Polychlorinated biphenyls (PCB)

Polychlorinated biphenyls (PCBs) are synthetic organochlorine chemicals that were once valuable industrial products. However, their production ceased due to their persistence in the environment and living organisms. PCBs were utilized in electrical, heat transfer, and hydraulic equipment, as plasticizers in paints, plastics, and rubber products, and in pigments, dyes, and carbonless copy paper, among numerous other industrial applications. Today, the unintentional generation of PCBs during industrial processes is permitted but regulated.

PCBs consist of mixtures of up to 209 different congeners, determined by the number and position of chlorines around the biphenyl ring. These fat-soluble substances are encountered by everyone through the ingestion of animal fats, inhalation, or skin contact. PCB exposure weakens the immune system, increasing the risk of various human diseases. Both ortho-substituted and coplanar (dioxin-like) congeners act as tumor promoters, amplifying the effects of other carcinogens. Exposure to PCBs, particularly during fetal and early life, can lower IQ and affect behavior. PCBs impact thyroid and reproductive functions in both males and females and elevate the risk of cardiovascular and liver diseases and diabetes. Women face a higher risk of giving birth to low birth weight infants, who have an increased lifetime risk for several diseases. As understanding of their toxic effects has grown faster than the decline in environmental levels, PCBs continue to be hazardous contaminants.

Sources:

https://doi.org/10.1515/reveh.2006.21.1.1