Legal "designer drugs" are on the increase worldwide with youngsters being misled into thinking they are safe, the UN drug control agency has warned.
They "can be far more dangerous than traditional drugs," the agency said in its annual report. "Street names, such as 'spice,' 'meow-meow' and 'bath salts' mislead young people into believing that they are indulging in low-risk fun."
The UN Office on Drugs and Crime warned that "the international drug control system is foundering, for the first time, under the speed and creativity" of their proliferation.
It said countries worldwide reported 251 such substances by mid-2012, compared with 166 at the end of 2009. The problem, said the report, is "hydra-headed" in that as fast as governments ban the drugs, manufacturers produce new variants.
Nearly 5% of European Union residents aged between 15 and 24 have already experimented with such drugs, said the report.
In the United States, 158 kinds of synthetic drugs were circulating during 2012, more than twice as many as in the EU, and use was growing in East and South-east Asia, including China, Indonesia, Japan, the Philippines, Thailand and Vietnam.
UNODC head Yury Fedotov said that while drug use and production overall appears to be stable in recent years, illicit drug consumption still kills around 200,000 people each year.
However, the office lowered its estimate of the number of people injecting drugs and those living with the HIV virus worldwide because of such injections.
It said 14 million people between the ages of 16 and 65 inject drugs and of those, 1.6 million have the virus as a result of such injections - 12% and 46% less respectively than last estimated five years ago.