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].
In laboratory experiments, HCAs and PAHs have been found to be mutagenicâthat is, they cause changes in DNA that may increase the risk of cancer. HCAs are formed when amino acids (the building blocks of proteins), sugars, and creatine (a substance found in muscle) react at high temperatures.