The United Nations drugs agency, however, said the effects of Irish laws aimed at addressing the problem “seem encouraging” and “could halt” the trend.
The UN Office on Drugs and Crime said new psychoactive substances (NPS) were “proliferating at an unprecedented rate” across the world and posed “unforeseen public health” effects.
In its 2013 annual report, the agency said the number of NPS had risen from 166 in 2009 to 251 in 2012, a jump of 50%.
“For the first time, the number of NPS exceeded the total number of substances under international control . Since new harmful substances have been emerging with unfailing regularity on the drug scene, the international drug control system is now challenged by the speed and creativity of the NPS phenomenon.”
It added: “Given the almost infinite scope to alter the chemical structure of NPS, new formulations are outpacing efforts to impose international control. While law enforcement lags behind, criminals have been quick to tap into this lucrative market. The adverse effects and addictive potential of most of these uncontrolled substances are at best poorly understood.”
It said the internet played a key role in the trade, with the European Monitoring Centre for Drugs and Drug Addiction identifying 693 online shops selling the drugs in 2012, up from 314 in 2011 and 170 in 2010.
The UN report said Ireland had the highest consumption rates of the drugs, with a lifetime (ever taken) usage rate of 16%, compared to an EU average of 5%. The next highest rate after Ireland was Poland at 9%.
It said the annual prevalence (last-year usage) stood at almost 10%.
“[This] was almost four times as high as the prevalence of cocaine, more than six times the rate for amphetamines and almost nine times the rate for ecstasy use in this age group.”
The report said Ireland was one country which had introduced generic- type laws banning psychoactive substances (current and future).
“On the surface, a generic scheduling system is extremely appealing. It is anticipatory instead of reactive.”
It said the legal systems of many countries are based on the concept that any offence must be clearly defined and that could pose problems for generic (catch-all) laws.
However, it added: “It must be noted that the European Court of Human Rights case law allows for some broader interpretations, and thus permits generic definitions as found in the drug laws of Ireland and the UK.”
It said initial results from Irish laws introduced in 2010 “seem encouraging” and the trend in Ireland “could well be halted”.
The Irish Health Research Board said the laws had “notable successes” in limiting the sale of the drugs and there was anecdotal evidence that use of the substances “appears to have decreased”.