact with the skin. Wearing earrings containing nickel in pierced ears may also sensitize people to nickel. Once a person is sensitized to nickel, further contact with the metal will produce a reaction. The most common reaction is a skin rash at the site of contact. In some sensitized people dermatitis may develop at a site away from the site of contact. For example, hand eczema is fairly common among people sensitized to nickel. Less frequently, some people who are sensitive to nickel have asthma attacks following exposure to nickel. People who are sensitive to nickel have reactions when nickel is in contact with the skin, and some sensitized individuals react when they eat nickel in food or water, or breath dust containing nickel. More women are sensitive to nickel than men. This difference between men and women is thought to be a result of greater exposure of women to nickel through jewelry and other metal items.

People who are not sensitive to nickel must eat very large amounts of nickel to suffer adverse health effects. Workers who accidently drank light green water containing 250 ppm nickel from a contaminated drinking fountain had stomachaches and suffered adverse effects to the blood (increased red blood cells) and kidneys (increased protein in the urine). A child who ate 5,700 milligrams (mg) (1 milligram = 1 thousandth of a gram) of nickel as crystals of nickel sulfate died from heart failure.

The most serious effects of nickel, such as cancer of the lung and nasal sinus, have occurred in people who have breathed nickel dust while working in nickel refineries or in nickel processing plants. The levels of nickel in the workplace were much higher than background levels. Lung and nasal sinus cancers occurred when the workers were exposed to more than 1 mg of nickel per cubic meter of air as nickel compounds that dissolved easily in water (such as nickel sulfate and nickel chloride) or 10 mg nickel/m3 as nickel compounds that were hard to dissolve (such as nickel subsulfide). The Department of Health and Human Services has determined that nickel and certain nickel compounds may be reasonably anticipated to be carcinogens. The International Agency for Research on Cancer (IARC) has determined that some nickel compounds are carcinogenic to humans and that metallic nickel may possibly be carcinogenic to humans. The EPA has determined that nickel refinery dust and nickel subsulfide are human carcinogens. Other lung effects including chronic bronchitis and reduced lung function have been observed in workers breathing nickel.

General: Antimony is a silvery-white metal that is found in the earth's crust. Antimony ores are mined and then mixed with other metals to form antimony alloys or combined with oxygen to form antimony oxide. Little antimony is currently mined in the United States. It is brought into this country from other countries for processing. However, there are companies in the United States that produce antimony as a by-product of smelting lead and other metals.

Antimony isn't used alone because it breaks easily, but when mixed into alloys, it is used in lead storage batteries, solder, sheet and pipe metal, bearings, castings, and pewter. Antimony oxide is added to textiles and plastics to prevent them from catching fire. It is also used in paints, ceramics, and fireworks, and as enamels for plastics, metal, and glass.

Sources: Local environmental pollution (i.e. via airborne particles from phosphorus fertilizer production and smelting processes) leads to these elevated hair levels. ²⁴

Target Organs: Antimony accumulates in the hair of exposed workers and their children, with higher levels observed in the children's hair.23 The smaller body mass of children combined with greater accumulations of antimony is perhaps cause for concern regarding potential toxicities in areas of high exposure.

Signs/Symptoms: Exposure to antimony at high levels can result in a variety of adverse health effects. Breathing high levels for a long time can irritate your eyes and lungs and can cause heart and lung problems, stomach pain, diarrhea, vomiting, and stomach ulcers. In short-term studies, animals that breathed very high levels of antimony died. Animals that breathed high levels had lung, heart, liver, and kidney damage. In long-term studies, animals that breathed very low levels of antimony had eye irritation, hair loss, lung damage, and heart problems. Problems with fertility were also noted. In animal studies, problems with fertility have been seen when rats breathed very high levels of antimony for a few months. Ingesting large doses of antimony can cause vomiting. We don't know what other effects may be caused by ingesting it. Long-term animal studies have reported liver damage and blood changes when animals ingested antimony. Antimony can irritate the skin if it is left on it. Antimony can have beneficial effects when used for medical reasons. It has been used as a medicine to treat people infected with parasites. The Department of Health and Human Services, the International Agency for Research on Cancer, and the Environmental Protection Agency (EPA) have not classified antimony as to its human carcinogenicity. Lung cancer has been observed in some studies of rats that breathed high levels of antimony. No human studies are available. We don't know whether antimony will cause cancer in people. Tests are available to measure antimony levels in the body. Antimony can be measured in the urine, feces, and blood for several days after exposure. However, these tests cannot tell you how much antimony you have been exposed to or whether you will experience any health effects. Some tests are not usually performed in most doctors' offices and may require special equipment to conduct them.

