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].
Though cancer itself isn't contagious, sometimes viruses, which are contagious, can lead to the development of cancer. Examples of viruses that can cause cancer include: Human papillomavirus (HPV) â a sexually transmitted infection â that can cause cervical cancer and other forms of cancer.