Challenge questions begin on page 4.
Older electrical transformers and capacitors can contain PCBs as a dielectric and heat transfer fluid. Leaks in the equipment could allow PCBs to volatilize under conditions of increased temperature, such as those in a basement. A person with chronic exposure to the residue could eventually receive a significant PCB dose through both dermal and inhalation routes.
Great Lakes fish, particularly from Lake Michigan, are known to be a potential source of PCBs. A correlation between consumption of PCB-contaminated fish and elevated serum PCB levels has been shown in a study of residents of New Bedford, Massachusetts. For the general population, however, a clinically significant human body burden of PCBs is unlikely to occur through fish consumption alone.
Persons with Gilbert’s syndrome have decreased UDP-glucuronyltransferase activity, resulting in impaired glucuronidation of bilirubin and, presumably, of PCBs also. Since a PCB elimination pathway is excretion of the glucuronide in urine, impaired capacity to conjugate PCBs with glucuronic acid can theoretically lead to accumulated PCBs and greater body burden. This hypothesis has never been tested, however.
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 was strong enough for EPA, NIOSH, and IARC (the International Agency for Research on Cancer) to conclude that PCBs may have carcinogenic effects in humans.
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. Testing human tissue for PCB content, therefore, remains principally a research tool.
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, while 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 less than 30 ppb. However, no serum PCB values are yet accepted as normal or toxic levels. Our patient’s PCB serum level of 125 ppb is nonetheless consistent with PCB exposure as an etiology for his unusual acne, and PCB exposure may be contributing to the hepatic effects noted.
The first response is clearly 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. He should also refrain from eating Great Lakes fish until his PCB level normalizes and the fish are known to be uncontaminated. Avoiding exposure is especially important, as there is no specific treatment for PCB accumulation. The need to avoid other hepatotoxic substances including alcohol should be stressed. Currently, there are no data to support monitoring serum PCB levels.
Since 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. This may 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.