Prenatal Arsenic Exposure Linked to Adverse Birth Outcomes, Study Suggests Stricter Regulations

A new study published in the Journal of American Medical Association showed that prenatal exposure to arsenic in public drinking water, even at levels below current federal limits, was associated with adverse birth outcomes. As public water is a major source of inorganic arsenic, this study recommend that the Environmental Protection Agency (EPA) consider stricter regulations to better protect maternal and fetal health.

While there is scant information about public water concentrations (which may be changed by federal regulatory action) in US populations, inorganic arsenic is linked to poor birth outcomes. Thus, this study assessed the relationship between birth outcomes in the US and prenatal exposure to arsenic in public water below the federal regulation threshold of 10 μg/L.

The Environmental Influences on Child Health Outcomes (ECHO) Cohort's observational pregnancy cohort data for birthing parent-infant dyads from 35 pregnancy cohort sites were examined in this cohort research. Births took place between 2005 to 2020. Analysis of the data took place in 2024 and 2025. Monthly home history data during pregnancy was combined with public water arsenic concentrations at the Zip Code Tabulation Area level to determine individual, time-weighted, mean prenatal exposures.

With a mean [SD] age of 30.8 [5.6] years, the cohort included 13,998 birthing parents, of whom 4.5% were American Indian, Alaska Native, Native Hawaiian, or Pacific Islander; 7.2% were Asian; 12.4% were Black; 56.1% were White; 4.2% were multiple races; 8.5% were another race; 28.1% were Hispanic/Latino, and 70.4% were non-Hispanic/Latino.

The range of arsenic in prenatal public water was less than 0.35 to 37.28 μg/L. Although impact estimates were imprecise, prenatal public water arsenic was linked in spline models to an increased risk of low birth weight, lower birth weight, and lower birth weight–for–gestational age z score.

Hispanic/Latino (1.07; 95% CI 1.02-l.12), Black (1.02; 95% CI, 1.01-1.03), and White (1.04; 95% CI, 102-1.06) birthing parents had higher rates of low birth weight per 1 μg/L higher prenatal water arsenic, and Hispanic/Latino birthing parents had higher rates of preterm birth (1.05; 95% CI, 1.01-1.09).

White birthing parents had the largest mean difference in infant weight and birth weight–for–gestational age z score for 1 μg/L higher prenatal water arsenic (−10 g [95% CI, −17 to −3 g]; −0.02 SDs [95% CI −0.03 to −0.01 SDs]). The relationship between birthing parent race and ethnicity and unfavorable birth outcomes was not shown to be mediated by prenatal public water arsenic.

Overall, birth outcomes were linked to levels of arsenic in public water systems that were lower than the maximum contamination level now set by the US Environmental Protection Agency. According to the results, the number of low birth weight babies in the US may decline if the maximum contamination level for arsenic is further reduced.

Source:

Nigra, A. E., Bloomquist, T. R., Rajeev, T., Burjak, M., Casey, J. A., Goin, D. E., Herbstman, J. B., Ornelas Van Horne, Y., Wylie, B. J., Cerna-Turoff, I., Braun, J. M., McArthur, K. L., Karagas, M. R., Ames, J. L., Sherris, A. R., Bulka, C. M., Padula, A. M., Howe, C. G., Fry, R. C., … ECHO Cohort Consortium. (2025). Public water arsenic and birth outcomes in the Environmental Influences on Child Health Outcomes cohort. JAMA Network Open, 8(6), e2514084. https://doi.org/10.1001/jamanetworkopen.2025.14084