SMOKING three cannabis joints will cause you to inhale the same amount of toxic chemicals as a whole packet of cigarettes, according to research published in France today. Cannabis smoke contains seven times more tar and carbon monoxide, the French National Consumers' Institute concluded in research published in the April edition of its monthly magazine. The institute tested regular Marlboro cigarettes alongside 280 specially rolled joints of cannabis leaves and resin in an artificial smoking machine. The tests examined the content of the smoke for tar and carbon monoxide, as well as for the toxic chemicals nicotine, benzene and toluene....