Potent Pot: Marijuana Is Stronger Now Than It Was 20 Years Ago

(Live Science, Feb. 8) Marijuana is much more potent than it was in the past. According to researchers who examined seized marijuana from the DEA, the level of THC, the main psychoactive ingredient in marijuana, had risen from 4 percent in 1995 to 12 percent in 2014. A lower dose of THC can give a "pleasant feeling" says one researcher, but high doses can cause panic attacks, psychosis and other negative effects. In addition, pot smokers develop a tolerance for THC, requiring higher doses each time for the same high. READ MORE.