The following information on perchloroethylene (Perc, PCE, tetrachlorethylene) has been summarized from various public sources and appears here for informational purposes only. The City of Ann Arbor does not warrant or guarantee the accuracy of the information summarized.
Background on Perc in Ann Arbor
Ann Arbor Study
What is Perc?
Perc, otherwise known as Perchloroethylene or PCE, is a clear, colorless liquid that has a sharp, sweet odor and evaporates quickly. It is a chemical solvent primarily used in dry-cleaning and metal degreasing, but it is also found in typewriter correction fluid, shoe polish and some household cleaning products.
It is an effective cleaning solvent and is used by most professional dry-cleaners because it removes stains and dirt from common types of fabric without causing fabric shrinkage or color bleeding. Approximately 85% of cleaners use Perc as their primary solvent. Since Perc can be reused, it is a cost-effective and efficient solvent for cleaning clothes. However, Perc is also a toxic chemical with both human health and environmental concerns.
What Happens to Perc in the Environment?
Most direct releases of Perc to the environment are to air. Perchloroethylene evaporates when exposed to air. It also evaporates from water and soil exposed to air. Perc can break down in soil, groundwater, and air over several weeks to months.
When mixed with water it dissolves only slightly. It does not bind well to soil and can therefore move through the ground and enter groundwater. Plants and animals living in environments contaminated with Perc can store small amounts of the chemical in their tissues.
How Does Exposure Occur?
Very low environmental levels of Perc (called background levels) are commonly found in the air we breathe, in the water we drink, and in the food we eat. The chemical is found most frequently in air and less often in water. Fortunately, the amounts found as “background” in air are usually small enough that they are not hazardous to the average person's health. If you work in or live next to a dry-cleaning facility, you might be exposed to higher levels and may have cause for concern.
Exposure to Perchloroethylene can occur in the workplace or in the environment following releases to air, water, land, or groundwater. Exposure can also occur when people:
- use products containing Perc
- spend time in dry cleaning facilities that use Perc,
- live above or adjacent to these dry cleaning facilities, or
- bring dry cleaned garments into their home.
Perc enters the body when breathed in with contaminated air or when consumed with contaminated food or water. It is less likely to be absorbed through skin contact. Once in the body Perc can remain there, stored in fat tissue.
How Does Perc Affect Human Health?
The effects of Perc on human health depend on the amount of Perc, as well as, the duration and frequency of exposure. People exposed to high levels of Perc, even for brief periods, may experience dizziness, fatigue, headaches, confusion and nausea. Breathing the vapors may cause eyes, nose and throat irritation. Contact with the chemical in its liquid form may cause skin irritation. It should be noted, however, only people working directly with Perc in poorly ventilated areas are likely to be at risk for this type of exposure. Workers exposed repeatedly to large amounts of Perc in air can also experience memory loss and confusion.
Laboratory studies show that Perc causes kidney and liver damage and cancer in animals exposed repeatedly through inhalation and ingestion. Breathing Perchloroethylene over longer periods of time can cause liver and kidney damage in humans. Repeat exposure to large amounts of Perc in air has been associated with increased cancer risk in humans. Perc levels of 42 ug/m3 (micrograms per cubic meter of air) and lower in indoor air are considered below action levels for long-term exposure in residential buildings. This value is the residential indoor air breathing concentration (IABC) developed by the Michigan Department of Environmental Quality. The IABC of 42 ug/m3 represents the amount of PCE in indoor air estimated to cause 1 additional cancer in 100,000 people who breathe this concentration 24 hours/day, 350 days/year for 30 years. This value was derived from long-term (2-year) inhalation studies in rats and mice.
In reading about Perc you may find that some studies use a measure of parts per billion vapor (ppbv) in measuring air concentrations. 1 ppbv of Perc is equivalent to 6.89 ug/m3. Therefore 42 ug/m3 is equal to approximately 6.1 ppbv.
Background on Perc in Ann Arbor
Ann Arbor Study