Heavy Metal Poisoning
Heavy Metal Poisoning
Definition
Heavy metal poisoning is the toxic accumulation of heavy metals in the soft tissues of the body.
Description
Heavy metals are chemical elements that have a specific gravity (a measure of density) at least five times that of water. The heavy metals most often implicated in accidental human poisoning are lead, mercury, arsenic, and cadmium. More recently, thallium has gained some attention in the media as the poison used in several murder cases in the 1990s. 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 function. People may come in contact with heavy metals in industrial work, pharmaceutical manufacturing, and agriculture. Children may be poisoned as a result of playing in contaminated soil. Lead poisoning in adults has been traced to the use of lead-based glazes on pottery vessels intended for use with food, and contamination of Ayurvedic and other imported herbal remedies. Arsenic and thallium have been mixed with food or beverages to attempt suicide or poison others.
Another form of mercury poisoning that is seen more and more frequently in the United States is self-injected mercury under the skin. Some boxers inject themselves with mercury in the belief that it adds muscle bulk. Metallic mercury is also used in folk medicine or religious rituals in various cultures. These practices increase the risk of mercury poisoning of children in these ethnic groups or subcultures.
Causes and symptoms
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.
Diagnosis
Heavy metal poisoning may be detected using blood and urine tests, hair and tissue analysis, or x ray. The diagnosis is often overlooked, however, because many of the early symptoms of heavy metal poisoning are nonspecific. The doctor should take a thorough patient history with particular emphasis on the patient's occupation.
In childhood, blood lead levels above 80 ug/dL generally indicate lead poisoning, however, significantly lower levels (>30 ug/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 ug/dL or higher in children a cause for concern. In adults, symptoms of lead poisoning are usually seen when blood lead levels exceed 80 ug/dL for a number of weeks.
Blood levels of mercury should not exceed 3.6 ug/dL, while urine levels should not exceed 15 ug/dL. Symptoms of mercury poisoning may be seen when mercury levels exceed 20 ug/dL in blood and 60 ug/dL in urine. Mercury levels in hair may be used to gauge the severity of chronic mercury exposure.
Since 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 ug/dL in people with arsenic poisoning. If acute arsenic or thallium poisoning is suspected, an x ray may reveal these substances in the abdomen (since both metals are opaque to x rays). Arsenic may also be detected in the hair and nails for months following exposure.
Cadmium toxicity is generally indicated when urine levels exceed 10 ug/dL of creatinine and blood levels exceed 5 ug/dL.
Thallium poisoning often causes hair loss (alopecia), numbness, and a burning sensation in the skin as well as nausea, vomiting, and dizziness. As little as 15-20 mg of thallium per kilogram of body weight is fatal in humans; however, smaller amounts can cause severe damage to the nervous system.
Treatment
When heavy metal poisoning is suspected, it is important to begin treatment as soon as possible to minimize long-term damage to the patient's nervous system and digestive tract. Heavy metal poisoning is considered a medical emergency, and the patient should be taken to a hospital emergency room.
The treatment for most heavy metal poisoning is chelation therapy. A chelating agent specific to the metal involved is given either 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. This process may be lengthy and painful, and typically requires hospitalization. Chelation therapy is effective in treating lead, mercury, and arsenic poisoning, but is not useful in treating cadmium poisoning. To date, no treatment has been proven effective for cadmium poisoning. Thallium poisoning is treated with a combination of Prussian blue (potassium ferric hexacyanoferrate) and a diuretic, because about 35% of it is excreted in the urine; however, if treatment is not started within 72 hours of ingesting the poisoning, damage to the patient's nervous system may be permanent.
In cases of acute mercury, arsenic, or thallium ingestion, vomiting may be induced. Activated charcoal may be given in cases of thallium poisoning. Washing out the stomach (gastric lavage) may also be useful. The patient may also require treatment such as intravenous fluids for such complications of poisoning as shock, anemia, and kidney failure.
Patients who have taken arsenic, thallium, or mercury in a suicide attempt will be seen by a psychiatrist as part of emergency treatment.
Prognosis
The chelation process can only halt further effects of the poisoning; it cannot reverse neurological damage already sustained.
