Half of young kids in the US have high levels of lead in their blood, study finds

• Just over 50% of kids tested for lead in the US had some level of the toxic metal in their blood.
• Children living in older houses and poorer communities were more likely to have elevated blood lead levels.
• Childhood lead exposure can lead to difficulties with learning, behavior, hearing, and speech.

More than half of young children in the US have detectable levels of lead in their blood, according to a study published Monday in JAMA Pediatrics.

The research included lab results from lead testing in more than 1.1 million children aged 5 or younger between October 2018 and February 2020, as well as US Census data to capture social and economic disparities. Just over 50% of kids tested had lead in their blood, although most had relatively low levels.

Childhood lead poisoning has long been a public health concern, since exposure to the toxic metal was found to damage the brain and nervous system. Significant levels of lead exposure can have long-term, potentially irreversible effects on kids' ability to learn, hear, speak, and pay attention in school.

Young kids are more likely to be exposed to lead if they put contaminated toys or fingers in their mouths. Common sources of lead in the home include lead paint on the walls and lead pipes, especially in pre-1950s housing.

Lead exposure has been found to disproportionately harm people living below the poverty line, and this analysis only underscored past findings. Although overall blood lead levels have decreased in recent decades, the socioeconomic gap for lead exposure remains.

About 2% of kids tested had concerningly high levels of lead

Most of the kids tested had very small amounts of lead in their blood, but about 2% had a level that is considered high.

Children living in pre-1950s housing were more likely to have any detectable level of lead in their blood. They were also the most likely to have elevated blood lead levels, along with children in the lowest socioeconomic bracket on the census.

Based on national lead exposure data, the CDC uses a blood lead reference value of 5 micrograms per deciliter (µg/dL) to identify kids with blood lead levels that are "much higher than most children's levels."

Previous research used that threshold to screen for childhood lead exposure, but the new analysis used a more sensitive technology to examine lead levels as low as 1 µg/dL.

There is no safe level of lead exposure, so any detectable level is cause for concern, the researchers wrote in the paper.