A new study by London's Imperial College's chair of neuropsychopharmacology, David Nutt, claims that the three most dangerous drugs in the world are alcohol, heroin, and cocaine -- in that order.  In the study Drug Harms in the U.K., published in what is arguably the medical community's most prestigious journal -- Lancet -- Professor Nutt outlines a convincing case for the controversial claim that alcohol is the most dangerous drug illegal or legal in the world today.

The study examined twenty different drugs, including tobacco, marijuana, methamphetamine, ecstasy, cocaine, heroin, and -- you guessed it -- alcohol.  The study gave each drug a rating in terms of its propensity to cause various personal problems --

health issues, injuries, dependency, mental impairment, loss of material wealth such as being fired from a job, and relationship loss.  Each drug was then rated on societal problems it caused -- crime, local decay, family problems, and a general economic cost to society.

Heroin and crack cocaine proved to be the most dangerous drugs to individuals.

However, when combined with the societal impact, alcohol came out ahead as the world's most dangerous drug.  And in most societies alcohol, unlike crack and heroin, is perfectly legal for adults to consume.

After alcohol, heroin, and crack cocaine, the next worse drugs were crystal methamphetamine and powder cocaine.  Then comes tobacco -- another legal drug.  In seventh place is amphetamine/speed.  Marijuana -- which is the subject of legalization controversy in the U.S. -- is deemed the eighth most harmful.

Surprisingly club drug ecstasy, despite a bad rap, is only in a three-way tie for fourteenth most harmful with qat and anabolic steroids.  Qat is a tropical flowering evergreen plant whose leaves can be chewed to provide a stimulant effect.  It is found in Northern Africa and on the Arabian Peninsula.

The least dangerous drug of the twenty evaluated in the study was magic mushrooms.

Despite the fact that the study states that cannabis is less harmful than alcohol or tobacco, Professor Nutt has urged that the drug be reclassified in the UK from a class C drug to a stricter Class B drug.  Conversely he's advocated that ecstasy -- which is also listed as less harmful by the study -- be downgraded from a Class A drug to a Class B or C drug.  Those opinions earned him termination from his government post.  Professor Nutt has worked on devising a less-harmful alcohol substitute consisting of valium-like solvated molecules.

Professor Nutt says this information is critical, in light of the ongoing international debate concerning what drugs should be legal and which ones should be made illegal.  He states on his personal blog, "By legislating on a substance without reliable scientifically based evidence, we run the risk of causing more harm through criminalizing users than might be caused by the drug itself. The evidence on drug harms should not be sacrificed for political and media pressure. "

In the article Professor Nutt asserts that "[Alcohol and tobacco do] have commercial benefits to society in terms of providing work and tax, which to some extent offset the harms."

But he says their legality increases their harmfulness, commenting, "[M]any of the harms of drugs are affected by their availability and legal status."

He concludes, "[A]ggressively targeting alcohol harms is a valid and necessary public health strategy."