What is Trichloroethylene (TCE)?

By July 19, 2019 No Comments

Perhaps the most common question posed to environmental professionals is:

“Is All This Really Necessary?”

And members of the environmental consulting industry have received questions and comments like these:

“How Harmful Could These Chemicals Be, Really?”

“It’s Not Like People Will Be Drinking This Stuff from the Container”

Or even:

“Everybody Knows These Chemicals Aren’t Really Dangerous, You’re Just Trying to Make Work for Yourself.”

So let us examine the history one of the most common contaminants found in groundwater in the United States, including California: Trichloroethylene, also known as TCE.  TCE is a colorless, volatile liquid. Liquid trichloroethylene evaporates quickly into the air.  It is nonflammable and has a sweet odor.  Its chemical formula is C2HCl3.  We will use TCE as a model case that demonstrates the necessity of environmental site assessments.

TCE was first prepared in 1864, and the commercial production of TCE began in Germany in 1920 and the USA in 1925.  From the 1930s through the 1970s, both in Europe and in North America, TCE was used as a volatile anesthetic administered with nitrous oxide.  But TCE was found to promote cardiac arrhythmia, have low volatility and high solubility preventing quick anesthetic induction, cause reactions with soda lime used in carbon dioxide absorbing systems, and cause prolonged neurologic dysfunction when used with soda lime.  In addition, TCE presented evidence of hepatotoxicity (liver damage), as had been found with chloroform (for which it had been promoted as a replacement).

However, TCE continued to be used as an industrial and commercial degreaser.  Spent TCE was then dumped into nearby disposal pits at industrial plants and military bases, where it seeped into aquifers.

Today, the two major uses of TCE are as a solvent to remove grease from metal parts, and as a chemical that is used to make other chemicals, especially the refrigerant, HFC-134a. TCE has also been used as an extraction solvent for greases, oils, fats, waxes, and tars; by the textile processing industry to scour cotton, wool, and other fabrics; and as a component of adhesives, lubricants, paints, varnishes, paint strippers, pesticides, and cold metal cleaners.  Eighty per cent of the USA’s 65,000 dry cleaners had used TCE as a dry cleaning solvent, although it was replaced in the 1950s by tetrachloroethylene (also known as perchloroethylene or PCE).  TCE continued to be used for spot cleaning where it was used until the year 2000. Although it was abandoned as an anesthetic in the USA and Europe by the 1970’s, its industrial use has continued into the present day.

TCE has been linked to cancer and other diseases for a long time. A letter from Dr. Carey McCord (medical advisor for Chrysler Corporation) published in the July 30, 1932 issue of the Journal of the American Medical Association stated that, “any manufacturer contemplating the use of TCE may find in it many desirable qualities. Too, in the absence of closed systems of operations [no ventilation], he may find in this solvent the source of disaster for exposed workmen”.

Since 1932, what has been learned about the health effects of exposure to TCE?  Until recently, the US Agency for Toxic Substances and Disease Registry (ATSDR) contended that TCE had little carcinogenic potential, and was probably a co-carcinogen—that is, it acted in concert with other substances to promote the formation of tumors.  However, state, federal, and international agencies now classify TCE as a known or probable carcinogen. In 2014, the International Agency for Research on Cancer updated its classification of TCE, indicating that sufficient evidence existed that TCE caused cancer of the kidney in humans as well as some evidence of cancer of the liver and non-Hodgkins lymphoma.  The US military has virtually eliminated its use of TCE.  The USEPA has proposed banning commercial use of TCE in vapor degreasing, and in commercial and consumer aerosol degreasing, and as a spot cleaner in dry cleaning.  However, that effort has been stalled since January 2017.  Meanwhile, TCE has been virtually banned in the European Union since 2016.

California, always the most pro-active state in regards to environmental legislation, considers TCE to be a known carcinogen and issued a risk assessment in 1999 that concluded that it was far more toxic than previous scientific studies had shown.  The use of consumer general purpose degreaser products that contain TCE are already banned in California and safer substitutes are in use.  Water-based cleaners are used extensively in California instead of TCE-based vapor degreasing, due to regulations that limit the use of solvents that are VOCs.  Under its Consumer Products Regulation, the California Air Resources Board banned dry cleaning uses of TCE-containing spot removers in California effective December 31, 2012. Safer substitutes to TCE-based spot removers are available, and include water-based cleaners, soy-based cleaners and acetone-based cleaners. The cost analysis indicates that the alternatives are less costly than the TCE spotting agents.

