The study, published in Liver International, found that exposure to tetrachloroethylene—also known as perchloroethylene or PCE—was associated with a threefold increase in the odds of significant liver fibrosis in U.S. adults. Liver fibrosis is a buildup of scar tissue that can progress to liver cancer, liver failure, or death.
PCE is a synthetic solvent, a colorless liquid, and a volatile chemical with a mildly sweet odor extensively used in dry cleaning, in consumer goods for removing grease and stains, in brake cleaners, in adhesives, and also in many industrial settings.
According to researchers, people are typically exposed to PCE through the air; for example, the chemical can be slowly released into the air over time from clothes that have been dry-cleaned. PCE can also be present in drinking water from contaminated sites due to spills and improper disposal of PCE that can seep into the soil and then into the groundwater, researchers state.
“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 Brian P. Lee, MD, MAS, a hepatologist and liver transplant specialist with Keck Medicine and the study’s lead author.
Researchers analyzed data from 1,614 adults in the National Health and Nutrition Examination Survey (NHANES) from 2017 to 2020 and found that about 7 percent of participants had detectable levels of PCE in their blood. Those with measurable exposure were three times more likely to develop significant liver fibrosis than those without. The risk increased five times for every one nanogram per milliliter rise in PCE concentration in the blood.
The study showed that individuals from higher-income households were most likely to be exposed, likely due to their more frequent use of dry cleaning services, although workers in dry cleaning facilities also face higher risks.
“People with higher incomes may be more likely to use dry cleaning services, which could increase their exposure to PCE,” said Lee. “However, people who work in dry cleaning facilities may also face elevated risk due to prolonged, direct exposure to PCE at work.”
PCE to Be Phased Out
In December 2024, the EPA issued a final rule regulating PCE under the Toxic Substances Control Act (TSCA) to safeguard against health risks. These include, as the EPA warns, “damage to the kidneys, liver, and immune system, neurotoxicity, reproductive toxicity, and cancer, resulting from inhalation or dermal exposure.”The EPA has established a timeline to phase out most consumer and commercial uses of PCE over the next several years. The agency also introduced regulations for companies and workplaces that use or handle the chemical.
According to the EPA, consumer sales of PCE will end by March 8, 2027, and commercial uses will be banned after June 7, 2027.
Dry cleaning use will be phased out in stages, which began on June 16, 2025, with a full ban starting on Dec. 19, 2034.
The EPA also requires new workplace protections for PCE handling, including ventilation and dermal protection by Dec. 15, 2025, and respiratory safety measures by March 13, 2026.
Lee emphasizes the need for more research into how environmental toxins contribute to liver disease. As he noted, “No doubt there are other toxins in our environment besides PCE that are dangerous to the liver.”
“We hope our research will help both the public and physicians understand the connection between PCE exposure and significant liver fibrosis,” he said. “If more people with PCE exposure are screened for liver fibrosis, the disease can be caught earlier and patients may have a better chance of recovering their liver function.”