The Japanese term for "drugs" is mayaku which literally means "hemp drugs". That leads people to believe that what is true for any of these drugs is true for all. This is not the case. All these substances come from different plants or chemicals. Hemp is a totally different plant from poppies. There is little that these drugs have in common with each other that they don't share with legal substances such as tobacco and alcohol. The English term "drug" is wider and catches alcohol and caffeine along with heroin and cannabis.
Just as with the legal drug alcohol not every case of use of other drugs is abuse. We only talk of abuse if use is continued despite serious negative effects, such as when use becomes compulsive and affects physical or mental health if it prevents the person from functioning as a member of society. The risk of such harm varies enormously from substance to substance (including legal ones such as alcohol, nicotine and caffeine) and from person to person. Though some substances have a higher potential for abuse than others, none are completely safe and none inevitably lead to addiction and disease. Whether a person uses or abuses a drug depends on many factors, such as their upbringing, their personal values, their family history of mental problems or substance abuse, the social context and regulations within these substances are used and the amount of information available to the users.
When you look into how scientists compare the abuse potential of drugs you'll see their rankings are quite different from those provided by our lawmakers. Contrary to what you'd expect, there is really no direct corelation between the legal status of a drug and its dangers (other than the danger of being arrested and prosecuted). Some of the most harmful drugs are legal while some of the least dangerous ones are strictly prohibited. The reasons drugs get banned are rarely medical and scientific. When drugs get banned it usually is for historical, social and racial reasons.
Cannabis is only relatively mildly intoxicating when compared to alcohol. Unlike opiates, alcohol and nicotine, marijuana doesn not cause physical addiction. If use is stopped there are no serious withdrawal symptoms, if any. It causes few problems with tolerance and is extremely safe with regards to overdoses. Though some people have died from taking too much caffeine or even drinking too much water, not even one person is known to have died of a marijuana overdose.
As more people discover the irrational aspects of our laws and the hypocritical double standards they represent, they lose their respect for the law and stop cooperating with law enforcement, ultimately making drug prohibition as unenforcable as alcohol prohibition was in the America of the 1920s and 1930s.
Various studies have analyzed the addiction potential of cannabis and compared it to legal substances such as alcohol and nicotine. Some these are the 1995 WHO report on cannabis, the 1997 German Kleiber study, the 1998 Roques report in France and the 1999 American Institute of Medicine report. Their consensus is that cannabis is physically non-addictive and that only a small minority of users (around 8%) develop a slight psychological dependence. The potential for dependence is generally rated lower than for alcohol and much lower than for nicotine.
Here are some figures from a table published in the 1999 Institute of Medicine report on marijuana that compare how many people in the USA use various drugs and how many of these drug users ever develop a dependency on this substance:
Prevalence of Drug Use and Dependencea in the General Population
As you can see, cannabis dependence is little more than half as likely as alcohol dependance. 10 out of 11 cannabis users do not become cannabis dependent, compared to 5 out of 6 alcohol users. Nicotine is more dependence forming than any of the other legal or illegal drugs reviewed.
Here is how two U.S. drug experts rated various drugs according to the individual factors that the U.N. World Health Organization (WHO) considers when determining addictive qualities . Both researchers were asked to rate six of the most common recreational drugs according to risk factors, from 1 being the most risky and 6 being the least risky of the six. This is how they ranked marijuana against caffeine and four other drugs:
Ratings by Dr. Jack Henningfield, NIDA:According to these ratings, marijuana is about as addictive a drug as coffee while alcohol, nicotine, cocaine and heroin are more risky, some considerably so. Alcohol is rated the most dangerous on withdrawal, as sudden abstinence can have life-threatening effects for an alcoholic. Alcohol is rated the most intoxicating of all the drugs listed while nicotine dependence is rated even ahead of heroin.
Dr. Henningfield works for the National Institute on Drug Abuse (NIDA), the U.S. government institution that conducts or finances about 80% of all drug abuse research worldwide.
Ratings by Dr. Neal L. Benowitz, University of California, San Francisco:The exact ratings by Dr. Benowitz were a little different, but the ranking is basically the same: Marijuana is one of the least addictive recreational substances, more comparable to coffee than to heroin or alcohol.
The nicotine contained in a single cigarette when eaten can kill a baby. The nicotine contained in 3-5 cigarettes can kill even a healthy adult. A large bottle of whisky in one night can kill an adult. Swallowing about fifty aspirin tablets will lead to unstoppable stomach bleeding that can be fatal. A tube of sleeping pills and you lose your liver... or your life! The caffeine in about 100 cups of coffee, taken in pill form, is lethal. All these substances are legal.
By comparison, according to tests on rats and monkeys, an adult would have to eat between 1 and 2 kg of marijuana, enough for rolling several thousand joints, all in a single day to run a risk of a fatal overdose. It is simply impossible to kill oneself by smoking or eating too much marijuana.
