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Lead Poisoning: What It Is, How to Test, What to Do
Daniel J. DeNoon
WebMD Health News
Reviewed By Louise Chang, MD
Aug. 15, 2007 -- Lead poisoning -- at levels that do not cause immediate symptoms -- can permanently damage kids' brains.
Before their second birthday, children are particularly susceptible to lead poisoning. They are, of course, more likely than older children to put lead-contaminated hands or toys or paint chips in their mouths. Moreover, a child's gastrointestinal tract also absorbs lead more readily than does the adult gut.
Most importantly, a child's rapidly developing brain is highly vulnerable to lead toxicity, says pediatrics professor John Rosen, MD, director of the lead program at the Children's Hospital at Montefiore Medical Center, Bronx, N.Y.
"Lead can be extremely dangerous for young children and can affect their lives forever," Rosen tells WebMD. "It is better to be conservative and safe and not ever sorry about excessive lead exposure."
Lead poisoning is almost never a single event in which a child ingests harmful quantities of lead, gets sick, and must be rushed to the hospital. Instead, lead poisoning is an insidious, month-by-month accumulation of lead in a child's body.
"I have supervised 30,000 cases of child lead poisoning, and I have not seen a case of symptomatic lead poisoning for many years," Rosen says.
That's why lead-painted toys can be such a problem, says John Benitez, MD, director of the Lawrence Poison and Drug Information Center and associate professor of pediatric and environmental medicine at the University of Rochester, N.Y.
"Parents need to know it is not an acute problem," Benitez tells WebMD. "If a kid just touches and plays with a lead painted toy, it is not a problem. But if that child sits and chews on it for weeks and months and absorbs lead -- that becomes a risk."
What, exactly, is lead poisoning? How do you know if your child is at risk? What should you do if your child has a worrisome level of lead exposure? WebMD consulted experts for answers to these and other questions.
What Is Lead Poisoning?
The risks of lead have been known for decades. But there is surprisingly little agreement on exactly when a child has accumulated a toxic amount of lead.
Everybody agrees that there is no "safe" level of lead exposure. However, the CDC doesn't recommend taking action unless a child's blood-lead level exceeds 10 micrograms/dL -- a threshold set in 1991. Rosen says that's far too high.
"There are now seven peer-reviewed articles in the medical literature that indicate the major loss of IQ occurs in children at blood-lead levels of less than 7.5 micrograms/dL," Rosen says. "A threshold of 10 is no longer protective of children. ... I would very strongly suggest lowering the threshold to 5, based on abundant data in the last five years."
The CDC says about 310,000 American kids (1 to 5 years old) have blood-lead levels over 10 micrograms/dL.
A U.S. child's main risk of lead poisoning comes from the lead-based house paints in near-universal use before 1950. The paints were banned for housing use in 1978. An estimated 24 million U.S. housing units -- which some 4 million young children call home -- have deteriorated lead paint contributing to lead-contaminated house dust.
"Very small particles of paint get into household dust you cannot see," Rosen says. "That gets on hair, fingers, toys, and skin. Through normal hand-mouth activity, that paint is absorbed."
How long it takes a child to absorb toxic levels of lead depends on the concentration of lead in the dust. Rosen says that in a typical lead-contaminated housing unit, it takes one to six months for a small child's blood-lead levels to rise to a level of concern.
"If the amount of hand-to-mouth activity is robust, and the concentrations of lead in that housing unit are substantial, it does not take long," he warns.
What about the recently discovered lead paint on children's toys?
"In terms of pervasiveness and widespread distribution of those toys, only time will tell how many children will be identified who develop lead poisoning. At the present time that is unknown, although the risk is definite," Rosen says.
What Are the Risks of Lead Poisoning?
Rosen says the ultimate effects of lead on children include:
- Loss of IQ points
- Impairments in language fluency or communication
- Memory problems
- Trouble paying attention
- Lack of concentration
- Poor fine-motor skills
- Difficulty with planning and organization
- Difficulty forming abstract concepts
- Poor cognitive flexibility (trying something else if the first thing you try doesn't solve a problem)
"To fully test children to see if there are any adverse outcomes from lead poisoning cannot be done until they reach their sixth birthday," Rosen says. "Many of these symptoms don't manifest until age 6 or 7 years. What a parent might know before that might well be some common complaints such as speech delay, hyperactivity, not being able to sit/listen/learn in school, and not being able to focus. Those observations may be the result of earlier childhood lead poisoning."
