Common Dry-Cleaning Chemical Linked to Triple the Risk of Liver Scarring

A chemical widely used in dry cleaning may be an overlooked risk factor for serious liver disease, according to a study published in Liver International by researchers at Keck Medicine of USC. People exposed to tetrachloroethylene, known as PCE, were three times more likely to have significant liver fibrosis — scarring caused by repeated injury that, if severe, can impair the liver's function and contribute to liver failure, liver cancer or death.

The researchers analyzed blood measurements from people aged 20 and older collected between 2017 and 2020 through the National Health and Nutrition Examination Survey, a nationally representative U.S. health survey. About 7% of the population had detectable PCE in their blood, and those with detectable PCE were three times more likely to have significant liver fibrosis than people without it, even after accounting for age, sex, race, ethnicity and education. For every one nanogram-per-millilitre increase in blood PCE concentration, the odds of significant liver fibrosis increased five-fold.

"This study, the first to examine the association between PCE levels in humans and significant liver fibrosis, underscores the underreported role environmental factors may play in liver health," said lead author Brian P. Lee, a hepatologist and liver transplant specialist at Keck Medicine. Notably, alcohol use and obesity-related fat buildup in the liver did not explain the fibrosis seen in people with PCE in their blood, raising the possibility that environmental exposure could account for some liver disease that otherwise seems hard to explain. Lee said patients without typical risk factors sometimes ask how they developed liver disease, "and the answer may be PCE exposure."

PCE is a colourless liquid effective at dissolving grease, and people are mainly exposed by breathing it in — dry-cleaned clothing can slowly release small amounts into the air — or through contaminated drinking water. The International Agency for Research on Cancer classifies PCE as a probable carcinogen linked to bladder cancer, multiple myeloma and non-Hodgkin lymphoma, and earlier studies have also associated it with liver cancer. The U.S. Environmental Protection Agency has begun a 10-year phase-out of PCE in dry cleaning, though the chemical may still be encountered in some products and industrial uses, particularly in countries without similar restrictions.