In 5.000 years of recorded marijuana history not a single person is known to ever have died from a marijuana overdose. After hearing extensive evidence Judge Young of the US Drug Enforcement Agency concluded in 1988 in his ruling on the legal status of marijuana as a medicine: "Marijuana, in its natural form, is one of the safest therapeutically active substances known to man."
Even though most users of marijuana do not develop problems, a small minority does use it a way that is problematic. The problem is not so much a function of the drug but of the people who use them in a way that can be disruptive. Many of these problem users also abuse other legal or illegal drugs, such as alcohol or amphetamines. Many come from troubled families, were abused as children or raised by parents with substance abuse problems. They don't have problems as a result of using cannabis but they use cannabis to avoid dealing with problems caused by their upbringing.
Cannabis doesn't solve their problems either but it can help to obscure them. For example, people who have low self esteem often feel adequate after they smoke cannabis. They feel they can live with their faults. This is only temporary, however and once they are sober again they feel just as bad as before. Therefore they tend to use cannabis excessively, rather than working to achieve something that would help build up their self esteem.
People who have difficulties interacting with others sometimes withdraw to avoid rejection. Normally they would get bored in their isolation, but cannabis lets them concentrate at the moment and shake off boredom. In essence, it allows them to survive as lonely, bored people rather than working on their problems.
The best way to help this sub-group of cannabis users is education and better availability of counseling and therapy. Treating them as criminals is actually counter-productive, as the threat of prosecution discourages them from admitting to their problems. Locking up problem users together with violent criminals exposes them to even more of the abusive behaviour that caused their personality problems in the first place.
A small group that got much attention in the past are cannabis using schizophrenics and other mentally ill people. It is estimated that about 1% of the population are at risk from schizophrenia, which mostly erupts in people in their early 20s, which coincides with a period when many people experiment with alcohol, cannabis or other drugs. Because some mental patients were found to be cannabis users, people claimed cannabis use led to their mental illness, the so called "cannabis psychosis" or "reefer madness". These claims were widely publicised by newspapers in the 1920s and 1930s. Some criminals took advantage of the hysteria, pleading innocent of violent crimes by virtue of temporary insanity caused by smoking cannabis. These well publicised cases provided where the reason given for banning cannabis in the USA and internationally, never mind that at the time estimates for the percentage of mental illness caused by cannabis quoted by supporters of a ban on cannabis varied as widely as between 60 and 2 percent of mental patients in a country where several percent of the population were current users.
By the 1940s scientists observed that there was really no evidence of any causal connection since the vast majority of cannabis users were as mentally sane as non-users. They concluded that "reefer madness" is simply a label attached to schizophrenia if the patient happened to be a cannabis user. There is no hard data proving that schizophrenia is more common amongst cannabis users than amongst non-users. Some psychiatrists event found fewer cannabis users amongst their patients than was estimated amongst the general population, suggesting that cannabis may help some mentally ill people to better cope with their illness. On the other hand it also may also obstruct recovery. There is little hard data if cannabis is harmful or helpful for mentally ill people. It would be cautious for people with a family history of mental illnesses to abstain from using cannabis and other psychoactive drugs unless prescribed by a doctor.
The risks associated with smoked marijuana can be avoided altogether by using it orally, as tea or cooked into food, which is how it has been used for centuries in India and other countries. It is estimated that in India about two thirds of all cannabis use was in the form of bhang, a drink made prepared from cannabis leaves. Only a minority of cannabis users actually smoked the plant as ganja (flowers) or charas (resin). Women in Jamaica typically use cannabis in the form a tea brewed from the leaves. In the late 19th century drug cannabis in the West was applied mostly as an alcoholic extract, or prepared as food or a drink, while smoking was relatively uncommon.
Unlike tobacco which can lead to cancer even when chewed or used as snuff, herbal cannabis itself is fairly non-toxic and does not contain any known cancer-causing substances. THC, the main active ingredient of marijuana, may even help to prevent cancer: A US government study in which rats were injected with high doses of THC found that fewer of those rats developed cancer than those that did not receive THC . A recent Spanish study found that THC reduced the size of tumors in rats and prolonged their survival.
The main reason oral cannabis use has become uncommon is because illegal cannabis is expensive. Since THC is absorbed more efficiently through the lungs than through the small intestine, smoking uses less of the relatively expensive substance. If marijuana was available legally and therefore at lower prices then far fewer people would smoke it and more would eat or drink it, eliminating those respiratory risks.
If science were to prove serious risks from smoking cannabis similar to those demonstrated for tobacco then from a public health point of view it still would not make sense to arrest users, which has proven ineffective. The most effective response would be to educate users about whatever risks there are and to suggest safer alternatives to smoking.
