The most common source of lead poisoning is lead-contaminated dust (LCD). This dust can be so fine that it cannot be seen by the naked eye. Dusts can have thousands of parts per million lead by weight. The high concentrations of lead in LCD means that even tiny quantities of dust exposure can result in a very high lead intake. The current government standards for safe levels of lead-contaminated dust in housing are 100 µg/ft2 on floors; 500 µg/ft2 on window sills; and 800 µg/ft2 on window wells. Some experts believe these levels are too high and should be lowered.
What is Lead Poisoning?
The Uses of Lead
Lead (Pb) is a basic chemical element, which can be combined with other substances to form lead compounds. A bluish-white metal of bright luster, lead is very soft, highly malleable, ductile, has a low melting point and is resistant to corrosion. These characteristics brought lead into common usage, even in ancient times. The ancient Egyptians used lead for sculpture, dishes, jewelry and sinkers for fishing nets. During the days of the Roman Empire, lead was used in shipbuilding, cooking pots, for weights and to line water supply lines. In fact, lead pipes bearing the insignia of early Roman emperors, used as drains for the baths, are still in service today.
In modern times manufacturers have used lead in a variety of products, some of which have included: gasoline, paint, plumbing, fine crystal, electric cable insulation, storage batteries, ammunition and insecticides. However, lead, which throughout history has been one of man's most useful and versatile metals, is one of man's oldest known poisons. Due to increased awareness and growing concern about the devastating health hazard lead poses, the United States federal government began placing restrictions on the use of lead in some products, including gasoline, insecticides and paint in housing, in the 1970s.
Today, lead poisoning is the leading environmental health risk in America, particularly in young children. The most common source of lead poisoning is lead-contaminated dust. This dust, which can be so tiny that it is invisible to the naked eye, becomes airborne and surface adherent, making it easily accessible, especially for young children, to ingest and/or inhale.
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Health Risks of Lead Poisoning
Lead is a toxin that has the ability to impede the development and function of every organ and system in the body. Once it enters the body, lead travels through the bloodstream. A small portion of the ingested lead remains in the bloodstream, while some is deposited and stored in the kidneys and brain. Most, however, is stored in the bones. This lead moves in and out of the bones as the body absorbs nutrients and grows. Lead stays in the body for a long time. The "half life" of lead in bone, or the time it takes half of the amount of lead stored in bones to leave the body, can be more than twenty years. Therefore, one can be lead poisoned through high exposure to lead during a short period of time (acute), or through low exposure over a long period of time (chronic). Even tiny amounts of lead can be dangerous to a person's health, and its effects on the body can be devastating and irreversible.
Health Risks To Children
The Center for Disease Control estimates that nearly two million American children under the age of six have at least low-level lead poisoning. The CDC also estimates that 10% of all children suffer from lead poisoning. Even children who appear to be healthy can have high levels of lead in their bodies. Children are usually lead poisoned by ingesting the invisible lead-contaminated dust through normal hand-to-mouth activity. A small child may eat paint chips or soil that contains lead. Children also are likely to place their hands or other objects covered with lead-contaminated dust into their mouths. They can breathe in lead-contaminated dust, especially during renovations that disturb painted surfaces. Lead poses a more serious threat to children than to adults because their growing bodies absorb more lead than adult's bodies, and their brains and nervous systems are more sensitive to the damaging effects of lead. The blood lead level of concern is 10 µg/dl or greater.
Blood lead levels in children of 100 to 150 µg/dl are associated with swelling of the brain, resulting in severe brain damage and even death. Lead exposures this high in the United States are relatively rare today; however, these levels are encountered in industrialized countries that are not controlling lead exposures.
At low exposures, the effects of childhood lead poisoning can include:
* Such as attention deficit hyperactivity disorder (ADHD).
- impaired growth
- hearing loss
- behavior problems*
- impaired short-term memory
Health Risks To Adults
Lead poisoning in adults occurs most often to those exposed to lead-contaminated dust in lead related jobs and hobbies. At high levels, the lead can have an adverse effect on various nerves, such as the motor nerves. This damage can result in the inability to maintain the hand or foot in a normal position due to weakness of muscle tone because of nerve damage ("wrist drop" or "foot drop").
According to a recent study published in the April 17, 1996, Journal of the American Medical Association (pp. 1171-1176), long-term exposure to lead is linked to an increased risk of hypertension in men. A second study published in the same issue (pp. 1177-1181) suggests that low-level lead exposure impairs kidney function in middle-aged and older men.
Additional effects of prolonged lead exposure in adults can include:
- respiratory problems
- nerve disorders
- reproductive disorders
- digestive problems
- memory loss
- difficulties during pregnancy
Health Risks To Pregnancies
Approximately 4.4 million, or 9 percent, of U.S. women of childbearing age have elevated blood lead levels. Lead, which is stored in the bones, moves out of the bones with calcium. If a woman was previously exposed to lead, the lead stored in her body may be released at an accelerated rate as calcium moves from her body to the unborn child, especially if her diet is calcium-deficient.
The tissues of the unborn baby can absorb lead as the infant develops in the womb. The developing brain is extremely vulnerable to the harmful effects of lead during this time. Due to the fact that lead can pass through the placenta to the fetus, a pregnant woman exposed to lead can place her unborn child at an increased risk of:
Health Risks To The Elderly
- low birth weight
- learning disabilities
- birth defects
- premature birth
- still birth
Lead moves in and out of the bones with calcium, an essential nutrient for body cells. When calcium intake is insufficient, due to dietary deficiencies or hormonal changes, bones release the stored lead along with calcium. Osteoporosis intensifies the mobilization of lead stored in the bones, placing the elderly who have previously been exposed to lead at risk of suffering the effects of lead poisoning.
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Symptoms of Lead Poisoning
Most lead-poisoned people show no overt symptoms, especially in low-to-moderate cases. Before symptoms appear, lead may cause unseen injury to the body. Symptoms of early stages of lead poisoning may resemble "flu-like" illnesses. Some symptoms may include the following:
Symptoms In Children:
Checking Your Family For Lead Poisoning
- loss of appetite
- abdominal pain
- loss of developmental skills
- loss of muscular coordination
|Symptoms In Adults:
- stomach cramps
- muscle aches and pains
- weight loss
- tendency to be aggressive
- pain in back and lower extremities
The total impact of lead on the nervous system has only recently been recognized. That means, earlier recommendations on "safe" amounts of lead in blood were dangerously close to levels now considered very likely to cause mental retardation in children. Medical professionals considered blood lead levels of greater than 60 mg/dl to be a health concern in the 1960s. This level was lowered to 25 mg/dl by the 1980s. In October of 1991, the Center for Disease Control (CDC) reduced the level of concern to 10 mg/dl.
Your doctor or health center can perform a simple blood test that will detect lead in your body. The blood test is inexpensive and sometimes free. Your doctor will explain what the test results mean. Blood tests are important for children who are six months to one year old, and for family members who may have high exposure to leaded dust. Lead tests may be important in certain areas as early as 6 months of age, and should be done routinely in many areas as early as one year of age. For further information, contact your local health department or the National Lead Information Center at 1-800-LEAD-FYI.
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