Prevention
Because arsenic and thallium were commonly used in rat and insect poisons at one time, many countries have tried to lower the rate of accidental poisonings by banning the use of heavy metals in pest control products. Thallium was banned in the United States as a rodent poison in 1984. As a result, almost all recent cases of arsenic and thallium poisoning in the United States were deliberate rather than accidental.
Because exposure to heavy metals is often an occupational hazard, protective clothing and respirators should be provided and worn on the job. Protective clothing should then be left at the work site and not worn home, where it could carry toxic dust to family members. Industries are urged to reduce or replace the heavy metals in their processes wherever possible. Exposure to environmental sources of lead, including lead-based paints, plumbing fixtures, vehicle exhaust, and contaminated soil, should be reduced or eliminated.
People who use Ayurvedic or traditional Chinese herbal preparations as alternative treatments for various illnesses should purchase them only from reliable manufacturers.
KEY TERMS
Alopecia— Loss of hair.
Chelation— The process by which a molecule encircles and binds to a metal and removes it from tissue.
Heavy metal— One of 23 chemical elements that has a specific gravity (a measure of density) at least five times that of water.
Prussian blue— The common name of potassium ferric hexacyanoferrate, a compound approved in the United States for treatment of thallium poisoning. Prussian blue gets its name from the fact that it was first used by artists in 1704 as a dark blue pigment for oil paints. It has also been used in laundry bluing and fabric printing.
Resources
BOOKS
Beers, Mark H., MD, and Robert Berkow, MD., editors. "Poisoning." Section 23, Chapter 307 In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.
Beers, Mark H., MD, and Robert Berkow, MD., editors. "Psychiatric Emergencies." Section 15, Chapter 194 In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.
Wilson, Billie A., Margaret T. Shannon, and Carolyn L. Stang. Nurses Drug Guide 2000. Stamford, CT: Appleton & Lange, 2000.
PERIODICALS
Boyarsky, Igor, DO, and Adrain D. Crisan, MD. "Toxicity, Thallium." eMedicine August 3, 2004. 〈http://www.emedicine.com/emerg/topic926.htm〉.
Centers for Disease Control and Prevention (CDC). "Adult Blood Lead Epidemiology and Surveillance—United States, 2002." Morbidity and Mortality Weekly Report 53 (July 9, 2004): 578-582.
Counter, S. A., and L. H. Buchanan. "Mercury Exposure in Children: A Review." Toxicology and Applied Pharmacology 198 (July 15, 2004): 209-230.
Ferner, David J., MD. "Toxicity, Heavy Metals." eMedicine May 25, 2001. 〈http://www.emedicine.com/EMERG/topic237.htm〉.
Prasad, V. L. "Subcutaneous Injection of Mercury: 'Warding Off Evil'." Environmental Health Perspectives 111 (September 2004): 1326-1328.
Schilling, U., R. Muck, and E. Heidemann. "Lead Poisoning after Ingestion of Ayurvedic Drugs." [in German] Medizinische Klinik 99 (August 15, 2004): 476-480.
Thompson, D. F., and E. D. Callen. "Soluble or Insoluble Prussian Blue for Radiocesium and Thallium Poisoning?" Annals of Pharmacotherapy 38 (September 2004): 1509-1514.
ORGANIZATIONS
American Society of Health-System Pharmacists (ASHP). 7272 Wisconsin Avenue, Bethesda, MD 20814. (301) 657-3000. 〈http://www.ashp.org〉.
Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. 〈http://www.cdc.gov〉.
Food and Drug Administration. Office of Inquiry and Consumer Information. 5600 Fisher Lane, Room 12-A-40, Rockville, MD 20857. (301) 827-4420. 〈http://www.fda.gov/fdahomepage.html〉.
National Institutes of Health. National Institute of Environmental Health Sciences Clearinghouse. EnviroHealth, 2605 Meridian Parkway, Suite 115, Durham, NC 27713. (919) 361-9408.
Heavy Metal Poisoning
Heavy metal poisoning
Definition
Heavy metal poisoning is the toxic accumulation of heavy metals in the soft tissues of the body.
