Arsenic in Drinking Water Linked to Lower Birth Weight, Preterm Birth

Researchers are calling on the EPA to lower acceptable arsenic levels in public drinking water.

A new study warns that pregnant women exposed to arsenic in public drinking water face a higher risk of delivering preterm, or having babies with lower-than-expected birth weights.

According to findings published in the journal JAMA Network Open, even low levels of arsenic exposure, below those considered safe by the  U.S. Environmental Protection Agency (EPA), still appear to have an effect on the length of a woman’s pregnancy and the odds of low birth weight.

Arsenic Health Risks

Arsenic is a heavy metal that is toxic to human health. There are two types: organic and inorganic. While organic forms pass through the body harmlessly, inorganic forms are toxic, especially with prolonged exposure.

Exposure to high levels of inorganic arsenic can cause neurological issues, lung and bladder cancers and other serious health effects. Research published in 2024 linked exposure to arsenic from drinking water to an increased risk of kidney cancer.

Drinking water is not the only vector for arsenic exposure, however. A study published last month warned that every brand of rice tested contained arsenic or other harmful heavy metals.

Recent testing conducted by Consumer Reports also found levels of arsenic and lead in infant formula. All samples tested contained heavy metals, plastics or other dangerous chemicals. Products that tested positive included major brands like Enfamil and Similac.

In the new study, researchers from Columbia University Mailman School of Public Health, looked at 14,000 parent-infant pairs from the Environmental Influences on Child Health Outcomes Cohort. They compared public water data with residential histories looking for indications of arsenic exposure.

The team, led by Dr. Anne E. Nigra, focused on arsenic in public water with levels below the regulatory standard of 10 micrograms per liter (μg/L), comparing the arsenic levels to birth outcomes for infants born in the U.S. between 2005 and 2020.

Prenatal arsenic exposure from public drinking water varied widely, with levels ranging from under 0.35 μg/L to 37.28 μg/L. About 22% of participants had exposure above 1 μg/L, and 2% were exposed to levels over 5 μg/L.

According to the findings, infants born to mothers exposed to even low levels of arsenic in drinking water suffered birth side effects, including preterm birth.

The findings indicate mothers exposed to high levels of arsenic in drinking water were more likely to give birth to infants with low birthweight or who were smaller than expected, the researchers determined.

Preterm birth occurs earlier than 37 weeks of pregnancy. It is linked with a range of other problems including infection, breathing problems, feeding difficulties and temperature regulation issues.

African American parents faced an even higher risk of having infants born at a low birth weight if they consumed arsenic in water, while Latino parents faced a higher risk of having infants born preterm.

The data indicates public water exposure is linked with birth side effects even at low levels. Researchers concluded their findings highlight a need for the EPA’s maximum arsenic levels to be reduced to improve outcomes for infant health and help reduce the number of infants born with low birth weight.