Every day, millions of people in the US turn on their taps, expecting clean, safe drinking water to flow out. But more studies are showing that the water we drink might not be as safe as we've been led to believe.
A new study from Columbia University has revealed alarming findings about a toxic element that's contaminating up to 90 percent of tap water across the US.
The researchers found that arsenic, a naturally occurring toxic element, is present in the drinking water of up to 280 million Americans and is putting children at risk of lifelong disability. Additionally, the study found that pregnant women exposed to just trace amounts of arsenic in drinking water were much more likely to have premature births or underweight babies.
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During pregnancy, arsenic can cross the placenta and directly interfere with foetal development, DNA expression and organ formation.
The contamination also disrupts nutrient absorption, which can stunt foetal growth, and triggers inflammation that increases the risk of premature birth.
These findings are particularly concerning, given that these health impacts can occur at levels generally considered 'safe' by federal standards.
The Environmental Protection Agency's (EPA) current maximum contamination limit (MCL) for arsenic in drinking water is 10 micrograms per litre (μg/L).
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But, according to researchers at Columbia University, even at levels much lower than this threshold, there are still notable health effects.
"Higher prenatal public water arsenic was associated with lower birth weight, reduced birth weight–for–gestational age [...] and a higher risk of low birth weight even at concentrations less than 5 μg/L," the research team wrote.
Arsenic naturally seeps into groundwater from rocks and soil, making its way into the water supply that reaches homes across America.
The greatest concern exists in water systems throughout the Southwest, where the presence of arsenic-rich rocks and volcanic sedimentary rock erosion leads to higher concentrations.
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Funded by the National Institutes of Health, the scientists analysed data from over 69 different groups of pregnant women and children across the US and Puerto Rico.
Out of 14,000 births studied, 1,190 were born too early, 840 infants were critically small, and 1,400 babies were dangerously undersized for their stage of development.
The study indicates that white mothers experienced the highest levels of arsenic exposure, with over 10 micrograms per litre found in public water sources. Interestingly, they accounted for 69 percent of those most affected by the enhanced arsenic levels, the study suggests.
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"Most U.S. residents rely on public drinking water, and our findings suggest that further reducing arsenic in public water systems could be an important step to improve infant health across the U.S.,” said Dr Anne Nigra, PhD, an environmental health scientist at Columbia's Mailman School of Public Health.
"Even low levels of arsenic in public drinking water were associated with low birth weight and other adverse birth outcomes in US infants."
Long-term exposure to arsenic-contaminated water has been linked to leukaemia and multiple types of organ cancer.
Meanwhile, tiny amounts of the substance can damage the cardiovascular system by causing oxidative stress that kills cells, inflammation that damages blood vessels, and arterial stiffening that impairs circulation.