Lead poisoning continues to be a serious health problem for young children, especially those living in cities, so a government committee is recommending that the definition of lead poisoning be changed, to include even lower levels of exposure to the toxic chemical.
The Centers for Disease Control (CDC), which is the agency responsible for defining lead poisoning in children, currently says that 10 micrograms of lead per dL of blood should be considered lead poisoning. At these levels, children can show symptoms such as abdominal pain, low appetite, difficulty sleeping and constipation, as well as behavior or attention problems, hearing difficulties and slower growth. Most of the adverse effects of lead on the brain and nervous system build over time, so these symptoms are difficult to pinpoint immediately after exposure.
An advisory committee to the CDC has reviewed the most recent data linking lead levels and developmental and physical problems in young children, and is now recommending that the definition of poisoning be changed to start at blood levels of 5 microgm/dL or more. That would mean that nearly a million children in the US would suffer from lead poisoning, says Dr. John Rosen, professor of pediatrics at Montefiore Medical Center and head of the hospital’s lead program. Under the current definition, about 250,000 children between age 1 and 5 have lead poisoning.
The CDC panel’s advice follows that of a similar panel convened by the Food and Drugs Administration (FDA) several days earlier, and that of the National Toxicology Program, which is part of the Department of Health and Human Services, which released a report in October. Both also recommended that lead poisoning be changed to include children with blood levels of 5 mcirogm/dL or higher.
“I would say that it’s long, long long overdue,” says Rosen of the advice.
The last change occurred in 1991, and Rosen chaired the advisory panel that recommended that level more than two decades ago. Since then, about 20 new studies involving 25,000 youngsters have documented adverse health effects in children with lead levels between 5 microgm/dL and 9 microgm/dL. These include loss of IQ, and impairment in intellectual and physical development that affects learning, motor skills, organization, higher thinking, and behavior. “The data is unequivocal, and it’s solid,” says Rosen.
Most lead exposure in the US occurs in the home, particularly those built before 1978 before regulations prohibited the use of lead in paint and household plumbing. Older homes are more likely to contain chipped or peeled paint that can release dust in the home that children either ingest or breathe. Some youngsters are also exposed to the chemical in imported toys or pottery made from lead-based materials, but these cases are increasingly rare as federal regulations have banned their use in products targeted to children.
The definition of lead poisoning doesn’t mean that levels below 5 microgm/dL are safe. “I like to say that no lead is good lead,” says Dr. Carla Campbell, a pediatrician at the Children’s Hospital of Philadelphia who also serves on an American Academy of Pediatrics council and was a non-voting member of the CDC panel. According to the Environmental Protection Agency (EPA), there is no safe level of lead; any exposure can potentially be harmful. But narrowing down a blood level of lead at which public health officials can take action is helpful. The new advice comes from a standard practice in which researchers look at average blood lead levels in a representative group of children and found that 97.5% of children had levels below 5 microgm/dL.
At the lead clinic at Montefiore, which is in New York City, for example, administrators will intervene for children who test at levels above 10 microgm/dL, calling a city hot line to have experts conduct an environmental inspection of their home to determine the source of the lead exposure. Medically, there is little that doctors can do for children until they test at extremely high levels, in the 40 microgm/dL range. At that point, they start chelation therapy with drugs that absorb the lead to lower its concentration in the blood.
The advice from the committee is only a recommendation; the CDC has several months to decide whether to act on it and change the definition of lead poisoning in children. Based on the similar conclusions reached by the FDA and DHHS, Rosen hopes the change will take place and that the “CDC will move fast so more children are protected.”