Researchers have linked a decade-long decline in the blood lead levels of American Indian adults to long-term cardiovascular health benefits, including reduced blood pressure levels and a reduction in a marker associated with hypertrophic cardiomyopathy and heart failure. The research team, supported by the National Institutes of Health, found that adults who had the greatest reductions in blood lead levels saw their systolic blood pressure fall by about 7 mm Hg, an amount comparable to the effects of blood pressure-lowering medication. Lead exposure is known to harm the health of children by damaging the brain and nervous system and slowing growth and development. It has also been associated with increased risks for heart disease in adults. The findings published in the Journal of the American Heart Association.
“This is a huge win for public health, especially since many American Indians can face higher risks for elevated lead levels,” said Anne E. Nigra, Ph.D., the senior study author and an assistant professor of environmental health sciences at Columbia University Mailman School of Public Health, New York City. “Compared to the general U.S. population, American Indian communities experience both a higher burden of cardiovascular disease and elevated metal exposure. We saw that even small decreases in a person’s blood lead levels can have meaningful health outcomes.”
Investigators partnered with 285 American Indian adults in the Strong Heart Family Study, an extension of the Strong Heart Study, the largest and longest study of cardiovascular health outcomes and risk factors among American Indian adults. Participants lived in one of four tribal communities in Arizona, Oklahoma, North Dakota, or South Dakota. The authors explained that features of the built environment can lead to elevated lead exposure in tribal communities. This includes being exposed to lead through well water, local waterways, foods, including canned goods, herbs, and spices, as well as paint and dust.
For this retrospective review, the researchers looked at blood lead levels and blood pressure readings over time. Lead was first measured in blood collected during a 1997-1999 study visit and again in blood collected during a follow-up visit between 2006-2009. During these visits, participants had their blood pressure taken and participated in medical exams that included echocardiographs, a test to assess the heart’s structure and function. To support equal comparisons among participants, researchers controlled for multiple factors, including social variables, including education and income, cardiovascular disease risks, and medical history.
At the start of the study, the average blood lead level was 2.04 µg/dL. Throughout the study, the average blood lead level fell by 0.67 µg/dL, or 33%. The most significant changes occurred in participants with average starting blood lead levels of 3.21 µg/dL and who experienced reductions of about 1.78 µg/dL, or 55%. This drop was linked to a 7 mm Hg reduction in systolic blood pressure.
Nigra and the study authors credit these improvements in large part to public health policies and efforts implemented in recent decades to reduced lead exposure through paint, gasoline, water, plumbing, and canned items. The decline in blood lead levels observed in the study are similar to those seen in the general U.S. population in recent years, but exposure to elevated levels of lead and other metals have been disproportionately higher among American Indians.
“This is a sign that policies and awareness and education campaigns in these communities to reduce blood lead levels are working,” said Mona Puggal, M.P.H., an epidemiologist in the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute (NHLBI). “The reductions in blood pressure are comparable to improvements one sees with lifestyle changes, such as getting 30 minutes of daily exercise, reducing salt intake, or losing weight.”
The investigators noted the importance of also conducting this research in other communities, especially for populations with elevated risks for lead exposure and cardiovascular disease.
“More research needs to be done to determine how environmental agents exacerbate cardiovascular and other diseases, and more needs to be done to improve the environmental health of American Indians,” said Lindsey A. Martin, Ph.D., a health science administrator at the National Institute of Environmental Health Sciences (NIEHS), also part of NIH.
This research was funded by NIEHS and NHLBI.
Study: Lieberman-Cribbin W, Li Z, Lewin M, et al. The contribution of declines in blood lead levels to reductions in blood pressure levels: longitudinal evidence in the Strong Heart Family Study. J Am Heart Assoc. 2024; doi: 10.1161/JAHA.123.031256.
About the National Heart, Lung, and Blood Institute (NHLBI): NHLBI is the global leader in conducting and supporting research in heart, lung, and blood diseases and sleep disorders that advances scientific knowledge, improves public health, and saves lives. For more information, visit https://www.nhlbi.nih.gov/.
About the National Institute of Environmental Health Sciences (NIEHS): NIEHS supports research to understand the effects of the environment on human health and is part of the National Institutes of Health. For more information on NIEHS or environmental health topics, visit www.niehs.nih.gov or subscribe to a news list.
About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit https://www.nih.gov/.
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Journal of the American Heart Association
The contribution of declines in blood lead levels to reductions in blood pressure levels: longitudinal evidence in the Strong Heart Family Study