Research Links Lower Blood Lead Levels to Lower Blood Pressure in American Indians

Research published in the Journal of the American Heart Association has linked a decline in the blood lead levels of American Indian adults to long-term cardiovascular health benefits, such as reduced blood pressure and a reduction in a marker associated with hypertrophic cardiomyopathy and heart failure.

According to the research, 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.”

The senior study writer, Anne E. Nigra, PhD, an assistant professor of environmental health sciences at Columbia University Mailman School of Public Health, writes that “American Indian communities experience both a higher burden of cardiovascular disease and elevated metal exposure” compared to the general U.S. population. “Even small decreases in a person’s blood lead levels can have meaningful health outcomes.”

285 American Indian adults participated in the Strong Heart Family Study, an extension of the Strong Heart Study, which is the largest and longest study of cardiovascular health outcomes and risk factors among American Indian adults. The authors of the study explained that “features of the built environment can lead to elevated lead exposure in tribal communities,” including “being exposed to lead through well water, local waterways, foods, including canned goods, herbs, and spices, as well as paint and dust.” The researchers looked at blood lead levels and blood pressure levels over time. Lead was measured in blood during a 1997-1999 study visit and again in a follow-up visit conducted in 2006-2009. Participants had their blood pressure measured and participated in medical exams including echocardiographs, which is a test that assesses the heart’s structure and function. Researchers controlled for multiple factors like social variables, cardiovascular disease risks, and medical history in order to support equal comparisons.

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 who experienced reductions of approximately 1.78 µg/dL, or 55%. This drop is associated with a 7 mm Hg reduction in systolic blood pressure. The study credits these improvements to “public health policies and efforts implemented in recent decades to reduced lead exposure through paint, gasoline, water, plumbing, and canned items.” The findings of the study are consistent with those seen in the general U.S. population, but exposure to lead and other metals has historically been disproportionately higher among American Indians.

Mona Puggal, M.P.H., an epidemiologist in the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute (NHLBI), said that “this is a sign that policies and awareness and education campaigns in these communities to reduce blood lead levels are working.” Blood pressure reductions at this level 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 stressed that similar research should be undertaken in other communities, especially those who historically have been at higher risk of lead exposure or cardiovascular disease. Lindsey A. Martin, Ph.D., a health science administrator at the National Institute of Environmental Health Sciences (NIEHS), urges that “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.”

NIH has the news release.