Exposure Pathways: Because antimony is found naturally in the environment, the general population is exposed to low levels of it every day, primarily in food, drinking water, and air. It may be found in air near industries that process or release it, such as smelters, coal-fired plants, and refuse incinerators. In polluted areas containing high levels of antimony, it may be found in the air, water, and soil. Workers in industries that process it or use antimony ore may be exposed to higher levels.

Health Effects: Exposure to antimony at high levels can result in a variety of adverse health effects. Breathing high levels for a long time can irritate your eyes and lungs and can cause heart and lung problems, stomach pain, diarrhea, vomiting, and stomach ulcers. In short-term studies, animals that breathed very high levels of antimony died. Animals that breathed high levels had lung, heart, liver, and kidney damage. In long-term studies, animals that breathed very low levels of antimony had eye irritation, hair loss, lung damage, and heart problems. Problems with fertility were also noted. In animal studies, problems with fertility have been seen when rats breathed very high levels of antimony for a few months.

Ingesting large doses of antimony can cause vomiting. We don't know what other effects may be caused by ingesting it. Long-term animal studies have reported liver damage and blood changes when animals ingested antimony. Antimony can irritate the skin if it is left on it. Antimony can have beneficial effects when used for medical reasons. It has been used as a medicine to treat people infected with parasites.

The Department of Health and Human Services, the International Agency for Research on Cancer, and the Environmental Protection Agency (EPA) have not classified antimony as to its human carcinogenicity. Lung cancer has been observed in some studies of rats that breathed high levels of antimony. No human studies are available. We don't know whether antimony will cause cancer in people.

Tests are available to measure antimony levels in the body. Antimony can be measured in the urine, feces, and blood for several days after exposure. However, these tests cannot tell you how much antimony you have been exposed to or whether you will experience any health effects. Some tests are not usually performed in most doctors' offices and may require special equipment to conduct them.

Regulations: The EPA allows 0.006 parts of antimony per million parts of drinking water (0.006 ppm). The EPA requires that discharges or spills into the environment of 5,000 pounds or more of antimony be reported. The Occupational Safety and Health Administration (OSHA) has set an occupational exposure limit of 0.5 milligrams of antimony per cubic meter of air (0.5 mg/m3) for an 8-hour workday, 40-hour workweek. The American Conference of Governmental Industrial Hygienists (ACGIH) and the National Institute for Occupational Safety and Health (NIOSH) currently recommend the same guidelines for the workplace as OSHA.

General: Barium is a silvery-white metal that occurs in nature in many different forms called compounds. These compounds are solids and they do not burn well. Two forms of barium, barium sulfate and barium carbonate, are often found in nature as underground ore deposits. Barium is sometimes found naturally in drinking water and food. Because certain forms of barium (barium sulfate and barium carbonate) do not mix well with water, the amount of barium usually found in drinking water is of a small quantity. Other barium compounds, such as barium chloride, barium nitrate, and barium hydroxide, are manufactured from barium sulfate. Barium compounds such as barium acetate, barium carbonate, barium chloride, barium hydroxide, barium nitrate, and barium sulfide dissolve more easily in water than barium sulfate.

