Dry Cleaning Process

Is dry cleaning toxic? No one had ever thought to test dry cleaned clothing for potentially harmful chemicals – that is until high school sophomore Alexa Dantzler chose the topic for a science fair. Dantzler knew she did not have the proper testing equipment to carry out the experiment herself, so she emailed several chemistry professors around the country to ask if they were interested in helping. Paul Roepe, who was the chairman of Georgetown University’s Chemistry Department at the time, was the only professor to offer help. Dantzler and Roepe’s results were groundbreaking and have raised questions about the safety of conventional dry cleaning.¹

Alexa Dantzler and Paul Roepeⁱ

Conventional Dry Cleaning Methods

Versions of “dry cleaning” have existed for centuries. In the Ancient Roman city of Pompeii, evidence of dry cleaning shops has been found. The cleaners used a type of clay called fuller’s earth mixed with lye and ammonia to remove sweat and dirt from clothing. Interestingly, the ammonia was derived from urine, so there were taxes on collecting urine.²  Fast-forward to the 1820s and dry cleaners began to use products like turpentine, benzene, kerosene, and gasoline in their processes. However, these products had large drawbacks. Turpentine caused clothes to smell even after they were cleaned, and all of the aforementioned products were highly flammable. Since the risk of fire was so high, the United Kingdom did not allow dry cleaners to exist in city limits—dry cleaners had small stores in the city where customers could drop off clothes, and then the clothes were taken to the cleaning facility outside the city.³

By the early 1900s, dry cleaners had found chlorinated solvents to replace the highly flammable solvents. The go-to chemical became perchloroethylene, or “perc,” which had already been discovered in the year 1821.⁴ Perc is still widely used today. In fact,  65-70% of dry cleaners in the United States use this solvent.⁵ While specific methods may vary cleaner to cleaner, the following is a basic rundown on how clothes are dry-cleaned:

1. https://web.archive.org/web/20160404110141if_/https://www.youtube.com/embed/yTMuJmZDPkAⁱⁱDry cleaners pre-treat stains on garments by hand.
2. Garments are put into a machine similar to your home washing machine with liquid solvents, detergents, and sometimes a small amount of water. The term “dry cleaning” continues to be used because the process involves little to no water.
3. Once clean, the garments are then either dried in the same machine or put into a separate dryer.
4. After the garments are dry, they are pressed and shaped.
5. The solvent used during the washing process is then distilled and filtered so that it can be reused. Most machines have a filter inside of them that takes care of this process.
6. The solvent filters and residues that are disposed of are hazardous waste and are thus sent to either recycling or incineration facilities.⁶

Health Impacts of Conventional Dry Cleaning

To collect samples for her experiment, Dantzler sewed squares of different materials (wool, cotton, polyester, and silk) into the lining of seven identical men’s jackets. She then took these jackets to be dry cleaned between one and six times at seven Northern Virginia dry cleaners (who were not aware of the experiment). Upon getting the dry cleaning back, she would freeze the patches to preserve them and drive them to Georgetown University. With the help of graduate students, Dantzler found that perc stayed in the fabrics and that the levels (especially in wool) increased each time that same garment was dry-cleaned. The study was published in September 2011 in Environmental Toxicology and Chemistry.  Roepe stated that without further research, it is difficult to predict the effects of long-term exposure to perc.⁷

The United States Environmental Protection Agency (EPA) has concluded that perc, depending on the amount and length of exposure, can cause negative health impacts such as damage to the reproductive, kidney, liver, and immune systems. The EPA has also determined that although perc is a “likely human carcinogen,” they do not believe wearing clothes that have been dry-cleaned using perc poses a threat. However, the EPA believes that workers in the dry cleaning industry who are consistently exposed to perc are at a higher risk for certain cancers such as bladder, non-Hogkins lymphoma, and multiple myeloma.⁸

Perc has several negative environmental impacts as well. Perc can be released into the atmosphere via windows and vents. Once in the atmosphere, perc breaks down into other chemicals, some of which are toxic. Perc is also toxic to plants and can enter the ground via spills, leaky pipes and tanks, and improperly handled waste. Lastly, even though the EPA has a limit on the amount of perc that can be present in drinking water, small amounts of perc in water can be toxic to aquatic organisms and stored in their fatty tissues.⁹

Safer Alternatives

Below are a few methods to safely clean clothes. These methods are also budget-friendly!

• Steam – The heat from steam kills odor-causing bacteria. Steam also removes wrinkles from clothes. You can buy a garment steamer, hang your garments in the bathroom while you shower, or put your delicate garments in the dryer with a damp washcloth.
• Brush – Use a microfiber cloth to brush clothes, which removes surface oils.
• Hand wash – Some garments are even too delicate for the dry cleaners. Hand washing with mild soap and then letting these garments air dry is a safe method. Make sure to reshape the garment before hanging it to dry.
• Avoid ‘dry clean only’  – To avoid the problem of dry cleaning altogether, refrain from buying clothing that is labeled as dry clean only.¹⁰

If you have a garment that truly needs a deep clean, there luckily are “green” dry cleaners. However, some dry cleaners advertise themselves as “green” because they don’t use perc, but they instead use hydrocarbon as a solvent, which is not a safe alternative and has the same environmental concerns as perc. Before picking a green dry cleaner, make sure they use pressurized (liquid) carbon dioxide as their solvent.¹¹

“Wet cleaning” is also considered to be a safe alternative to conventional dry cleaning. Wet cleaners place garments in computer-controlled washers (with soap and water) and dryers. They then reshape the garments using special equipment. Since no solvents are used, the waste is just soapy water, which can be washed down the drain. The downsides are that the wet cleaning process requires more water and more labor than other methods.¹²