For the past four years, kids under the age of 6 who had a 5-micrograms-per-deciliter blood lead level warranted a public health response. Now a handful of sources who've received word from the CDC say the agency may lower that level another 30%—down to 3.5 micrograms per deciliter—in the next few months to help ID more kids with lead in their systems, as no level in a child is safe, Reuters reports. The CDC estimates about 500,000 US kids are at or above the current threshold level, with children in thousands of areas having lead levels even higher than those found in Flint, Mich., during its water crisis. The agency changes the threshold periodically to adjust to declining level averages nationwide based on a national survey that examines the health and nutritional status of US citizens. "The revision in the blood lead reference level is to push local governments to tighten the regulations on lead in the environment," a University of Hong Kong professor tells Reuters.
But not everyone is thrilled with the new lower threshold. Some states, for example, still haven't put in place programs adjusting to the current 5 micrograms per deciliter, down from the previous level of 10 before the 2012 update. Another technical problem: Measurement devices and labs can't easily detect lead levels in the 3-micrograms-per-deciliter range. "You could get false positives and false negatives," a Washington State Department of Health epidemiologist says. But perhaps the biggest concern is that critics say resources and funds will now be spread more evenly among more kids with lead exposure, even though the ones with the highest levels need the most help. "A lower reference level may actually do harm by masking reality—that significant levels of lead exposure are still a problem throughout the country," the CEO of a company that makes blood lead testing machines says. (Read more lead stories.)