Drugs that pull lead from the body don't reverse brain damage from the metallic toxin, at least in children with all but the severest form of poisoning, new research shows. The findings appears in the May 10 issue of The New England Journal of Medicine . Because of successful prevention efforts, lead exposure and rates of lead poisoning in the United States are waning. Yet an estimated 890,000 children suffer lead poisoning, defined as more than 10 micrograms of lead per deciliter of blood. The latest CDC figures show that 8 percent of low-income children and 1 percent of wealthy children have elevated blood lead levels.
Most contamination occurs in poor, inner-city housing.
The ages of structures usually indicate their risks as a lead hazards. Nearly 22 percent of black children who live in homes built before 1946 have elevated blood lead levels, compared with only 1.5 percent of whites living in homes built later, Kim says. The American Academy of Pediatrics doesn't recommend chelation therapy, which strips lead from the blood, in children whose blood lead levels are less than 45 micrograms per deciliter. Even in children with blood lead counts greater than 45 micrograms, chelation isn't clearly effective at reversing brain damage, says Dr. Walter Rogan, an epidemiologist at the National Institute of Environmental Health Sciences in Research Triangle Park, N.C., and lead author of the latest study. The study compared the chelation drug succimer with placebo therapy in 780 inner city children with blood levels between 20 and 44 micrograms per deciliter, well above the government's threshold for nerve damage.