Dry Cleaning

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Dry cleaning is the use of solvents instead of water to clean fabrics. It is believed to have originated in France in 1828 when a factory worker spilled lamp oil, a flammable petroleum-based solvent , on a soiled tablecloth. When the tablecloth dried, the spots had disappeared. The original solvents used in the dry cleaning industry included turpentine, kerosene, benzene, and gasoline. These are extremely flammable, often resulting in fires and explosions. Around 1900, scientists developed chlorinated hydrocarbons, which are nonflammable solvents. Initially, carbon tetra chloride was the preferred solvent, but because of its toxicity, it was eventually replaced by tetrachloroethylene, also known as perchloroethylene (PERC).

PERC is a colorless, clear, heavy liquid used by 90 percent of dry cleaners in the United States. Because of its significant adverse health effects, the government has imposed regulations for the control of PERC exposures and emissions . In addition to PERC, other compounds are used in dry cleaning, particularly during removal of stains. These include other chlorinated solvents, petroleum naptha, acetic acid, hydrogen peroxide, ammonia, and mineral spirits.

PERC enters the human body through both inhalation and skin exposure. Symptoms associated with overexposure include central nervous system depression, damage to liver and kidneys, and irritation of the respiratory system and skin. Those exposed may experience confusion, impaired memory, dizziness, headache, drowsiness, and eye, nose, and throat irritation. Repeated skin exposure often results in dermatitis. PERC is a known animal carcinogen and a suspected human carcinogen. The other solvents used in dry cleaning may also cause central nervous system depression and irritation of the mucous membranes, nasal passages, and skin.

The dry cleaning process begins when soiled garments are brought to dry cleaning stores. Garments with visible stains are treated at spotting stations. Spotting chemicals, contained in squeeze bottles, are applied to the stain. The next step in the process involves washing, extracting, and drying. Clothes are manually loaded into washing machines. Detergent and solvents are poured over the garments. Water is also added to the system to aid in the removal of water-soluble soils. The contents of the machine are agitated, allowing the solution to remove the soils. Next, the clothes are spun at high speed to extract solvents. After extraction, the fabric is spun dry. Warm air vaporizes the residual solvent and unheated air is passed through to reduce wrinkles. Fresh air is added to freshen and deodorize clothing. Garments are removed and placed on the pressing machine, where they are heated to temperatures around 150°C (300°F).

There are many steps during the dry cleaning process in which PERC and other solvents have the potential to become airborne. Filtration and distillation are the main methods used to recover solvents. Distillation removes soluble oils and greases not recovered by filtration. These processes convert PERC into a solid form that then renders it disposable as hazardous waste. The government regulates dry cleaning stores to levels of less than one hundred parts per million (ppm), but encourages them to operate at levels below twenty-five ppm. The main danger outside a dry cleaning store is to residences in the same building. Inexpensive technology, such as exhaust fans, can safely remove these potentially dangerous substances. Despite such measures, residents who live in buildings housing dry cleaning establishments, as well as workers, may be exposed to concentrations of PERC that are of public health concern.

The potential continues to exist for environmental contamination of water and soil due to improper disposal of PERC. In Katonah, New York, well water was polluted because PERC was poured down the drain in dry cleaning establishments. Proper disposal and collection of this material as a hazardous substance should be performed in order to minimize the environmental impact.

SEE ALSO A IR P OLLUTION ; C LEAN A IR A CT ; W ATER P OLLUTION .

Bibliography

Garetano, G., and Gochfeld, M. (2000). "Factors Influencing Tetrachloroethylene Concentrations in Residences above Dry Cleaning Establishments." Archives of Environmental Health, 55(1):59–68.

U.S. Department of Health and Human Services, Public Health Service, CDC, NIOSH. (1997). "Control of Health and Safety Hazards in Commercial Dry Cleaners." In Chemical Exposures, Fire Hazards, and Ergonomic Risk Factors, No. 97-150.

Internet Resource

National Institute for Occupational Safety and Health. "Drycleaning." Available from http://www.cdc.gov/niosh/drycleaning/drycleaning.html .

Iris Udasin