Environmental Medicine Integrating a Missing Element into Medical Education (1995) / Chapter Skim
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Case Study 41: Tetrachloroethylene Toxicity
Case Study 41: Tetrachloroethylene Toxicity
Pages 707-726
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From page 707... ...
EN Like most chlorinated solvents, tetrachloroethylene can cause CNS depression. EN Chronic exposure to tetrachloroethylene may adversely affect the necrologic system and firer.
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From page 708... ...
The infant, whom you saw 5 weeks ago for otitis media, is still breastfeeding. A month ago the patient returned to her job as a word processor, worl |
From page 709... ...
It is used as a solvent and cleaner in consumer formulations including auto brake cleaners, suede protectors, paint removers, water repellents, silicone lubricants, belt lubricants, adhesives, spot removers, wood cleaners, and many products used by hobbyists. Chemical synonyms for Tetrachloroethylene include tetrachloroethene, perchloroethylene, 1 ,1,Z,2-tetrachloroethylene, and ethylene tetrachloride.
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From page 710... ...
Much higher tetrachloroethylene levels are associated with cleaning spills or replacing dry-cleaning filers. (The current permissible workplace exposure level as promulgated by the Occupational Safety and Health Administration [OSHA]
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From page 711... ...
In one case report, a nursing mother, who had been repeatedly exposed to tetrachloroethylene fumes during lunchhourvisits with her husband at a dry-cleaning plant, had tetrachloroethylene levels of 300 ~g/dL in blood and 1000,ug/dL in breast milk. The nursing infant developed obstructive jaundice, possibly as a result of tetrachloroethylene exposure.
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From page 712... ...
Studies of dry-cleaning shop workers have shown that urinary metabolite levels increase linearly with airconcentrations up to 100 ppm tetrachloroethylene, then level off at higher concentratons. This indicates the saturability of the tetrachloroethylene metabolic pathways.
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From page 713... ...
At higher air levels, unconsciousness can occur. Acute tetrachloroethylene ingestion rarely occurs, but as much as 500 mg/kg did not cause death in one case, and, in another case, CNS depression was nosed with ingestion of 4.2 to 16 9.
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From page 714... ...
In animal studies, intermittent exposures to air levels as low as 9 ppm Tetrachloroethylene have produced irreversible hepatic injury. Nonproliferative kidney lesions are characteristic of other chlonnated compounds with similar chemical structure; thus, teirachloroethylene should be regarded as a possible nephrotoxic agent in humans.
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From page 715... ...
In studies using mice or rats, high-dose oral administration of tetrachloroethylene was associated with an increased incidence of hepatocellular carcinoma, and inhalation exposure was associated with leukemia, renal tubular cell adenomas, and adenocarcinomas. Data from animal studies, togetherw~h supposing data on tetrachloroethylene mutagenicity, constituted a sufficient level of evidence for EPA to classify tetrachloroethylene as an animal carcinogen and a probable human carcinogen.
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From page 716... ...
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 occupational exposures, the employer or manufacturer is required by law to provide a material safety data sheet (MSDS)
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From page 717... ...
Pulmonary edema has occurred in one laundry worker found unconscious after exposure to tetrachloroethylene vapor. Symptoms associated with acute high-level tetrachloroethylene exposure may include the following: Nervous system Euphoria Headache Dizziness Light-headedness Sleepiness Forgetfulness Gastrolntestinal Nausea ENT Eye and nose irritation Upper airway irritation and cough Chronic Exposure Irritability Slurred speech Confusion Loss of coordination Loss of consciousness Mild CNS symptoms are often reported in conjunction with exposure to tetrachloroethylene containing household products in confined spaces, and with exposure in industrial settings.
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From page 718... ...
Expired air and blood tetrachloroethylene levels and urine trichloroacetic acid levels have been linearly correlated with ambient air concentrations up to 100 ppm. In workers, a trichloroacetic acid level of 7 rr~L in urine obtained at the end of the workweek was O Tetrachloroethylene Itself may be measured In breath and blood; Its metabolltes can be measured In blood and urine.
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From page 719... ...
In general, results of routine laboratory tests, including renal and liver function tests, will also be normal unless the patient has had a significant exposure and has concurrent necrologic symptoms. Transient elevation of transaminase levels has been reported in tetrachloroethylene exposures, but frank hepatic necrosis has not been documented.
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From page 720... ...
How do you interpret these results? Treatment and Management Acute Exposure No specific treatments are available for acute tetrachloroethylene exposures.
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From page 721... ...
CNS symptoms due to acute tetrachloroethylene inhalation exposure are transient but may lingerfor hours after exposure ceases. Patients usually recover rapidly without permanent necrologic sequelae if hypoxia and shock have been prevented.
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From page 722... ...
Agency Focus Level Comments ACGIH Air-Workplace 50ppm Advisory; TLV-lWAt;STEL§of 200 ppm NIOSH Air -Workplace N/A Advisory; lowest feasible level OSHA Air-Workplace 25ppm Regulation;PEL over8-hour workday EPA Air-Environment None Regulation under development; due early 1991 Water-Environment None Regulation; proposed 5 ppb to take effect winter 1990 ACGIH = American Conference of Governmental Industrial Hygienists; EPA = Environmental Protection Agency; NIOSH = National Institute for Occupational Safety and Health; 0SHA = Occupational Safety and Health Administration tTLV-TWA (Threshold Limit Value-Time-Weighted Average) = time-weighted average concentrabon for a normal 8-hour workday and 40-hour workweek to which nearly all workers may be repeatedly exposed.
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From page 723... ...
In 1978, NIOSH recommended that tetrachloroethylene be handled in the workplace as a potential human carcinogen and that occupational exposure be reduced to the lowest feasible level. The AIT erican Conference of Govemmental Industrial Hygienists (ACGIH)
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From page 724... ...
Int Arch Occup Environ Health 1983;52:69-77. MonsterA, Regouin-Peeters W
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From page 725... ...
A complete blood count, urinalysis, BUN, serum creatinine, and liver function tests would be appropriate. Challenge Challenge questions begin on page 3.
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From page 726... ...
While this level indicates definite exposure, it may not be high enough to cause her symptoms; however, the patient could have been periodically exposed to short-term levels much higher than this average level, which could have caused her symptoms. Although not relevant here, the linear correlation between urinary trichloroacetic acid and tetrachloroethylene exposure levels breaks down when the exposure is above 100 ppm tetrachloroethylene.
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