There has been limited research into vaporizers or inhalers (as used for asthma treatment), devices which allow for rapid onset of the effcets of THC in patients, without generating irritating smoke. Development of such alternatives was explicitly encouraged by the American Institute of Medicine to the US government in a study ordered by US "drug czar" McCaffrey. Currently, so-called "drug paraphernalia" laws that have been passed in many US-states make it illegal to sell or possess any device meant for consuming illegal drugs, even though some of these devices could help avoid or reduce risks associated with smoked cannabis.
This may sound like a bold statement, but it comes from the premier medical publication in the UK, and there are good reasons why the authors chose to make that statement. Though marijuana smoke and tobacco smoke contain many of the same substances (such as carbon monoxide and tars) there are still some major differences:
Three out of four tobacco deaths are not cancer-related. Instead, they happen because of cardiovascular diseases caused by nicotine which leads to a hardening of arteries. Cannabis does not contain nicotine. Therfore, even if the cancer risks were comparable cannabis should cause far fewer deaths and illnesses than does tobacco.
Amongst the cancer causing substances in tobacco smoke, nitrosamines are suspected to be major culprit. Nitrosamines are produced from nicotine when tobacco leaves are fermented. As cannabis contains no nicotine its smoke contains far lower levels of nitrosamines.
The main difference however is that cannabis smokers smoke a lot less cannabis than tobacco smokers smoke tobacco. While most tobacco users are daily smokers most marijuana users are not. The Japanese ministry of Health and Welfare estimates 53.9% of Japanese smokers are tobacco-dependent. A study by the German Ministry of Health estimated that by the same criteria, only 2% of cannabis users are psychologically cannabis-dependent. Cannabis is not physically addictive.
Only about a quarter of all Americans who have ever tried marijuana used it in the previous twelve months. Only half of those used it during the previous month. Many users only use it at parties, on weekends, or a single joint in the evening, to relax after a day's work. Unlike nicotine THC is not addictive and no serious withdrawal symptoms are produced when use of the drug is stopped even after extended periods of regular use.
Another difference is that like with crack cocaine the effects of nicotine on the central nervous system wear off after only about 15 minutes while THC remains active for between one and four hours. If the effects of the particular drug are experienced pleasant then one would have to smoke a lot more cigarettes than joints to experience those effects for any length of time. This is why two out of three male cigarette smokers in Japan smoke 20 and more cigarettes per day, while even heavy marijuana smokers smoke no more than maybe 5 times a day. Furthermore, a tobacco cigarette is contains between twice and ten times more tobacco than the typical dose of cannabis. The difference is greatest when compared to high grade marijuana, which as far as effects on the lung is concerned is actually less harmful than low grade marijuana.
Long-term studies by Dr. Donald Tashkin of the University of California, Los Angeles (UCLA) showed that lung function degrades with age by about as much for marijuana-only smokers as for non-smokers. Lung function degraded much more dramatically amongst tobacco-only smokers. Smokers who used both tobacco and marijuana actually did a little better than tobacco-only smokers, as the latter probably smoked more cigarettes in total.
The bottom line is that whatever risks there are from cannabis smoke, in practice they are likely to be significantly lower than for tobacco smoke. So far scientists have been unable to establish conclusive evidence of a relationship between marijuana smoking and lung cancer or other serious diseases that often affect tobacco smokers, despite millions of dollars of government money spent specifically trying to establish such links.
The largest study conducted so far involved 65,171 patients of the American medical insurance company Kaiser Permanente and was completed in June 1996. It found that marijuana-smoking women and men had a lower death rate than either cigarette smokers or people who drank three beers or more per day.
As long as cigarettes and beer remain legal while marijuana is not, the legal status of these drugs is inconsistent with their risks and people are given the false impression that alcohol and cigarettes are less harmful than cannabis when in truth they are much more harmful.
 See http://ntp-db.niehs.nih.gov/NTP_Reports/NTP_Chem_H&S/
NTP_Chem1/Radian1972-08-3.txt for toxicity data on delta-9 THC,
the main active ingrediant of marijuana.
http://ntp-server.niehs.nih.gov/htdocs/LT-studies/tr446.htm for the study
that showed fewer cancers in THC-treated animals.
 New Scientist (UK), 8 May, 1999, p18-19:
"The Lesser of two Evils"
 Japan Times, 1999.11.12: "33.63 Million Japanese smoke"
 Dieter Kleiber: "Cannabiskomsum in der Bundesrepublik Deutschland"
 See http://ntp-db.niehs.nih.gov/NTP_Reports/NTP_Chem_H&S/ NTP_Chem1/Radian1972-08-3.txt for toxicity data on delta-9 THC, the main active ingrediant of marijuana.
 See http://ntp-server.niehs.nih.gov/htdocs/LT-studies/tr446.htm for the study that showed fewer cancers in THC-treated animals.
 New Scientist (UK), 8 May, 1999, p18-19: "The Lesser of two Evils"
 Japan Times, 1999.11.12: "33.63 Million Japanese smoke"
 Dieter Kleiber: "Cannabiskomsum in der Bundesrepublik Deutschland"