Scientists in a new study have identified a link between “forever chemical” exposure and the development of the most common type of liver cancer.
One specific type of forever chemical, called perfluorooctane sulfonic acid (PFOS), may have a particularly strong connection to the manifestation of this deadly disease, according to the study.
PFOS is one of thousands of humanmade per- and polyfluoroalkyl substances (PFAS) and is found widely throughout the environment.
Notorious for their presence in jet fuel firefighting foam and industrial discharge, PFAS are a set of toxic chemicals found in a variety of household products, including nonstick pans, waterproof apparel and cosmetics.
While prior research in animals have suggested that PFAS exposure increases the risk of liver cancer, Monday’s study — published in JHEP Reports — is the first to confirm a connection in human samples.
“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,” lead author Jesse Goodrich, a postdoctoral researcher at the University of Southern California’s (USC) Keck School of Medicine, said in a statement.
Scientists first demonstrated a “probable link” between PFAS and six conditions — diagnosed high cholesterol, ulcerative colitis, thyroid disease, testicular cancer, kidney cancer and pregnancy-induced hypertension — in 2012, as part of a settlement in West Virginia.
But in the past decade, researchers around the world have conducted a plethora of studies identifying both potential and more definitive links between PFAS and other illnesses.
Goodrich and his colleagues utilized human samples collected as part of a large epidemiological study, in collaboration with the University of Hawaii.
This project, called the Multiethnic Cohort Study, has tracked more than 200,000 residents of Los Angeles and Hawaii for the development of cancer and other illnesses, according to the researchers.
The scientists combed through this trove of human blood and tissue samples to find 50 participants who eventually developed the most common form of liver cancer, known as nonviral hepatocellular carcinoma.
They analyzed samples taken prior to the cancer diagnoses and compared them to those of 50 individuals who did not develop cancer.
The researchers identified several types of PFAS in the blood samples taken before patients developed liver cancer, according to the study.
But the strongest link was to PFOS: participants who ranked in the top 10 percent for PFOS exposure were 4.5 times more likely to develop liver cancer than those with the lowest blood levels of the compound, the authors found.
Taking their research one step further, the scientists also were able to shed light on some ways in which PFOS can alter the liver’s normal function.
Probing the blood samples, they said they found evidence that PFOS can alter the process of glucose metabolism, bile acid metabolism and the metabolism of certain amino acids — molecules that merge to form proteins — in the liver.
Such disruption can cause more fat to accumulate in the liver, leading to a condition known as non-alcoholic fatty liver disease, which has been on the rise in recent years, according to the study.
In that study, the researchers also identified a possible link between PFAS exposure and nonalcoholic fatty liver disease.
The authors of both that study and Monday’s report warned that nonalcoholic fatty liver disease is expected to impact some 30 percent of all adults in the U.S. by 2030.
Acknowledging that some manufacturers have begun to phase out the use of PFOS, the scientists stressed that these compounds still pose a threat because they are so long-lasting.
The toxins are known as forever chemicals because they break down slowly and accumulate in both the environment and human tissue, including in the liver.
As far as liver cancer is concerned, hepatocellular carcinoma is responsible for about 85 percent of such cancer cases — which was the fifth and seventh leading cause of cancer deaths among U.S. men and women, respectively, according to Monday’s study.
With a five-year survival rate of less than 20 percent, this disease is also among the most fatal cancers, the researchers added.
Emphasizing the “urgent need to identify the risk factors” for this deadly cancer, the authors said that doing so could “improve the identification and surveillance of high-risk populations and ultimately reduce the burden of this disease.”