Arsenic in Water Linked to Increased Heart Disease Risk

A recent study from Columbia University Mailman School of Public Health suggests that long-term exposure to arsenic in water may raise the risk of cardiovascular illness, particularly heart disease, even at levels below the federal regulation limit (10µg/L). This is the first study to describe exposure-response correlations at concentrations lower than the existing regulatory limit, and it demonstrates that chronic exposure to arsenic in water leads to the development of ischemic heart disease.

The researchers evaluated several time windows of exposure and discovered that the previous decade of water arsenic exposure prior to a cardiovascular disease episode conferred the most risk. The findings were reported in the journal Environmental Health Perspectives.

Our findings shed light on critical time windows of arsenic exposure that contribute to heart disease and inform the ongoing arsenic risk assessment by the EPA. It further reinforces the importance of considering non-cancer outcomes, and specifically cardiovascular disease, which is the number one cause of death in the U.S. and globally. This study offers resounding proof of the need for regulatory standards in protecting health and provides evidence in support of reducing the current limit to further eliminate significant risk.”

Danielle Medgyesi, a doctoral Fellow in the Department of Environmental Health Sciences at Columbia Mailman School

According to the American Heart Association and other leading health organizations, there is strong evidence that arsenic exposure raises the risk of cardiovascular disease. This includes evidence of risk at high arsenic levels (>100 µg/L) in drinking water. In 2006, the United States Environmental Protection Agency reduced the maximum contamination limit (MCL) for arsenic in community water supplies (CWS) from 50µg/L to 10µg/L. Nonetheless, drinking water remains a significant source of arsenic exposure for CWS users. Arsenic can be found naturally in groundwater throughout New England, the upper Midwest, and the West, including California.

To assess the link between long-term arsenic exposure from CWS and cardiovascular disease, the researchers examined statewide healthcare administrative and mortality records collected for the California Teachers Study cohort from enrollment to follow-up (1995-2018), identifying both fatal and nonfatal cases of ischemic heart disease and cardiovascular disease. Working closely with researchers at the California Office of Environmental Health Hazard Assessment (OEHHA), the team collected water arsenic data from CWS over three decades (1990–2020).

The study included 98,250 people, 6,119 ischemic heart disease cases, and 9,936 cardiovascular disease cases. Participants aged 85 and up, as well as those with a history of cardiovascular disease at enrollment, were excluded. The majority of participants (92 percent) lived in areas served by a CWS, which is similar to the proportion of California’s population that depends on it (more than 90 percent). Using the considerable years of arsenic data available, the researchers examined time periods of relatively short-term (3-year) to long-term (10-year cumulative) average arsenic exposure. This offers fresh perspectives on pertinent exposure periods that are essential for the onset of ischemic heart disease.

The average arsenic exposure for nearly half (48 percent) of participants was below California’s non-cancer public health target of less than 1 µg/L. Those exposed to 1 to less than 5 µg/L had a slightly increased risk of ischemic heart disease, with increases of 5 to 6 percent, compared to this low-exposure group. The risk more than doubled to 42 percent for those exposed to levels at and above the existing EPA limit ≥10µg/L, and it increased to 20 percent for those in the exposure ranges of 5 to <10 µg/L (or half below the present regulatory limit). There was no indication of stroke risk, and the association was consistently higher for ischemic heart disease than cardiovascular disease. These findings are generally in line with other studies and the findings of the current EPA risk assessment.

These findings demonstrate the grave health risks that arise not just when community water systems fall short of the existing EPA limit but also when levels fall short of it. About 3.2 percent of participants were found to be at a major 20 percent risk for arsenic doses ranging from 5 to <10 µg/L, indicating that the population would benefit greatly from stricter controls. According to previous studies, the study also discovered that residents of communities with lower socioeconomic status and Hispanic and Latina populations are disproportionately affected by greater arsenic concentrations, including values above the existing standard.

“Our results are novel and encourage a renewed discussion of current policy and regulatory standards,” said Columbia Mailman’s Tiffany Sanchez, senior author. “However, this also implies that much more research is needed to understand the risks associated with arsenic levels that CWS users currently experience. 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.”