A large clinical study has found that people with high levels of a type of per- and polyfluoroalkyl substance (PFAS) in their blood are more likely to develop hepatocellular carcinoma, the most common form of liver cancer (JHEP Rep. 2022, DOI: 10.1016/j.jhepr.2022.100550).
PFAS have been used for decades in fire-fighting foams and to manufacture water-resistant clothing, food packaging, and nonstick pans, among other products. These persistent pollutants are commonly found in people’s blood, in municipal water supplies, and even in rain and snow.
The study builds on previous evidence linking PFAS to liver cancer in animal studies, says University of Southern California environmental health researcher Jesse Goodrich. Earlier this year, his team established a link between non-alcoholic fatty liver disease—a major risk factor for liver cancer—and PFAS exposure. “This is the first time we’ve put it all together” to determine risk in humans, he says.
Goodrich’s team drew on data from the Multiethnic Cohort Study, which followed a racially and ethnically diverse group of people in California and Hawaii over time. They tested prediagnostic blood samples for six types of PFAS and found a strong link between perfluorooctanesulfonic acid (PFOS) and future cancer risk. People in the 90th percentile for blood PFOS levels were 4.5 times as likely to develop hepatocellular carcinoma than people in the same geographic location who had lower levels and were of the same age, race, and sex as listed on medical records.
The blood-sample analysis linked high levels of PFOS to metabolic changes in the liver, suggesting that the chemical increases cancer risk by disrupting fat metabolism and driving fat accumulation in the liver, which increases cancer risk, Goodrich says.
PFOS has been phased out in the US but still persists in the environment. “Next, we need to look at the new replacement chemicals,” Goodrich says. “We’re still being exposed to multiple types of PFAS, and many of them do cause the same effects in animal models.”