Barium and barium compounds are used for many important purposes. Barium sulfate ore is mined and used in several industries. It is used mostly by the oil and gas industries to make drilling muds. Drilling muds make it easier to drill through rock by keeping the drill bit lubricated. Barium sulfate is also used to make paints, bricks, tiles, glass, rubber, and other barium compounds. Some barium compounds, such as barium carbonate, barium chloride, and barium hydroxide, are used to make ceramics, insect and rat poisons, additives for oils and fuels, and many other useful products. Barium sulfate is sometimes used by doctors to perform medical tests and take x-ray photographs of the stomach and intestines.

Sources: Absorbable barium salts (hydroxide, chloride, or carbonate) may occur in some pesticides.26 Barium compounds are used by the oil and gas industries to make drilling muds. Drilling muds make it easier to drill through rock by keeping the drill bit lubricated. They are also used to make paint, bricks, tiles, glass, and rubber. Barium is found in most soils and foods at low levels. Fish and aquatic organisms accumulate barium.

Target Organs: Few studies relate barium levels in the hair to pathologic processes, although one retrospective study indicated that high levels in the hair along with an elevated calcium/magnesium ratio correlated with myocardial infarction.25 The insoluble form of this element, barium sulfate, is used as an X- ray contrast medium and is non-problematic.

Signs/Symptoms: Difficulties in breathing; increased blood pressure; changes in heart rhythm (digitalis-like toxicity) and ventricular fibrillation, extra systoles; stomach irritation; brain swelling (cerebral cortex - digitalis-like effect); convulsive tremors and muscle weakness; damage to liver, kidney, heart, and spleen; effects on the haematopoietic system erythrocytopenia, leukocytopenia, reduced haemoglobin levels); benign pneumoconiosis; fibrinogenic activity in the development of diffuse, progressive pneumosclerosis after prolonged inhalation.

The effects in people of ingesting low levels of barium over the long term are unknown. Animal studies showed increased blood pressure and changes in the heart from ingesting barium over a long time. Effects of barium from breathing it or from touching it are unknown, too.

Discussion: Contamination of table salt with barium chloride caused an endemic state of barium intoxication in China. Barium fluoride inhaled by pregnant rats resulted in embryotoxic effects such as increased pre- and postnatal mortality, haemorrhaging, reduced blood haemoglobin and kidney damage in the offspring

Fate & Transport: The length of time that barium will last in the environment following release to air, land, and water depends on the form of barium released. Barium compounds that do not dissolve well in water, such as barium sulfate and barium carbonate, can last a long time in the environment. Barium compounds that dissolve easily in water usually do not last a long time in the environment. Barium that is dissolved in water quickly combines with sulfate or carbonate ions and becomes the longer lasting forms (barium sulfate and barium carbonate). Barium sulfate and barium carbonate are the forms of barium most commonly found in the soil and water. If barium sulfate and barium carbonate are released onto land, they will combine with particles of soil.

Exposure Pathways: Background levels of barium in the environment are very low. The air that most people breathe contains about 0.0015 parts of barium per billion parts of air (ppb). The air around factories that release barium into the air has only about 0.33 ppb or less of barium. Most surface water and public water supplies contain only about 0.38 parts of barium per million parts of water (ppm) or less. In some areas that have underground water wells, drinking water may contain more than the 1 ppm limit set by EPA. The highest amount measured from these water wells has been 10 ppm. The highest amount of barium found in soil is about 100 to 3,000 ppm. Some foods, such as Brazil nuts, seaweed, fish, and certain plants, may contain high amounts of barium. The amount of barium found in food and water usually is not high enough to be a health concern. However, information is still being collected to find out if long-term exposure to low levels of barium causes any health problems.

Barium waste may be released to air, land, and water during industrial operations. Barium is released into the air during the mining and processing of ore and during manufacturing operations. Some industries dump wastes containing barium compounds onto land or into the ocean and other bodies of water. Barium compounds are found in more than 150 hazardous waste sites in the United States. We do not know the exact number of hazardous waste sites containing barium because not all waste sites have been examined for barium.

