There is widespread public concern and anxiety about GM foods or crops. Genetically Modified substances raise anxiety over possible dangers - yet illegal drugs could also be targeted by GM technology.

Cannabis is the most controversial drug worldwide in terms of safety, yet it's also probably the most illegally consumed drug of abuse.

Using cannabis, you are courting a twofold increase in the risk for later developing schizophrenia - one of the most serious psychiatric disorders. This statistic is according to a review of the link between cannabis and psychosis published in the British Journal of Psychiatry in 2004 by Louise Arseneault, Sir Robin Murray and colleagues at the Institute of Psychiatry in London. These authors argued that complete elimination of cannabis would reduce the incidence of schizophrenia by approximately 8%.

The active ingredient in terms of producing mental effects is Tetrahydrocannabinol (THC); eliciting mood, memory, coordination, cognitive, sensory and self-perception changes. There's also an increased sense of well-being or euphoria, followed with relaxation and sleep. It's this component which also triggers acute anxiety and even psychotic reactions in the previously healthy, and it precipitates relapse in those suffering from schizophrenia.

But there are also potential therapeutic benefits to cannabis; nausea, vomiting, multiple sclerosis, various neurological diseases, as well as depression, are being actively researched as possible candidates for medically justified uses of cannabis.

The paradox at the heart of cannabis is another active ingredient - Cannabidiol (CBD) - seems to directly counter-act the effects of psychosis and anxiety provoking aspects of THC. CBD is increasingly found to display powerful anti-anxiety and anti-psychotic effects. CBD may even, ironically enough, turn out to be used in a modified form as an anti-psychotic treatment in the future.

Sources of cannabis vary widely in the concentration of THC and given this active ingredient is sensitive to temperature and light, storage conditions over time leads to a decrease in THC content through oxidation of THC to CBD.

One problem is the varying concentrations of the bad stuff (THC) with the good (CBD), depending on what you are taking. Some analyses are that Hash (Resin) has 4% THC with 4% CBD, but other analyses put the level of THC up to 20%. Marijuana is found to boast 9% THC with 1% CBD; Skunk (Sinsemilla) - 16% THC AND 0% CBD, with some analyses suggest hash oil sometimes jumps over 50% THC.

Dr Fidelia Cascini, a Forensic Scientist at the University of Rome, has found dramatically increased concentrations of THC in police seizures of cannabis recently. This appears to be a replicated finding across the world. She is about to publish a review of all research on the strength of THC in cannabis from 1970-2009 in the academic journal 'Current Drug Abuse Reviews'. She has found a rise in THC concentration over this time, but a particular jump in more recent years. Previously this had been put down to cultivation techniques, such as indoor intensive growing.

THC is the psycho-active and therefore dangerous component of cannabis, and the more recent hike in its concentration raises the suspicion that the plant may have been covertly genetically modified to produce these high and more dangerous levels.

Dr Cascini has investigated the prospect of genetic modification, and in one sample she tested she found a trace of a substance often associated with genetically modified crops, strengthening concerns that some strains of cannabis have been genetically modified.

In her study entitled 'Investigations into the Hypothesis of Transgenic Cannabis' just published in the 'Journal of Forensic Sciences', Dr Cascini raises the possibility that this substance is a contaminant perhaps from a cover crop used to conceal the illegal cultivation.

Dr Cascini points out we already know that cultivation techniques have increased the potency of marijuana. Novel varieties such as, for instance, ''sinsemilla'' (from the Spanish ''sin semilla''--without seeds-- which is obtained from unpollinated female plants) and growing plants from selected seeds via intensive indoor methods, mean THC concentrations can reach as high as 20-30%.

Cascini also points out that genetic modification of plants used to produce psychoactive drugs has already definitely happened. Research recently published in the academic journal 'Plant Biotechnology Journal' demonstrated it was possible to genetically modify the morphine poppy to boost production of morphine-like substances from the plant by 15-30% dry weight.

Genetic modification of plants is growing - Vitamins have been increased 6-15-fold in plants through GM. Genetic modification of tobacco has altered aroma and nicotine content.

If Dr Cascini is right and Cannabis has been genetically modified to render it more potent - who would have done this? She speculates that those interested in the transgenic modification of cannabis might not just be those involved in illegal production, but could in fact include the Pharmaceutical Industry, because of the economic implications.

Dr Cascini points out that Cannabinoids from cannabis plants, even if derived from transgenic modifications, may be cheaper than those produced synthetically. Furthermore she speculates that the Pharmaceutical Industry are already known to be interested in the effects of other cannabinoids, and it would therefore make sense for them to be investigating genetic modification of cannabis. Different combinations of the chemicals this plant produces, could lead to massive possible therapeutic benefits.

Dr Cascini is continuing to investigate this story, but whatever she eventually finds, is this not a possible argument for legalising this drug? Legalisation would allow consumers proper knowledge of what they are taking, and make it more possible to choose less dangerous varieties. A transparent production process would in fact illuminate risks which remain outside of public debate. We now know you can be less sure than ever what is actually in the stuff. This changing landscape should prompt a review of the legal approach to drugs.

Further chemical analyses are obviously required to rule out the possibility the high concentrations of THC are not simply due to innovative and advanced cultivation techniques.

Linked to illegal drugs this week are the reports of fatal tragedies involving the wealthy Rausing family and the son of Sylvester Stallone. Is it not possible that many families would find it easier to confront the problems of drug abuse and be more likely to obtain medical help, if there wasn't the taboo associated with criminalising these substances?