A toxin up to 90 percent of Americans’ tap water is putting children at risk of lifelong disability, a study suggests.

Arsenic, a toxic element found naturally in the Earth, is found in up to 280 million homes that rely on public water systems.  

Researchers at Columbia University discovered that pregnant women exposed to even minimal levels of arsenic in drinking water were significantly more likely to give birth prematurely or have babies with low birth weights. 

Babies born early or with low weight face long-term challenges, including cognitive impairments, developmental delays, and chronic illnesses such as diabetes, heart problems, and weakened immune systems.

Arsenic crosses the placenta and disrupts fetal development by interfering with hormones, DNA expression, and organ formation. 

It also disrupts nutrient absorption, stunting growth, and triggers inflammation, raising the risk of an early birth.

The EPA’s current max contamination limit (MCL) for arsenic in drinking water is 10 micrograms per liter (μg/L).

The study revealed: ‘Increased prenatal exposure to arsenic in public water was linked to lower birth weights, smaller sizes for gestational age, and a heightened risk of low birth weight, even when concentrations were below 5 μg/L.’

Sixty-nine percent of expectant mothers exposed to high arsenic levels (>5 micrograms per liter) were White. Their babies faced higher risks, including eight percent low birth weight

Arsenic seeps into groundwater and contaminates the supply that ultimately reaches tap water in homes. 

An estimated 2.1 million people throughout the US may be drinking domestic well water high in arsenic. 

The element has also been found in municipal water supplies in all 50 states. Up to 280 million people rely on public water systems. 

The greatest concern is water systems in the Southwest due to arsenic-rich rocks and arsenic-rich volcanic and sedimentary rock erosion. 

The new paper, funded by the NIH, analyzed data from a nationwide research project called the ECHO Cohort, which tracks over 69 different groups of pregnant women and children across the US and Puerto Rico.

It revealed white mothers were most exposed to higher arsenic levels – over 10 micrograms per liter (μg/L) in public water – making up 69 percent of this group.

Slightly under eight percent had underweight newborns,1,190 of 14,000 births births came too early, 840 infants were critically small, and 1,400 babies were dangerously undersized for their stage of development. 

Map shows arsenic concentrations in public water systems nationwide, with participant locations from 14,000-mother study

This study revealed racial and ethnic disparities in birth outcomes. Hispanic/Latino mothers had healthier babies—higher birth weights and fewer complications—than non-Hispanic/Latino mothers. 

In contrast, Black mothers’ babies were, on average, 245 grams lighter and faced higher risks of preterm birth, low birth weight, and being small for gestational age.

‘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 birthweight and other adverse birth outcomes in U.S. infants.’

Long-term exposure has been linked to leukemia and cancers of the colon, skin, breast, stomach, mouth, kidney, and more, as well as heart disease. 

Even tiny amounts of inorganic arsenic — the kind found in drinking water — wreak havoc on your cardiovascular system by causing oxidative stress that can kill cells, inflammation that damages blood vessels, and stiff, damaged arteries.

‘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, an environmental health expert at Columbia University’s Mailman School of Public Health.

The Columbia researchers behind the latest study analyzed arsenic exposure in 14,000 US pregnancies by linking EPA water system data recorded from 2006 to 2019 to records of where the participants lived during pregnancy.

Researchers tracked monthly water arsenic levels and examined four birth outcomes: preterm delivery, low birth weight, small gestational size, and birth weight scores.

The analysis accounted for factors like maternal age and education while intentionally preserving racial/ethnic differences.

Even small increases in arsenic levels (one μg/L) in public water raised low birth weight risks by three percent, with higher exposures (five μg/L) increasing risks by 16 percent.

They reported some caveats. The majority of ECHO participants reside in urban areas. 

They estimated arsenic exposure based on local water systems near people’s homes, but they do not yet know if this fully captures their actual exposure. People do not just drink water at home. They are also exposed at work, school, or other places they go to frequently.

The researchers’ findings were published in the journal JAMA Network Open.