Pre-Course Knowledge Check

This case study will help you assess your pre-course knowledge about tetrachloroethylene toxicity. Read the case presentation and answer the questions that follow.

A 37-year-old woman who is 4 months postpartum visits her physician’s office with complaints of headache, increasing irritability, and difficulty concentrating. She says she has become impatient and short-tempered with her husband and new child and becomes angry about minor things. These feelings began about 1 month ago. She is most irritable in the evenings, when she also has a throbbing frontal headache. She has no psychiatric history. She has been having three drinks of alcohol a day since her marriage 4 years ago. However, she did not drink during the pregnancy and does not use other drugs or medications. She has no trouble sleeping.

Two weeks ago, the patient and her family visited her parents for a week. During that time she felt well; the irritability and headaches subsided. Since she returned home last week, however, the symptoms have returned.

The patient is worried that something in the home is causing her symptoms. She reports that the house was sprayed for termites 2 years ago, but she does not remember the name of the pesticide. Her husband feels fine and has not been ill. Her infant daughter’s delivery was uneventful. The baby appears to be developing normally, but has been “very fussy” lately. The infant, whom the physician saw 5 weeks ago for otitis media, is still breast-feeding.

One month ago, the patient returned to her job as a word processor. She works mornings and relaxes with her new hobby, silk screening, in the afternoons. She gets along well with her employer and fellow employees, and the job is not generally stressful. However, she is concerned that a loss in typing accuracy and a decreased ability to concentrate might lead to conflict with her supervisor. The patient had no history of headaches before she resumed her job and began her silk printing hobby.

Vital signs: Blood pressure: 125/85 mmHg; pulse: 68 beats/minute and regular; respirations: 14 breaths/minute; temperature: 98.6°F (37°C)

Head, ears, eyes, nose, and throat (HEENT); respiratory; cardiovascular; and abdominal examinations: The physical examination reveals that the woman is slightly overweight. Her nail beds are pale. The conjunctiva are mildly injected, but the nares and oral mucosa are not swollen or injected. The thyroid is not enlarged, and no lymphadenopathy is present. She has no focal muscle tension or tenderness. Her liver is not enlarged, and examination of the abdomen is unremarkable. Respiratory and cardiovascular examination results are normal with no crucial findings.

Skin: She has no skin rashes, lesions, or stigmata of liver disease.

Neurology: The patient’s neurological examination results are within normal limits. Her recent and distant memory are intact. Proverb interpretation and mini-mental state examination results are normal. Sensory and motor functions are normal, as are Romberg test results and gait. Deep tendon reflexes are normal and symmetrical.

1. What should be included in this patient’s problem list?
2. What further information would assist in establishing a diagnosis?
3. What laboratory tests would a physician order for this patient?
4. On questioning, the patient explains that silk screening involves stretching a large piece of cloth across a support frame, masking it to create a pattern, then dying the unmasked areas. The cloth is cleaned before masking. The patient mentions that she started using a new fabric cleaner 5 weeks ago. Her cousin, who also enjoys silk screening, assured her it was harmless and the best available. The product is called “Clean Cloth,”* but the patient can remember little else about it. Assuming the label on the container does not list the contents, how can the doctor determine the ingredients of this consumer product?
   * “Clean Cloth” is fictional; it does not represent any actual product.
5. The poison control center serving this region informs the doctor that Clean Cloth is 90% tetrachloroethylene and 10% inert propellant. Does the patient’s use of this product pose any risk to her child? Explain.
6. How could a physician determine if a patient has been exposed to tetrachloroethylene?
7. What should a physician tell a patient about the hazards of tetrachloroethylene?
8. What other history will help determine whether the neurological symptoms of this patient are due to Clean Cloth?
9. The patient asks why her cousin, who uses Clean Cloth for the same purpose, has not been ill. What can her doctor tell her?
10. The patient’s laboratory tests show urinary trichloroacetic acid of 4.2 mg/L immediately after a 1-week exposure and slightly elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT). What do these results indicate?
11. If the patient wishes to continue using Clean Cloth, what could the doctor recommend?
12. What authorities should be notified if a product is used improperly in an industrial setting or by a large number of hobbyists?

