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].
What Really Causes Cancer. Most people think that DNA damage is what causes a cell to be cancerous. While it is true that cancer cells may have DNA damage, it is highly unlikely that DNA damage can cause any cell to become cancerous. In fact, the DNA damage is a result of the true cause cancer. So let us discuss what really causes cancer. There have been many discoveries about cancer in the past 125 years. For example, William Russell (1852-1940), in 1890, discovered that there are microbes inside and outside of cancer cells.