The term 'Banned Chemical' refers to four different chemicals: ALAR (4 letters), DDT (3 letters), PCB (3 letters), and PCP (3 letters). ALAR, or Alarcon, is a plant growth regulator that was banned in 1989 due to its potential to cause cancer. DDT, or dichlorodiphenyltrichloroethane, is an insecticide that was banned in 1972 due to its environmental toxicity. PCB, or polychlorinated biphenyls, are a group of man-made organic chemicals that were banned in 1979 due to their potential to cause cancer and other health problems. PCP, or phencyclidine, is a dissociative anesthetic that was banned in 1978 due to its potential for abuse and addiction. All four of these chemicals have been banned due to their potential to cause serious health and environmental problems.