Agency for Toxic Substances and Disease Registry
Polychlorinated Biphenyls (PCB) Toxicity
Answers to Pretest and Challenge Questions

Answers to Pretest Questions

1. The patient's problem list includes acne vulgaris, which is atypical because of the location of the lesions and their late onset with no history of outbreaks during adolescence. The mildly altered liver functions are nonspecific but are clinically unexpected. Gilbert syndrome is a hereditary, relatively common, benign, unconjugated hyperbilirubinemia. It might contribute to the laboratory findings of elevated bilirubin (especially after a fast), but would not explain the clinical picture or elevated liver enzymes.
2. The combination of asymptomatic hepatomegaly and mild nonspecific elevations of hepatic enzymes is suggestive of a chronic inflammatory liver process or hepatitis. The causes of hepatitis can be classified as drug-induced, toxic, infectious, genetic, and connective tissue disease-associated. The major cause of liver disease in the United States is ethanol ingestion. Less common are environmental exposures, resulting in either acute or chronic toxic hepatitis. Infectious hepatitis includes those due to the viruses such as A (infectious), B (serum), C (transfusion-associated), and other possible agents of non-A, non-B hepatitis. Some connective tissue diseases such as lupus erythematosus are associated with a specific type of hepatitis. Hepatitis can also occur with Epstein-Barr virus and cytomegalovirus infections. Infiltrative diseases such as sarcoidosis or amyloidosis, and rare genetic diseases such as Wilson disease, primary hemochromatosis, and alpha-1-antitrypsin deficiency must be excluded.
3. Viral serology and a heterophil antibody test should be considered. If suggestive signs or symptoms exist, a serum iron and total iron binding capacity, serum copper and ceruloplasmin, and antinuclear antibodies might be helpful. Assays for suspected hepatotoxins might also be of value. Further evaluation might include ultrasound and percutaneous liver biopsy if other tests do not provide sufficient information.

Answers to Challenge Questions

1. Older electrical transformers and capacitors can contain PCBs as a dielectric and heat-transfer fluid. Leaks in this equipment could allow PCBs to volatilize under conditions of increased temperature. A person with chronic exposure to the vapors or residue could eventually receive a significant PCB dose through both dermal and inhalation routes.
2. In addition to the patient's possible exposure through dermal and inhalation contact, he might also be exposed through consumption of contaminated fish. Great Lakes fish, particularly from Lake Michigan, are a potential source of PCBs.
3. Persons with Gilbert syndrome have decreased UDP-glucuronyltransferase activity, resulting in impaired glucuronidation of bilirubin and, presumably, of PCBs as well. Because one elimination pathway for PCBs is excretion of the glucuronide in urine, impaired capacity to conjugate PCBs with glucuronic acid could theoretically lead to accumulated PCBs and greater body burden. This hypothesis has not been tested, however.
4. Yes. It is important to be aware that potential carcinogenicity is the main reason PCB production was banned in the United States. Human evidence is still considered inadequate, but the animal evidence is strong enough for EPA, NIOSH, and the International Agency for Research on Cancer (IARC) to conclude that PCBs are probably carcinogenic in humans (Group 2A classification).
5. Testing human tissue for PCB content, therefore, remains principally a research tool.

   Selected laboratories have the capability to perform PCB analyses on human tissue. The lipophilic nature of PCBs causes them to accumulate in fat; consequently, analysis of adipose tissue obtained by biopsy has been advocated as a measure of long-term exposure. Serum PCB analysis, which is less invasive than fat biopsy, can also be done. However, such tests are expensive and health risks often cannot be determined from the results.

6. A correlation between increasing levels of serum PCBs and dermatologic findings, including chloracne, has not been consistently found in human epidemiologic studies. However, one study involving 153 workers with occupational exposure to PCBs showed 22 subjects with dermal abnormalities and a mean plasma PCB level of 87 ppb, whereas 131 subjects without abnormalities had a mean serum level of 50 ppb. The difference was statistically significant. By comparison, plasma PCB levels in unexposed populations are <30 ppb. However, no serum PCB values are yet accepted as normal or toxic levels. The case study patient's PCB serum level of 125 ppb is nonetheless consistent with PCB exposure as an etiology for his unusual acne, and PCB exposure might be contributing to the hepatic effects noted.
7. The first objective should be to stop the exposure. In this case, the patient should stay away from the basement until the transformer is repaired and the basement area cleaned by a professional familiar with PCB removal. He should also refrain from eating fish from the Great Lakes until his PCB level normalizes and the fish are known to be uncontaminated. Guidance is available on how to choose safer fish to eat and on safer ways to prepare and cook fish (EPA 2002). Avoiding exposure is especially important because no specific treatment exists for PCB accumulation. The need to avoid other hepatotoxic substances including ethanol should be stressed. No data exist to support monitoring serum PCB levels.
8. Because cessation of exposure is of prime importance, the physician can be most helpful by specifically recommending proper abatement. In this case, the owner of the building should be notified of the potential health hazard and should contact the local public health agency. This might require the assistance of local, state, or federal agencies such as the department of public health and EPA. These agencies can work cooperatively with those involved to bring about remediation of the harmful exposure. It is important to prevent others from using the basement areas until cleanup is complete. In addition, the patient should be informed of the availability of fishing and game advisories and should be encouraged to observe the recommendations of these advisories.

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