How Dangerous Are Dry Cleaning Chemicals?

The term “dry cleaning” is actually a misnomer. Although the process doesn't involve water, it still uses other liquid solvents to gently clean fabrics such as leather, silk, or wool, that water or vigorous scrubbing might damage. Some of these solvents are rather intimidating—hazardous chemicals that can, in the wrong circumstances, harm humans or the environment. So it’s easy to wonder, once you become aware of the substances used in dry cleaning, just how much of them remain on clean clothes—and how safe it is to wear clothes that have bathed in them.

Dry cleaning is actually an ancient practice, and the materials used for it have shifted over time. In ancient Rome, specialized cleaners used ammonia extracted from urine, lye, and a particular kind of clay. But by the dawn of the modern dry cleaning era, the 1820s, most cleaners used materials like benzene, kerosene, petroleum, and turpentine, which did a fair job of pulling out stains but were blatantly toxic, and often flammable.

In the 1930s, it was the concerns about flammability and a World War II-linked shortage of natural petrochemicals led to the rise in usage of perchloroethylene, a synthetic chemical substance more commonly known as PERC. Also used in industrial degreasing, paint stripping, and metalworking, PERC seemed like a convenient and comparatively safe substance, and quickly became the most common dry cleaning solvent.

But by the 1970s, health and safety concerns about PERC started to gain traction. Researchers and regulators determined that acute blasts of it can cause dizziness, drowsiness, headaches, loss of consciousness, limited memory loss, skin blistering, and visual and coordination issues. Long-term exposure (over the course of several years) to PERC also seems to be linked to several forms of cancer (like bladder cancer, non-Hodgkin lymphoma, and multiple myeloma), as well as damage to the central nervous system, kidneys, liver, lungs, and possibly the reproductive system and fetuses.

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These concerns mainly apply to dry cleaning workers, who can get a good whiff of PERC when loading or unloading clothes from a dry cleaning machine, or performing maintenance on it. A fair number of workers, at least in some parts of the country often operate in “small, poorly ventilated units, typically in shopping malls,” noted Steve Whittaker of the Haz Waste Program (HWP) in King County, Washington. (The HWP is one of the most proactive government bodies researching dry cleaning safety and health today.) In these environments—especially if workers or employers are lax about safety (usually due to ignorance of the risks of PERC) or use old, leaky machines—PERC can build up and become a long-term ambient toxin within that workplace.

However PERC can become a wider environmental toxin as well. Regulators often worry that dry cleaners who clean clothes on their premises—rather than sending clothes out to industrial cleaning facilities—and share a building with residential units may cause high levels of PERC contamination for people in those homes. PERC can also leech into the air, soil, and water when spilled, becoming a long-term and at times far-traveling environmental contaminant. Some worry that such environmental PERC contamination may lead to low-level cancer risk boosts across neighborhoods or cities—not to mention seriously endanger local plant and animal life.

However, regulators like the Environmental Protection Agency have not classified PERC as a risk to dry cleaning patrons, said John Meijer of the Drycleaning & Laundry Institute International (DLII), an industry group involved in dry cleaning education, business support, and research. There has been relatively little research done on the risks of PERC to people who wear dry cleaned clothes.

At least one study has shown that storing dry cleaned clothes in a closet can boost ambient PERC concentrations, suggesting that ambient chemicals remain in clothes and slowly evaporate off into the environment. Another study, conducted almost a decade ago by a high school science student in conjunction with university researchers, found that PERC builds up in cotton and polyester over two to three cleanings before leveling off. It can continue to build after even six cleanings in wool. In rare cases, like keeping four fresh-cleaned wool suits in a hot car with the windows up for an hour, this build up could lead to dangerous ambient PERC levels which could affect someone then exposed to that air immediately.

However these studies acknowledge that they were limited in their methodologies and scopes, and so are not conclusive. Kirk Cumpston, a toxicologist and medical director of the Virginia Poison Center, noted that the risks are probably insignificant. If there was a serious risk, he argues, considering how many people use dry cleaning, there would be a massive exposure with similar symptoms, and he has heard no reports of such a thing.

Thanks to tightening regulations (especially on the age and state of machines and use of PERC in buildings with residential units) and taxes on the solvent, PERC is falling out of fashion. California is also leading a charge to outlaw PERC wholesale; in 2007, it mandated a total phase out of PERC by 2023. Minneapolis also earned some press in 2018 as the first city to make its dry cleaners go entirely PERC-free.

