The Persistence of ‘Forever Chemicals’.
The Persistence of ‘Forever Chemicals’
SPH researchers are examining associations between PFAS chemicals and COVID-19 susceptibility, adverse pregnancy outcomes, and high cholesterol levels.
Most people in the United States have been, and continue to be exposed to per- and polyfluoroalkyl substances (PFAS) because these chemicals are widely used to make common products such as food packaging, nonstick cookware, stain- and water-resistant coatings, waxes, paints and cosmetics. PFAS use in industrial processes and aqueous film forming foams used in firefighting have led to contamination of drinking water and air. Known as “forever chemicals” because of their persistence in the environment, these man-made substances pose numerous threats to human health, including increased risks of cancer, preeclampsia, liver damage, reduced birth weight, and reduced response to vaccination.
Three School of Public Health researchers in the Department of Environmental Health are part of a cross-disciplinary team at Boston University conducting laboratory research to better understand the known and potential human health effects of exposure to PFAS. These data are used by state regulators to set drinking water standards, to limit the exposure to these chemicals and ultimately to restrict their manufacture.
Jennifer Schlezinger, associate professor of environmental health, leads a lab that is spearheading studies to explore associations between certain PFAS exposure and an increased risk of high serum cholesterol, COVID-19 susceptibility, and adverse pregnancy outcomes.
Schlezinger is collaborating with Wendy Heiger-Bernays, clinical professor of environmental health, Thomas Webster, professor of environmental health, and several BU researchers, including Florian Douam, Peter Paul Career Development Professor at BU’s National Emerging Infectious Disease Laboratories (NEIDL) and assistant professor at the School of Medicine, and Joyce Wong, professor of biomedical engineering at the College of Engineering.
The laboratory research incorporates both in vivo mouse models, as well as in vitro cell cultures to investigate the adverse effects of more dominant types of the thousands of PFAS that exist, such as perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) and GenX.
“Human epidemiological data are the driving force between several end points that my collaborators and I are addressing, including a reduced immune response to vaccinations, higher levels of bad cholesterol in the body, and a greater risk for adverse pregnancy and birth outcomes,” says Schlezinger.
Last fall, Schlezinger led an SPH study coauthored by Heiger-Bernays, Webster, and other SPH researchers that explored the effects of PFOA—which has already been found in human blood samples—on lipid levels in mice. Published in the journal Toxicology and Applied Pharmacology, the study found that PFOA disrupted lipid regulation in the mice, by increasing their liver mass, which was associated with dyslipidemia—an abnormal amount of lipids—particularly low-density lipoproteins (the “bad” cholesterol) and triglycerides. When combined, these lipoproteins can increase the buildup of fat within arteries, which can lead to a heart attack or stroke.
“We generated an animal model that re-created the increase in serum lipids seen in people with higher levels of PFAS in their blood, to begin to understand what is changing in the liver that could result in lipid increases and an increased risk in cardiovascular disease,” says Schlezinger. As the team continues to study these human-relevant models, the goal is to “do what epidemiology cannot do and show that PFAS causes these effects” she says.
Schlezinger is also a co-principal investigator of a new National Institute of Health-funded study with Douam to examine the potential association between PFAS exposure and increased susceptibility to SARS-CoV-2 infection, the virus that causes COVID-19. In addition to increased lipid levels, previous epidemiologic studies have linked PFAS to a reduced immune response to routine vaccinations in humans. With this data, and evidence that links obesity-related factors as comorbidities of COVID-19, the researchers expect to find a link between the chemical exposure and susceptibility to coronavirus, Schlezinger says.
SPH is also integrating and innovating across multiple schools with regard to adverse health outcomes of these forever chemicals, she says. Wong in the College of Engineering is organizing a team of BU epidemiologists, clinicians, toxicologists, and bioengineers to study the potential association of PFAS and adverse pregnancy outcomes. The group just submitted a grant proposal for the 2021 Magee Prize by the Magee-Womens Research Institute, which would provide $1 million in funding from the Richard King Mellon Foundation to support the project. PFAS exposure is already linked to low birth weight and preeclampsia, and the researchers aim to better understand how PFAS interacts with nuclear receptors in the human placenta that can lead to adverse pregnancy outcomes, Schlezinger says.
She says that all of this work is critically needed to push back against the well-funded chemical industry that has largely dismissed the health threats of PFAS.
“It’s important to produce data for health risk assessment,” she says. “What we’re finding is that lower exposures—the ones that are lower than occupational-level exposures—may be most likely to induce adverse health effects.”
Ultimately, she says, PFAS aren’t going to completely disappear. They are used in everything from firefighting foam, to electronics, vehicle engines, medical devices and dental floss.
“We need to understand if there is a level of these chemicals that humans can be exposed to without increasing the risk of adverse effects,” Schlezinger says, and then “we can work to identify the safest of these chemicals so that essential uses can proceed with as little risk as possible.”
“Maybe we don’t need to completely ban PFAS, but do we really need it in our dental floss?”