Researchers studying the health effects of environmental chemicals spend decades trying to solve a fundamental problem. You cannot ethically expose people to toxic substances in a controlled experiment. Scientists pay close attention when the environment offers natural experiments. In December 2025, University of Arizona researchers published exactly this kind of study. They published it in the Proceedings of the National Academy of Sciences. The setting was New Hampshire. The design was elegant. The results were incredibly sobering.
The Natural Experiment
New Hampshire has detailed records showing where contamination entered groundwater. Contamination came from industries and landfills. It also came from firefighting foam at airports and military installations. Chemicals in soil migrate downward into groundwater. They flow in the direction of gravity and hydrology. Researchers identified mothers with drinking wells downstream of contaminated sites. They compared their birth outcomes to mothers with upstream wells. Both groups lived near the contamination. One group drank water passing beneath the sites. The other group drank unexposed water. Mothers never knew their exact well placement. They could not voluntarily choose their exposure group based on risk awareness. The study included thousands of births near contaminated sites between 2010 and 2019. Researchers called the comparison practically identical to a randomized experiment.
What They Found
The downstream group experienced dramatically worse birth outcomes. Their water passed through contaminated soil before reaching their taps. Their infants faced a 191 percent higher rate of mortality during their first year. This relative increase does not stem from a tiny baseline. It equals approximately 611 additional infant deaths per 100,000 births. They experienced a 168 percent higher rate of extremely early births. These early births happened before 28 weeks of gestational age. This threshold carries severe lifelong consequences. They experienced a 43 percent higher rate of low birth weights. They also experienced a 20 percent higher rate of early births. Economist Derek Lemoine authored the study. He expressed surprise at detecting extremely early births in this sample size. A strong finding in clean data implies a substantial underlying effect.
The Cost Calculation
The Arizona team went a step further. They estimated lifetime social costs caused by infant health effects. These costs include medical care and developmental delays. They also include reduced education and lower lifetime earnings. They calculated approximately eight billion dollars in annual costs. These costs affect each new cohort of infants born across the contiguous United States. This number represents a floor rather than a ceiling. It only counts costs traceable to birth outcomes. It excludes health harms affecting the mothers. It excludes older children drinking contaminated tap water. It also excludes adults consuming these chemicals for decades. The American Water Works Association estimated cleanup costs. Meeting EPA limits would cost utilities roughly four billion dollars annually. The Arizona study suggests cleanup benefits exceed costs significantly. They exceed costs by a factor of two or more based solely on infant health.
The Significance for Water System Operators
Food, cookware, and clothing did not cause the primary exposure for affected mothers. Tap water caused their exposure. Contamination migrated through local groundwater for years to reach these taps. Water system operators must recognize this direct line. Contaminated source water causes measurable harm to vulnerable community members. Infants cannot filter their own water. Their protection depends entirely on parental water supplies. Water systems must detect and address contamination. The study also strengthens the economic case for treatment investment. The societal benefit of removing contamination from drinking water is not speculative. It is measurable and appears to substantially exceed the cost. Stag Liuzza represents public water systems pursuing recovery of PFAS treatment and remediation costs. Contact us for more information.