1. The patient is 4 months postpartum. She has transient headaches, irritability, decreased ability to concentrate, slightly impaired coordination, possible alcohol use disorder, and possible post-partum depression.
   • The Case Presentation in the Pre-Course Knowledge Check covers this information
2. More information about the history of her headaches and her silk-screening hobby would help in diagnosing her symptoms. An accurate history of her current drinking pattern, using an assessment tool for alcohol or other drug-related problems, would also be helpful. Several screening and assessment instruments now are available in computer- or web-based versions [NIAAA 2005]. A toolkit designed to screen and diagnose patients with possible post-partum depression is available [ACOG 2009].
   • Chapter 3, Section 3.1 covers this information
3. Because the patient is postpartum and possibly drinks alcohol in excess, the doctor should order tests to rule out anemia and thyroid problems, as well as tests checking renal and hepatic function. The following tests would also be appropriate: complete blood count, urinalysis, blood urea nitrogen (BUN) and serum creatinine; thyroid stimulating hormone (TSH) screening; and liver function.
   • Chapter 3, Section 3.1 covers this information
4. The doctor can first search this product online. Information in the Household Products Database is from a variety of publicly available sources including brand-specific labels and Safety Data Sheets (SDS) when available from manufacturers and manufacturers’ web sites https://householdproducts.nlm.nih.gov/index.htm; the National Library of Medicine (NLM) TOXNET portal provides reliable information on toxicology, hazardous chemicals, environmental health, and toxic releases https://toxnet.nlm.nih.gov/; and 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/en/. If searching these sites is unsuccessful, the doctor may call the regional poison control center to get help. In the United States, calling 1-800-222-1222 or checking http://www.aapcc.org/ will provide an updated list of U.S. Poison Control Centers.
   • Chapter 3, Section 3.4 covers this information.
5. Yes. Maternal exposure to tetrachloroethylene could transmit the chemical to the nursing infant because the solvent selectively concentrates in breast milk due to its lipophilicity. In addition, the infant could be exposed through inhalation if she is nearby when the patient is cleaning the fabric.
   • Chapter 1, Section 1.4 covers this information.
6. A reasonable first step would be to halt the exposure and determine if the symptoms resolve. Measuring tetrachloroethylene levels in breath, blood or urine would provide direct biologic indicators of tetrachloroethylene exposure. However, these laboratory studies are not rapidly available and do not change management priorities. Thus the diagnosis of hydrocarbon exposure is based upon clinical features [Lewander WJ and Aleguas, A. 2017].
   • Chapter 3, Section 3.1 covers this information.
7. The patient should understand the adverse effects of acute and chronic exposure to tetrachloroethylene and the potential long-term risks, particularly to nursing infants. She and her cousin should work in a well-ventilated area and use personal protective equipment, such as gloves, goggles, and a respirator that provide protection from tetrachloroethylene, when cleaning cloth during silk-screening [NIOSH 2018, OSHA 2005].
   • Chapter 2, Section 2.2, and Chapter 3, Section 3.4 cover this information.
8. Questions about symptoms and their association with using Clean Cloth might reveal a direct connection, as well as questions about the type and amount of ventilation and use of personal protective equipment.
   • Chapter 3, Section 3.1 covers this information.

   For example, the patient might respond that she sprays the cloth in late afternoon in a small garage and keeps the door closed to prevent dust from entering. She also recalls that one day last week, when it was hot, she felt particularly ill after spraying the cloth.

   • Chapter 3, Section 3.1 covers this information.
9. To answer this question, a review of the factors that could reduce the cousin’s actual exposure might be helpful. These include intensity, frequency, and duration of exposure; existing health conditions; etc. For example, the cousin
   • might work outdoors or in a better ventilated area,
   • might put rags soaked with the compound in a closed container, or
   • might follow directions on safe product use. Individual variability can also explain why some people become ill and others do not after similar exposures (e.g., breathing rate; effects of other exposures such as smoking, drugs, and alcohol on metabolic function; genetic differences in metabolic function).
   • Chapter 1, Section 1.3 and Section 1.4 cover this information.
10. The urinary trichloroacetic acid level indicates a possible ambient air exposure of about 30 ppm tetrachloroethylene. It is a non-specific indicator though because exposure to other chemicals, such as 1,1,1-trichloroethane and trichloroethylene, also produce trichloroacetic acid in blood and urine. Although the lab results indicate possible exposure of tetrachloroethylene from using “Clean Cloth,” the level might not be high enough to cause her symptoms. However, the patient could have also experienced periodic exposure to short-term levels much higher than this average level that could have caused her symptoms. The slightly elevated levels of AST and ALT are inconclusive for tetrachloroethylene exposure because of the confounding factor of alcohol consumption. An AST:ALT ratio greater than 1 (i.e., AST greater than ALT) tends to support an alcoholic-induced etiology. A ratio less than 1 (i.e., AST less than ALT) supports toxic, infectious, or other etiologies [AACC 2015]. Advising the patient to reduce alcohol consumption and counseling her about alcohol use disorder would be appropriate, as well as repeating liver function tests in several months.
    • Chapter 3, Section 3.1 covers this information.
11. The doctor could recommend using a less toxic cleaner. If the patient insists on using Clean Cloth, she could
    • reduce exposure to the product by using gloves, protective clothing, using a respirator or other PPE, be sure they are right for you and the chemical you work with,
    • ensure appropriate ventilation, and
    • get proper industrial hygiene consultation or other professional assistance.

    Since tetrachloroethylene crosses the placenta and can be found in breast milk; therefore, the fetus and nursing newborn could be at increased risk for adverse effects from maternal exposure. The tetrachloroethylene presently in her milk can be eliminated in several days if she continues to pump her breasts.

    • Chapter 3, Section 3.4 and Chapter 2, Section 2.1 cover this information.
12. The Occupational Safety and Health Administration (OSHA) has regulatory responsibility for the workplace and should be notified if employees might be dangerously exposed. Upon request, NIOSH could initiate a health hazard evaluation of the workplace. A product with hazardous potential used by a number of hobbyists should be reported to the local or state health department.
    • Chapter 3, Section 3.3 covers this information.