Description
Heavy metals are chemical elements that have a specific gravity (a measure of density) 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 can be toxic in larger quantities. Heavy metals may enter the body through 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 function. People may come in contact with heavy metals in industrial work, pharmaceutical manufacturing, and agriculture. Children may be poisoned as a result of playing in contaminated soil.
Sources of exposure for some heavy metals
- lead: old paint, leaded gasoline, old pipes
- mercury: contaminated fish, industrial and agricultural wastes
- cadmium: industrial waste, insecticides, old galvanized pipes
- arsenic: insecticides and industrial processes, some drinking water
Causes & symptoms
Symptoms will vary, depending on the nature and quantity of the heavy metal, and whether it was ingested or inhaled. Patients who ingest a heavy metal may complain of cramps, nausea, vomiting, diarrhea , stomach pain, headache , sweating, and a metallic taste in the mouth. Mercury can cause skin burns if it has touched the skin, and inhaled mercury vapor can cause severe inflammation of the lungs. If lead is inhaled in the form of lead dust, insomnia , headache, mania, and convulsions may occur. In severe cases of heavy metal poisoning, patients exhibit obvious impairment of cognitive, motor, and language skills. The expression "mad as a hatter" comes from the mercury poisoning prevalent in seventeenth-century France among hatmakers who soaked animal hides in a solution of mercuric nitrate to soften the hair.
Diagnosis
Heavy metal poisoning may be detected using blood, urine, and stool tests, hair and tissue analysis, or x rays. In children, blood lead levels above 80 mcg/dl generally indicate lead poisoning ; however, significantly lower levels (>.30 mcg/dL) can cause mental retardation and other cognitive and behavioral problems in chronically exposed children. The Centers for Disease Control and Prevention considers a blood lead level of 10 mcg/dl or higher in children a cause for concern. In adults, symptoms of lead poisoning are usually seen when blood lead levels exceed 80 mcg/dl for a number of weeks. Blood levels of mercury should not exceed 3.6 mcg/dl, while urine levels should not exceed 15 mcg/dl. Symptoms of mercury poisoning may appear when mercury levels exceed 20 mcg/dl in blood and 60 mcg/dl in urine. Mercury levels in hair may be used to gauge the severity of chronic mercury exposure, but a 2002 report says that these tests have questionable validity.
Since 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 mcg/dl in people with arsenic poisoning. If acute arsenic poisoning is suspected, an x ray may reveal ingested arsenic in the abdomen (since arsenic is opaque to x rays). Arsenic may also be detected in the hair and nails for months following exposure. Cadmium toxicity is generally indicated when urine levels exceed 10 mcg/dl of creatinine and blood levels exceed 5 mcg/dl.
Treatment
Emergency treatment of acute poisoning, especially in children, can be handled by calling a poison control line (800-222-1222) or by dialing 911. Alternative practitioners often rely on the same chelating agents used by standard doctors to treat heavy metal poisoning, but also use natural supplements and additional techniques to assist the body's own detoxification processes. One highly contested issue between alternative medicine and mainstream dentistry surrounds mercury poisoning. Alternative practitioners believe that there is a large body of evidence suggesting that silver amalgam tooth fillings, which contain mercury, are a major factor in mercury poisoning. For those with high mercury levels in their bodies, they recommend that all mercury-containing tooth fillings be removed by a holistic dentist. The National Institutes of Health hope to put some of the debate over amalgam fillings to rest with two clinical trials on fillings currently underway. However, the results are not expected until 2005.
Dietary changes are used to support the treatment of heavy metal poisoning. Detoxification diets are predominantly vegetarian, and reduce or avoid foods that may stress the immune system, such as processed foods, fried foods, sugar, fat, alcohol, caffeine , meat, and dairy products. Organic foods are recommended to avoid exposure to pesticides and chemicals. Detoxification diets include plenty of high-fiber foods, including oat bran and psyllium seeds, to help cleanse the digestive tract. Apples, pears, and legumes are high in pectins, which are believed to have chelating effects on heavy metals. Foods high in antioxidants are recommended, such as fruits, vegetables, and fresh juices. Sulfur-containing foods such as garlic , onions, and eggs (organically produced) are utilized, as are dark-green leafy vegetables that contain high amounts of chlorophyll. Foods that may contain heavy metals are avoided, including many fish and shellfish. Factory-farmed chicken and eggs are avoided as well, because chickens are often fed fish meal. A 2002 study reported that eating tofu may reduce lead levels in the blood. Tofu is rich in calcium, which may help reduce the blood's ability to absorb and retain lead.
