How does perc end up in the environment and what happens when it does? For the most part, it gets into the air, water, and ground during the cleaning and disposal phases of dry cleaning operations. The following is adapted from EPA's Design for the Environment website (EPA DFE, 2005):
Most of the perc used by the dry cleaning industry escapes incidentally into outdoor air through windows, vents, and air conditioners. In older systems perc may still be vented directly outdoors.
EPA has detected perc in ambient air at average levels of 0.16 parts per billion (ppb) in rural and remote areas, 0.79 ppb in urban and suburban areas, and 1.3 ppb in areas near emission sources (EPA TTN, 2000).
Once outdoors, perc can remain in the atmosphere for several weeks, and although small amounts are always in the air, the chemical itself does not deplete the ozone layer. After a few weeks, however, perc breaks down into other chemicals, some of which are toxic and some of which are suspected to deplete the ozone layer (EPA DFE, 2005).
We may also have perc in our indoor air by living or working near a dry cleaner. EPA states that "People who live or work in the same building as a co-located drycleaner can have greater than average exposures to perc. This is because perc vapors can pass through floor, ceiling, and wall materials of the drycleaning shop and into adjacent building space. Perc can also travel outside and re-enter nearby building spaces through holes, vents, and other means. A drycleaner could contaminate the air in neighboring apartments or offices if the cleaner has old equipment, does not properly maintain equipment, or does not follow proper safety procedures" (EPA DFE, 2005).
Perc is known to be toxic to plants. It can enter the ground in liquid form through spills; leaky pipes, tanks, or machines; and from improperly handled waste. Significant amounts of perc have been found in the waste resulting from drycleaning, which EPA considers a hazardous waste.
Most of the solid waste materials resulting from dry cleaning are filters used during the process, as well as residual solvent and soils, and are collected by hazardous waste management companies for recycling and/or incineration (EPA DFE, 2005).
However, if incinerated, greater problems may be caused, as the "incineration of perc waste leads to the formation of dioxin, a potent carcinogen in humans" (Greenpeace, 2003). Dioxin is a pernicious contaminant, formed by combustion, which is found worldwide in everything from smog to the breast milk of Inuit women in the Arctic Circle.
At the end of the dry cleaning process, the cleaning fluid is separated from wastewater. In the past, the wastewater was often poured directly down floor drains. In newer equipment, the wastewater is collected and evaporated, or removed by hazardous waste handlers; however, there are still many cleaners who do not follow EPA-approved methods (EPA DFE, 2005).
Perc does not bind well with soil and tends toward other liquids; therefore, it typically seeps through the ground and contaminates surface water, groundwater, and, potentially, drinking water. A small amount of perc can contaminate a large amount of water, and people can be exposed by drinking or using the water (EPA DFE, 2005).
With regard to potable water a survey of groundwater sources reported a median concentration of 0.75 parts per billion (ppb) for the samples in which perc was detected, with a maximum level of 69 ppb (EPA TTN, 2000). And according to Greenpeace, "70% of all of perc used ends up in the environment where it extensively contaminates both ground- and drinking water. At least 1.2 million Americans are exposed to perc in drinking water at levels that exceed safety limits (Greenpeace, 2003).
There are limits placed on the amount of perc that is allowed to be in drinking water. According to the Safe Drinking Water Act, the drinking water standard for perc is 0.005 milligrams per liter (mg/L) (EPA OPPT, 1994). However, even small amounts of perc in the water have been shown to be toxic to aquatic animals that can store the chemical in their fatty tissues (EPA DFE, 2005). And since chemicals that store in fatty tissues tend to bioaccumulate, humans and animals that then eat the contaminated fish or other aquatic animals will, in turn, become contaminated themselves.
If this almost 200-year-old chemical is everywhere, and we don't know the extent of the damage it has done and is doing, what's next? Do we keep wearing it, breathing it, drinking it? Alternative chemicals and other cleaning methods that may help solve the problem are on the way. Or will the solution cause more problems? Find out in Part II of Looking Good, Feeling Bad in coming in April 2006.
If you need to cite this page, you can copy this text:
Jennifer Manning. Looking Good, Feeling Bad; or, What's the Problem with Perc (Percholorethylene)?. EnvironmentalChemistry.com. March 7, 2006. Accessed on-line: 1/22/2019