The most common type of liver cancer has been linked to exposure to forever chemicals, according to a new study confirming the connection in humans for the first time.
Nicknamed 'forever chemicals' because they don't naturally break down, the group of chemicals called per- and polyfluoroalkyl substances (PFAS) are widespread and accumulate in humans and the environment. They're found in consumer and industrial products, including non-stick pans, takeaway containers, makeup, carpet and textiles.
Researchers found that people most exposed to the chemical were 4.5 times more likely to develop liver cancer. They believe PFAS disrupts the liver's functions and can lead to non-alcoholic fatty liver disease (NAFLD) - a risk factor for liver cancer.
Scientists from the Keck School of Medicine at the University of Southern California (USC) say their research is a step forward. Previous research indicated that PFAS exposure increases the risk of liver cancer, but the US study is the first to confirm a link using 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," said Jesse Goodrich, PhD, a postdoctoral scholar and co-author.
The study, published in JHEP Reports, says forever chemicals are linked to non-viral hepatocellular carcinoma - the most common type of liver cancer.
Alarmingly, subjects in the top 10 percent of forever chemical exposure were 4.5 times more likely to develop liver cancer than those with the lowest levels of PFAS in their blood.
The team used human samples collected from the Multiethnic Cohort Study from the University of Hawaii which followed more than 200,000 residents of Los Angeles and Hawaii for the development of cancer and other diseases.
The data led to 50 participants who eventually developed liver cancer. The scientists evaluated blood samples that were taken prior to their cancer diagnosis and compared these with 50 people who did not develop cancer from the same study.
Researchers believe PFAS leads to liver cancer by disrupting metabolic processes in the organ that lead to more fat accumulation, a condition known as non-alcoholic fatty liver disease, which could explain the "dramatic" rise of NAFLD cases.
"There has been a dramatic and unexplained rise in NAFLD around the globe in recent years, which is concerning because people with NAFLD have a much higher risk of developing liver cancer," explain the authors. "NAFLD is expected to affect 30% of all adults in the US by 2030."
PFAS, which are used in a wide range of consumer and industrial products, were first detected in the blood of people exposed to these chemicals in the workplace in the 1970s.
By the 1990s, they were found in the blood of the general population, which has led to a growing awareness of the potential health risks.
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