CDC establishes new reference value for dangerous blood lead levels

Photo by Dr. Matthias Ripp via Flickr.

The Flint, Michigan water crisis remains a prime example of the importance of public health journalism. Without the dogged reporting and local medical research by a persistent pediatrician, thousands of children would likely continue being harmed by unsafe lead levels in the water. The crisis also spotlighted the fact that lead remains a significant health threat to children and one that disproportionately affects already vulnerable kids, particularly Black children, those living in poverty, and immigrant and refugee children.

Lead poisoning can cause brain damage, learning and attention difficulties, memory problems, reduced growth and development, and behavioral problems in children, and the effects are irreversible.

Two years after the water crisis began, the Water Infrastructure Improvements for the Nation (WIIN) Act of 2016 authorized creation of the Lead Exposure Prevention and Advisory Committee (LEPAC), a committee that was officially formed in 2018 with four main objectives:

  • Reviewing federal programs and services available to lead-exposed people and communities.
  • Reviewing current research on lead poisoning to identify additional research needs.
  • Reviewing and identifying best practices, or the need for best practices, regarding lead screening and prevention of lead poisoning.
  • Identifying effective services for people and communities affected by lead exposure.

One of the biggest challenges of protecting children from lead poisoning is, as with many toxic chemicals, the lowest level of lead that can be tolerated without causing harm is unknown. It’s generally recognized that no “safe” level exists, but since it’s impossible to ensure children have zero lead exposure — it occurs naturally in our environment — we need a reference point to determine how much is too much. Until recently, the CDC had determined the blood lead reference value to be 5 µg/dL — the amount of lead in a child’s blood that indicates higher-than-average, and potentially dangerous, exposure.

But the Lead Exposure Prevention and Advisory Committee recommended in May 2021, based on their review of available evidence, that the reference value be adjusted down to  3.5 µg/dL, and the CDC has just adopted that recommendation and updated the reference value. That means children ages one to five who have at least 3.5 µg/dL of lead in their blood have higher lead blood levels than 97.5% of other U.S. children their age.

Children should be screened for lead exposure at well-child visits; those at risk should have their blood levels tested. If their levels are at 3.5 µg/dL or higher, interventions are necessary to identify and reduce their exposure, reduce their blood lead levels, and receive treatment to mitigate negative health effects. According to the Morbidity and Mortality Weekly Report with the updated reference value, “the most common sources of lead exposure in the United States are lead-based paint and dust, lead-contaminated soil, and lead in water from lead pipes and plumbing fixtures.”

What does all this mean for journalists? First and foremost, lead exposure remains a problem and one that requires media watchdogs keeping an eye out to prevent or uncover the next lead water crisis. It also means, when researching lead in the medical literature to pay attention to the blood lead reference value used and how it differs from today’s new level. How you use or interpret older studies may change now that the blood lead reference value has been updated, depending on how you’re using that evidence. For example, if you use a study to cite the prevalence of children who have high blood lead levels, you’ll need to pay attention to what their reference value was and ask your expert sources how that translates to prevalence rates today.

It’s worth reading the full “Update of the Blood Lead Reference Value — United States, 2021” in for thorough context on lead poisoning and a review of the most recent evidence.

Helpful links

Relevant medical studies

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