Agency for Toxic Substances and Disease Registry
Case Studies in Environmental Medicine (CSEM) 

Trichloroethylene Toxicity
Who Is at Risk of Trichloroethylene Exposure?

Learning Objectives

Upon completion of this section, you should be able to:

• identify the populations most heavily exposed to TCE
• identify who is at risk of exposure to TCE

Introduction

Most significant exposures to TCE occur in the workplace. Occupational exposure to TCE in the U.S. has been identified in various degreasing operations, silk screening, taxidermy, and electronic cleaning.

Worker Exposure

The National Institute for Occupational Safety and Health (NIOSH) conducted a survey of various industries from 1981 to 1983 and estimated that approximately 401,000 U.S. employees in 23,225 plants are potentially exposed to TCE. Time-weighted average concentrations from personal monitoring ranged from 1.2 to 5.1 ppm at individual industrial sites where TCE was used (Agency for Toxic Substances and Disease Registry 1997; Wu and Schaum 2000)

Deaths have occurred in workers who were accidentally exposed to high levels (up to 8,000 ppm) of TCE, and in solvent abusers deliberately sniffing typewriter correction fluid (King, Smialek et al. 1985). Some of these deaths were due to asphyxia, whereas others were attributed to either ventricular fibrillation or asystole

Although no human studies have directly assessed potential dysrhythmogenic effects of TCE, no evidence exists to show that persons exposed to TCE at background environmental concentrations or at allowable workplace levels are at increased risk of developing cardiac dysrhythmias (Candura and Faustman 1991).

Increased potential for exposure may be encountered by the following workers:

• dry cleaners
• mechanics
• oil processors
• printers
• resin workers
• rubber cementers
• shoe makers
• textile and fabric cleaners
• tobacco denicotinizers
• varnish workers

TCE Inhalant Abuse

Inhalants - particularly volatile solvents, gases, and aerosols - are often among the first drugs that young children use. One national survey indicates that about 3.0 percent of U.S. children have tried inhalants by the time they reach fourth grade. About 17% of US youth has ever tried to get ‘high’ from inhaled solvents, including TCE. National surveys indicate that more than 22.9 million Americans have abused inhalants at least once in their lives (NIDA 2005). Inhalant abuse can become chronic and extend into adulthood. Sudden death due to TCE abuse has been reported (Miller, Mycyk et al. 2002).

Banned Uses

Until 1977, when certain uses were banned, TCE was employed as an inexpensive, nonflammable, and self-administered obstetrical anesthetic (Tri-lene). It was discovered that alkali in rebreathing systems could lead to the production of dichloroacetylene, which produces cranial nerve injuries. Workers in environments containing this TCE-decomposition product could also be at risk of developing injury to trigeminal, optic, or facial nerve (Lawrence and Partyka 1981).

Degreaser’s Flush

Alcohol potentiates TCE's effects on the central nervous system (CNS). Concurrent alcohol consumption and exposure to TCE can result in "degreaser's flush," (Stewart, Hake et al. 1974) a temporary redness and itching of the back, neck, and face. Liver dysfunction or disulfiram (Antabuse) treatment could reduce the metabolism of TCE thereby increasing its CNS depressant effects.

Use of Groundwater

TCE is one of the volatile organic contaminants most frequently found in groundwater. There have been a number of studies reported that examined the health of persons who ingested TCE-contaminated groundwater over varying period of time. The results of these studies have been inconsistent. A link between ingestion of TCE and incidence of cancer in humans is controversial, but has not been excluded.

Maternal Transmission

TCE rapidly crosses the placenta in both humans and animals, and can accumulate in the fetus (Agency for Toxic Substances and Disease Registry 1997). To gather information on the health effects of ingesting TCE-contaminated water, the ATSDR, in cooperation with the states, has established a national registry. This registry is discussed in Sources of Information section.

Key Points

• Workers in metal-fabricating and cleaning operations have the greatest likelihood of exposure to high concentrations of TCE.
• Persons using groundwater contaminated with trichloroethylene can be exposed by inhalation as well as ingestion.
• Trichloroethylene crosses the placenta and can accumulate in the fetus.
• Ingestion of alcohol may potentiate the central nervous system depressant effects of TCE.

Progress Check