Statement Highlights:
- Around the world, most people are regularly exposed to low or moderate levels of lead, cadmium and arsenic in the environment, increasing risk of coronary artery disease, stroke and peripheral artery disease, according to a new American Heart Association statement.
- These metals, considered contaminant metals, have no function in the human body. They are found in groundwater, water pipes, paint, tobacco products, fertilizer, plastic, electronics, gasoline, batteries, some foods and other commonly used items.
- Lead, cadmium and arsenic are absorbed via the respiratory and/or gastrointestinal tract. People who live in lower economic neighborhoods often have high exposure to these metals.
- A multi-faceted approach to reducing the cardiovascular risks of contaminant metals may include public health measures, such as environmental monitoring and abatement; individual testing; further evaluation of the consequences of metal exposure and the development of treatments.
Newswise — DALLAS, June 12, 2023 —Prolonged exposure to small amounts of lead, cadmium, and arsenic via everyday household objects, air, water, soil, and food is linked to a heightened likelihood of cardiovascular illness, as stated in a recent scientific declaration by the American Heart Association. This statement was published today in the Journal of the American Heart Association, a peer-reviewed, open-access journal of the American Heart Association.
This scientific statement examines the evidence connecting prolonged exposure to modest or moderate levels of three metallic contaminants, namely lead, cadmium, and arsenic, with cardiovascular ailments such as coronary artery disease, stroke, and peripheral artery disease. It underscores the significance of these findings for clinical and public health considerations. Presently, environmental toxicants, including contaminant metals, are not included among the conventional risk factors for cardiovascular disease. However, the field of environmental cardiology recognizes the exposure to pollutants, including metallic contaminants, as changeable factors that contribute to the risks associated with cardiovascular disease.
"Extensive studies involving large populations reveal that nearly everyone experiences some degree of exposure to metallic contaminants, even at low levels, which significantly adds to the prevalence of cardiovascular disease. This includes a higher risk of heart attacks, strokes, peripheral artery disease, and premature cardiac-related mortality," stated Gervasio A. Lamas, M.D., FAHA. Dr. Lamas serves as the chair of the writing group responsible for this statement and holds the position of chairman of medicine and chief of the Columbia University Division of Cardiology at Mount Sinai Medical Center in Miami Beach, Florida.
"Crucial biological processes are disrupted by these metals, impacting a vast majority of the global population," explained Ana Navas-Acien, M.D., Ph.D., vice chair of the writing group responsible for the statement. Dr. Navas-Acien is a professor of environmental health sciences at Columbia University's Mailman School of Public Health and the director of the Columbia University Northern Plains Superfund Research Program in New York City. "Following exposure, lead and cadmium accumulate in the body and persist in bones and organs for extended periods. In the United States alone, a significant study suggested that over 450,000 deaths per year may be attributed to lead exposure."
Where are people exposed to contaminant metals?
Inadvertent exposure to metallic contaminants commonly transpires during routine activities. For instance, lead can be encountered in various items including paint in older residences (as lead paint was prohibited in the U.S. since 1978), tobacco products, second-hand smoke, contaminated food (as groundwater, pottery, ceramics, and kitchenware can be sources of lead contamination in food), water pipes, spices, cosmetics, electronics, and industrial emissions. Both lead and cadmium can be derived from cigarette smoking.
Nickel-cadmium batteries, pigments, plastics, ceramics, glassware, and construction products are common sources of cadmium. Additionally, industrially manufactured fertilizers utilize phosphate rock that naturally contains elevated levels of cadmium. As a result, root vegetables and leafy green plants, including tobacco, can become contaminated with cadmium through the uptake of these fertilizers.
The primary route of arsenic exposure is through groundwater, which impacts drinking water, soil, and food cultivated in contaminated soil. It is worth mentioning that arsenic tends to accumulate in rice more significantly compared to other food crops.
Although exposure and risks related to toxic metals are present among diverse populations regardless of socioeconomic status, the statement acknowledges that certain individuals face higher levels of exposure. Those living in proximity to major roadways, industrial sources, and hazardous waste sites, as well as those residing in older houses or areas with inadequate enforcement of environmental regulations and insufficient response to community complaints, have an elevated risk of exposure.
"This is a worldwide problem where lower-income communities bear a disproportionate burden of exposure to toxic metals through contaminated air, water, and soil," stated Navas-Acien. "By addressing metal exposure in these populations, we can potentially mitigate disparities in cardiovascular disease and promote environmental justice."
What are the cardiovascular risks of contaminant metals?
