What does PCB stand for in the context of environmental safety?

In the context of environmental safety, PCB stands for polychlorinated biphenyls. These are a group of man-made organic chemicals composed of carbon, hydrogen, and chlorine atoms. PCBs were widely used in industrial applications, particularly in electrical equipment like transformers and capacitors, because of their desirable chemical properties, such as electrical insulation and chemical stability. However, they were banned in the late 1970s due to environmental and health concerns, as PCBs are persistent in the environment and can accumulate in the food chain, leading to significant ecological and human health risks, including cancer and other serious health issues.

The other options do not correctly define PCB in this context: polymerized chlorinated benzene and polycyclic chlorinated biotoxins do not accurately describe the chemical structure or properties associated with PCBs, and polychlorinated hydrocarbons is a more general term that may refer to numerous substances without specifically identifying the biphenyl structure inherent in PCBs.