Arsenic in water linked to increased risk of cardiovascular disease

Long-term exposure to arsenic in water can increase the risk of cardiovascular disease and especially the risk of cardiovascular disease, even at exposure levels below the federal legal limit (10 µg/L), according to a new study at the Columbia University Mailman School of Public Health. This is the first study to describe exposure-response relationships at concentrations below the current regulatory limit and substantiate that long-term exposure to arsenic in water contributes to the development of ischemic heart disease.

The researchers compared different time periods of exposure and found that the previous ten years of exposure to water arsenic up to the time of cardiovascular disease presented the greatest risk. The findings are published in the journal Environmental health perspectives.

Our findings shed light on critical time windows of arsenic exposure that contribute to heart disease and provide the basis for the EPA’s ongoing arsenic risk assessment. It further reinforces the importance of considering non-cancer outcomes, and especially cardiovascular disease, which is the number one killer in the US and worldwide. This study provides compelling evidence of the need for regulatory standards for health protection and provides evidence to support lowering the current limit to further eliminate significant risks.”

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

According to the American Heart Association and other leading health agencies, there is substantial evidence that arsenic exposure increases the risk of cardiovascular disease. This includes evidence of risks from high arsenic levels (>100 µg/l) in drinking water. The U.S. Environmental Protection Agency has lowered the maximum contaminant level (MCL) for arsenic in community water supplies (CWS) from 50 µg/L to 10 µg/L beginning in 2006. However, drinking water remains an important source of arsenic exposure among CWS users. The natural occurrence of arsenic in groundwater is commonly observed in regions of New England, the upper Midwest, and the West, including California.

To evaluate the relationship between long-term arsenic exposure from CWS and cardiovascular disease, the researchers used statewide health care administration and mortality data collected for the California Teachers Study cohort from enrollment to follow-up (1995-2018), involving fatal and non-fatal cases of ischemic heart disease and cardiovascular disease. Working closely with staff at the California Office of Environmental Health Hazard Assessment (OEHHA), the team collected water arsenic data from CWS over three decades (1990-2020).

The analysis included 98,250 participants, 6,119 cases of ischemic heart disease and 9,936 cases of cardiovascular disease. Excluded were those who were 85 years or older and those with a history of cardiovascular disease at enrollment. Similar to the share of the California population that relies on CWS (over 90 percent), most participants lived in areas served by a CWS (92 percent). Using the years of available arsenic data, the team compared time periods of relatively short-term (3 years) with long-term (10 years to cumulative) average arsenic exposure. The study found that 10-year exposure to arsenic up to the time of cardiovascular disease was associated with the greatest risk, consistent with a study in Chile where peak mortality from acute myocardial infarction occurred approximately 10 years after a period of very high exposure to arsenic was found. This provides new insights into relevant exposure windows that are crucial for the development of ischemic heart disease.

Nearly half (48 percent) of participants were exposed to an average arsenic concentration lower than California’s cancer-free public health target

These results highlight the serious health consequences not only when community water systems do not meet the current EPA standard, but also at levels below the current standard. The study found that there is a substantial 20 percent risk associated with arsenic exposure, ranging from 5 to

“Our results are novel and encourage renewed discussion about current policies and regulations,” said Columbia Mailman senior author Tiffany Sanchez. “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 inform future investigations support and inform and can be extended to evaluate other drinking water exposures and health outcomes.”

Co-authors are Komal Bangia, Office of Environmental Health Hazard Assessment, Oakland, California; James V. Lacey Jr. and Emma S. Spielfogel, California Teacher Study, Beckman Research Institute, City of Hope, Duarte, California; and Jared A. Fisher^, Jessica M. Madrigal, Rena R. Jones, and Mary H. Ward^, Division of Cancer Epidemiology and Genetics, National Cancer Institute.

The study was supported by National Cancer Institute grants U01-CA199277, P30-CA033572, P30-CA023100, UM1-CA164917, and R01-CA077398; and also funded by the Superfund Hazardous Substance Research and Training Program P42ES033719; NIH National Institute of Environmental Health Sciences P30 Center for Environmental Health and Justice P30ES9089, NIH Kirschstein National Research Service Award Institutional Research Training Grant T32ES007322, NIH Predoctoral Individual Fellowship F31ES035306, and the NCI Intramural Research Program Z-CP010125-28.