While there is really no “safe” level of lead, the CDC has lowered the threshold level for defining lead poisoning in children from 10 micrograms per deciliter of blood to 5 mcg/dl.
The change was made at the recommendation of a CDC advisory committee that based the new threshold on a growing number of studies indicating that even low blood lead levels can cause lifelong health effects including lower IQ. The old 10 mcg level has been in place for 20 years.
Lowering the level deemed unsafe is good news as parents who would have been told their child tested negative will now be alerted to a problem with lead. With the new lower threshold, the number of children over the limit could double, from approximately 250,000 to 450,000.
The CDC suggests that parents contact their local health departments for testing of paint and dust to detect lead levels. If lead is present, the CDC recommends that parents regularly wash children’s hands and toys and wet-mop floors and windowsills. Children should also not be allowed to play on bare soil.
The vast majority of lead poisoning is linked to ingestion of dust and flakes from lead-based paint, which was widely used in homes through the 1950s. It was banned for residential use in 1978, but the paint remains in many older houses. Other possible sources include older water pipes, lead dust in soil and imported toys or jewelry made of lead or coated with lead-based paint.
Even at very low levels, lead can cause irreparable cognitive impairment. Recent studies have found that third-grade test scores, which are highly correlated with high-school dropout rates, were significantly lower among children exposed to lead. Many of these children had blood levels as low as 3 or 4 mcg/dl which is even less than the new threshold.
National Center for Biotechnology Information