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, stored in fat tissue( United States EPA, 1997).

According to the United States Environmental Protection Agency;

   "Effects of perchloroethylene on human health and the environment depend on the amount of PERC present and the length and frequency of exposure.  Effects also depend on the health of a person or the condition of the environment when exposure occurs.

     Breathing PERC for short periods of time can adversely affect the human nervous system.  Effects range from dizziness, fatigue, headaches and sweating to incoordination and unconsciousness.  Contact with PERC liquid or vapor irritates the skin, the eyes, the nose, and the throat.  These effects are not likely to occur at levels of PERC that are normally found in the environment.

     Breathing perchloroethylene over longer periods of time can cause liver and kidney damage in humans.  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 by inhalation and by mouth.  Repeat exposure to large amounts of PERC in air may likewise cause cancer in humans.

     Perchloroethylene by itself is not likely to cause environmental harm at levels normally found in the environment.  PERC can contribute to the formation of photochemical smog when it reacts with other volatile organic carbon substances in air.  These reactions tend to eliminate PERC before it
reaches the upper atmosphere in amounts sufficient to damage the ozone layer" (US EPA, 1997).

 Vapors are irritating to skin, eyes, and upper respiratory tract. Inhalation exposure
produces giddiness, headache, inebriation, nausea, vomiting, and sinus inflammation. Skin exposure
will cause redness and chapping. If ingested, perchloroethylene can result in central nervous system
depression and liver damage. Chronic exposure may also result in liver damage.

Perchloroethylene is a chlorinated hydrocarbon solvent that slowly breaks down in the environment.
It is fat soluble which allows it to collect in the tissues of living organisms and accumulate in the
environment. Perchloroethylene is a known animal carcinogen that has caused liver cancer in mice.

According to Priorities Environmental Health Magazine;

The Environmental Protection Agency (EPA) classifies perc as an animal carcinogen and places it on the continuum between possible and probable human carcinogens. The initial claims that perc might be a human carcinogen were based upon animal tests. A 1977 bioassay conducted by the National Cancer Institute indicated that perchloroethylene could induce liver cancer in mice, but not in rats. A
1985 study on rats and mice of both sexes conducted by the National Toxicology Program also concluded that there was "clear evidence" of the rodent carcinogenicity of perchloroethylene. Yet, while positive results in animal tests can provide some indication of whether a compound is potentially carcinogenic to humans, such tests are never conclusive.

 If low-to-moderate exposure to perc presents a cancer threat to humans, one would expect to see epidemiological evidence, such as increased rates of cancers among dry-cleaning workers, who are
exposed to significant levels of perc in their working environment. According to the assumptions of the EPA, one would expect approximately 350 additional cancers annually among dry-cleaning
workers from perc exposure.

But occupational exposure studies have not found a smoking gun to correlate any cancer risk with occupational perc exposure. Some studies, such as that conducted by the National Institute of
Occupational Safety and Health (NIOSH), have found a slight increase in cancer mortality rates for dry-cleaning workers. Other studies suggest, however, that this increase could result from the fact
that "dry cleaners may smoke more than members of other occupations" and suggest that alcohol use and expected socioeconomic status may also be factors. In those studies in which it was possible to subdivide workers by exposure to different solvents, the slight increase in cancer mortality was not observable in those subgroups exposed only to perc. If dry-cleaning workers are at risk from perc, scientific studies have yet to bear that out. In the words of  the EPA Science Advisory Board, perc "is an example of a chemical for which there is no compelling evidence of human cancer risk."

This is not to say that perc is harmless. As with most chemical substances, the ill effects of perc are dependent upon the level of exposure. Exposure to high levels of perc — 200 parts per million
(ppm) or more — for prolonged periods of time can induce headaches, dizziness, nausea and eye and skin irritation. Even higher exposures intensify these reactions and can, in extreme cases, result in unconsciousness or even death. High levels of perc exposure also have been correlated with damage to the liver and the central nervous system. Perc is also moderately toxic if ingested. Yet, exposure to such high levels of perc is extremely rare, if not nonexistent. The level inside most dry cleaners is no more than 30 ppm, far below the level at which acute effects can be observed (Priorities,Vol.8 no.1, 1997).

Portions of this article were adapted from Jonathan Adler's Taken to the Cleaners: A Case Study of the Overregulation of American Small Business, published by the Cato Institute (1993).