Cannabis is hundreds of times less deadly than alcohol at both a personal and population-wide level, a study has found.
Scientists examined drugs ranging from alcohol and tobacco to ecstasy and heroin, comparing known lethal doses and the average amount used to find which substances posed the biggest problems to society.
Alcohol, nicotine, cocaine and heroin all fell into the 'high risk' category for individuals, while only alcohol posed a 'high risk' in terms of population exposure.
But THC - the active component in cannabis - was found to be significantly outside any risk in both categories.
And even some of the Class A drugs which posed a 'high risk' for individuals - which included opiates, cocaine, amphetamine-type stimulants, ecstasy and benzodiazepines - fell below the 'risk' threshold when looked at on a population-wide level.
The paper's authors, led by Dr Dirk Lachenmeier of the Technische Universitat Dresden, Germany, warned that the results should not be taken to mean, for example, that moderate, regular heroin use was safer than moderate, regular alcohol use.
But, they added, it points towards the idea that governments should focus more on tackling problems caused by alcohol and cigarettes than on banning substances.
Writing in the Scientific Reports journal, they said:
The study used a measurement called the 'margin of exposure' (MOE), which measures the ratio between the lethal dose of a substance derived from animal studies and estimated typical human intake of that substance.
The lethal doses ranged from two milligrams per kilogram of bodyweight for heroin to 531mg for alcohol.
A MOE ratio of less than 10 put the drug into the 'high risk' category, while less than 100 categorised it as a 'risk'.
On a population scale, cannabis had a MOE of more than 10,000 - well outside the 'risk' limits - and of around 600 on personal scales.