Injury: Lead Poisoning
Injury: Lead Poisoning
Lead poisoning is a form of chronic (long-term) damage to the nervous system and other body organs. It is caused by inhaling dust containing lead or eating or drinking material contaminated with lead.
Lead poisoning has been a source of human illness and premature death since people first began to use lead in pottery, plumbing, cosmetics, jewelry, metal cookware, and even medicines. The oldest known lead mine, opened about 6500 BCE, is located in present-day Turkey. Lead poisoning was first identified around 200 BCE by Nicander of Colophon, a Greek doctor. The metal was popular in the ancient world, however, because it is easily worked, it has a low melting point, and it does not rust. The most common sources of lead poisoning from ancient Rome through the Middle Ages were drinking vessels made of pewter, a metal made mostly of tin with small amounts of copper and lead added; and wine, which was often sweetened by a compound of lead called lead acetate or sugar of lead.
Lead poisoning in humans is often slow to develop because of the small quantities of the metal that can cause health problems. Lead harms the body by preventing the body from using iron, zinc, and calcium in the production of hemoglobin (a pigment found in red blood cells) and in other important body processes. In addition, lead is not easily removed from the body. After it enters the body through the lungs or the digestive tract, it travels first to the blood and other internal organs and then is stored in the bones and teeth. Lead in the blood and soft tissues is
gradually filtered by the kidneys over a period of sixty to seventy days but may remain in the bones and teeth for several years.
In the United States, lead poisoning is most likely to affect children below the age of five years and adults in certain high-risk occupations. About 1.5 million workers are exposed to lead in the workplace. The number of children with risky blood levels of lead, or BLLs, has decreased 68 percent since 1991. As of 2002, the most recent survey year, 1.6 percent of American children between one and five years of age had BLLs above 10 micrograms of lead per deciliter (about 3.5 ounces) of blood.
Children of any race living in cities or near highways with high levels of auto exhaust fumes are at greater risk of high BLLs than children living in rural areas. African American children are at greater risk than either Hispanic or Caucasian children. Boys and girls are at equal risk.
The basic cause of lead poisoning is inhaling, swallowing, or otherwise being exposed to lead in paint, soil, or lead-based products in the environment. Although lead is no longer used in the manufacture of paints,
gasoline, and other products, people can still be exposed to dangerous amounts of lead. In the United States, the most common sources of exposure to lead include:
- Houses built before the 1960s and painted before 1978. House paint was made with lead until 1978, but many older houses have layers of paint that were applied before lead-free paints were available. Stripping or sanding away older paint can be dangerous, too, because the removal process releases fine dust particles containing lead into the air. Children can breathe in this dust or take in lead by swallowing paint chips or dust from lead-based paint.
- Toys and furniture that were painted before 1976.
- Plumbing, pipes, and faucets.
- Storage batteries.
- Children's toys made outside the United States, including paint sets and art supplies.
- Soil contaminated by long years of car exhaust, such as soil along the sides of highways or near gas stations.
- Lead bullets, fishing sinkers, and curtain weights.
- Homemade illegal whiskey (“moonshine”).
- Pewter pitchers, goblets, and dinnerware.
- Lead-based costume jewelry.
- Hobbies that involve soldering, glazing pottery, making jewelry, or making items out of stained glass.
Other sources of lead poisoning in some ethnic groups in the United States are folk remedies for various ailments. These include the practice of eating soil, certain traditional medicines imported from Southeast Asia, and a folk remedy called litargirio, sold in Hispanic grocery stores.
The symptoms of lead poisoning usually develop gradually over time rather than coming on suddenly. In many cases the symptoms are not specific to lead poisoning and may be mistaken for the symptoms of other disorders. In children, whose nervous systems are more vulnerable to lead, symptoms of lead poisoning include irritability, loss of appetite and weight, tiredness, abdominal cramps, vomiting, constipation, a pale complexion due to anemia, impulsive behavior, seizures, lowered IQ, and learning difficulties.
Symptoms of lead poisoning in adults may include:
- Pain, numbness, or tingling sensations in the arms and legs
- Difficulty conceiving in women or abnormal sperm in men
- Headache and memory problems
- Abdominal cramps and constipation
- Mood disorders and personality changes
- Muscle pains and weakness
- Hypertension (high blood pressure)
Most cases of lead poisoning are detected by screening people at risk rather than because the doctor suspects that the symptoms are caused by lead. The diagnosis of lead poisoning is based on a blood test called the blood lead level or BLL. The test can be given to measure the effects of treatment for lead poisoning as well as to screen people for exposure to harmful amounts of lead.
The blood test results are evaluated according to standards set by the American Academy of Pediatrics and the Centers for Disease Control and Prevention (CDC). The BLL is measured in micrograms of lead per deciliter of blood (mcg/dL). A deciliter is about a fifth of a pint. The definition of what is considered a dangerous level of blood lead has changed over the years. In 1997 the blood lead level of concern for children was decreased from 25 micrograms per deciliter to 10 micrograms per deciliter.
