Cannabis use in the US has seen a sharp rise in states where it has been legalised, new research has shown.
Pro-legalisation campaigners had claimed it would not lead to an increased use of the drug.
But a study of 3,400 twins by the University of Minnesota found that usage jumped by one-fifth in states where the law allows recreational use.
The research included 111 sets of identical twins, where one lived in a state where cannabis is legal and the other where it is not.
The results showed a “20% average increase in cannabis use frequency attributable to recreational legalization”.
The study also said cannabis is “an addictive substance associated with many negative health and psychosocial outcomes”.
The findings follow a recent report by America’s National Institute on Drug Abuse (NIDA) that a record number of 19 to 30-year-olds – 43 per cent – used cannabis last year.
Its Director, Dr Nora Volkow, told the Mail Online that the surge in cannabis use was likely because legalisation has made it “more appealing”.
She said that making it legal has not only made “access to cannabis easier for its regular use, but it has also contributed to the perception that cannabis is a ‘safe’ drug”.
legalisation has made cannabis more appealing
Former White House drug advisor, Kevin Sabet said the studies expose the lies of the pro-legalisation arguments that drug use would be lowered, the illegal market reduced and tax revenue would outweigh the costs.
He said: “None of that has been fulfilled, and instead we see today’s supercharged THC being marketed, commercialized, and promoted by a for-profit industry that will stop at nothing to make money at the expense of public health.”
Tetrahydrocannabinol (THC) is the psychoactive component of cannabis, that leads to depression, schizophrenia and brain development problems.