Cannabis is less dangerous than alcohol or tobacco, according to a major review published by the EU drugs agency.
The report said most users cease smoking cannabis by their late 20s or early 30s and that the vast majority did not experience any negative effects.
“On every comparison of dangerousness we have considered, cannabis is at or near the bottom in comparison with other psychoactive substances,” said author Robin Room, in an analysis contained in a 700-page EU report on cannabis.
The report, A Cannabis Reader: Global Issues and Local Experiences, was published yesterday by the European Monitoring Centre for Drugs and Drug Addiction to coincide with international day against drug abuse and illicit trafficking.
Mr Room examined a range of research on the health effects of legal and illegal drugs, which compared the substances based on dangerousness or harm, degree of intoxication and dependence. These found:
* Harm: Ecstasy and cocaine highest, followed by alcohol and heroin, with cannabis lowest.
* Intoxication: Alcohol highest, heroin next, then cocaine, cannabis fourth.
* Dependence: Tobacco highest, heroin second, cocaine third, alcohol fourth and cannabis lowest.
The study follows a report this week by the National Advisory Committee on Drugs, which highlighted sharp rises in cannabis use in many parts of Ireland.
Mr Room said a report by the French Roques committee divided the effects of drugs between general toxicity — involving direct health damage — and “social dangerousness”, with criminal and other behaviour resulting.
It rated cannabis as “very weak” in terms of toxicity and “weak” in terms of social dangerousness.
In comparison, alcohol was rated “strong” for both, with tobacco “very strong” and “none” respectively.
Heroin was rated “strong” (except for medical doses) for toxicity and “very strong” for social dangerousness. Cocaine was also rated “strong” and “very strong”.
Mr Room said the current international restrictions on cannabis were “too harsh”, compared with the greatly under-regulated systems for alcohol and tobacco.
In a separate analysis on the health impact of cannabis, researcher John Witton concluded: “Most cannabis users cease smoking cannabis by their late 20s or early 30s and the vast majority do not experience any adverse effects.”
He said a minority continue their use and that long-term heavy users reported negative health effects.
Irish cannabis use in 2007
* Nationwide: 22% of 15-64 year olds have taken cannabis (18% in 2003), 6% in the previous year and 3% in the previous month.
* East coast: the respective figures are: 36% (24%, 2003), 11% and 4%.
* West: 21% (12%, 2003), 4% and 2%. *(Source: NACD)