A new Dartmouth-led study, published in the journal BMC Public Health, shows that even small effects from environmental exposures to toxins like air pollution, PFAS (forever chemicals), and arsenic in well water can adversely affect the health of vulnerable groups like mothers and their babies.
A major challenge in the field of epidemiology, which seeks to find the underlying causes of disease, is knowing when a measured impact of an environmental exposure is large enough to be clinically important and warrant intervention or practice change.
“We know that in general, vulnerable populations are more at risk of poor health outcomes than healthy populations when both are subjected to the same environmental exposure,” says Janet Peacock, PhD, a professor of epidemiology and biomedical data science at Dartmouth’s Geisel School of Medicine and lead author on the study. “We wanted to get a sense of how much this actually matters in real data.”
For their research, the team conducted a simulation study modeling birthweight and sociodemographic data from 28,000 mother/child pairs who have participated in the NIH-funded Environmental influences on Child Health Outcomes (ECHO) program—a national consortium of more than 50 pregnancy cohorts, including the New Hampshire Birth Cohort Study led by Dartmouth’s Margaret Karagas, PhD, principal investigator and chair of the Department of Epidemiology at Geisel.
To help illustrate the extent of health disparities (differences) experienced by vulnerable subpopulations within the ECHO program, the team categorized them by the race, ethnicity, insurance status, and education of the pregnant person.
“Along with looking at the effects of environmental exposures across whole populations, as we often do in research, it’s important to look at what’s happening within the more vulnerable groups,” Peacock explains. “Something that may not seem like it will have an appreciable impact overall, actually may have a big impact in terms of risk for certain groups.”
That is, indeed, what the researchers found. Key among their results were that among populations with higher average birthweights, the percentage of babies at high-risk for poor health was smaller, as compared to populations experiencing lower average birthweights.
“Something that may not seem like it will have an appreciable impact overall, actually may have a big impact in terms of risk for certain groups.”
- Janet Peacock, PhD
They also found that a small-to-medium exposure increased the estimated percentage of the mother/child population who are at high risk of later poor outcomes to nearly 20 percent in the most vulnerable participants, compared to less than 10 percent in the least vulnerable.
“We were able to provide tangible examples of how participants in vulnerable subpopulations who are already at higher risk of poor health, fare worse than the general population when exposed even to small effects from environmental exposures,” says Peacock. “And I think this illustrates another facet of health disparity in vulnerable individuals.”
Understanding the impacts of environmental exposures in vulnerable subpopulations, says Peacock, will be critical to building the evidence base needed to guide public and environmental health policy efforts and preventive programs.
About the ECHO Program
Launched in 2016, the Environmental influences on Child Health Outcomes (ECHO) Program is a research program in the Office of the Director of the NIH with the mission to enhance the health of children for generations to come. ECHO investigators study the effects of a broad range of early environment influences on child health and development. For more information, visit https://echochildren.org.
About the Geisel School of Medicine
Founded in 1797, the Geisel School of Medicine at Dartmouth strives to improve the lives of the communities it serves through excellence in learning, discovery, and healing. The Geisel School of Medicine is renowned for its leadership in medical education, healthcare policy and delivery science, biomedical research, global health, and in creating innovations that improve lives worldwide. As one of America’s leading medical schools, Dartmouth’s Geisel School of Medicine is committed to training new generations of diverse leaders who will help solve our most vexing challenges in healthcare.
