Tetrachloroethylene (PCE, Perc)

PCE became the dominant dry-cleaning solvent in the 1950s, replacing more flammable petroleum-based solvents [1]. By the 1970s, virtually every dry cleaner in America used it — and virtually every dry cleaner, through drains, leaking machines, and improper disposal, was contaminating soil and groundwater below their shops. The problem was compounded by the fact that dry cleaners moved frequently, leaving behind contaminated sites, and that many dry cleaners operated in urban residential neighborhoods and apartment buildings — with contaminants migrating directly into residential structures through vapor intrusion [2]. Boston, New York, Chicago, and Los Angeles all have thousands of PCE-contaminated sites from legacy dry cleaning operations. PCE is also used in metal degreasing, textile processing, and as a chemical intermediate in making other chlorinated solvents [3].

The most universal exposure is bringing freshly dry-cleaned clothes into your home — garments retained in plastic bags off-gas PCE vapor for days in your closet and bedroom [1]. Ask your dry cleaner to remove the plastic, air garments outside before bringing them in, or use a dry cleaner that uses non-PCE alternative solvents ("wet cleaning," liquid CO₂, or silicone-based). Vapor intrusion from underground PCE plumes is the second major pathway: apartments and homes above former dry cleaning sites — particularly in urban areas — can have significantly elevated indoor PCE concentrations [2]. Drinking water near dry cleaning sites or chemical plants is contaminated in many urban areas; municipal water treatment removes some but not all PCE. Occupational exposure occurs among dry cleaning workers who handle the solvent directly and experience the highest liver cancer risks [3].

PCE is classified by the EPA as likely carcinogenic to humans, with the strongest evidence for bladder cancer and non-Hodgkin lymphoma [1]. Occupational studies consistently show elevated liver and kidney cancer risks in dry cleaning workers. PCE is metabolized to trichloroacetic acid and trichloroethanol in the liver — the same reactive intermediates as TCE — that damage DNA and cause oxidative stress. The nervous system is also targeted: PCE causes impaired cognitive function, memory problems, and mood disturbances in chronically exposed workers [2]. Animal studies show reproductive toxicity and developmental neurotoxicity at concentrations relevant to human exposures. People who lived as children in homes above dry cleaning sites show measurable neurocognitive deficits in adult testing [3].

People who live or lived in apartments above active or former dry cleaning shops — particularly in older urban neighborhoods — face elevated vapor intrusion exposures [1]. Dry cleaning workers, especially those in older facilities without closed-loop equipment, carry the highest occupational burdens. Anyone who regularly brings freshly dry-cleaned garments home in plastic wrap is exposed to meaningful PCE off-gassing in their bedroom and living spaces [2]. Communities near petrochemical facilities and large industrial dry cleaning operations (commercial laundries, military uniform cleaners) face groundwater risks. Children are particularly susceptible to PCE's neurodevelopmental effects.

Remove dry-cleaned items from plastic immediately at the cleaners, or as soon as you get home, and hang them outside or in a well-ventilated area for several hours before bringing them into your living space [1]. Seek out dry cleaners that use PCE-free processes: wet cleaning, liquid CO₂, and professional wet-cleaning are effective alternatives for most garments. Check EPA's Cleaners with Alternative Technologies database [2]. If you live in an older urban apartment, look up your address in your state's environmental cleanup database to determine if your building sits above a known PCE plume. If vapor intrusion is a concern, contact your state environmental agency for testing. Use a carbon block water filter certified for volatile organic compounds if your drinking water source may be impacted [3].