Recent scientific research conducted worldwide has provided compelling evidence linking lead, cadmium, and arsenic to premature death, primarily due to an elevated risk of cardiovascular disease. The global epidemiologic studies include the following findings:
A scientific statement by the American Heart Association in 2021 acknowledged exposure to toxic metals as an unconventional risk factor for peripheral artery disease.
A comprehensive review published in the British Medical Journal in 2018 examined 37 studies encompassing nearly 350,000 individuals from various countries. The review revealed that higher levels of arsenic in urine and lead and cadmium in blood were associated with a 15% to 85% increased risk of stroke and heart disease.
In a study conducted in China, elevated blood lead levels were found to be linked to carotid plaque in individuals with Type 2 diabetes. Additionally, another study observed associations between cadmium, arsenic, and a higher incidence of heart disease and ischemic stroke.
A population-based study conducted in Spain discovered that higher levels of cadmium in urine were correlated with an elevated incidence of newly diagnosed cardiovascular disease.
These scientific findings collectively demonstrate the detrimental impact of lead, cadmium, and arsenic exposure on human health, particularly in relation to cardiovascular health and premature mortality.
What can be done about metals in the environment?
According to the writing group, it is crucial to implement effective public health initiatives by monitoring environmental metal levels and conducting metal testing in individuals. Currently, health professionals utilize blood tests to monitor lead levels in children exhibiting symptoms of exposure. However, there are no existing monitoring guidelines or established exposure limits for contaminant metals in adults, except for those applicable to certain occupational settings. Therefore, further research is necessary to determine whether such testing can serve as an effective strategy for identifying and safeguarding individuals at risk of cardiovascular disease.
The statement authors note that decreasing metal exposure in tobacco, protecting community water systems and wells, and minimizing metal contamination in air, food and soil are all examples of public health measures that may reduce exposure to metals.
Lamas, a professor of medicine at Columbia University Irving Medical Center in New York City, emphasized the potential for enhancing cardiovascular health through a comprehensive strategy that encompasses environmental cardiology. This approach involves various components such as environmental monitoring and biomonitoring of contaminant metals, managing and reducing sources of metal exposure, and developing clinical interventions that either eliminate metals from the body or mitigate their impact. By adopting this multi-pronged approach, it is anticipated that cardiovascular health can be positively influenced and improved.
At present, there is no established medical therapy specifically designed to counteract the vascular consequences of contaminant metals. However, ongoing research is focused on exploring potential treatments for individuals who have been exposed to these metals. One avenue being investigated is the use of chelating agents, which are medications capable of removing contaminant metals from the body, particularly lead and cadmium. Chelating agents work by binding to the metals, facilitating their excretion from the body. Furthermore, the statement highlights the importance of conducting research to explore the potential of nutritional supplements in mitigating the effects of contaminant metals and expediting their elimination. Some promising supplements identified in small-scale trials include folate and N-acetyl cysteine. Nonetheless, further research is needed to comprehensively understand the effectiveness and safety of these interventions.
The scientific statement discussed above was formulated by a volunteer writing group representing multiple councils of the American Heart Association (AHA). These councils include the Council on Epidemiology and Prevention, the Council on Cardiovascular and Stroke Nursing, the Council on Lifestyle and Cardiometabolic Health, the Council on Peripheral Vascular Disease, and the Council on Kidney in Cardiovascular Disease. AHA scientific statements play a vital role in raising awareness about cardiovascular diseases and stroke-related issues, as well as aiding in making informed healthcare decisions. These statements summarize the current understanding of a particular topic and highlight areas that require further research. It is important to note that while scientific statements contribute to the development of guidelines, they do not provide treatment recommendations. The official clinical practice recommendations of the AHA are presented in their guidelines.
In addition to the volunteer writing group, the scientific statement writing committee included the following members: Aruni Bhatnagar, Ph.D., FAHA; Miranda R. Jones, M.H.S., Ph.D.; Koren K. Mann, Ph.D.; Khurram Nasir, M.D., M.P.H., FAHA; Maria Tellez-Plaza, M.D., Ph.D.; and Francisco Ujueta, M.D., M.S. The manuscript of the scientific statement contains disclosures from the authors, providing transparency regarding any potential conflicts of interest or financial disclosures they may have.
The Association obtains funding mainly from individuals. Foundations and corporations (including pharmaceutical, device manufacturers, and other firms) also contribute and support particular Association initiatives and gatherings. The Association maintains stringent guidelines to ensure that these connections do not impact the scientific content. Details regarding income from pharmaceutical and biotech companies, device manufacturers and health insurance providers, as well as the Association's complete financial information, can be found at this location.
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