More U.S. children may be adversely affected by environmental lead than previously estimated, according to a study published in the New England Journal of Medicine. Researchers found that lead poisoning impacts children’s IQ at lower levels than stipulated in current federal health guidelines.

It is estimated that 2 percent of the 434,000 children younger than 6, about 2 percent of the U.S. population, currently have blood-lead concentrations above the federal guidelines.

(via Knight Ridder Newspapers)