Answer:
PCBs- polychlorinated biphenyls cause cancer, suppress the immune system, disrupt hormonal signals and impair reproduction.
Step-by-step explanation:
1. Widespread
PCBs can easily be spread, they often fail to remain in the medium in which they are released, moving instead within and between different phases or compartments of the environment (atmosphere, soil, sediment, and water). Plankton ingest the PCB, fish consume the plankton and whales eat the fish. With this tier of food Web, PCB becomes more concentrated.
2. Global purification
Though the use of PCB is banned in most countries, it's widespread usage lead to its remaining in the ecosystem and being spread further in the ocean.