New Study Links Arsenic in Drinking Water to Increased Heart Disease Risk
A colorless, odorless, and tasteless metal found in drinking water across the US has been linked to an increased risk of heart disease, according to a significant new study conducted by researchers from Columbia University.
The study examined the health records of over 100,000 Californians over 23 years and compared these records to the estimated exposure levels to arsenic in their drinking water.
Researchers found that individuals exposed to high levels of arsenic for a decade or more had a 42 percent higher likelihood of developing heart disease. This was evident even after controlling for other risk factors such as high blood pressure, smoking, and exercise habits.
Moreover, drinking water with arsenic levels below the Environmental Protection Agency (EPA) limit of 10 parts per billion (ppb) for extended periods still posed a five to twenty percent elevated risk of heart disease.
Dr. Tiffany Sanchez, an environmental and molecular epidemiologist and lead study author, indicated that these findings suggest a need to re-evaluate current arsenic standards in drinking water. She emphasized: “Our results are novel and encourage a renewed discussion of current policy and regulatory standards.”
This map from the United States Geological Survey estimates areas of the country with higher levels of naturally occurring arsenic in private drinking wells.
Dr. Sanchez stressed that this study is one of the first to comprehensively describe risks at arsenic exposure levels below the current regulatory limit.
While it remains unclear how arsenic causes heart issues, earlier studies suggest it may lead to inflammation affecting blood vessel shape near the heart, which can hinder blood flow and subsequently damage the organ.
Arsenic, a naturally occurring heavy metal present in the Earth’s crust, can contaminate air, water, and soil, with the highest concentrations found in groundwater in regions like New England, the northern Midwest, and parts of the West, including California.
The National Institute of Environmental Health Sciences states that most human exposure to arsenic occurs through drinking water. Those using private wells and lacking regular arsenic testing are at significantly higher risk compared to individuals using community water supply, which serves approximately 90 percent of Americans.
Long-term exposure to high arsenic levels can damage cardiovascular, immune, and endocrine systems and can accumulate in vital organs like the liver, kidneys, prostate, and bladder.
The study published in the journal Environmental Health Perspectives focused on narrowing down how arsenic exposure relates to health outcomes and included an extensive analysis of participants from the California Teachers Study.
Among the 98,250 participants, lifestyle habits, location data, and health outcomes were meticulously tracked from 1995 to 2018. Researchers evaluated cases of ischemic heart disease and cardiovascular disease.
Ischemic heart disease, or coronary artery disease, results from reduced blood flow due to plaque buildup or blood clots and is recognized as the primary cause of heart attacks. In contrast, cardiovascular disease is a broader term covering conditions like stroke, heart failure, and peripheral artery disease.
The analysis found a significant correlation between arsenic exposure and ischemic heart disease, with no evidence linking arsenic to other forms of cardiovascular disease like stroke.
The study found arsenic in water linked to coronary artery disease, but not stroke. Ischemic heart disease is the leading cause of heart attacks.
The current EPA limit for arsenic in drinking water is set at 10 ppb. Researchers observed that about 48 percent of study participants had exposure to less than one ppb of arsenic, with no significant heart disease risk associated. However, those exposed to one to ten ppb did experience an increased risk, ranging from five to twenty percent depending on specific exposure levels.
Of particular note, individuals with a decade or more of exposure had an 18 to 20 percent higher risk of ischemic heart disease compared to those with shorter exposure histories.
These findings, while groundbreaking, are not the first to associate arsenic exposure with heart disease. A 2018 study of Indigenous populations revealed that higher urinary arsenic levels correlated with a 1.5-fold increase in high blood pressure and myocardial thickening—both indicators of cardiac stress that can lead to heart disease.
Despite these correlations, Dr. Sanchez notes that further research is necessary to conclusively determine arsenic’s role in heart disease and to understand its mechanisms. Traditionally, cardiovascular issues have been attributed to lifestyle factors like diet, raising questions about arsenic’s specific contributions.
Concluding, Dr. Sanchez stated that their research serves as a foundation for future studies: “We believe that the data and methods developed in this study can be used to bolster and inform future studies and can be extended to evaluate other drinking water exposures and health outcomes.”