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Addressing Lead Exposure in Children
Concerns about lead exposure in U.S. children have grown with the continuing massive federal recalls of toys produced in China using lead paint. To better understand the health effects of lead poisoning in children under the age of six-the age group at the greatest risk for health effects from exposure to lead-At the Frontline spoke with Joseph Graziano, PhD, professor of Environmental Health Sciences and associate dean for research, whose work focuses on understanding the health consequences of exposure to metals in adults and children.
What are the dangers of exposure to lead in children?
Lead exposure in children can have adverse effects on several organ systems, including the kidneys, the nervous system, and red blood formation. The major concern is that the developing brain is particularly sensitive to the toxic effects of lead, even when the magnitude of exposure is relatively small. Numerous studies, including our own, have demonstrated that even at low levels of exposure, lead can cause subtle deficits in intelligence in young children, and that these deficits persist into later life. The normal hand-to-mouth activity of children between 1 and 3 years of age typically leads to the ingestion of lead-containing dust in the environment. Usually, blood lead concentrations peak during this age period.
Very high blood lead concentrations can be associated with much more serious effects, including convulsions, coma, and death-a syndrome known as lead encephalopathy. The average blood lead concentration in U.S. children peaked in the 1970s, at a time when leaded gasoline and lead-based paints were widely used and lead encephalopathy was quite common. Since that time, due to the removal of lead from gasoline, house paint, and other products, blood lead levels have fallen from a mean of 17 to 2 ug/dl. The Centers for Disease Control (CDC) threshold for "normal" is < 9 ug/dl, however recent studies have suggested that subtle effects of lead on intelligence occur at levels below that. It is notable that the CDC has not issued new guidelines concerning lead poisoning since 1991.
If a child has played with one (or more) of the recalled toys, should parents have their children tested for lead?
I believe that it would be prudent for parents to ask their pediatricians for advice. Personally, I would recommend that children under the age of six who have played with lead-contaminated toys should have a blood lead test.
Can lead poisoning be treated?
Yes, and the treatment varies as a function of the child's blood lead concentration. The key for all children found to have an elevated blood lead is to identify the source of exposure and eliminate it immediately. This is called an environmental intervention. Drugs called chelating agents, which bind to lead and foster its elimination into urine, are available to treat children with markedly elevated blood lead levels. My laboratory developed one of these drugs (called Succimer), which is the only orally active chelating agent for lead. However, because these drugs can have adverse effects of their own, their use is generally limited to those children who have blood lead levels of 45 ug/dl or higher. Children with blood lead levels of 70 ug/dl are at risk for lead encephalopathy and are considered to be a medical emergency and require both medical and environmental management. For those whose blood levels fall between 10-44 ug/dl, environmental and, at times, nutritional interventions are called for. Children with iron deficiency absorb more lead from the gastrointestinal tract than those who are sufficient in iron. Children with elevated blood lead levels are often found to have concomitant iron deficiency which, of course, can be treated. This rectifies the iron deficiency and at the same time reduces the amount of lead absorbed from the gut.
What advice do you have for parents to help prevent their children from being exposed to lead?
It is important to appreciate that lead is not absorbed from the skin. Lead must be ingested in order to enter the bloodstream. Thus, the mere act of playing with contaminated toys does not necessarily mean that the child has been exposed. Nevertheless, any toys that have been recalled by their manufacturers should be removed from the home. The most dangerous toy items appear to be lead-contaminated jewelry. The CDC has reported a couple of cases of severe poisoning, including one death, due to the ingestion of lead-contaminated children's jewelry (http://www.cdc.gov/nceh/lead/faq/jewelry.htm).
I have little doubt that some lead exposure has likely occurred in association with the use of other larger toys, such as trains and dolls painted with lead-based paint. Such exposure would be sporadic, however, and dependent on the child's mouthing behavior while playing with the toys. In my opinion, the bottom line for parents is that contaminated toys should be disposed of, and young children who have played with them should have a blood lead measurement.
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