A meta-analysis was recently published in the British Medical Journal to try and understand if there was a link between heart events and exposure to toxic metals. The heart events that were considered include: stroke, non-fatal heart attack, angina, coronary revascularization, and coronary artery disease. Toxic metals that were part of the investigation included arsenic, lead, copper, and mercury.
Researchers found their articles for analysis by searching databases and coming through all the studies available up until that date. In the end, they settled on 37 studies that contained data on 350,000 participants.
What researchers found was that exposure to these metals is “possibly and importantly associated with cardiovascular disease and stroke.” For arsenic, lead and cadmium, exposure and cardiovascular disease outcomes were approximately liner.
The analysis adds to previous studies on arsenic of which has been associated with a severe peripheral vascular disease called Blackfoot disease. This condition has been seen in elevated levels amongst people who were exposed to high cumulative doses of arsenic.
The study also reinforced lead exposure risks. With a strong positive association between lead exposure and accelerated systolic blood pressure and damage to renal function. Lead may also accelerate atherosclerosis following exposure.
In the case of carbon, though an essential trace element, this metal can cause stress in the cells. The stress can lead to endothelial dysfunction. Although based on limited data, researchers made a point to suggest that even low, average doses of exposure to copper may be detrimental to vascular health.
Surprisingly, for all we have heard of the dangers of mercury exposure in fish meals, the metal was not associated with increased cardiovascular disease outcomes in the review. While some studies have observed inverse relations between mercury and cardiovascular disease risk, researchers found no explanation for this link.
Strengths of the study include the focus on individual-level assessments of toxic metal exposure. Additionally, the levels of exposure were measured by using objective biomarkers or well-established measures like the testing of drinking water. It should be noted, however, that various biomarkers may reflect long-term exposure differently.
There are a few implications of this analysis for policymakers and clinicians. The current strategy of preventing non-communicable diseases worldwide is focused on individual behaviors like getting enough exercise and eating a healthy diet. The study will help gain support for system-level legislation to help protect public health. It will also help secure the funding for such changes. Secondly, funding for additional research on the potentially elevated risk of those metals with linear associations to undesirable cardiovascular outcomes should be considered. For providers, treatments for exposures to heightened levels of toxic metals and additional testing for exposures might be enhanced.
Sources: The British Medical Journal, The Lancet, The University of Waterloo
