PERC – PCE – perchloroethylene

2 04 2012

The solvents used in dry cleaning establishments have long been known to effect human health.

Perchloroethylene  –  also called perchlorethylene, tetrachloroethylene, tetrachlorethylene, PCE, or PERC – is used for dry cleaning clothing and  fabrics. Perc removes stains and dirt without causing clothing to shrink or otherwise get damaged. You know that sweetish smell from a newly dry cleaned sweater?  That’s it.  PERC may also be an ingredient in spot removers, rug and upholstery cleaners, water repellents, aerosols, adhesives, sealants, wood cleaners and polishes, lubricants, typewriter correction fluid and shoe polish.

From "Greening the Apple" blogspot.

The U.S. Environmental Protection Agency lists PERC as a “likely carcinogen” and by the World Health Organization as a “probable carcinogen” because long-term exposure to perchloroethylene can cause leukemia and cancer of the skin, colon, lung, larynx, bladder, and urogenital tract; recent studies have been published linking PERC to breast cancer.[1] The US Environmental Protection Agency says that it causes liver and kidney damage in humans; workers exposed to large amounts of PERC experience memory loss and confusion; if you are pregnant, long-term exposure to perchloroethylene may damage a developing fetus.  Just not something you want to live with.

It has been found that homes with freshly dry cleaned clothing have perchloroethylene levels that are 2 to 30 times higher than average background levels.[2]   The U.S. Department of Labor, in its Occupational Safety & Health guidelines (OSHA), attempts to protect workers by limiting their exposure to PERC to 100 parts per million.[3]

Last year a high school student, Alexa Dantzler, looking for a memorable science-fair project, decided to look at what chemicals might remain in dry cleaned clothing.  But since she didn’t have access to the proper equipment, she emailed several chemistry professors with her idea and hit gold with Paul Roepe, then-chairman of Georgetown University’s chemistry department.  He took on the project “for fun.

According to The Washington Post (read article here):

… what started out as something to “sponsor the kid’s curiosity” prompted a chain reaction in the university lab: an email exchange, an invitation to collaborate and, last week, a paper published online in a peer-reviewed environmental journal. The paper gives new details about the amount of a toxic chemical that lingers in wool, cotton and polyester clothing after it is dry-cleaned.

“At the end of the day, nobody, I mean nobody, has previously done this simple thing — gone out there to several different dry cleaners and tested different types of cloth” to see how much of the chemical persists, said Roepe, who supervised the study.

Dantzler, with help from her mother, sewed squares of wool, cotton, polyester and silk into the lining of seven identical men’s jackets, then took them to be cleaned from one to six times at seven Northern Virginia dry cleaners. The cleaners, who were not identified, had no prior knowledge of the experiment.

She kept the patches in plastic bags in the freezer — to preserve the samples — and went to Georgetown once or twice a week to do the chemical analysis with two graduate students, Katy Sherlach and Alexander Gorka. The research team found that perchloroethylene, a dry cleaning solvent that has been linked to cancer and neurological damage, stayed in the fabrics and that levels increased with repeat cleanings, particularly in wool. The study was published online  in  Environmental Toxicology and Chemistry.[4]

What they found is consistent with most regulations concerning fabrics:  that although there are voluntary guidelines for atmospheric concentrations of PERC in the workplace, there are no standards which exist for levels in dry-cleaned fabric.

According to the team, it is difficult to say how much risk consumers accept from wearing dry cleaned clothing for a year – or from breathing air from a closet full of dry cleaned clothes.  It’s most likely that the risk depends on how much and how long – sort of like UV exposure and cigarette smoke.

How much PERC did they find in the clothing?  The study found that cotton and polyester absorption of PERC leveled off after two or three cleaning cycles, but that levels in wool increased with each of six cycles.   Researchers calculated what they thought would happen if four people in a car each had on a freshly dry cleaned item of wool clothing.  After one hour of driving, with windows closed, the PERC circulating in the air would produce a level as high as 126 parts per million – which both exceeds the OSHA guidelines for workplace safety, as well as the limits widely recommended by industry and government scientists.

It’s possible that the dry cleaning delivery man might be exposed to more PERCE than the workers at the plant, who are covered by OSHA regulations.

And yes, Alexa Dantzler won first place in chemistry at last year’s Arlington county science fair.  Way to go Alexa!

How to minimize exposure to perchloroethylene:

    • One of the easiest ways to avoid PERC is by choosing alternatives to dry-cleaning your clothes. Be aware, however, that some non-PERC dry-cleaners use alternatives, sometimes called “hydrocarbon” treatments, that are also toxic. Wetcleaning, a professional alternative to perchloroethylene that uses biodegradable soaps  instead, is also available. Look for a cleaner near you at the Professional Wetcleaning Network’s website . There is ongoing research into different ways to dry clean without perc, so check local professionals to see what they might be looking into to move away from perc.
    • Another good option, but less available, is CO2 cleaning, which uses liquid carbon dioxide to clean clothes. Check the Pollution Control Center site at Occidental College for wet-cleaners and CO2 cleaners near you. Another resource is the National Clearing House for Professional Wet Cleaners.
      • If dry-cleaned goods have a strong chemical odor when you pick them up, ask your cleaner to dry them further. If it keeps happening, switch to a different cleaner.
      • Air out dry-cleaned garments by taking them out of the plastic sheath and hanging them briefly outdoors before bringing them indoors.
  • Some clothing labeled “Dry Clean Only” may be safely handwashed, according to Consumer Reports. “Dry Clean Only” labels are overused because manufacturers prefer to err on the side of caution.
    • Handwash plain-weave rayon and solid-colored silks separately in cool water, squeeze rather than wring, and lay flat to dry.
    • Wash sweaters in cold water by hand or machine; cashmere and cotton do best in the washing machine inside out; dry sweaters flat, except cotton sweaters, which can be machine-dried.
    • Angora sweaters and structured or lined garments should be sent to a professional cleaner, however.

[1] Aschengrau, A., et al., “Perchloroethylene-Contaminated Drinking Water and the Risk of Breast Cancer: Additional Results from Cape Cod, Massachusetts, USA”, Environmental Health Perspectives,  February 2003

[2] Report on Carcinogens, Twelfth Edition (2011); U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program. http://ntp.niehs.nih.gov/ntp/roc/twelfth/profiles/Tetrachloroethylene.pdf

[4]  Sherlach, K; Gorka, A., Dantzler, A and Roepe, P.,  “Quantification of perchloroethylene residues in dry cleaned fabrics”, Environmental Toxicology and Chemistry;  20 September 2011