November 10, 2023

By Audrey Smith

A new study, recently published in the journal Environmental Health, found that in North Carolina, prenatal exposure to certain metals in private well water was linked with a significantly increased risk of preterm birth. 

The research team, which included several UNC Gillings School of Global Public Health researchers, analyzed over 1.3 million birth certificates and leveraged data from the NCWELL database, which contains 117,960 well water tests between 1998 and 2019. Monitoring the quality of well water is a major public health focus in N.C., which has the largest portion of residents on private well water nationally. 

Dr. Lauren Eaves

Dr. Lauren Eaves

“I became interested in the environmental causes of adverse birth outcomes while working as a doula and lactation consultant supporting families who have experienced preterm birth,” said Lauren Eaves, PhD, IBCLC, who is a research scientist at the Institute for Environmental Health Solutions at the Gillings School and the study’s first author. “I hope our research can inform policy and practice to reduce the prevalence of preterm birth and other devastating pregnancy outcomes for N.C. families.” 

Researchers focused on the concentrations of arsenic, manganese, lead, cadmium, chromium, copper and zinc in private well water. The team used logistic regression models to analyze individual metal exposures. To analyze mixtures, they used a new modeling technique developed by Alexander Keil of the National Cancer Institute called quantile-based g-computation. 

They found that those who lived in census tracts with over 25% of well water tests exceeding the Environmental Protection Agency (EPA) standard for public water systems for lead or cadmium had a greater risk of preterm birth (10% and 11% higher adjusted odds, respectively). For metal mixtures, a simultaneous quartile increase in the mean concentrations of cadmium, lead and chromium resulted in a 2% increase in adjusted odds of preterm birth. 

While public water utilities are regularly tested and are regulated by the EPA, private wells are not. This leaves well water users responsible for water quality stewardship and more vulnerable to the health issues that can accompany poor water quality. 

Previous studies have demonstrated disparities in the testing and treatment of private well water between Black, Indigenous and People of Color (BIPOC) well water users and white well water users. This study confirmed that preterm birth risks varied across racial and ethnic groups, with the effect of metal mixture in drinking water having the greatest risk of preterm birth among American Indian individuals. The odds of preterm birth associated with exposure to metal mixtures was 19% higher among American Indian individuals than among white individuals.  

Dr. Rebecca Fry

Dr. Rebecca Fry

Rebecca Fry, PhD, Carol Remmer Angle Distinguished Professor in Children’s Environmental Health and interim chair of the Department of Environmental Sciences and Engineering at the Gillings School and the senior author of the paper, said, “It is absolutely critical that our research identifies those populations that are most vulnerable to metals-induced preterm birth. These findings will allow for targeted interventions and policies that can mitigate the disproportionate impact of environmental factors on our most at-risk individuals and promote maternal and infant well-being for all.”

These findings underscore the importance of regular well water testing and the urgent need to improve private well water quality to protect communities. This data demonstrates that exposure-reducing interventions, like providing families on private well water with free water filters, could significantly impact reproductive health in N.C. 

The team is continuing to investigate environmental impacts on health. One study currently underway is exploring the interaction between metal exposures, air pollutants, heat and preterm birth risks. Another study is investigating how to best predict metal contamination in private wells across the state and in collaboration with community partners, working to test well water and distribute filters in communities with high levels of contamination.

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