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Getting the Lead Out - The News About an Old Problem
Drs. Farjami, Nesheiwat and Karmen are physicians in the Department of Internal Medicine at New York Medical College, Westchester Medical Center. They report no conflicts of interest. In the past three years, Dr. Lerner has been a speaker for Aventis, Novo Nordisk and Pfizer.
A Mysterious Case?A 44-year-old man walks into a doctor's office complaining of stomach pain and loss of appetite. He says the pain started about three months earlier and has been getting worse. And, he tells the doctor, he's lost about 20 pounds. He describes the pain as "coming and going;" he does not remember having had nausea, vomiting or diarrhea.
After a blood test reveals anemia (low levels of red blood cells or hemoglobin in the blood), the man is sent to a gastroenterologist who tests for internal bleeding, a common cause of anemia. None is found.
Because the man has both abdominal pain and anemia, his doctor orders a blood test to measure blood lead levels. Sure enough, they come back off the charts. He has lead poisoning. The next step is to find the source of the lead. An investigation of materials used at his contruction job, as well as his household water, provides no answers. The man is admitted to the hospital, where x-rays turn up a clue. There is a bullet near his right pelvis and bullet fragments in his right lower leg. He explains that 18 years ago he was shot twice during a robbery. The mystery is solved; somehow, lead from 18 year-old bullets is finding its way into the man's bloodstream.
The story has a happy ending. Doctors at the hospital use drugs to bring down the lead levels in his blood and operate to remove the bullet from his pelvis. While the fragments are too small and too numerous to be taken out, he eventually recovers and goes home.
Lead in Human HistoryThere are two common ways to get lead poisoning: you can breathe it or you can eat it. Lead is breathed into the lungs from polluted air or absorbed into the body through the digestive tract. As the above scenario suggests, however, there is a third way — being shot.
Human beings have mined and used lead for thousands of years and lead poisoning has been part of our history since ancient times. The first cases were caused by exposure to fumes during smelting. More recently, the Industrial Revolution provoked a tremendous increase in the number of cases of lead poisoning. Many early industrial workers exposed to lead became psychotic or died. Doctors made the connection between lead exposure and sickness, but they thought that only extremely high levels of exposure were harmful. They were wrong.
In the early 20th century, along with the automobile, came leaded oil and gasoline. Once lead from auto or incinerator emissions enters the environment it remains airborne indefinitely. It can contaminate soil and water across a wide area. Aside from its effect on humans, acute lead toxicity can damage entire eco-systems. Effects include low growth rates in plants; developmental, reproductive and nervous system problems in mammals, birds and fish; and, in severe cases, death. Lead is highly toxic to aquatic life, particularly in soft water. Since lead accumulates in the tissues of plants and animals that serve as food for other creatures, it can build up in the tissues of humans and other animals who sit at the top of the food chain.
Lead Poisoning 101Lead exists in both organic and inorganic forms. Both are potentially harmful. Basically, lead that is ultimately derived from carbon-containing compounds — for example, petroleum products — is organic and lead that comes from other sources, such as mining, is said to be inorganic.
Children and adults handle and react to lead exposure differently. Children are typically exposed to lead through the gastrointestinal tract, often after eating paint chips contaminated with lead. Because of their small size and rapid development, children are more vulnerable than adults to lead exposure. Children between one and two years old absorb 40 to 50% of ingested lead, whereas adults absorb only 10 to 15%. Rates of absorption increase in those who because of poor diet are deficient in iron, calcium, zinc or phosphate.
In developing countries, where leaded gasoline and leaded paint are common, it has been estimated that virtually all children under age two and more than 80 percent of those between three and five have blood lead levels that exceed the World Health Organization (WHO) safety threshhold. An estimated 15 to 18 million children in developing countries have suffered permanent damage from lead poisoning, including lowered IQ, learning disabilities, hearing loss, reduced attention span and behavioral abnormalities.
Once inside the body, lead accumulates in the bones, where it can remain for decades. The skeletal system contains 95% of the body's total lead. Lead stored in bone tissue is not a health issue in itself; the problem occurs during a process called "bone turnover." Bone turnover refers to the breakdown and replacement of bone tissue that is a natural part of bodily functioning. During this process, harmful stored lead is released into the bloodstream. Conditions such as pregnancy, menopause, breast-feeding, hyperthyroidism and hypermetabolic states may increase bone turnover and, consequently, blood lead levels.(1)(2)(3)(3)
Occupational exposure is responsible for most adult lead poisoning. Workers at particular risk include welders, iron cutters, abrasive blasters, painters, laborers, renovation and remodeling contractors, people who work at firing ranges; and those who are involved in the manufacture and disposal of car batteries and the maintenance and repair of bridges, water towers and other steel structures. The first sign of lead poisoning is usually anemia. Anemia causes fatigue, fainting, pain, thirst, and weak or rapid pulse.
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