What are polychlorinated biphenyls in transformer oil and their health risks?

Polychlorinated biphenyls (PCBs) in transformer oil are synthetic organic chemicals used as coolants and insulators in electrical equipment. They are hazardous due to their potential to bioaccumulate and cause adverse health effects, including cancer, immune system suppression, and reproductive issues. Exposure can occur through skin contact, inhalation, or ingestion of contaminated materials. Due to these risks, the use of PCBs in transformer oil has been banned in many countries, necessitating proper disposal and remediation of contaminated transformers.