PROVIDENCE, R.I. [Brown University] — For nearly two decades, Brown University Associate Professor of Epidemiology Joseph Braun has been studying the human health effects, from before conception through adolescence, of exposure to environmental pollutants. Through interdisciplinary, multi-institution research projects, Braun and his collaborators measure levels of exposure and analyze associations with a range of different disorders and health issues, from those that may be experienced by individuals to those that can be passed along through genes to children.
The health effects of these chemicals are becoming indisputable, said Braun, who directs the Center for Children's Environmental Health at Brown’s School of Public Health.
“There are multiple research groups around the country and the world that are finding more and more ways that exposure to these chemicals not only impacts the health of individuals but also their offspring,” he said. “It’s no longer a matter of ‘if’ but ‘how’ — and there are many answers to ‘how.’”
The studies are valuable, Braun said, not just in terms of their findings, but their sheer volume: “The more information we have, the better able we’ll be to create regulations to protect human health and stop these chemicals from entering our environment.”
A class of chemicals Braun studies, referred to as to as PFAS, makes frequent news for prevalence, persistence and potential impact on human health. This week, the National Academies of Sciences, Engineering and Medicine issued a 300-plus-page report providing detailed advice for clinicians on how to test, diagnose and treat the millions of Americans who may have been exposed to PFAS chemicals.
Amid growing awareness of the toxicity of PFAS and efforts at national and municipal levels to inform and warn the public, Braun’s team is focusing on the chemicals’ health effects and what can be done to mitigate exposure in the first place, as well as possible intervention strategies to reduce the impact of exposure. Braun discussed recent findings as well as where his research is headed.
Q: What are PFAS and why do they matter?
PFAS refers to perfluoroalkyl and polyfluoroalkyl substances, which are characterized by a chain of linked carbon and fluorine atoms. PFAS have water- and oil-repellant properties that make them very desirable for industrial and commercial applications. They're found in stain-repellent textiles, waterproof outerwear, camping equipment, non-stick cookware, firefighting foams — as well as cosmetics, guitar strings and many more items. Through manufacturing and daily use, they end up in our drinking water and our food. Because of the carbon-fluorine bond, these substances are very persistent. They can last for decades, if not indefinitely — which is why they’ve been dubbed “the forever chemicals.” And humans aren’t very good at excreting them, so they can hang around in our bodies for years.
Q: According to your research, how can these chemicals affect the health of children?
A few things we’ve found: We have seen that prenatal exposure to PFAS is associated with greater adiposity in children — which means they have a higher risk of obesity as well as of insulin resistance, which is a precursor to type 2 diabetes. In that study, we found that levels of that particular PFAS were associated with persistent changes in epigenetics, which suggests that these chemicals may program certain aspects of our biology that may predispose children to being at increased risk of adverse health effects.
Another study showed that higher levels of a PFAS called PFOA during pregnancy were associated with decreased duration of breastfeeding as well as a greater likelihood of ending breastfeeding early. That's actually been observed in studies around the world — some research even suggests that the chemicals have an impact on breast tissue development. We’re now collaborating with a researcher in Denmark who is looking at exposure to multiple chemicals in relationship to breastfeeding in several studies.
Q: How do you study the effects of environmental contaminants on children’s health?
It’s highly collaborative across many institutions in the U.S. and Canada. We work with an interdisciplinary team that includes epidemiologists, biostatisticians, exposure scientists, physicians and engineers to study the health effects of environmental pollutant exposures before conception and during gestation, infancy, childhood and adolescence. That's a real advantage to our studies. With a large group of collaborators, we have worked to establish three different cohorts in which we've enrolled women during pregnancy or even before pregnancy, with their partners. And then we've been following these women throughout their pregnancy and then after they give birth, into childhood. We conduct visits with them during pregnancy or with their children, so we have data during gestation, infancy, childhood, adolescence — in one of the studies, we’re bringing the kids back in and they're 16 to 18 years old.
We measure chemical exposures repeatedly across the lifespan at what we think are susceptible life stages, using very sensitive and specific biomarkers. We can measure levels of these chemicals in blood, urine, hair and even shed baby teeth. We conduct detailed assessments of health — everything from behavior, learning, memory, motor skills, puberty, metabolic rates, adiposity (which is related to obesity) and more. We also look at asthma and allergies, and now, in later stages of the studies, we’re looking at diet and physical activity. As an additional layer of research, we've been incorporating molecular biomarkers to identify potential biologic pathways that are in between chemical exposures and health. We look at epigenetics, which includes heritable modifications to the genome, and also thousands of different biomolecules that could be influenced by chemicals. In turn, we see how these molecular biomarkers influence health.