New research from Columbia University Mailman School of Public Health indicates that long-term exposure to arsenic in drinking water may heighten the risk of cardiovascular disease, particularly heart disease, even when exposure levels are lower than the federal regulatory limit of 10µg/L. This groundbreaking study is the first to illustrate the relationship between exposure and response at concentrations beneath the current regulatory threshold, confirming that extended exposure to arsenic contributes to the onset of ischemic heart disease.
In their research, scientists investigated different durations of arsenic exposure, discovering that the most significant risk came from arsenic levels in drinking water during the decade leading up to a cardiovascular disease event. The findings have been reported in the journal Environmental Health Perspectives.
Danielle Medgyesi, a doctoral Fellow in the Department of Environmental Health Sciences at Columbia Mailman School, remarked, “Our research highlights critical time frames of arsenic exposure that are linked to heart disease, and it guides the U.S. Environmental Protection Agency’s ongoing evaluation of arsenic risks. It underlines the necessity of considering outcomes beyond cancer, especially cardiovascular diseases, the leading cause of death in the U.S. and worldwide. This study strongly supports the need for updated regulatory standards to better protect health and advocates for lowering the current exposure limit to mitigate significant risks.”
Numerous health entities, including the American Heart Association, have found substantial evidence linking arsenic exposure to an increased risk of cardiovascular diseases. This risk is particularly notable at elevated arsenic levels (>100µg/L) in drinking water. In 2006, the U.S. Environmental Protection Agency lowered the maximum contaminant level (MCL) for arsenic in community water systems (CWS) from 50µg/L to 10µg/L. However, drinking water still poses a notable source of arsenic exposure for CWS users. The presence of arsenic in groundwater is often seen in areas of New England, the upper Midwest, and parts of the West, including California.
To investigate the correlation between long-term exposure to arsenic in CWS and cardiovascular disease, researchers analyzed healthcare and mortality data from the California Teachers Study cohort from its start in 1995 through 2018, pinpointing both fatal and nonfatal instances of ischemic heart disease and cardiovascular disease. Collaborating with the California Office of Environmental Health Hazard Assessment (OEHHA), they collected water arsenic data from CWS spanning three decades (1990-2020).
The research reviewed data from 98,250 participants, identifying 6,119 cases of ischemic heart disease and 9,936 cases of cardiovascular disease. Individuals aged 85 and older and those with pre-existing cardiovascular conditions at enrollment were not included in the study. Like the majority of California’s population relying on CWS (over 90 percent), 92 percent of the participants lived in areas served by a CWS. The researchers compared various exposure durations, ranging from relatively short-term (3 years) to long-term (10 years or more). They found that exposure over a decade leading up to cardiovascular events corresponded to the highest risk, echoing a study in Chile that observed peak mortality from acute myocardial infarction about ten years after significant arsenic exposure. This sheds light on important exposure windows crucial for the development of ischemic heart disease.
Almost half (48 percent) of the participants were exposed to average arsenic levels below California’s non-cancer public health target of <1 µg/L. Compared to this low-exposure group, those with exposure from 1 to <5 µg/L showed a modest increase in ischemic heart disease risk of 5 to 6 percent. The risk escalated to 20 percent for those exposed to 5 to <10 µg/L (amounting to half or below the current regulatory limit), and even more than doubled to 42 percent among those with exposure at or above the current EPA limit of ≥10µg/L. The link was consistently stronger for ischemic heart disease compared to cardiovascular disease overall, and no stroke risk was identified, aligning with prior findings and the current EPA risk assessment.
These findings emphasize the serious health repercussions when community water systems fail to meet current EPA standards, as well as at lower levels than these standards. The study found a significant 20 percent risk associated with arsenic exposure between 5 and <10 µg/L, impacting around 3.2 percent of participants, suggesting that stricter regulations could greatly benefit public health. In accordance with previous studies, this research also indicated that higher arsenic levels, particularly those surpassing existing standards, disproportionately impact Hispanic and Latina populations and residents from lower socioeconomic backgrounds.
“Our findings are innovative and call for a renewed examination of current policies and regulatory standards,” commented Tiffany Sanchez, senior author from Columbia Mailman. “However, this underscores the need for further research to thoroughly understand the risks linked to arsenic levels encountered by CWS users. We believe that the data and methodologies developed in this study can aid future research initiatives and can be adapted to evaluate other drinking water exposures and health outcomes.”
The co-authors of this study include Komal Bangia from the Office of Environmental Health Hazard Assessment in Oakland, California; James V. Lacey Jr and Emma S. Spielfogel from the California Teacher Study at Beckman Research Institute, City of Hope, Duarte, California; and Jared A Fisher, Jessica M. Madrigal, Rena R. Jones, and Mary H. Ward from the Division of Cancer Epidemiology and Genetics at the National Cancer Institute.
This research was funded by the National Cancer Institute through various grants (U01-CA199277, P30-CA033572, P30-CA023100, UM1-CA164917, and R01-CA077398), along with support from the Superfund Hazardous Substance Research and Training Program (P42ES033719), the NIH National Institute of Environmental Health Sciences (P30 Center for Environmental Health and Justice P30ES9089), the NIH Kirschstein National Research Service Award Institutional Research Training grant (T32ES007322), the NIH Predoctoral Individual Fellowship (F31ES035306), and the Intramural Research Program of the NCI (Z-CP010125-28).
