How Lead Poisons the Human Body
Lead is devastating to the human body, inhibiting oxygen and calcium transport and altering nerve transmission in the brain. Most lead poisoning occurs when people swallow lead paint chips or breathe in lead dust. The lead builds up in soft tissue -- kidneys, bone marrow, liver, and brain -- as well as bones and teeth. Lead absorption rates vary; the gastrointestinal tracts of adults typically absorb 10-15 percent of ingested lead, while those of pregnant women and children can absorb up to 50 percent.
Lead Poisoning in Children
Studies show that even low concentrations of lead can cause permanent damage including reduced IQ, learning disabilities, and shortened attention span. Some scientists believe that low-level chronic lead exposure in childhood can alter secretion of the human growth hormone, stunting growth and promoting obesity. In rare cases, children with high, untreated blood-lead concentrations (150 micrograms per deciliter) can die from encephalopathy or massive brain damage.
New research indicates that no amount of lead is safe for a child; yet according to the Centers for Disease Control and Prevention, almost one million American children under the age of six have elevated levels of lead in their blood. Even low lead doses are a concern for children, since continuing exposure can add up to a significant dose over time.
Children's Special Vulnerability
Children are in double jeopardy from lead because their highest potential for exposure occurs when they are most vulnerable. Since children engage in more hand-to-mouth activity than adults, crawling and playing on the ground, they ingest more contaminants in dust or dirt. This high exposure comes at a time when children's bodies are building their vital organs and skeletal and neural structures; lead is particularly toxic to children's developing nervous systems.
Unfortunately, most children do not present overt symptoms of poisoning. Because their symptoms (ranging from irritability to stomach upset) may not be immediately recognizable as lead-related the majority of cases go undetected.
last revised 11/5/2000
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