Nutritional supplements include antioxidant vitamins A, C, and E, and multimineral supplements that contain calcium, iron, magnesium, copper, chromium, selenium , and zinc. Cysteine, methionine , L-gluthione, and DMSA (dimethyl succinate) are other supplements. Herbal support includes herbs that have detoxification effects, such as milk thistle , burdock, and numerous others. Spirulina and chlorella sea algae are used as well, and acidophilus helps rebuild the digestive tract.
Homeopathic remedies, which prompt the body's detoxification mechanisms, have shown success with heavy metal poisoning. Detoxification therapies are also highly recommended, including fasting , sweating, colonics, and therapeutic vomiting. Ayurvedic medicine has an intensive detoxification and healing program called panchakarma .
Allopathic treatment
In an emergency, patients should call 911 or a poison control hotline (800) 222-1222. The treatment 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 edetate calcium disodium, dimercaprol (BAL), and penicillamine. Succimer (DMSA) is used for children suffering from lead poisoning. The chelating agent encircles and binds the metal in the body's tissues, forming a complex that is then released from the tissue and travels in the bloodstream. The complex is filtered out of the blood by the kidneys and excreted in the urine. This process may be lengthy and painful, and typically requires hospitalization. Chelation therapy is effective in treating lead, mercury, and arsenic poisoning, but is not useful in treating cadmium poisoning . To date, no treatment has been proven effective for cadmium poisoning. In cases of acute mercury or arsenic ingestion, vomiting may be induced. Washing out the stomach (gastric lavage) may also be useful. The patient may also require treatment such as intravenous fluids for complications of poisoning such as shock, anemia , and kidney failure.
Expected results
The chelation process can only halt further effects of the poisoning; it cannot reverse neurological damage already sustained.
Prevention
Because exposure to heavy metals is often an occupational hazard, protective clothing and respirators should be provided and worn on the job. Protective clothing should then be left at the work site and not worn home, where it could carry toxic dust to family members. Industries are urged to reduce or replace the heavy metals in their processes wherever possible. Exposure to environmental sources of lead, including lead-based paints, plumbing fixtures, vehicle exhaust, and contaminated soil, should be reduced or eliminated.
Resources
BOOKS
Goldberg, Burton. Chronic Fatigue, Fibromyalgia and Environmental Illness. Tiburon, CA: Future Medicine, 1998.
Lappe, Marc. Chemical Deception: The Toxic Threat to Health and the Environment. San Francisco: Sierra Club, 1991.
Lawson, Lynn. Staying Well in a Toxic World. Chicago: Noble, 1993.
PERIODICALS
Kales, Stefanos N., and Rose H. Goldman. "Mercury Exposure: Current Concepts, Controversies, and a Clinic's Experience." Journal of Occupational and Environmental Health (February 2002): 143–146.
"Should Amalgam Fillings be Banned? Evidence on the Risks of Mercury Fillings is Mixed. Should They be Outlawed Anyway?." Natural Health (March 2002): 26.
"Tofu May Lower Lead Levels in Blood." Townsend Letter for Doctors and Patients (February–March 2002): 23.
ORGANIZATIONS
American Association of Poison Control Centers. 3201 New Mexico Avenue, Suite 310. Washington, DC 20016. (800) 222-1222. <http://www.aapcc.org>.
American Holistic Medical Association. 12101 Menaul Blvd. NE, Suite C., Albuquerque, NM 87112. (505) 292-7788. info@ holisticmedicine.org. <http://www.holisticmedicine.org>.
Center for Occupational and Environmental Medicine. 7510 Northforest Drive, North Charleston, SC 29420. (843) 572-1600. allanl@coem.com. <http://www.coem.com>.
