Overall, they include drugs that have long been abused, such as marijuana and cocaine, and drugs whose abuse is a more recent development. Some are stimulants, some depressants, and some hallucinogens-while most exhibit multiple pharmacological properties.
Studies of PCBs in humans have found increased rates of melanomas, liver cancer, gall bladder cancer, biliary tract cancer, gastrointestinal tract cancer, and brain cancer, [1] and may be linked to breast cancer. PCBs are known to cause a variety of types of cancer in rats, mice, and other study animals. [2].
PCBs (polychlorinated biphenyls) are a type of organic chemical known as chlorinated hydrocarbons. PCBs are formed from a combination of one or more chlorine atoms and two benzene molecules. Two other names for PCBs are arochlors and chlorodiphenyls. In any PCB commercial mixture there may be 40 to 70 different compounds present.