Studying the studies Not many epidemiological studies human studies have been done on PCBs simply because of a lack of control groups on which to study. Epidemiological studies are divided into two categories, morbidity studies, which are studies of human illness, and mortality studies, which are studies of causes of death. A study from the Center for Environmental and Human Toxicology at the University of Florida, Gainesville, analyzed PCB clinical and scientific reports spanning over 50 years. This literature, though extensive, is somewhat fragmented, said the report on the study done by doctors. After careful analysis, the weight of evidence suggests the only adverse health effects attributable to high, occupational PCB exposures are dermal.
Dermal effects are the only clear-cut health effects linked to PCB and dioxin exposure.
Chloracne is a skin effect of exposure. The condition resembles severe blackheads, which are usually located in a C shaped pattern at the temples, the back of the neck and in the area of the scrotum. Kaley admits that transient elevations of liver enzymes can arguably be an effect of PCB exposure, but cautions that studies are not consistent. A study published in 1995 and conducted by Dr. Renate D. Kimbrough of the Institute for Evaluating Health Risks, Washington D.C., and funded by the Institute and the Aluminum Company of America, concludes that doses of PCBs in humans can only be estimated, while more precise information is available for PCB-fed laboratory animals. The study further indicates that In the U.S., in PCB-exposed workers or in the adult general population, the combination of hyperpigmentation, chloracne and discolored nails have never been observed, however, these alternations in skin and nails were identified in subhuman primates following the administration of PCBs.