I have been predicting this for a number of years. But now it is really happening, and at a truly amazing, historically unprecedented speed: The number of untested, but freely available psychoactive substances is dramatically rising. In the European Union new drugs were detected at the rate of roughly one per week during the previous year, according to the EMCDDA– Europol 2011 annual report on new psychoactive substances, released on 26 April 2012.

A total of 49 new psychoactive substances were officially notified for the first time in 2011 via the EU early-warning system. This represents the largest number of substances ever reported in a single year, up from 41 substances reported in 2010 and 24 in 2009. All in all this means 164 new drugs since 2005—but also that the annual record has now been broken for three years in a row.

All of the new compounds reported in 2011 were synthetic. They are cooked up in underground labs, but increasingly organized crime begins to develop the market and import them, for example from China. Almost nothing is known about pharmacology, toxicology, or general safety; almost all of these substances have never been tested in vivo or in animal models. This makes the situation difficult for medical staff at psychiatric emergency units, with kids coming in tripping on substances the names of which doctors have never even heard during their university education. The doctors have not heard of these substances because the substances did not yet exist while the doctors were being trained.

I sometimes naively tend to assume that in the end most of these substances will turn out to be rather benign, but even for "Spice Drugs" (that is, synthetic cannabinoids sprayed on herbal smoking mixtures, often marketed as "Legal Highs") deaths and serious heart problems have now already been reported in young, healthy adolescents.

Last October a 21-year old in New Orleans died from taking only one single drop of 25-I (25I-NBOMe), a new synthetic hallucinogenic drug. In the USA, at least 3 more deaths from this new phenethylamine (originally discovered in Germany) have been reported from Minnesota and North Carolina, with victims being 17, 18 and 25 years old.

Everybody knows about acute adverse reactions, psychotic effects, addiction—we do have some cultural experience. But what about long-term effects such as early-onset cognitive decline, say, a somewhat steeper slope as in normal ageing? Unexpected carcinogenic agents? It would take us very long to discover and verify such effects.

Does anybody remember Thalidomide? The situation is now completely out of hand. And it is a complicated situation: We might ban (or attempt to ban) early generations of substances with low health hazard profiles, creating a psychopharmacological arms race, leading to a replacement by ever new and potentially more dangerous compounds.

In 2011, the list of substances registered was dominated by synthetic cannabinoids (23 new compounds on the market) and synthetic cathinones (8 new molecules). They now represent the two largest drug groups monitored by the European early warning system and make up around two-thirds of the new drugs reported last year – but, of course, this may change soon. The War on Drugs has failed, but the process of scientific discovery is going on. The number of substances in the illegal market will increase, and perhaps altogether new categories of drugs will emerge – plus the corresponding "neurophenomenological state-classes", as I like to call them.

What are the main causal factors that have brought about this development?

First, it is a combination of scientific progress and human nature: Fundamental research, for example in neuropharmacology, simply moves on, new knowledge and newly developed technologies meet age-old human desires for spiritual self-transcendence, hedonism and recreation. Plus greed.

For me, new psychoactive substances are a paradigm example how neurotechnology turns into consciousness technology (I like to call it "phenotechnoloy"). Low-level, nuts-and-bolts molecular neuropharmacology creates not only new forms of subjective experience, but also high-level effects for society as a whole. Invisible risks. New industries. Emerging markets.

The second causal factor is the Internet. An "internet snapshot" conducted in January 2012 resulted in 693 online shops offering at least one psychoactive substance or product, rising from 314 in January 2011 and 170 in January 2010.

Recipes for many of these new illegal substances, as well as first-person reports about the phenomenology associated with different dosages, are available on the Internet—easily accessed by the alternative psychotherapist in California, the unemployed professor of chemistry in the Ukraine, or the Chinese mafia. And now the sheer, increasing speed at which new drugs appear on the market makes all established procedures obsolete.

But there is at least one deeper reason for the situation we will have to face in the decades to come: Half a century ago the Western world deliberately opted for a culture of denial and repression. In the Sixties, we first witnessed a semisynthetic psychedelic drug of the ergoline family spread around the world, with millions of new users, and a new generation of underground chemists. The appearance of LSD was a historically new situation.

We might perhaps have had a chance to deal with the challenge then, rationally, based on ethical arguments. The really difficult, and most important, task would have been to honestly weigh the psychological and social risks against a general principle of liberty and the intrinsic value of the experiences resulting from one or another altered brain state. But we decided to push it underground and look the other way. Half a century later, a globalized and scientifically well-informed underground chemistry strikes back. More kids are going to die. It would be starry-eyed optimism to think that we can still control the situation.