Scientists link ‘forever chemical’ exposure to development of liver cancer
Scientists in a new study have identified a link between “lifelong chemical” exposure and the development of the most common type of liver cancer.
A specific type of forever chemical, called perfluorooctane sulfonic acid (PFOS), may have a particularly strong link to the outbreak of this deadly disease, according to the study.
PFOS is one of thousands of man-made per- and polyfluoroalkyl substances (PFAS) and is found widely in the environment.
Famous for their presence in jet fuel fire-fighting foam and industrial releases, PFAS are a collection of toxic chemicals found in a variety of household products, including non-stick pans, rainwear and cosmetics.
While previous animal research has suggested that exposure to PFAS 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 effects of liver disease and this is the first human study to show that PFAS are associated with this disease,” said the lead author. Jesse Goodrich, postdoctoral researcher at the University of Southern California (USC) Keck. Medicine School, said in a statement.
Scientists demonstrated for the first time a “probable link” between PFAS and six conditions – diagnosed with 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 over the past decade, researchers around the world have conducted a plethora of studies identifying both potential and more definitive links between PFAS and other diseases.
Goodrich and his colleagues used human samples collected as part of a large epidemiological study, in collaboration with the University of Hawaii.
This project, called the Multiethnic Cohort Study, followed more than 200,000 residents of Los Angeles and Hawaii for the development of cancer and other diseases, researchers said.
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 before cancer diagnoses and compared them to those from 50 people who did not develop cancer.
Researchers identified several types of PFAS in blood samples taken before patients developed liver cancer, according to the study.
But the strongest link was with PFOS: Participants who ranked in the top 10% most exposed to PFOS were 4.5 times more likely to develop liver cancer than those with the lowest blood levels of the compound. , found the authors.
Taking their research a step further, the scientists were also able to shed some light on some ways that PFOS can alter normal liver function.
By probing 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 fuse together to form proteins – in the liver.
Such disruption can lead to fatty buildup in the liver, leading to a condition known as nonalcoholic fatty liver disease, which has been on the rise in recent years, according to the study.
Earlier this year, members of the same USC cohort discovered how exposure to three common types of PFAS, including PFOS, could elevate an enzyme that is a biomarker of liver damage.
In this study, researchers also identified a possible link between PFAS exposure and non-alcoholic fatty liver disease.
The authors of that study and Monday’s report warned that non-alcoholic fatty liver disease is expected to affect about 30% of all adults in the United States by 2030.
Acknowledging that some manufacturers have started phasing out the use of PFOS, the scientists pointed out that these compounds still pose a threat because they last so long.
Toxins are known as forever chemicals because they slowly break down and accumulate both in the environment and in human tissues, including the liver.
When it comes to liver cancer, hepatocellular carcinoma is responsible for about 85% of these cancer cases — which were the fifth and seventh leading causes of cancer death for men and women, respectively, in the United States, according to Monday’s study.
With a five-year survival rate of less than 20%, the disease is also among the deadliest cancers, the researchers added.
Highlighting the “urgent need to identify risk factors” for this deadly cancer, the authors said it could “improve the identification and surveillance of high-risk populations and ultimately reduce the burden of this sickness”.