A new study comes to provide worrying context to recent findings around the prevalence of man-made “forever chemicals” exposure among the public.

The true extent of exposure to the class of chemicals known as PFAS, comprising more than 4,700 types of perfluoroalkyl and polyfluoroalkyl substances currently being used commercially, has been gradually revealed in the last few months by a series of studies. Humans and some animals seem to harbor high concentrations of these substances in their bodies, coming into contact with these through a variety of household products.

However, so far, their effect on health was not known. New research comes to address that lack of understanding on our part — and the findings are not good. According to the results, high levels of exposure to PFAS can increase the odds of developing liver cancer by 350%.

Keep away from liver

PFAS were first commercialized during the 1930s in non-stick, heat-resistant cookware through products such as Teflon coatings. They were quickly adapted and expanded to a wide range of other products and packaging, finding their way into industries ranging from construction to cosmetics.

They are known as forever chemicals because they are very hard to degrade naturally or through the action of heat or liquids. While that makes them desirable materials in various products, it also means that they are an environmental nightmare, building up in soils, drinking water, and the bodies of living animals.

The presence of these compounds has been linked to the onset of diseases including cancer in lab animals. Based on this data, together with anecdotal evidence that perfluorooctanesulfonic acids (PFOS) and perfluorooctanoic acid (PFOA), two common PFAS in consumer products, were making users of those products sick, the US’ Environmental Protection Agency (EPA) ordered back in 2006 that eight multinational corporations represented in the US phase out the use of these chemicals. Despite this, PFAS are still being used in items produced elsewhere and are still being detected in natural environments and the tissues of individuals.

The current study is the first to show that there is a clear association between PFAS and nonviral hepatocellular carcinoma (the most common type of liver cancer) in humans, too.

“This builds on the existing research, but takes it one step further,” said Jesse Goodrich, a postdoctoral public health researcher at Keck School of Medicine, in a University of Southern California news release. “Liver cancer is one of the most serious endpoints in liver disease and this is the first study in humans to show that PFAS are associated with this disease.”

“Part of the reason there has been few human studies is because you need the right samples,” added Keck School of Medicine professor Veronica Wendy Setiawan. “When you are looking at an environmental exposure, you need samples from well before a diagnosis because it takes time for cancer to develop.”

For the study, the team requested access to data from the Multiethnic Cohort Study database, which records a survey of cancer development from more than 200,000 residents of Hawaii and Los Angeles conducted by the University of Hawaii.

From this dataset, the team isolated the data from 100 participants, 50 with liver cancer and 50 without, who had blood and tissue samples available for analysis. These were studied to see whether they showed traces of PFAS before they developed cancer.

The team found several types of PFAS among participants, with PFOS being most common in the group with liver cancer. Based on a statistical analysis of members in the cancer group, the team explains, those who fell in the top 10% of PFOS exposure were 4.5 times more likely to develop hepatocellular carcinoma when compared to those with the least exposure.

Although this can’t be used to establish a causal link between the compounds and the condition, it does underscore a correlation between the two, with further research needed to determine whether one causes the other. But the team is confident that that is the case already; they believe that high levels of PFOS impaired the ability of some subjects’ livers to metabolize glucose, bile acid, and branched-chain amino acids. This led to unhealthy levels of fat accumulation in the organ, otherwise known as nonalcoholic fatty liver disease — a high-risk factor for liver cancer. The rise in liver diseases including cancer recorded alongside the advent and spread of PFAS use in consumer products further supports this hypothesis.

“We believe our work is providing important insights into the long-term health effects that these chemicals have on human health, especially with respect to how they can damage normal liver function,” said study author Dr. Leda Chatzi. “This study fills an important gap in our understanding of the true consequences of exposure to these chemicals.”

The paper “Exposure to Perfluoroalkyl Substances and Risk of Hepatocellular Carcinoma in the Multiethnic Cohort: A Proof-of-Concept Analysis” has been published in the journal JHEP Reports.