Adverse Birth Outcomes May be Associated with Arsenic Levels in Public Drinking Water

Authors: Anne Nigra, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Regulated U.S. public drinking water is a source of exposure to arsenic. Because arsenic occurs naturally, water that comes in contact with certain rocks and soils may contain it. Contamination from various industrial processes also contributes to increased levels of arsenic in some areas. Prenatal exposure to arsenic has been associated with adverse birth outcomes, including preterm birth and low birthweight. Researchers studied how arsenic in public drinking water—at levels below the federal limit—may affect birth outcomes in the ECHO Cohort. Previous evidence has been limited to private well exposures, studies using urinary biomarkers, and single-site studies with limited racial, ethnic, and geographic diversity.

What were the study results?

The study found that when pregnant women lived in areas with publicly reported high levels of arsenic in public drinking water, even at levels below the current federal safety standard of 10 micrograms per liter, their babies were more likely to be born with low birthweight (weighing less than 5 lbs 8 oz) or are small for their gestational age (smaller than babies born at the same number of weeks of pregnancy). These patterns were seen across several racial and ethnic groups, including White, Black, and Hispanic/Latino families. For example, babies born to Hispanic/Latino parents were about 40% more likely to have low birthweight with just a 5 microgram-per-liter increase in water arsenic. The study also found that babies born to Black parents had higher risks of being born early, with low birthweight, or smaller for their gestational age. Similar risks were observed among babies born to American Indian, Alaskan Native, Native Hawaiian, and Pacific Islander parents.

What was this study's impact?

The study shows that even low levels of arsenic in public drinking water may increase the risk of babies being born too early, too small, or underweight.

Who was involved?

Participants included 13,998 birthing mother-infant pairs from the ECHO Cohort.

What happened during the study?

Researchers estimated how much arsenic people were exposed to through public drinking water during pregnancy by combining water quality data with where each person lived each month. They then looked at whether that exposure was linked to outcomes like being born early (preterm birth), having a low birthweight, or being small for their gestational age.

Footnote: Results reported here are for a single study. Other or future studies may provide new information or different results. You should not make changes to your health without first consulting your healthcare professional.

What happens next?

Future research could help researchers understand how current efforts to reduce arsenic in drinking water are working—whether those efforts happen across the country, in local communities, in homes, or for individuals. Studies could also help identify where arsenic levels are highest, which may support ongoing work to make sure communities have safe drinking water.

Where can I learn more?

Access the full journal article, titled “Public water arsenic and birth outcomes in the Environmental influences on Child Health Outcomes Cohort,” in JAMA Network Open.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published June 16, 2025

Access the associated press release.

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Adverse Birth Outcomes May be Associated with Arsenic Levels in Public Drinking Water

Exposure to Low Levels of Arsenic in Public Drinking Water Linked to Lower Birthweight, Preterm Birth, Study Finds

Posted on June 16, 2025August 27, 2025 by Jodi Snare

Babies born to mothers potentially exposed to low levels of arsenic in public drinking water—even at levels below the federal safety standard—were more likely to be born preterm, with lower birthweight, or be smaller than expected, according to a study funded by the National Institutes of Health’s Environmental influences on Child Health Outcomes (ECHO) Program.

While the U.S. Environmental Protection Agency sets a maximum contaminant level of 10 micrograms per liter for arsenic in public water systems, this study examines how even lower-level arsenic exposures may still affect pregnancy outcomes in a large population. Previous research largely focused on private wells or smaller study groups.

Because arsenic occurs naturally, water that comes in contact with certain rocks and soils may contain it. Contamination from various industrial processes also contributes to increased levels of arsenic in some areas.

“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 Anne Nigra, PhD, of Columbia University’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.”