Not everyone needs to be screened for possible lead poisoning. The CDC recommends screening for adults employed in certain occupations, particularly metal working, glass working, lead plating, ore refining, auto repair, road repair, and construction. Children in the following categories should be screened for possible lead poisoning:
- Children whose families are receiving federal assistance
- Children who live in or regularly visit a house or apartment built before 1950, or before 1978 if the house has been or is undergoing remodeling
- Children who have a sibling or playmate diagnosed with lead poisoning
- Children from refugee or immigrant families
The CDC divides the results of the BLL test into six groups or classes:
- Class I: Less than 10 mcg/dL
- Class IIA: 10–14 mcg/dL
- Class IIB: 15–19 mcg/dL
- Class III: 20–44 mcg/dL
- Class IV: 45–69 mcg/dL
- Class V: 70 mcg/dL or higher (This blood lead level is considered a medical emergency.)
Mild cases of lead poisoning (Classes I through III) can often be treated simply by removing the source of the lead. Children should have their BLL retested a month later to make sure their blood lead level is dropping.
People with higher BLLs are usually treated with chelation therapy. This is a type of treatment in which the person is given a drug that binds with the lead in the body so that it can be excreted in the urine. People in Class III and some in Class IV are given a drug called succimer, which is taken by mouth. People with BLLs above 50 mcg/dL are usually treated with a drug called EDTA, which must be given intravenously.
Children who have developed anemia as a result of lead poisoning may be given iron supplements.
The prognosis for recovery from lead poisoning depends on the patient's age and the level of lead in his or her body. Adults with low levels of lead often recover without problems. Those with higher levels have a greater risk of long-lasting health problems and must be monitored carefully by their doctor. Their nerves and muscles may no longer function well. Moreover, other body systems may be harmed to various degrees, including the kidneys and blood vessels. People who survive toxic lead levels may suffer some permanent brain damage. However, death from lead poisoning is rare in the early 2000s because of the widespread use of chelation therapy.
Some people also develop complications after chelation therapy, as treatment with chelating drugs does not always reverse nerve damage. Depression, increased aggressiveness, impotence, and infertility have been reported in adults.
The National Institute for Environmental Health Sciences (NIEHS) recommends the following measures to reduce people's exposure to lead:
- People who think they may have lead paint in their homes should get advice on safe paint removal from the Housing and Urban Development (HUD) at 800-RID-LEAD or the National Information Center at 800-LEAD-FYI.
- Parents who work in occupations where they are exposed to lead should change clothes before coming home.
- Everyone should wash their hands before meals.
- People should have the household tap water tested for lead levels. If it is high, filter it or use bottled water for drinking and cooking.
- Throw out old painted toys if it is unclear whether the paint contains lead.
- The home should be kept as dust-free as possible.
- Avoid using candies, canned goods, or folk medications produced outside the United States.
Lead poisoning is likely to continue to be a public health problem for some time. One reason is that lead is not biodegradable. This means that lead persists in the outside environment for a long time. There are still many older buildings that were painted with lead-based paints before 1978, and many people are still unaware of the dangers of removing old paint without safeguards. In addition, it is difficult to control the entry and sale of folk medicines containing lead in the United States.
WORDS TO KNOW
Chelation therapy: Treatment of lead poisoning by administering medications that help the body excrete the lead in the urine.
Pewter: A metal made mostly of tin and small quantities of copper. Modern pewter is no longer made with lead.
Plumbism: The medical name for lead poisoning.
SEE ALSO Cataracts; Depression; Hypertension
Bothell, Joan, Mary-Margaret Gaudio, and Maureen T. Mulroy. How Mother Bear Taught the Children about Lead. Storrs, CT: University of Connecticut Cooperative Extension System, 2003. Developed by the Penobscot Indian Nation and the Environmental Protection Agency, this is a 29-page illustrated storybook for young readers about the dangers of lead. It can be downloaded in PDF format at http://www.kids.niehs.nih.gov/bear/fullbook.pdf (accessed May 5, 2008).
Brody, Jane E. “Personal Health: Dally No Longer; Get the Lead Out.” New York Times, January 17, 2006. Available online at http://query.nytimes.com/gst/fullpage.html?res=9B03E4D6143FF934A25752C0A9609C8B63&sec= &spon=&pagewanted=all (accessed May 5, 2008).
Agency for Toxic Substances and Disease Registry (ATSDR). Lead Webcast for the Community. Available online at http://www.atsdr.cdc.gov/csem/lead/community/index.html (accessed May 5, 2008). This is a ten-minute web-cast with PowerPoint presentation about lead poisoning and its treatment.
Centers for Disease Control and Prevention (CDC). Childhood Lead Exposure. Available online at http://www.cdc.gov/Features/ChildhoodLead/ (updated November 2, 2007; accessed May 5, 2008).
Mayo Clinic. Lead Poisoning. Available online at http://www.mayoclinic.com/health/lead-poisoning/FL00068 (updated March 15, 2007; accessed May 5, 2008).
National Institute of Environmental Health Sciences (NIEHS). Lead and Your Health. Available online in PDF format at http://www.niehs.nih.gov/health/topics/agents/lead/docs/lead.pdf (updated April 2006; accessed May 5, 2008).