How are polychlorinated biphenyls currently being produced, despite the production ban, and do they pose a risk to the environment?

Polychlorinated biphenyls (PCBs) are a group consisting of 209 congeners, differing in the number and site of substitution of chlorine atoms to the biphenyl molecule. Due to their physicochemical properties, they have found wide industry use. As a result of many years of large-scale use of PCBs, their toxic properties began to be noticed as they manifested in poisoning among humans. After thorough testing of PCBs, they were classified in the group of persistent organic pollutants (POPs), and their production was banned and they were withdrawn from use. Although PCBs are no longer produced in factories, they can still be formed. In this article, will be presented and explained methods of accidental formation of PCBs. Based on data from the literature, we performed an environmental risk assessment for PCB-contaminated soils.