Reducing exposure to arsenic in household essential slashes cancer and heart disease death by 50%
Millions of Americans are unknowingly being exposed to a cancer-linked toxin in their household water, but now, scientists have discovered that reducing contamination can halve the risk of disease – even after years of accumulated exposure.
Arsenic has been found in drinking water systems across the country, with research estimating that between 100 million and 280 million Americans drink water, typically well water, laced with the heavy metal.
Arsenic has been linked to multiple forms of cancer, cardiovascular disease, developmental issues in children and skin lesions. Arsenic accumulates in the body over time, compounding the health risks.
Unlike some toxins that the body can quickly process and eliminate, arsenic is stored in tissues like the skin, hair, nails and organs. The chronic, low-level exposure means the damage adds up, increasing the risk of disease the longer a person is exposed.
Now, scientists have found that by reducing arsenic in water by about 70 percent could slash people’s risk of dying from chronic diseases and cancers by more than 50 percent – despites years-long contamination.
In the 20-year study of nearly 11,000 adults from Bangladesh, researchers found that those who switched to water with lower arsenic levels saw their risk of death from chronic disease, heart disease, and cancer plummet more than 50 percent compared to those who continued drinking contaminated water.
Switching to safer wells reduced arsenic in drinking water by up to 70 percent and this reduction was so effective that people who switched eventually saw the same low mortality rates as people who had always used clean water.
The study’s authors liken the health benefit to quitting smoking. The risk doesn’t vanish overnight, but it begins to decline steadily.
Arsenic is a hidden danger in millions of kitchens. It has no taste or smell, yet it contaminates millions of Americans’ primary water source, private wells, raising the risks of cancers and heart disease (stock)
Arsenic is a silent threat. It occurs naturally in groundwater, has no taste or smell, and can seep undetected into the water supply of private wells.
Chronic arsenic exposure is a known carcinogen, linked to skin, lung, and bladder cancer, with growing evidence showing its role in liver and prostate cancers as well.
It also significantly increases the risk of cardiovascular diseases, including heart disease, stroke, and conditions caused by narrowed or blocked arteries.
In the US, naturally occurring arsenic in water is typically low (around 1 ppb), but in contaminated groundwater, it can exceed 1,000 ppb, according to the CDC.
In the US the legal limit for arsenic in public water systems is 10 parts per billion. Public health experts stress that no level of arsenic is safe, as even long-term exposure to low concentrations can increase cancer risk.
Teams of researchers at New York University and Columbia University in New York City conducted the study with an average follow-up time of nearly 20 years. In that time, 1,401 people died from chronic diseases, including 256 from cancer and 730 from heart disease.
To ensure an accurate measurement of arsenic exposure and its concentration in the body, scientists report it as micrograms of arsenic per gram of creatinine (μg/g creatinine).
This method corrects for urine dilution by using creatinine, a natural waste product with a stable baseline, as a reference point, thereby providing a reliable result regardless of the amount of water a person has consumed.
The United States Geological Survey found arsenic in nearly half of the wells tested across major US aquifers. About seven percent of wells exceeded the federal safety standard of 10 µg/L, indicating a widespread potential health risk.
The X-axis shows the change in a person’s urinary arsenic level over the study. For example, a value of -12 means a person’s urinary arsenic level dropped by 12 micrograms per gram of creatinine from their baseline measurement
Urine samples showed that, as mitigation measures were implemented, arsenic concentrations fell from an average of 283 μg/g to 132 μg/g creatinine.
For each major decrease in urinary arsenic, specifically, a reduction of 197 micrograms per gram of creatinine, the risk of death fell by 22 percent from chronic diseases, 23 percent from cardiovascular disease, and 20 percent from cancer.
They also concluded that participants who reduced their arsenic levels from high (at or above the median of 199 µg/g creatinine) to low (below that median) saw their risk of dying from chronic diseases fall by 54 percent compared to those who remained consistently highly exposed to the toxin.
To reach their conclusions, researchers took water samples and recorded geographic coordinates from all 5,966 wells within a 25-square-kilometer area of Araihazar, Bangladesh.
They recruited men who had lived in the area for at least five years.
Researchers tracked participants from 2000 to 2018, collecting health data through repeated interviews, physical exams, and urine tests.
During this period, public health efforts to label unsafe wells and install safe ones naturally reduced arsenic exposure for many, creating a real-world experiment to see how lowering exposure improved health.
The researchers established familiar risk factors for specific cancers and heart disease, including a history of smoking and high body mass index, indicating obesity.
Like figure A, the graph shows that as arsenic is reduced (moving left of 0), the hazard ratio drops steadily and consistently below 1.0, indicating a continuously lower risk of cancer death
For every unit of arsenic reduced, the drop in the risk of dying from heart disease is the largest. Even moderate reductions in arsenic lead to a significantly lower risk of CVD death
The study also concluded that if everyone with high arsenic exposure had reduced their levels, it would have prevented approximately 5.1 chronic disease deaths per 1,000 people annually.
Over the study period, many households in the city reinstalled their own private wells.
This typically offers safety from arsenic because the wells involved were drilled deeper to tap into aquifers that are naturally protected from the arsenic contamination found in shallow groundwater.
Dr Alexander van Geen, a researcher at the Columbia Climate School’s Lamont-Doherty Earth Observatory, said: ‘We show what happens when people who are chronically exposed to arsenic are no longer exposed.
‘You’re not just preventing deaths from future exposure, but also from past exposure.’
Their research was published in the Journal of the American Medical Association.
