NEW YORK – Researchers from Quest Diagnostics and Boston Children's Hospital have found that more than half of participants in a nationwide study of child lead levels had detectable amounts of lead in their blood.
The study, published Monday in JAMA Pediatrics, also found that detectable (1.0 µg/dL or greater) and elevated (5.0 µg/dL or greater) lead levels were associated with poverty and pre-1950s housing.
The study used data from de-identified lab tests done by Quest between October 2018 and February 2020 on 1,141,441 children under 6 years old in all 50 states and the District of Columbia. According to Quest, it is the first effort of its size to examine blood lead levels down to 1.0 µg/dL.
The researchers found that 51 percent of children tested had blood lead levels of 1.0 µg/dL or more and 2 percent had blood lead levels of 5.0 µg/dL or more. While the health effects of lead exposure at the 1.0 µg/dL level have not been thoroughly explored, there is no known safe level of lead exposure in children.
The study also found that poverty was associated with increased lead exposure, with children in the bottom quintile for poverty being more likely to have both detectable and elevated lead levels than those in the top quintile. Children living in areas in the highest quintile for percentage of pre-1950s housing were also more likely to have detectable and elevated lead levels than children living in areas in the lowest quintile.
Children living in zip codes with majority Black populations had higher odds of having detectable blood lead levels but lower odds of having elevated blood levels, the researchers found.
While the research indicates that childhood lead exposure remains an issue despite significant public policy efforts to address the problem, it also highlights progress made. Of the children tested, 1.9 percent had elevated blood lead levels, a decline of 36 percent from the 3 percent of children who had elevated levels in a previous Quest study using data from 2009 to 2015.
"Our Quest analysis finds that while exposure to the highest levels of lead has declined in recent years, most American children are exposed to lead, a substance that is not safe for children at any level," Harvey Kaufman, senior author on the study and senior medical director and head of the health trends research program for Quest, said in a statement. "Moreover, our analysis finds that kids in areas with the highest rates of poverty are also the most at risk, highlighting the critical role of social disparities in health."
"Public health authorities have worked commendably to reduce lead exposure for decades, and yet, substantial risk remains," he added. "Our study is a cautionary tale of the enormous challenge of remediating environments following contamination with toxins dangerous to human health."