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 causes carcinoma cancer? WebMD reports that ultraviolet rays from the sun or from a tanning bed are the primary cause of basal cell carcinoma. Tumors vary widely in appearance and include small shiny bumps, patches of red, slightly scaly skin and waxy, hard growths.