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Clinical Context

The Centers for Disease Control and Prevention (CDC) identify no safe blood lead levels (BLLs) in children and considers a blood lead reference value (BLRV) of 5 μg/dL sufficient to warrant clinical and public health intervention. Among children aged < 6 years, BLLs (> 70 μg/dL) can cause neurologic problems, organ failure, and death.

In the United States, the most common childhood lead exposures are from lead-based paint used in pre-1978 housing, lead-contaminated soil or lead-containing pollutants from industrial sources, and water from old lead pipes and fixtures. Very young children are particularly vulnerable because of their tendency to put fingers or objects in their mouths and their greater absorption of lead as their bodies are rapidly developing.

Study Synopsis and Perspective

Childhood BLL testing rates fell by a third in the period March 2020 through September 2020 compared with the same calendar months from 2017 to 2019. Although 2021 testing rates showed some improvement, they were still significantly below prepandemic levels.

The research was presented earlier this month at the 2022 Epidemic Intelligence Service (EIS) Conference,^[1] held virtually. EIS is a 2-year epidemiology training program sponsored by the CDC.

Lead exposure in young children can result in serious health consequences, such as brain and nervous system damage, slowed growth, lower IQ, underperformance in school, behavioral issues, and hearing and vision problems. Some of the most common ways children are exposed to lead is lead-based paint chips or lead-contaminated dust, although other sources include soil, drinking water delivered through degrading lead pipes, consumer products such as toys and jewelry, and medicines. Although there is no safe level of lead exposure, the CDC's blood lead reference value (BLRV), which identifies children with the highest blood lead levels, is 3.5 μg/dL.

Lead exposure continues to be an issue of health equity, as children in low-income housing are at a higher risk for lead exposure, according to the CDC.^[2] Most children with elevated blood lead levels are asymptomatic, which is why universal screening is recommended, said Hillary Spencer, MD, MPH, an EIS officer at the Chicago Department of Public Health, who presented the research.^[1]

"It's similar to the importance of testing someone's blood pressure, because rarely do people have symptoms because of hypertension," she told Medscape Medical News. "You have to test to know."

To find out how the past 2 years of the COVID-19 pandemic have affected childhood blood lead testing, Spencer and her team tallied the total number of lead tests reported to the Illinois Healthy Homes and Lead Poisoning Surveillance System from Chicago children aged 11 months to 4 years. They compared the average number of tests conducted from March through September in the years 2017 to 2019 as well as the total tests performed in the same months in 2020 and 2021.

Spencer's team found that testing levels had dropped 33% in 2020 from prepandemic years, from a mean of 36,307 tests in 2017 to 2019 to 24,387 in 2020. This is consistent with a 34% national drop in childhood blood lead testing that same year, according to a study in the CDC's Morbidity and Mortality Weekly Report.^[3] In 2021, the number of tests from March through September rose to 28,622, which was still 21% below the tests performed in prepandemic years.

The results of the study are not particularly surprising, said Alan Woolf, MD, MPH, the director of the Pediatric Environmental Health Center at Boston Children's Hospital, Boston, Massachusetts. He was not involved with the research. "I think it was unreasonable to expect that the level of testing would rise to prepandemic levels in terms of its frequency, at least right away," he told Medscape Medical News.

The pandemic led to a drop-off in people seeking out primary care, which resulted in a decline in BLL testing in Chicago and nationally. There was some improvement in 2021, but in May of that year, a major diagnostic company announced the recall of its point-of-care blood lead test due to unreliable results.^[4]

Without that point-of-care testing available in pediatric offices, fewer children ended up getting their BLLs checked.

Beyond prioritizing BLL testing, Woolf said providers can also counsel families to lower risk for lead exposures by:

• Maximizing dietary sources of iron, calcium, and vitamin D, which discourage gut absorption of lead
• Removing shoes when entering the house
• Frequent dusting and damp mopping of baseboards, windowsills, and tabletops
• Washing toys with soap and water
•  Frequent handwashing

"We call lead an 'old adversary' but it's still a threat to young children, especially because of its potential effects on their intelligence, learning ability, and behaviors," Woolf said. "Even in 2022, we need to be vigilant and take action to try to lower [exposure]."

Spencer is an officer of the Epidemic Intelligence Service, a program sponsored by the US Centers for Disease Control and Prevention. Woolf reports funding by the Environmental Protection Agency and the Agency for Toxic Substances and Disease Registry.

Clinical Implications

• The COVID-19 pandemic hindered identification of children with elevated BLLs, exposure elimination, and linkage to critical services.
• Clinicians should ensure that young children receive appropriate lead testing and care management.
• Implications for the Healthcare Team: In-person visits are still necessary for childhood BLL testing and other essential health examinations. Collaboration among the child’s extended medical home interprofessional care team is essential for coordination of care.

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