[{"from": "human", "value": "Describe this molecule. [C][=C][C][=Branch2][Ring1][Branch1][=C][C][=C][Ring1][=Branch1][C][=C][Branch1][O][C][=C][Branch1][=Branch1][C][=C][Ring1][=Branch1][Cl][Cl][Cl][Cl]"}, {"from": "gpt", "value": "The molecule is one of 209 polychlorinated biphenyls (PCBs). PCBs are a group of synthetic organic compounds with 1-10 chlorine atoms attached to biphenyl. They were manufactured as commercial mixtures but banned in the 1970's because they were found to bioaccumulate and cause harmful health effects. However, PCBs do not break down readily and are still found in the environment. (L4)"}]