OTHER
A Citizen's Toxic Waste Manual. Greenpeace USA, 1436 U St. NW, Washington, DC 20009. (202) 462-1177.
Douglas Dupler
Teresa G. Odle
Heavy Metal Poisoning
Heavy metal poisoning
Definition
Heavy metal poisoning is the toxic accumulation of heavy metals in the soft tissues of the body.
Description
Heavy metals are chemical elements that have a specific gravity (a measure of density) 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 function. People may come in contact with heavy metals in industrial work, pharmaceutical manufacturing, and agriculture. Children may be poisoned as a result of playing in contaminated soil.
Demographics
Heavy metal poisoning is relatively uncommon. In children, lead ingestion is the major culprit of heavy metal poisoning. In 2000, an estimated one in 22 American children had high levels of lead in their blood. Children in urban areas with old lead water pipes and lead-painted homes are especially at risk. Mercury poisoning is possible from eating contaminated fish.
Causes and symptoms
Symptoms will vary, depending on the nature and the quantity of the heavy metal ingested. Affected people 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, people exhibit obvious impairment of cognitive, motor, and language skills. The expression "mad as a hatter" comes from the mercury poisoning prevalent in seventeenth-century France among hat makers who soaked animal hides in a solution of mercuric nitrate to soften the hair.
When to call the doctor
A healthcare professional should be contacted whenever exposure to any heavy metal is suspected. The Centers for Disease Control and Prevention (CDC) recommends testing all children for lead exposure at 12 months of age and, if possible, again at 24 months. Testing should start at six months for children at higher risk for lead poisoning .
Diagnosis
Heavy metal poisoning may be detected using blood and urine tests, hair and tissue analysis, or x ray.
In childhood, blood lead levels above 80 mg/dL generally indicate lead poisoning; however, significantly lower levels (>30 mg/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 mg/dL or higher in children a cause for concern. In adults, symptoms of lead poisoning are usually seen when blood lead levels exceed 80 mg/dL for a number of weeks.
Blood levels of mercury should not exceed 3.6 mg/dL, while urine levels should not exceed 15 mg/dL. Symptoms of mercury poisoning may be seen when mercury levels exceed 20 mg/dL in blood and 60 mg/dL in urine. Mercury levels in hair may be used to gauge the severity of chronic mercury exposure.
Since 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 mg/dL in people with arsenic poisoning. If acute arsenic poisoning is suspected, an x ray may reveal ingested arsenic in the abdomen (since arsenic is opaque to x rays ). Arsenic may also be detected in the hair and nails for months following exposure.
Cadmium toxicity is generally indicated when urine levels exceed 10 mg/dL of creatinine and blood levels exceed 5 mg/dL.
Treatment
The treatment 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. This process may be lengthy and painful and typically requires hospitalization . Chelation therapy is effective in treating lead, mercury, and arsenic poisoning, but it is not useful in treating cadmium poisoning. As of 2004, no treatment had been proven effective for cadmium poisoning.
In cases of acute mercury or arsenic ingestion, vomiting may be induced. Washing out the stomach (gastric lavage) may also be useful. The affected person may also require treatment such as intravenous fluids for complications of poisoning such as shock, anemia, and kidney failure.
Prognosis
The chelation process can only halt further effects of the poisoning; it cannot reverse neurological damage already sustained.
Prevention
Because exposure to heavy metals is often an occupational hazard, protective clothing and respirators should be provided and worn on the job. Protective clothing should then be left at the work site and not worn home, where it could carry toxic dust to family members. Industries are urged to reduce or replace the heavy metals in their processes wherever possible. For the sake of children's health along with everyone else's, exposure to environmental sources of lead, including lead-based paints, plumbing fixtures, vehicle exhaust, and contaminated soil, should be reduced or eliminated.
Nutritional concerns
Parents should avoid preparing or serving food in containers that have lead in their glazing.
