Pressure to control the consumption of tobacco has grown in tandem with the pressure to liberalize the consumption of marijuana. Perhaps this is not a paradox in the most literal sense, but it is certainly very striking.  The yin of prohibition, it seems, always goes along with the yang of permission.

An article in a recent edition of the New England Journal of Medicine discusses the forthcoming tussle between what it calls Big Marijuana – the commercial interests, analogous to Big Tobacco, that will inevitably grow if marijuana ever becomes as accepted as tobacco once was – and the public health authorities.  For while the smoking of marijuana does not yet cause anything like as many health problems as tobacco or alcohol, it would do so if its use were as general as the use of tobacco or alcohol. A little statistic that was published some time ago in the Lancet caught my eye: the French police attribute 3 percent of fatal road accidents to intoxication with cannabis and 30 percent to intoxication with alcohol. If, as seems likely, ten times as many Frenchmen drive drunk as drive stoned, marijuana is as dangerous as alcohol where driving is concerned.

The authors of the article point out that commercial growers and marketers of marijuana are likely, given the chance, to resort to all the techniques and obfuscations employed by the tobacco companies. They will minimize the harms done by marijuana while trying to increase the concentration of the very substance in their product that does the harm. The concentration of tetrahydrocannabinol (THC) in modern cannabis plants is already much higher than it was when hippiedom first struck the western world; Uruguay, where the cultivation and sale of cannabis has recently been legalized, is attempting to control the strains of cannabis that can be sold, with what success remains to be seen.