Vinyl chloride, a chemical found in several train cars that derailed and ignited in East Palestine, Ohio, in February 2023, can severely damage the human liver. Research has shown it can lead to liver cancer and a non-cancerous liver condition called TASH, or toxicant-associated steatohepatitis. In TASH, the liver of a healthy person can accumulate fat, become inflamed, and develop scarring (fibrosis and cirrhosis) similar to the damage seen in people with cirrhosis from alcohol or obesity. This type of liver damage usually requires high levels of vinyl chloride exposure, like what an industrial worker might face on the job.
However, exposure to lower environmental levels is still worrisome. This concern arises partly because we know little about how low-level exposure impacts liver health, particularly in individuals with existing liver disease or other risk factors. As an assistant professor of medicine and environmental and occupational health, I research the effects of vinyl chloride exposure on the liver, focusing on individuals with pre-existing liver conditions. Recent discoveries have shifted our understanding of the risk. Vinyl chloride is used to create PVC, a durable plastic for pipes, and is also found in certain packaging, coatings, and wires. Its health risks were identified in the 1970s at a B.F. Goodrich factory in the Rubbertown neighborhood of Louisville, Kentucky.
There, four workers involved in the process of making polyvinyl chloride each developed angiosarcoma of the liver, a highly uncommon tumor type. These cases became pivotal in occupational medicine history, leading to the global acknowledgment of vinyl chloride as a carcinogen. The liver acts as the body’s filter to eliminate toxins from the blood. Specialized cells called hepatocytes work to decrease the toxicity of drugs, alcohol, caffeine, and environmental chemicals, ultimately passing the waste for excretion. The signature of liver exposure to vinyl chloride is an unusual combination of normal liver function tests with fat accumulation in the liver and death of hepatic cells, which compose most of the liver’s mass.
However, the detailed mechanisms that result in vinyl chloride-induced liver disease remain largely unknown. Recent studies have shown that exposure to vinyl chloride, even at levels below federal safety limits, can worsen liver disease linked to a “Western diet” — one high in fat and sugar. This newly discovered interaction between vinyl chloride and underlying fatty liver diseases raises concerns that the risk from lower vinyl chloride exposure may be underestimated. In outdoor air, vinyl chloride rapidly dilutes. Sunlight also decomposes it, usually within nine to 11 days.
Consequently, outdoor air exposure is likely not problematic unless there are intense exposure periods, such as directly after a vinyl chloride release. If there’s a chemical smell, or if you feel itchy or disoriented, leave the area and seek medical help. Vinyl chloride can also spread in water. The federal Clean Water Act mandates monitoring and removal of volatile organic compounds, including vinyl chloride, from city water supplies, so these should not be a concern. However, private wells could become contaminated if vinyl chloride reaches the groundwater. Private wells aren’t regulated by the Clean Water Act and usually aren’t monitored.
Vinyl chloride easily evaporates into the air from water and can build up in enclosed areas above contaminated groundwater. This is particularly concerning if the water is heated, such as during showers or cooking. In enclosed spaces, vinyl chloride gas can accumulate like recent worries about fumes from natural gas stoves in poorly ventilated homes. While there are defined safety levels for acute and intermediate exposure, these don’t exist for chronic exposure, making ongoing testing important.