Synthetic “forever” chemicals in everything from furniture to food wrappers may be damaging the livers of everyone they come into contact with. Researchers at the Keck School of Medicine at USC have found a link between these widely used substances and liver damage in humans.
These chemicals, called per and polyfluoroalkyl substances (PFAS), are manmade substances which manufacturers use in all sorts of consumer and industrial products. The most common include non-stick cookware, stain-resistant carpeting and furniture, waterproof clothing, and fast-food wrappers.
Scientists call these substances “forever chemicals” because they break down very slowly, leak into the environment, and can contaminate human tissue.
“PFAS are ubiquitous, and we know that all adults in the United States have detectable levels of PFAS in their bodies,” says Dr. Leda Chatzi, a professor of population and public health sciences at the Keck School of Medicine, in a media release. “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.”
Researchers say this is the first study to examine PFAS exposure and its impact on the liver. The team reviewed 111 previous studies involving both humans and rodents.
From that information, researchers discovered elevated levels of alanine aminotransferase (ALT) in patients exposed to PFAS. ALT is a liver enzyme which serves as a marker for liver damage when levels are high.
Study authors found that humans and animals with exposure to three of the most common PFAS – perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorononanoic acid (PFNA) – all had higher levels of ALT in their blood.
Are PFAS causing fatty liver disease?
The USC team says high ALT levels are also typical in cases of non-alcoholic fatty liver disease (NAFLD). The condition, which affects one in four people, sees excess fat build up in the liver. Complications can eventually cause liver cancer or liver failure in patients. The new study points to a possible link between PFAS and rising rates of NAFLD cases in recent years.
Animal studies show that PFAS are also endocrine-disrupting chemicals, causing metabolic changes – another trigger of fatty liver disease. Moreover, epidemiological studies reveal PFAS exposure can lead to changes in cholesterol, triglycerides, and uric acid – which are all markers for metabolic problems.
“We see that the prevalence of NAFLD in humans is increasing but the explanations are unclear,” says Sarah Rock, MPH, a PhD student in the department of population and public health sciences at the Keck School of Medicine. “Though the human research connecting PFAS to liver disease is limited, there is much evidence in animal research showing hepatotoxicity of PFAS. A challenge for PFAS researchers is that humans are exposed to mixtures of hundreds if not thousands of these chemicals. Mixture analyses is one potential tool for addressing this complexity in the future.”
PFAS have been a problem for decades
Study authors note that scientists first detected forever chemicals in the blood of people in workplaces in the 1970s. Twenty years later, studies found PFAS in the blood of people in the general population, raising public awareness of the potential danger to human health. This has also led some manufacturers in the U.S. to stop using PFOA and PFOS in their products.
“This research clearly shows that PFAS need to be taken seriously as a human health concern because even after they are phased out, they persist in the environment,” says Elizabeth Costello, MPH, a PhD student in the department of population and public health sciences. “There is enough evidence, we believe, to demonstrate a need to clean up sources of exposure to PFAS and to prevent future exposures.”
“Understanding more about how PFAS injure the liver may allow us to more confidently predict which PFAS will be responsible and if any are safe,” adds Alan Ducatman MD, MS. “In addition to preventing future exposures, the data show why there should be serious consideration of what can be done for those who already live or work in high PFAS exposure circumstances.”
The study is published in the journal Environmental Health Perspectives.