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

Trichloroethylene Toxicity
Answers to Progress Check Questions

1. The best choice is D. TCE (Cl₂C=CHCl) is a clear, colorless, nonflammable liquid possessing a sweet, fruity odor characteristic of chloroform. 80% of TCE is used for vapor degreasing of fabricated metal parts in the automotive and metal industries. Before its ban for certain applications in 1977, TCE was also used as a general anesthetic (mostly in obstetric settings), grain fumigant, disinfectant, pet food additive, and extractant of spices in foods and caffeine in coffee.
2. The best choice is D. Because of its widespread use, TCE has become a common environmental contaminant. Contamination results from evaporative losses during use; discharge to surface waters and groundwater by industry, commerce, and individual consumers; leaching from hazardous waste landfills into groundwater; and from the incidental addition of TCE during food production.
3. The best choice is B. The air pathway is the most common route of exposure to trichloroethylene, and the route that most commonly leads to illness.
4. The best choice is D. Increased potential for exposure may be encountered by workers performing degreasing and metal cleaning shoemakers, rubber cementers, dry cleaners, etc.
5. The best choice is D. It’s unnecessary for those workers from answers A-C to entail high risk of exposure to trichloroethylene. Mechanics who degrease fabricated metal parts in the automotive industries, however, certainly bear a higher risk of exposure to TCE.
6. The best choice is B. The current OSHA 8-hour TWA for TCE is 100 ppm.
7. The best choice is B. EPA has established a drinking water maximum contaminant level (MCL) for trichloroethylene of 5 ppb.
8. The best choice is D. A relatively small amount of absorbed TCE is exhaled unchanged; most of an absorbed dose is metabolized in the liver and excreted in the urine as trichloroacetic acid and trichloroethanol.
9. The best choice is A. The cytochrome P450 pathway generates tri- and dichloroacetate as metabolites of trichloroethylene, and these are associated with hepatic toxicity and carcinogenicity.
10. The best choice is B. Brain cancer risk has not been reported to be significantly elevated in association with TCE exposure.
11. The best choice is B. Trigeminal abnormalities (abnormal blink reflex and masseter).
12. The best choice is B. Inhalation or oral exposure to high doses of TCE for a prolonged period is likely to induce liver and lung tumors in both animals and humans.
13. The best choice is C. A temporal relationship between onset of symptoms and work or other activity may provide important clues on the cause. If a temporal association between symptoms and exposure to certain products is suspected, an attempt should be made to identify the specific chemical ingredients involved.
14. The best choice is B. Short-term memory impairments gradually clear after exposure to TCE ceases. Patients may be mistakenly diagnosed with various forms of dementia, such as Alzheimer disease or other CNS disorders, when they in fact suffer from a preventable and possibly reversible toxic disorder.
15. The best choice is D. Diarrhea is one of the effects from ingestion of TCE.
16. The best choice is B. If the cause of symptoms is questionable, direct biologic testing, such as measuring TCE level in breath, blood, or urine, may be warranted to confirm TCE exposure.
17. The best choice is D. Supportive care directed to adequate ventilation and circulation should be provided. Patients should be removed from the contaminated environment as soon as possible; begin artificial ventilation, if needed.
18. The best choice is D. There is no antidote for TCE poisoning. Treatment should focus on support of respiratory and cardiovascular functions.
19. The best choice is D. If exposures are occupational, patients should speak to their employer about PPE. Patients should be advised to avoid exposures and conditions that might further increase their risk of disease or worsen their existing condition. In addition, patients should contact their physician if they develop neurological problems or other health changes.

Previous Section