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Polychlorinated Biphenyls (PCBs) Toxicity
Clinical Assessment

Course: WB 2460
CE Original Date: May 14, 2014
CE Expiration Date: May 14, 2016
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Learning Objective

Upon completion of this section, you will be able to

  • Describe characteristic findings on clinical assessment of patients exposed to PCBs, and
  • Describe a rational approach for evaluating a patient with a history of occupational or environmental exposure, or both, to PCBs.

Introduction

Patients who have been exposed to PCBs often are undergoing clinical assessment long after their last exposure occurred (possibly years). The ability to extrapolate peak blood levels is problematic in these cases.

PCBs have low acute toxicity but are of public health concern because they persist in the environment, bioaccumulate in human and animal tissues, and potentially can cause chronic or delayed toxicity.

Documenting an adequate occupational and environmental exposure history in addition to a physical examination is essential for identifying health effects related to PCBs.

Identifying cases of chloracne may be helpful, but the absence of chloracne would not rule out significant exposure.

Patient History and Physical Examination

A detailed history will facilitate the diagnosis of chronic PCB poisoning. Pertinent information includes occupational histories of all household members and history of the patient’s sport and subsistence fish consumption. Because PCBs are hepatotoxins, history of exposure to other potentially hepatotoxic agents, such as ethanol intake and medications with known hepatotoxicity, should be obtained.

During the physical examination, physicians should pay particular attention to the skin and hepatic systems. Encountering a patient with PCB toxicity should trigger consideration of whether this is a sentinel event, indicating the possibility of other similarly exposed persons such as co-workers or family members.

Signs and Symptoms-Acute Exposure

Acute exposure

PCBs have very low potential for producing acute toxic effects. The only overt sign of exposure to PCBs is chloracne, which is a specific skin lesion. Although chloracne may resemble typical adolescent acne, it has certain distinct features [Crow 1970; Letz 1983].

  • Chloracne's most distinctive feature is cystic, skin colored lesions that measure 1-10 mm.
  • Chloracne's other prominent feature is comedonal lesions.

The comedones and cysts can become inflamed and secondarily infected with large pustules.

Unlike adolescent acne, chloracne may occur at any age and may involve the arms, back, face, legs, neck, and trunk.

Chloracne can be very persistent and refractory to treatment.

Acneiform lesions do not appear in all severely exposed patients, so the absence of chloracne does not rule out exposure. New cases of chloracne should be reported to the local or state health department.

Other acute effects that may be seen include eye irritation, nausea, and vomiting [LaDou 2006].

Elevated liver enzymes are the most sensitive indicator of exposure to PCBs in animals, and alterations in

  • AST (SGOT),
  • GGT (GGTP),
  • Bilirubin, and
  • Albumin levels have been reported in human epidemiologic studies.

The absence of alterations in these liver function markers does not rule out excessive exposure to PCBs.

The presence of specific signs, symptoms, or laboratory abnormalities, with the possible exception of chloracne, is difficult to relate to exposure to PCBs absolutely in any given patient. A practical approach for the routine work-up of individual patients potentially exposed to PCBs would be to do the following:

  • Take a through occupational and environmental exposure history,
  • Examine the skin,
  • Order baseline liver function tests, and
  • If indicated, perform subsequent testing limited to patients with clinical problems or history of extensive exposure such as an accidental spill or a capacitor rupture that caused heavy skin contamination [Letz 1983].

This clinical approach may be used for monitoring electrical utility workers or other persons with some potential for ongoing occupational exposure.

Serum PCB level is a useful indicator of a patient's exposure. Serum PCB tests are readily available at most commercial reference laboratories. However, serum PCB levels may not be consistent with adverse health effects. [Roseman 2005].

Signs and Symptoms-Chronic Exposure

Chronic exposure

Many people who are chronically exposed to PCBs exhibit no overt signs or symptoms of toxicity. Among persons with hepatic involvement, signs of exposure to PCBs can include

  • Abdominal pain,
  • Anorexia,
  • Jaundice,
  • Nausea,
  • Vomiting,
  • Weight loss, and
  • Uroporphyria.

Headache, dizziness, and edema have also been reported (see earlier section on Adverse Health Effects for more detail).

Differential Diagnosis

Occupational exposure to PCBs may be accompanied by exposure to chlorinated dibenzodioxin and dibenzofuran contaminants, which are much more toxic than PCBs in comparative animal studies. These substances can cause chronic fatigue and elevated liver enzymes.

Mild chloracne should not be confused with other rashes (e.g., acne, seborrheic keratitis, keratoma). A skin biopsy of lesions may help establish the diagnosis [LaDou 2006].

Medical Surveillance

Workers intermittently exposed to PCBs should have a baseline skin examination and liver function tests. Follow-up examination can be limited to symptomatic persons and workers exposed as a consequence of accidental contamination. For persons with signs and symptoms consistent with high exposures to PCBs (e.g., chloracne, elevated AST and ALT), a serum PCB level should be obtained to confirm exposure.

Key Points

  • Chloracne is the only known overt sign of PCB toxicity; however, the absence of chloracne does not rule out exposure.
  • Signs of low level, chronic exposure to PCBs are generally subtle, if present at all.
   

Progress Check

10. Which of the following should be included in the clinical evaluation of a patient with a history of exposure to PCBs?

A. A thorough occupational and environmental exposure history.
B. A thorough skin examination.
C. Liver function tests.
D. All of the above.

Answer:

To review relevant content, see "Patient History and Physical Examinations" in this section.

11. PCB exposure may manifest clinically as which of the following?

A. Acne vulgaris.
B. Chloracne
C. Parkinsonism.
D. Acute tubular necrosis.

Answer:

To review relevant content, see "Signs and Symptoms - Acute Exposure" and "Signs and Symptoms - Chronic Exposure" in this section.

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