How Should Patients Exposed to Trichloroethylene Be Evaluated?
CE Original Date: November 8, 2007
CE Renewal Date: November 8, 2010
CE Expiration Date: November 8, 2012
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Upon completion of this section, you should be able to:
When considering the human health effects of TCE, it is important to make a distinction between occupational exposures to relatively high levels by inhalation and general environmental exposures to low levels in drinking water and ambient air.
An occupational history should be routinely obtained. It should include items such as:
An environmental history should also be obtained, including:
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. In the situation involving occupational or consumer product exposure, if the product label does not list the chemical ingredients, the regional poison control center may maintain a list of ingredients in consumer and proprietary products. In the U.S.: call 1-800-222-1222, or check http://www.aapcc.org/ for an updated list of U.S. Poison Control Centers. The World Health Organization and the International Program on Chemical Safety maintain an international list of poison control centers: http://www.who.int/ipcs/poisons/centre/directory/en/index.html
In occupational exposures in the U.S., the employer or manufacturer is required by law to provide a material safety data sheet (MSDS), which lists the chemical ingredients and describes their potential toxicity.
The patient's complaints should be identified in terms of onset, duration, and intensity. Complaints should be investigated by focusing first on major organ systems that are likely to be affected by exposure to TCE (CNS, hepatic, integumentary, cardiovascular, renal), and then on systems unlikely to be affected (respiratory, gastrointestinal, endocrine, skeletal).
Vital signs should be recorded, especially abnormalities of heart rate or rhythm. Eyes, nose, throat, and skin should be examined carefully for inflammation or irritation. The conjunctiva may be injected, and nasal mucosa may be injected and swollen. Repeated inhalation exposures to trichloroethylene can cause defatting of nasal mucosa, leading to a friable condition with drying, cracking, or bleeding. Skin contact may cause dermatitis by irritation and defatting.
The patient's abdomen should be palpated for hepatomegaly and right upper quadrant tenderness.
Patients should receive a complete neurological examination, including a mental status exam and evaluation of the cranial nerves, to detect either peripheral or central nervous system involvement. Cranial neuropathies in patients with a history of TCE exposure are uncommon.
No unique pattern of symptoms characterizes TCE-induced illness.
With inhalation of high concentrations, TCE causes initial CNS excitation followed by CNS depression. Depending on the duration and intensity of exposure, symptoms (Meditext 2004) can include:
Coma and respiratory depression may occur with prolonged, high-level exposure (i.e., above 2,000 ppm). Serious ventricular arrhythmias can develop up to 24 hours after large TCE ingestions (Agency for Toxic Substances and Disease Registry 1997).
Effects from ingestion include:
The main systemic response is CNS depression (Meditext 2004).
TCE is a skin irritant and may cause defatting dermatitis of the skin. Scleroderma has been linked with TCE exposure. Dermal absorption is not likely to be significant if dermatitis is prevented. Vasodilation and malaise ('degreasers flush') recur in workers who drink ethanol after exposure to TCE (Meditext 2004).
After any type of acute exposure, the clinician should keep in mind that:
The symptoms seen in humans in cases of long-term exposure were similar to those seen in acute exposure, but occurred in more extreme and persistent forms (Kleinfeld and Tabershaw 1954; Fan 1988).
Reported neurological effects associated with chronic workplace exposure to TCE have included nonspecific symptoms such as:
WHO (1985) noted that chronic effects such as disturbance of the nervous system can occur following prolonged exposure to TCE concentrations of about 100 ppm (WHO 1985).
Although some CNS symptoms may disappear within several weeks after cessation of exposure, other CNS adverse health effects such as memory loss and mood swings may persist in persons who have been exposed to TCE for long periods (Agency for Toxic Substances and Disease Registry 1997).
Persistent neurological symptoms suggest the possibility of psychiatric disorders and also prompt a search for exposure to neurotoxicants, such as alcohol and other drugs of abuse.
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