Tetrachloroethene
Tetrachloroethene is a liquid used in dry cleaning, to remove grease from metals, to make other chemicals, and in some consumer products. It has many synonyms, including tetrachloroethylene, PCE, and perc.
Environmental Fate and Transport
Tetrachloroethene evaporates quickly. Much of the tetrachloroethene released to the environment ends up in the atmosphere, where it degrades slowly. The half-life of tetrachloroethene in the atmosphere is typically about a hundred days.
Tetrachloroethene released to the ground can move down through the soil and end up in groundwater. Tetrachloroethene vapors can also move through the soil and end up in buildings.
Tetrachloroethene can persist in soil and groundwater for many years. However, microorganisms in the soil can break down tetrachloroethene, especially under anaerobic conditions, via a process called reductive dechlorination. A typical breakdown sequences sees tetrachloroethene break down to trichloroethene, then one of the dichloroethenes, then vinyl chloride, and finally ethene.
Exposure Pathways
Tetrachloroethene released into the air by the dry cleaning and other industries can travel long distances before breaking down. Tetrachloroethene that is released to the ground may end up in groundwater that people drink. Tetrachloroethene released to the ground may also evaporate and move through the soil in vapor form, potentially entering buildings.
Metabolism
Tetrachloroethene most commonly enters our bodies via breathing air or drinking water that contains tetrachloroethene. Tetrachloroethene can also enter our bodies if it contacts our skin, usually via soil or a product containing tetrachloroethene. Tetrachloroethene has a half-life in the body of approximately three days.
Health Effects
Known health effects from tetrachloroethene exposure range widely from dizziness and headaches to more serious effects on the kidneys, liver, nervous system, and reproductive system. High exposures, usually in work settings, may cause death. Tetrachloroethene may be harmful to fetuses and increase the risk of certain cancers, including bladder cancer, non-Hodgkin's lymphoma, or multiple myeloma.
The preceding paragraphs are summarized from the Public Health Statement for Tetrachloroethylene published by the Agency for Toxic Substances and Disease Registry.
Additional Cancer Assessments
U.S. EPA's Integrated Risk Information System states that tetrachloroethylene is likely to be carcinogenic to humans.
The National Institutes of Health has determined that tetrachloroethylene is reasonably anticipated to be a human carcinogen.
The International Agency for Research on Cancer has determined that "There is limited evidence in humans for the carcinogenicity of tetrachloroethylene. Positive associations have been observed for cancer of the bladder." and "There is sufficient evidence in experimental animals for the carcinogenicity of tetrachloroethylene." (IARC, page 329).
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