Polychlorinated Biphenyls (PCBs) and Their Impacts on Human Health: A Review

Abstract

Polychlorinated biphenyls (PCBs) are synthetic organic compounds in which 2-10 chlorine atoms are attached to the biphenyl. They were industrially produced as complex mixtures by the direct chlorination of biphenyls using anhydrous chlorine. Theoretically 209 individual PCB compounds are possible, but only about 130 congeners have been identified in commercial PCB mixtures. Although their properties vary across a class, all PCBs are insoluble in water and persistent in both the environment and within biological systems. They are highly lipophilic and therefore tend to bioaccumulate and biomagnify in tissues of living organisms. Because of their chemical and physical stability and electrical insulating properties, they have had a variety of uses in industry included widely as coolants and lubricants in transformers, capacitors, and other electrical equipments. PCBs production was banned in many courtiers, 40 years ago; however, they are still present in the environment and their entry into the environment still occurs. Human exposure to PCBs contaminants can occur by ingestion, dermal contact, and inhalation. Some of the PCBs that enter the body are metabolized and excreted within a few days; whereas others stay in human body for months and even years. Thus, they are considered potent toxicants capable of producing a wide spectrum of adverse health effects in humans such as skin diseases, enzyme induction, liver toxicity, vitamin A deficiency, endocrine effects, immune system effects, brain dopamine levels deficiency, and genotoxicity.