The ATSDR, as well as that of the Canadian Centre for Occupational Health and Safety (CCOHS) websites now state that there is strong evidence that TCE can cause kidney cancer in people and some evidence that it causes liver cancer and malignant lymphoma (a blood cancer). Lifetime exposure to TCE resulted in increased liver cancer in mice and increased kidney cancer in rats at relatively high exposure levels. There is some evidence for TCE-induced testicular cancer and leukemia in rats and lymphomas and lung tumors in mice.  The National Toxicology Program (NTP) has determined that trichloroethylene is a “known human carcinogen”. The EPA and the International Agency for Research on Cancer (IARC) have determined that trichloroethylene is “carcinogenic to humans.”  In addition, the ATDSR (but not the CCOHS) states that some human studies indicate that TCE may cause developmental effects such as spontaneous abortion, congenital heart defects, central nervous system defects, and small birth weight. However, these people were exposed to other chemicals as well. In some animal studies, exposure to TCE during development may have caused effects such as decreased body weight, increased incidences of heart defects, functional or structural changes in the developing nervous system, and effects on the immune system.

Exposure to TCE occurs mainly through contaminated drinking water. With a specific gravity greater than 1, TCE can be present as a dense non-aqueous phase liquid (DNAPL) if sufficient quantities are spilled in the environment. When TCE is found in water, it can enter your body when you drink or touch the water, or when you breathe in steam from the water. TCE in air can easily enter your body when you breathe.  Another significant source of vapor exposure in Superfund sites that had contaminated groundwater was by showering. TCE readily volatilizes out of hot water and into the air. So therefore, long, hot showers would then volatilize more TCE into the air. In a home closed tightly to conserve the cost of heating and cooling, these vapors would then recirculate.  Furthermore, a growing concern in recent years at sites with TCE contamination in soil or groundwater has been vapor intrusion in buildings.                                           

The Department of Defense (DoD) has about 1,400 military properties nationwide that are contaminated with TCE.  Twenty three sites in the Energy Department’s nuclear weapons complex — including Lawrence Livermore National Laboratory in the San Francisco Bay area — and NASA centers, including the Jet Propulsion Laboratory in La Cañada Flintridge, are reported to have TCE contamination.  TCE was one of the many contaminants that contributed to the now notorious toxic stew that caused Camp Lejeune to be perhaps the most polluted of the DoD facilities in the country.  Camp Lejeune is one of 141 DoD EPA Superfund sites, fully one-tenth of all Superfund sites in the country.

In 1988, the EPA discovered tons of TCE that had been leaked or dumped into the ground by the United States military and semiconductor industry (companies including Fairchild Semiconductor, Intel Corporation, and Raytheon Company) just outside NASA Ames in Moffett Field, Mountain View, California.  In 1998, the View-Master factory supply well in Beaverton, Oregon was found to have been contaminated with high levels of TCE. It was estimated that 25,000 factory workers had been exposed to it from 1950–2001.  The 1998 film A Civil Action dramatizes the EPA lawsuit Anne Anderson, et al., v. Cryovac, Inc. concerning TCE contamination that occurred in Woburn, Massachusetts in the 1980s.

But how common is TCE outside of industrial and defense facility boundaries?  How much of the TCE that was used for half a century by your local dry cleaner has made its way into the general environment?  Do average people have to worry about exposure to TCE, to the point where their health is affected?

Between nine to 34 per cent of the drinking water supply sources tested in the U.S. may have some TCE contamination, although the US Environmental Protection Agency (EPA) has reported that most water supplies are in compliance with the maximum contaminant level (MCL) of 5 parts per billion (ppb).

Recently, the city of Franklin, outside of Indianapolis, Indiana, has been in the news.  Children contracting cancer at an alarming rate – and not just the kidney and liver cancers and lymphoma that the EPA had finally was able to associate with TCE exposure.  Multiple children with Ewing’s sarcoma, a rare bone cancer.   Fifteen children with acute lymphocytic leukemia.  Pilocytic astrocytoma, which causes tumors in the brain and spinal cord.

The people of Franklin thought that the cancer cluster could be associated with an industrial site in town that had supposedly been cleaned up years ago.  The TCE contamination has been traced to a former factory that, for years, discharged industrial wastewater into a municipal sewer. Amphenol, an electronics maker based in Wallingford, Connecticut, became responsible for the cleanup after acquiring the site, although it no longer owns the property.

TCE is the most widespread water contaminant in the nation. TCE has been discovered in nearly every state but in none more widely than California.  Huge swaths of California (as well as New York, Texas, and Florida) lie over TCE plumes. The solvent has spread under much of the San Gabriel and San Fernando valleys, as well as the shuttered El Toro Marine Corps base in Orange County.

The Los Angeles metropolitan area overlies a checkerboard of underground plumes of TCE, and has high ambient levels of the chemical in the air. More than 30 square miles of the San Gabriel Valley lie in one of four Superfund sites that contain TCE. The San Fernando Valley overlies a large plume grouped into three separate Superfund sites.  Military bases including Camp Pendleton and Edwards Air Force Base have Superfund sites with TCE contamination.  The former Marine Corps Air Station El Toro in Orange County sat over a plume several miles long.  TCE contaminated the groundwater under the base, which complicated plans to reuse the property for private housing and a public park. Redevelopment of the base into residential and recreational uses commenced by 2013, and the 18 of the 25 designated clean-up sites have been granted environmental closure.  Seven individual sites within the footprint of the former Marine Corps Air Station are still open environmental cases.

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