Lower blood lead tied to reduced systolic BP in American Indians exposed to toxic metals
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Key takeaways:
- American Indians experienced more chronic toxic metal exposures vs. the general U.S. population.
- Reduced blood lead via lowering exposure was tied to reduced systolic BP and interventricular septum thickness.
Reduced blood lead in American Indians, a population that experienced increased chronic exposure, was associated with reductions in systolic BP and reduced interventricular septum thickness, researchers reported.
“Over the last decades, lead exposure has been declining in the United States, which is public health victory, although further work remains. Little is known, however, about the CV benefits of this reduction in communities across the country, particularly among American Indian communities who experience both a higher burden of CVD and elevated chronic metal exposures compared with the general U.S. population,” Wil Lieberman-Cribbin, MPH, doctoral student in the department of environmental health sciences at Columbia University Mailman School of Public Health, told Healio. “Lead has historically been known to increase BP levels and the risk of hypertension, but it is unknown if declines in blood lead concentrations, even at low levels, are associated with changes in BP and metrics of cardiac geometry and function. We were able to investigate this in the Strong Heart Family Study, an extension of the Strong Heart Study, the largest prospective cohort study of CVD and its risk factors among American Indian adults.”
Data were derived from Lieberman-Cribbin W, et al. J Am Heart Assoc. 2024;doi:10.1161/JAHA.123.031256.
Toxic metal exposure among American Indians
Elevated blood lead can result from exposure to lead in gasoline, residential paint, plumbing, food cans and other items. Despite regulations designed to lower lead exposure in public drinking water and air emissions, American Indian communities experience higher burden of CVD as well as increased chronic metal exposures compared with the general U.S. population, according to the study.
For this retrospective review, Lieberman-Cribbin, and colleagues used data from the Strong Heart Study (SHS), an ongoing, prospective cohort of 4,549 American Indian adults from more than 10 tribes and communities in Arizona, Oklahoma, North Dakota and South Dakota, developed to evaluate CVD and risk factors in this population. The Strong Heart Family Study (SHFS) was a multigenerational study of descendants of participants in the original SHS cohort.
The researchers reported that available blood lead data from a subset of SHFS participants from two study visits from 1997 to 1999 and 2006 to 2009 indicated that within-person blood lead levels declined approximately 23% during this period, and decline similar to the population-level estimates from the National Health and Nutrition Examination Survey.
Leiberman-Cribbin and colleagues evaluated whether declines in blood lead, even at low levels of exposure, were associated with change in BP and metrics of cardiac geometry and function over time in SHFS.
The primary outcome was change in systolic and diastolic BP. Secondary outcomes included metrics of cardiac geometry and function measured via transthoracic echocardiography.
Reduced blood lead and change in BP
The analysis included 285 SHFS participants with blood lead measurements taken in 1997-1999 and 2006-2009 and subsequent measures of BP, cardiac geometry and function were taken in 2001-2003 and 2006-2009.
At baseline, average blood lead was 2.04 g/dL, which declined an average of 0.67 g/dL over 10 years.
After adjustment, the mean difference in systolic BP highest tertile of blood lead decline (> 0.91 g/dL) compared with the lowest tertile (< 0.27 g/dL) was –7.08 mm Hg (95% CI, –13.16 to –1).
The researchers reported a nonlinear association between decline in blood lead and decline in systolic BP, with significant systolic BP decline when there was blood lead decline of 0.1 g/dL or more.
Decline in blood lead was not significantly associated with decline in diastolic BP; however, lower levels of blood lead were associated with reduced interventricular septum thickness, according to the study.
“Declines in blood lead levels were associated with reductions in systolic BP and a decrease in interventricular septum thickness, highlighting lead as a CVD risk factor, the importance of reducing exposure and relatively quick improvements in blood pressure,” Lieberman-Cribbin told Healio.
“American Indian communities are still exposed to toxic metals from a variety of sources, including from drinking water, drinking water infrastructure and a legacy of anthropogenic mining activities,” he said. “Recent research has emphasized racial and socioeconomic disparities in exposures to metals, including lead, cadmium, arsenic and uranium that are relevant for American Indian communities. Ideally these findings can draw attention to metal exposures in American Indian communities and encourage community-driven solutions. Further, metals and lead exposures are national issues and these findings from the Strong Heart Study are relevant to many communities across the United States.”
Reference:
- Reduced blood lead levels linked to lower blood pressure in American Indians. https://www.eurekalert.org/news-releases/1030727. Published Jan. 11, 2024. Accessed Jan. 11, 2024.
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