Parental concerns
Parents living in homes built prior to 1978 should be vigilant in removing flaking or peeling paint because it might contain lead. Simply repainting such surfaces will not solve the problem. Parents must monitor the environments in which their children play and the objects that go into their children's mouths. Cleanliness is a must if old paint is in a child's environment. Removal (stripping paint to bare metal or bare wood) of lead is the best way to prevent lead exposure in children. Areas where removal is taking place should be sealed off from the rest of the house. In addition, children should be kept away from occupational sources of other heavy metals. Parents who are concerned about their child's exposure to lead should have the child tested.
KEY TERMS
Chelation —The process by which a molecule encircles and binds to a metal and removes it from tissue.
Heavy metal —One of 23 chemical elements that has a specific gravity (a measure of density) at least five times that of water.
See also Lead poisoning.
Resources
BOOKS
Goto, Collin S. "Heavy Metal Intoxication." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman, et al. Philadelphia: Saunders, 2003, pp. 2355–7.
Gupta, S. K., et al. Emergency Toxicology: Management of Common Poisons. Boca Raton, FL: CRC Press, 2003.
Klaasen, Curtis D., and John Doull. Casarett and Doull's Toxicology: The Basic Science of Poisons, 6th ed. New York: McGraw Hill, 2001.
Markowitz, Morrie. "Lead Poisoning." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman, et al. Philadelphia: Saunders, 2003, pp. 2358–61.
PERIODICALS
Clark S, et al. "The influence of exterior dust and soil lead on interior dust lead levels in housing that had undergone lead-based paint hazard control." Journal of Occupational and Environmental Hygiene 1, no. 5 (2004): 273–82.
Counter, S. A., and L. H. Buchanan. "Mercury exposure in children: a review." Toxicology and Applied Pharmacology 198, no. 2 (2004): 209–30.
Dorea, J. G. "Mercury and lead during breast-feeding." British Journal of Nutrition 92, no. 1 (2004): 21–40.
Yassin, A. S., and J. F. Martonik. "Urinary cadmium levels in the U.S. working population, 1988–1994." Journal of Occupational and Environmental Hygiene 1, no. 5 (2004): 324–33.
ORGANIZATIONS
American Academy of Clinical Toxicology. 777 East Park Drive, PO Box 8820, Harrisburg, PA 17105–8820. Web site: <www.clintox.org/index.html>.
American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211–2672. Web site: <www.aafp.org/>.
American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007–1098. Web site: <www.aap.org/default.htm>.
American Association of Poison Control Centers. 3201 New Mexico Avenue NW, Washington, DC 20016. Web site: <www.aapcc.org/>.
American College of Occupational and Environmental Medicine. 55 West Seegers Road, Arlington Heights, IL 60005. Web site: <www.acoem.org/>.
Multiple Sclerosis Foundation. 6350 North Andrews Ave., Fort Lauderdale, Fl 33309–2130. Web site: <www.msfacts.org/>.
National Multiple Sclerosis Society. 733 Third Avenue, New York, NY 10017. Web site: <www.nmss.org/>.
WEB SITES
"Heavy Metal Poisoning." Med Help International. Available online at <www.medhelp.org/HealthTopics/Heavy_Metal_Poisoning.html> (accessed November 10, 2004).
"Heavy Metals (Toxicology)." National Multiple Sclerosis Society. Available online at <www.nationalmssociety.org/Sourcebook-Heavy%20Metals.asp> (accessed November 10, 2004).
Hoekman, Theodore. "Heavy Metals Toxicology." Available online at <www.luminet.net/~wenonah/hydro/heavmet.htm> (accessed November 10, 2004).
"Toxicity, Heavy Metals." eMedicine. Available online at <www.emedicine.com/emerg/topic237.htm> (accessed November 10, 2004).
L. Fleming Fallon, Jr., MD, DrPH
Itai-Itai Disease
Itai-itai disease
The symptoms of Itai-Itai disease were first observed in 1913 and characterized between 1947 and 1955; it was 1968, however, before the Japanese Ministry of Health and Welfare officially declared that the disease was caused by chronic cadmium poisoning in conjunction with other factors such as the stresses of pregnancy and lactation, aging, and dietary deficiencies of vitamin D and calcium. The name arose from the cries of pain, "itai-itai" (ouch-ouch) by the most seriously stricken victims, older Japanese farm women. Although men, young women, and children were also exposed, 95% of the victims were post-menopausal women over 50 years of age. They usually had given birth to several children and had lived more than 30 years within 2 mi (3 km) of the lower stream of the Jinzu River near Toyama.