Key takeaways include:

Potential arsenic exposure during pregnancy—even at levels below the current federal safety standard—may be linked to adverse birth outcomes.
Mothers exposed to higher levels of arsenic in public drinking water were more likely to have babies born with low birthweight or smaller than expected for the number of weeks of pregnancy.
These patterns were seen across several racial and ethnic groups, including White, Black, and Hispanic/Latino families. Similar risks were also observed among babies born to American Indian, Alaskan Native, Native Hawaiian, and Pacific Islander parents.
Babies born to Black parents faced higher risks of being born early, having low birthweight, or being smaller than expected.

Researchers analyzed data from nearly 14,000 mother-infant pairs from the ECHO Cohort. Arsenic exposures during pregnancy were estimated by combining water quality data with the residential histories of participants. No actual arsenic levels were tested for these participants.

This collaborative research was published in JAMA Network Open.

Nigra, A., et al. (2025) Public water arsenic and birth outcomes in the Environmental influences on Child Health Outcomes Cohort. JAMA Network Open. DOI: 10.1001/jamanetworkopen.2025.14084

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About ECHO
The ECHO Cohort Consortium is a research program supported by the National Institutes of Health (NIH) with the mission to enhance the health of children for generations to come. ECHO Cohort investigators study the effects of a broad range of early environmental influences on child health and development. For more information, visit echochildren.org.

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ECHO Study Finds No Association Between Arsenic Exposure and Birth Outcomes

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ECHO Study Finds No Association Between Arsenic Exposure and Birth Outcomes

Authors: Jonathan Lewis, Emily A. Knapp, Amii M. Kress, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of The Director, National Institutes of Health supported this research.

Why was this study needed?

Arsenic is a naturally occurring, toxic chemical that can be present in groundwater and surface water. Drinking water, as a result, is one of the most common ways people are exposed to arsenic in the U.S. and globally. There have been a limited number of small studies of the association between arsenic and birth outcomes, mostly outside of the U.S. In this study, ECHO researchers examined a diverse group of pregnant participants from across the country to determine if birth outcomes—birth weight, gestational age at birth, preterm birth, and size at birth—are influenced by arsenic concentrations that are above regulatory action levels.

What were the study results?

Researchers found that low birth weight, gestational age at birth, preterm birth, and birth size were not associated with potential exposure to arsenic among pregnant women living in a county with active arsenic level violations. There was a statistically significant increase in birth weight among infants whose mother’s experienced continuous exposure (from three months before conception through birth) compared with infants from areas without violations.

Footnote: Results reported here are for a single study. Other or future studies may provide new information or different results. You should always consult with a qualified healthcare provider for diagnosis and for answers to your personal questions.

What was this study's impact?

Overall, drinking water violations for arsenic that could indicate the presence of the chemical above regulatory action levels are relatively uncommon. Researchers captured proxy exposure using residential history arsenic violations from the preconception period throughout pregnancy, a time when environmental influences could disrupt fetal growth.

Who was involved?

The study included over 15,000 mother-child pairs at 51 ECHO Cohort Study Sites across the United States. The children were born in 2006 or later, as the U.S. Environmental Protection Agency (EPA) changed the enforceable standard for arsenic concentrations in drinking water to 10 parts per billion during that year. Only 794 participants experienced arsenic violations.

What happened during the study?

Researchers grouped pregnant participants based on where they lived three months before conception and during pregnancy. Within those areas, investigators determined which public water systems had violations for arsenic. Then they looked at how living in a county with an arsenic violation might affect birth outcomes.

What happens next?

Future research could better identify ECHO participants’ exposure to arsenic by considering other sources of drinking water (e.g., bottled or filtered water) and exposure to arsenic in foods.

Where can I learn more?

Access the full journal article, titled “Associations Between Area-Level Arsenic Exposure and Adverse Birth Outcomes: An ECHO-Wide Cohort Analysis,” in Environmental Research.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published November 1, 2023

Access the associated article.

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ECHO Study Finds No Association Between Arsenic Exposure and Birth Outcomes

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Adverse Birth Outcomes May be Associated with Arsenic Levels in Public Drinking Water