A Yale School of Public Health scientist contributed to a new study by researchers from the University of Southern California’s Keck School of Medicine linking the chemicals known as PFAS to liver damage. The study was published Wednesday, April 27, in Environmental Health Perspectives.
Vasilis Vasiliou, Ph.D., department chair and Susan Bliss Professor of Epidemiology (Environmental Health Sciences) at YSPH, was one of the 17 co-authors of the study, Exposure to per- and Polyfluoroalkyl Substances and Markers of Liver Injury: A Systematic Review and Meta-Analysis. Elizabeth Costello and Sarah Rock, Ph.D. students in the Department of Population and Public Health Sciences at USC’s Keck School, were the principal authors, and Lida Chatzi, M.D., Ph.D., professor of population and health sciences at the school, was the lead investigator. Funding for the research came from the National Institute for Environmental Health Sciences.
The chemicals – per- and polyfluoroalkyl substances, or PFAS – are a group of man-made chemicals found in a wide range of consumer and industrial products, including non-stick cookware, stain-resistant carpets and furniture, waterproof clothing and fast-food wrappers. They’re sometimes called “forever chemicals” because they break down very slowly and accumulate in both the environment and in human tissue, including the liver.
“This is the first systematic review of the data on per- and polyfluoroalkyl substances (PFAS) exposure and damage to the liver,” Vasiliou said. His laboratory studies liver damage/toxicity, including alcoholic liver diseases (ALD) and non-alcoholic fatty liver disease (NAFLD). He collaborated with Chatzi and her laboratory, and has contributed to the systematic review of the data on PFAS exposure and liver damage.
“The importance of the study,” he added, “is that we found consistent evidence from rodent and epidemiological studies for PFAS associated with liver damage/toxicity, including non-alcoholic fatty liver disease (NAFLD). We [authors] say that this review identifies a need for additional research evaluating next-generation PFAS, mixtures and early life exposures.”
This study synthesized the results of 111 peer-reviewed studies involving both humans and rodents. The researchers evaluated whether PFAS exposure was associated with elevated levels of alanine aminotransferase, or ALT, a liver enzyme that is a biomarker for liver damage when elevated.
The researchers determined that three of the most commonly detected PFAS in humans – perfluorooctane (PFOA), perfluorooctane sulfonate (PFOS) and perfluoronanoic acid (PFNA) – are all connected with elevated ALT levels in both humans and rodents. They also noted differences in effects of PFAs on liver injuries between females and males; this suggests a potential mechanism through hormone dysregulation.
The importance of the study is that we found consistent evidence from rodent and epidemiological studies for PFAS associated with liver damage/toxicity, including non-alcoholic fatty liver disease (NAFLD). We [authors] say that this review identifies a need for additional research evaluating next-generation PFAS, mixtures and early life exposures.
Vasilis Vasiliou, Ph.D., department chair and Susan Bliss Professor of Epidemiology (Environmental Health Sciences)
In addition, there are elevated ALT levels in humans with NAFLD; this suggests a possible link between PFAS and a dramatic rise in NAFLD in recent years. It has become a public health crisis that now affects 25 percent of the world’s adults; In the U.S., one-third of all adults are expected to be afflicted with NAFLD by 2030.
“PFAS are ubiquitous, and we know that all adults in the U.S. have detectable levels of PFAS in their bodies,” Chatzi said. “There is growing interest in the long-term health effects of PFAS exposure, and this study supports that there is evidence that PFAS are associated with liver injury.”
The study should be a wake-up call to people who widely use products with PFAS in their everyday lives, and should also spur further research into the damage these chemicals cause through extended exposure.
“We want to bring awareness about the per- and polyfluoroalkyl substances, or PFAS chemicals,” Vasiliou said. “PFAS are ubiquitous, and it is unfortunate that most, if not all, adults in in the U.S. have detectable levels of PFAS in their bodies. This study supports suggests that there is evidence that PFAS are associated with liver injury. We need further studies on the long-term health effects of PFAS exposure in humans.”
YSPH Communications Staff Writer Fran Fried wrote the article. A news release from the University of Southern California was used extensively in this article.