The disease started with symptoms similar to rheumatism, neuralgia, or neuritis. Then came bone lesions, osteomalacia, and osteoporosis, along with renal disfunction and proteinuria. As it escalated, pain in the pelvic region caused the victims to walk with a duck-like gait. Next, they were incapable of rising from their beds because even a slight strain caused bone fractures. The suffering could last many years before it finally ended with death. Overall, an estimated 199 victims have been identified, of which 162 had died by December 1992.
The number of victims increased during and after World War II as production expanded at the Kamioka Mine owned by the Mitsui Mining and Smelting Company. As 3,000 tons of zinc-lead ore per day were mined and smelted, cadmium was discharged in the wastewater . Downstream, farmers withdrew the fine particles of flotation tailings in the Jinzu River along with water for drinking and crop irrigation . As rice plants were damaged near the irrigation inlets, farmers dug small sedimentation pools that were ineffective against the nearly invisible poison.
Both the numbers of Itai-Itai disease patients and the damage to the rice crops rapidly decreased after the mining company built a large settling basin to purify the wastewater in 1955. However, even after the discharge into the Jinzu River was halted, the cadmium already in the rice paddy soils was augmented by airborne exhausts. Mining operations in several other Japanese prefectures also produced cadmium-contaminating rice, but afflicted individuals were not certified as Itai-Itai patients. That designation was applied only to those who lived in the Jinzu River area.
In 1972 the survivors and their families became the first pollution victims in Japan to win a lawsuit against a major company. They won because in 1939 Article 109 of the Mining Act had imposed strict liability upon mining facilities for damages caused by their activities. The plaintiffs had only to prove that cadmium discharged from the mine caused their disease, not that the company was negligent. As epidemiological proof of causation sufficed as legal proof in this case, it set a precedent for other pollution litigation as well.
Despite legal success and compensation, the problem of contaminated rice continues. In 1969 the government initially set a maximum allowable standard of 0.4 parts per million (ppm) cadmium in unpolished rice. However, because much of the contaminated farmland produced grain in excess of that level, in 1970 under the Foodstuffs Hygiene Law this was raised to 1 ppm cadmium for unpolished rice and 0.9 ppm cadmium for polished rice. To restore contaminated farmland, Japanese authorities instituted a program in which, each year, the most highly contaminated soils in a small area are exchanged for uncontaminated soils. Less contaminated soils are rehabilitated through the addition of lime, phosphate, and a cadmium sequestering agent, EDTA.
By 1990 about 10,720 acres (4,340 ha), or 66.7% of the approximately 16,080 acres (6,510 ha) of the most highly cadmium contaminated farmland had been restored. In the remaining contaminated areas where farm families continue to eat homegrown rice, the symptoms are alleviated by treatment with massive doses of vitamins B1, B12, D, calcium, and various hormones. New methods have also been devised to cause the cadmium to be excreted more rapidly. In addition, the high costs of compensation and restoration are leading to the conclusion that prevention is not only better but cheaper. This is perhaps the most encouraging factor of all.
See also Bioaccumulation; Environmental law; Heavy metals and heavy metal poisoning; Mine spoil waste; Smelter; Water pollution
[Frank M. D'Itri ]
RESOURCES
BOOKS
Kobayashi, J. "Pollution by Cadmium and the Itai-Itai Disease in Japan." In Toxicity of Heavy Metals in the Environment, Part 1, edited by F. W. Oehme. New York: Marcel Dekker, 1978.
Kogawa, K. "Itai-Itai Disease and Follow-Up Studies." In Cadmium in the Environment, Part II, edited by J. O. Nriagu. New York: Wiley, 1981.
Tsuchiya, K., ed. Cadmium Studies in Japan: A Review. Tokyo, Japan, and Amsterdam, Netherlands: Kodansha and Elsevier/North-Holland Biomedical Press, 1978.