People with the greatest known risk of exposure to high levels of barium are those working in industries that make or use barium compounds. Most these exposed persons breathe air that contains barium sulfate or barium carbonate. Sometimes they are exposed to one of the more harmful forms of barium (for example, barium chloride or barium hydroxide) by breathing the dust from these compounds or by getting them on their skin. Many hazardous waste sites contain barium compounds, and these sites may be a source of exposure for people living and working near them. Exposure near hazardous waste sites may occur by breathing dust, eating soil or plants, or drinking water that is polluted with barium. People near these sites may also get soil or water that contains barium on their skin.

Metabolism: Barium enters your body when you breathe air, eat food, or drink water containing barium. It may also enter your body to a small extent when you have direct skin contact with barium compounds. Barium that you breathe seems to enter the bloodstream very easily. Barium does not seem to enter the bloodstream as well from the stomach or intestines. How much barium actually gets into your bloodstream depends on how much barium you breathe, eat, or drink and how easily the form of barium you breathe dissolves in the fluids in your body. Some barium compounds (for example, barium chloride) can enter your body through your skin, but this is very rare and usually occurs in industrial accidents at factories where they make or use barium compounds. Barium at hazardous waste sites may enter your body if you breathe dust, eat soil or plants, or drink water polluted with barium. Barium can also enter your body if polluted soil or water touches your skin.

Barium that enters your body by breathing, eating, or drinking is removed mainly in feces and urine. Most of the barium that enters your body is removed within a few days, and almost all of it is gone within 1-2 weeks. Most barium that stays in your body goes into the bones and teeth. We do not know the long-term health effects of the barium that stays in your body.

Health Effects: The health effects of the different barium compounds depend on how well the specific barium compound dissolves in water. For example, barium sulfate does not dissolve well in water and has few adverse health effects. Doctors sometimes give barium sulfate orally or by placing it directly in the rectum of patients for purposes of making x-rays of the stomach or intestines. The use of this particular barium compound in this type of medical test is not harmful to people. Barium compounds such as barium acetate, barium carbonate, barium chloride, barium hydroxide, barium nitrate, and barium sulfide that dissolve in water can cause adverse health effects. Most of what we know comes from studies in which a small number of individuals were exposed to fairly large amounts of barium for short periods. Eating or drinking very large amounts of barium compounds that dissolve in water may cause paralysis or death in a few individuals. Some people who eat or drink somewhat smaller amounts of barium for a short period may potentially have difficulties in breathing, increased blood pressure, changes in heart rhythm, stomach irritation, minor changes in blood, muscle weakness, changes in nerve reflexes, swelling of the brain, and damage to the liver, kidney, heart, and spleen. One study showed that people who drank water containing as much as 10 ppm of barium for 4 weeks did not have increased blood pressure or abnormal heart rhythms. We have no reliable information about the possible health effects in humans who are exposed to barium by breathing or by direct skin contact. However, many of the health effects might be similar to those seen after eating or drinking barium. We have no information about the ability of barium to cause birth defects or affect reproduction in humans. Barium has not been shown to cause cancer in humans.

The health effects of barium have been studied more often in experimental animals than in humans. Rats that ate or drank barium over short periods had build- up of fluid in the trachea (windpipe), swelling and irritation of the intestines, changes in organ weights, decreased body weight, and increased numbers of deaths. Rats that ate or drank barium over long periods had increased blood pressure and changes in the function and chemistry of the heart. Mice that ate or drank barium over a long period had a shorter life span. We have no reliable information about the health effects in experimental animals that are exposed to barium by breathing or by direct skin contact. We also have no reliable information to tell whether barium causes cancer or birth defects in experimental animals.

The Department of Health and Human Services, the International Agency for Research on Cancer, and EPA have not classified barium as to its carcinogenicity.

Target Organs: Increased exposure to uranium dust has long been associated with increased incidence of lung cancer. ³² Although there are no strong studies linking hair uranium with either cancer risk or radon exposure, hair levels (measuring U238) do correlate with environmental exposure to this element.

Discussion: The accumulation of uranium in the hair may be related to blood group, with types AB and B having a higher apparent affinity for the element. ³³

In animal studies, a condition of low iron nutriture led to greater retention of uranium as evidenced by hair levels. ³⁴