Is Your Child at Risk of Lead Poisoning?
Except in those rare cases in which a child ingests a huge amount of lead, lead poisoning has no obvious, immediate symptoms.
"Over time, you may notice tiredness, nonspecific belly complaints, or a child may become anemic," Benitez says. "Unless you are eating blocks of lead, there are no acute or sudden symptoms that would appear in minutes. That is the problem with lead -- the subtle, slow dose over time."
There is a sure way to know whether your child has accumulated dangerous amounts of lead: a simple blood test. Such tests cost about $15 or $20. Results come back in two days, says Emory University pediatrician Robert J. Geller, MD, medical director of the Georgia Poison Center and chief of pediatrics at Grady Health System, Atlanta. Rosen says, "To be cautious, if a child has been playing with a leaded toy for about one month or more, it is suggested that a child should be tested for lead."
"The average American blood level is 2 to 3 micrograms/dL," Geller tells WebMD. "Your body does get rid of lead very slowly. So a small amount that gets in will be excreted. It is not a permanent blood level."
A recent U.S. Preventive Services (USPS) Task Force panel noted in a 2006 report that children's blood-lead levels usually peak at about age 2 and go down after that.
Rosen says all children's blood lead levels should be tested at age 12 months and again at age 24 months -- with additional testing every six months if the child is at high risk of lead exposure.
"If a child has never been tested for lead, it should be done regardless of the child's age," Rosen says. "The prime question for a pediatrician to ask is what is the status of the apartment or home where the child lives: Is there peeling paint? Is it an old building, or new construction?"
The USPS panel reached a different conclusion. It found no evidence that universal lead-exposure screening leads to better clinical outcomes than targeted screening of at-risk children.
What to Do for Children With Lead Poisoning
Unfortunately, once a child has absorbed a dangerous amount of lead, there's no quick way to make the lead go away.
Children with dangerously high blood lead levels -- 45 micrograms/dL or more -- can be treated by chelation (pronounced key-LAY-shun). Chelation involves giving a child one of two drugs that quickly remove lead from the blood.
Chelation can save the life of a child with acute lead poisoning. But it does not remove all lead from the body. Most ingested lead is stored in the bones and leaches back into the bloodstream -- and brain -- over time.
"Chelation stops lead poisoning from being life-threatening," Rosen says. "Has damage already been done to the brain? Yes. Chelation does not reverse the adverse effects of lead on the brain. What it does do is save lives. Chelation is of no value -- and may actually harm -- children with lead levels under 45 micrograms/dL."
The USPS panel notes that repeated chelation may temporarily lower blood lead levels, but these reductions are not sustained. The panel found no evidence that these temporary reductions improve health or behavioral outcomes.
What does work? Rosen says the first thing to do is to have the child's pediatrician work with local health authorities to find and remove the source of lead poisoning.
Second, Rosen recommends making sure children with high lead levels get a diet rich in calcium and iron. This, he says, helps prevent intestinal absorption of lead and speeds elimination of lead from the body.
"We are recommending a diet replete in calcium-rich foods such as milk and cheese and iron-rich foods such as fresh green vegetables and some red meat," he says. "If a child is iron deficient, yes, we recommend supplements, but unless lab tests show this, we do not put these children on iron supplements."
This does not mean forcing a child to drink gallons of milk and to eat pounds of spinach.
"In essence, I am really saying a child with high lead levels should be on a well-balanced, healthy diet," Rosen says.
Rosen admits that frustrated parents may want to do more. But he says that if lead has been removed from the child's environment and the child gets a healthy diet, lead levels will naturally decrease over time.
Rosen also suggests that children who have had high blood lead levels should be assessed by a neuropsychologist at age 6 years to evaluate the need for educational interventions.
SOURCES: John Rosen, MD, professor of pediatrics; director, lead program, and director, division of environmental sciences, Children's Hospital at Montefiore Medical Center, Bronx, N.Y. John Benitez, MD, associate professor of emergency medicine, pediatrics, and environmental medicine, and director, Lawrence Poison and Drug Information Center, University of Rochester, N.Y. Robert J. Geller, MD, associate professor of pediatrics, Emory University School of Medicine; medical director, Georgia Poison Center; chief of pediatrics, Grady Health System, Atlanta. Rischitelli, G. Pediatrics, December 2006; vol 118: pp e1867-e1895. U.S. Preventive Services Task Force web site. CDC web site. Environmental Protection Agency web site.
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