Lead exposure necessary to address ‘if we want to prevent chronic disease’

Key takeaways:

• Low-level lead poisoning accounts for several diseases and adverse health outcomes in adults and kids.
• Researchers highlighted a need for screening and the elimination of environmental sources of lead.

Low-level lead poisoning remains prevalent across the United States and globally, warranting screening and identification of those at highest risk, according to a recently published review.

Such poisonings are especially dangerous in children because of their adverse links to cognitive and behavioral development, the researchers pointed out in The New England Journal of Medicine.

“Low-level lead poisoning is a great example of how most chronic disease is man-made and driven by environmental (not genetic) determinants that are beyond the control of individuals,” Bruce Lanphear, MD, MPH, a professor at Simon Fraser University in Canada, told Healio. “This concept — which is foreign or novel to most physicians and counterintuitive for people who are convinced chronic disease is driven by lifestyle choices — is critical to appreciate if we want to prevent chronic disease.”

In the analysis, Lanphear and colleagues reviewed the exposure trends and health effects of chronic, low-level lead poisoning across various populations.

An old problem lingers

The researchers noted that lead poisoning has decreased by over 95% since the 1970s, but people today still have body lead levels that are 10 to 100 times as high as those who lived in preindustrial times.

They explained that 95% of absorbed lead in adults and 70% in children is stored within the skeleton.

Certain people are at a greater risk for lead poisoning, such as:

• infants and toddlers because of their mouthing behaviors;
• toddlers who live in poorly maintained houses built before the 1960s;
• people who drink tap water near airports or other sites that emit air pollution;
• people who use firearms or have retained bullet fragments in their bodies; and
• workers in smelting, recycling, battery and construction.

“[P]hysicians assume that lead poisoning is a problem of the past,” Lanphear said in a press release. “Yet exposures linger from lead paint in older houses, leaded gasoline in soil, seeping lead from water lines, and emissions from industrial plants and incinerators.”

Links to ADHD, CVD

Lead exposure in adults is associated with an increased risk for several negative health conditions like preterm birth, hypertension, chronic kidney failure and CVD, with 5.5 million deaths from the latter disease attributed to lead poisoning in 2019.

Meanwhile, lead poisoning in children puts them at a heightened risk for increased BP, reduced heart rate variability and brain volume, antisocial and criminal behaviors and cognitive disorders.

Specifically, lead poisoning accounts for one in five cases of ADHD, a yearly loss of 765 million IQ points in children and 30% of the global burden of idiopathic intellectual disability, the researchers pointed out.

“Unfortunately, we have failed to learn from the lead pandemic and we continue to believe that we can solve our problems with chemistry,” Lanphear told Healio. “You only need to look at the global burden of disease estimates to appreciate that toxic chemicals and pollutants contribute 20% to 25% of global burden of disease and yet we invest too little in solving those problems.”

No safe level exists

Guidance on the limits of lead in blood vary across health organizations and have been changed several times.

For example, 2021 guidelines from WHO recommend action in individuals with lead concentration equal to or greater than 5 µg/dL, whereas CDC guidance lowered the lead blood level in children considered elevated from 100 g/L to 50 g/L in 2012 and to 35 g/L in 2021, Lanphear and colleagues wrote.

However, no safe level of lead in blood in children has been identified because even levels as low as 3.5 µg/dL may be tied to lowered intelligence, according to background information WHO.

If primary care providers and pediatricians “care about preventing death, disease and disability, [they] need to begin to appreciate upstream risk factors and population strategies” Lanphear explained.

“Screening should be reserved for high-risk people and workers,” he said. “The focus of lead poisoning should be on prevention; identifying and reducing or eliminating all sources of lead in our environment.”

References:

• Columbia University. Low-level lead poisoning Is still pervasive in the U.S. and globally. Available at: https://www.publichealth.columbia.edu/news/low-level-lead-poisoning-still-pervasive-u-s-globally. Published Oct. 30, 2024. Accessed Nov. 4, 2024.
• Lanphear B, et al. N Engl J Med. 2024;doi:10.1056/NEJMra2402527.
• WHO. Lead poisoning. Available at: https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health. Accessed Nov. 4, 2024.