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12 hours ago
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A new map has revealed a disturbing truth about drinking water in the US.
Scientists found millions of Americans may be regularly exposed to dangerous levels of arsenic, which is a naturally occurring element in soil and rock that seeps into groundwater over time.
Using data collected between 2017 and 2019, researchers mapped population-weighted arsenic levels in community water systems.
Alarming hotspots were found in parts of Michigan, New York, Pennsylvania, Tennessee, Utah, Arizona, California, Oregon and Washington, where levels exceed 5 micrograms per liter (µg/L), a point considered hazardous to human health.
The World Health Organization (WHO) recommends a maximum arsenic level of 10 µg/L in drinking water.
However, research has shown that even lower levels can increase the risk of cancer, cardiovascular disease and developmental issues.
Moderate-to-high levels (1.0–5.0 μg/L) were found in Ohio, Indiana, Illinois, Missouri, Nebraska, Colorado, New Mexico, Nevada, Texas and Idaho.
While some states have low overall arsenic exposure, the map shows pockets of chronic contamination that disproportionately affect rural and low-income populations, many of whom may be unaware of the risks.
The findings identified alarming hotspots, particularly in California’s Central Valley, parts of the Midwest, and swaths of the Southwest, where arsenic concentrations exceed 5 micrograms per liter (µg/L), a level considered hazardous to human health
Some studies suggest that more than two million Americans may be exposed to arsenic in their water supply, though not all at levels above the EPA's 10 micrograms per liter (μg/L) limit.
The map was created by scientists at Columbia University who utilized records from the US Environmental Protection Agency (EPA) to assess arsenic levels across specific regions.
The team collected data to determine arsenic levels in each Zip Code Tabulation Area (ZCTA), geographic zones defined by zip codes, based on 13,998 participants across 35 sites from 2005 to 2020.
The map reveals the highest arsenic concentrations, exceeding 5.0 μg/L, in Michigan’s Lower Peninsula, where industrial and agricultural activity may contribute.
Sheridan Haack, a research hydrologist with the US Geological Survey (USGS), previously said that several counties in Michigan have elevated levels of arsenic.
Counties in the Thumb had the highest levels in the state, along with Oakland, Washtenaw and Ingham counties.
New York’s southern tier, particularly around Binghamton, features bedrock and soils that may contain arsenic-bearing minerals that release the element into groundwater under certain conditions.
This is a common phenomenon in parts of the Northeast, where glacial deposits and sedimentary rock layers can concentrate arsenic.
While some states have low overall arsenic exposure, the map shows pockets of chronic contamination that disproportionately affect rural and low-income populations, many of whom may be unaware of the risks
This map from the United States Geological Survey estimates the parts of the country with higher levels of naturally occurring arsenic in private drinking wells
California’s Central Valley, known for intensive farming, also emerged as a hotspot.
Other critical areas included Pennsylvania’s western counties near Pittsburgh, Tennessee’s eastern Appalachian areas, Utah’s northern Cache and Weber counties, Arizona’s southwest near Yuma, and Oregon’s Willamette Valley.
Concerned citizens can use at-home filters to reduce their arsenic risk, but popular brands like Brita likely aren't effective at getting rid of arsenic
Instead, people can look for reverse osmosis systems, activated alumina filters or anion exchange resins, according to EcoWater Systems.
A 2023 study by a separate team from Columbia found that arsenic in drinking water was linked to an increased risk for heart disease.
They examined the health records of 100,000 Californians over 23 years and compared the data to their estimated exposure to arsenic in drinking water.
They found that people exposed to high levels of the toxic metal for a decade or more were 42 percent more likely to develop heart disease.
The study author, Dr Tiffany Sanchez, an environmental and molecular epidemiologist, suggested that current policy on the amount of arsenic allowed into drinking water may need to be re-examined.
'Our results are novel and encourage a renewed discussion of current policy and regulatory standards,' she said.