It’s hard to gauge how often and how much people are using PERC, but it seems as if usage in the American dry cleaning industry has dropped from about 85 percent to 65 percent during he last few decades. Meijer claimed that no one getting into the industry today plans to use PERC. Whittaker has found that, in King County at least, most people still using PERC processes only do so because they can’t afford to buy new machines that use alternative solvents. (Dry cleaning profits are especially fragile now as consumers switch to more durable clothes and figure out they actually can home wash many ‘dry clean only’ items.) But the HWP and other bodies now offer grants to help dry cleaners change solvents.

The alternatives to PERC are fairly diverse—but many of them don’t seem any safer. N-propyl bromide, Whittaker pointed out, was a popular alternative in some parts of the country for a while because it could be used in some PERC-purposed dry cleaning machines. (You can only use certain solvents in certain machines.) “The problem is,” he added, “that n-propyl bromide is a neurotoxin and there are reports out there from the Centers for Disease Control and Prevention of a couple of dry cleaners developing neurological diseases” after switching to it. Concerns have also been raised about GreenEarth, a silicon-based solvent that’s marketed as environmentally friendly but that has been linked to the development of cancer in lab rats. Gen-X has been linked to dermal, ocular, and respiratory irritation and perhaps reproductive system toxicity at high concentrations. And these are just a few of the PERC alternatives out there, all less studied than the substance they replace.

Whittaker’s team analyzed alternatives such as DF-2000, EcoSolv, CalypSolv, an emerging high-flash hydrocarbon, and found that, while they can still be considered dangerous waste, they do not contain high-risk impurities often associated with petroleum-based products. Studies of propylene glycol ether and butylol have similarly found that, while these substances may be dangerous at certain doses, they don’t seem to pose much of a threat to dry cleaning workers, especially when compared to PERC, and thus likely pose even lower risks to patrons. These specific hydrocarbons, Whittaker noted, may even be easier to clean than PERC if they leak into the environment.

However, research into PERC alternatives is still nascent. Whittaker noted that he thinks the jury is still out on butylol. He added that, while the three high-flash hydrocarbon solvents he tested seem relatively safe, there are tons of less studied hydrocarbon solvents out there, some of which may contain risky substances, like benzene. And there doesn’t seem to be any direct research on how much of these substances might linger and accumulate in clothes cleaned using them.

Most health, safety, and environmental entities, including the HWP and the Toxic Use Reduction Institute (TURI), ultimately suggest that dry cleaners should consider switching to “wet cleaning,” a gentler version of home washing that uses mild and often eco-friendly detergents and computer controls to ensure the right PH, temperature, and agitation for every particular fabric. Wet cleaning, a 2012 report by TURI notes, uses equipment that costs about as much as PERC cleaning. The detergents used are a little more expensive than PERC. However, Whittaker noted, wet cleaners often save on their utility bills because cooling PERC systems and recycling solvent is a water- and energy-intensive process.

Meijer and other industry experts remain skeptical of wet cleaning. He argued that there are few 100 percent wet cleaners because many clothes don’t wash well through the process. Doing wet cleaning well requires substantial knowledge of fabrics and fibers, as well as more effort. Most cleaners, he said, explore mixing wet cleaning with other dry cleaning services. Whittaker countered that this might have been true two or three years ago, but said that new wet cleaning systems are sophisticated enough to work with most, if not all, fabrics with greater ease.

Wet cleaning isn’t perfect. Like home detergents, those used in wet cleaning could cause irritation for some people. Whittaker noted that he and his colleagues are still working on cataloguing all the chemicals in the incredibly complex detergents used, which thus far seem relatively benign.

Regardless of the process used by one’s local dry cleaner, current research on the subject, though a bit hazy, does suggest that patrons—even obsessive dry cleaners—probably aren’t at risk. If you do want to exercise extreme caution, or mitigate any potential risks to dry cleaning workers and the environment, then be proactive, said Felice Kincannon, an outreach manager at TURI. Ask what chemicals your local dry cleaners use. That way, people can “give their business to one that uses professional wet cleaning,” she said. “This will help drive more cleaners to switch to a safer alternative,” ideally eliminating even the slim or theoretical risks the industry poses.