Also...this is written from an economic perspective...so it can get a bit dry.
What are the health effects of marijuana?
From the reproductive system to the nervous system, marijuana use affects a wide range of systems in the body. Wayne Hall and Nadia Solowij wrote a comprehensive report in 1998 that aptly summarizes clinical evidence of the array of health effects that face users. Hall and Solowij’s analysis is a guide for determining whether marijuana is a harmful drug, and it highlights the important attributes of marijuana that are still unclear to the general public.
Hall and Solowij emphasize that cannabis dependence is the most common form of illicit-drug dependence in the United States (1998, p. 1614). Interestingly, the rate at which first time marijuana users become addicted occurs at a similar rate to that of alcohol. In the United States, about ten percent of people who ever try cannabis become daily users compared to that of alcohol at 15% and nicotine at 32% (1998, p. 1614). There is also clinical evidence that marijuana’s withdrawal effects are analogous to those of alcohol (1998, p. 1614). THC, the critical component in marijuana, affects the reward system in the body as alcohol, cocaine, and opioids such as codeine and morphine do (1998, p. 1614). Hall and Solowij advise doctors to warn patients that persistent/heavy use of marijuana affects an individual’s cognitive skills, ability to concentrate, and short-term memory during intoxication (1998, p. 1614). In the long term, heavy cannabis users are prone to respiratory problems such as chronic bronchitis and more seriously, aerodigestive and respiratory cancers linked to the inhalation of the carcinogenic smoke (1998, p.1613). Long-term use also subtly diminishes attention and memory that may not be reversible through prolonged abstinence (1998, p. 1614).
Hall and Solowij point to a number of statistics about marijuana that are similar to alcohol and tobacco. Considering the rates of addiction, marijuana is similar to alcohol, but the long term effects of heavy marijuana do not profoundly affect memory and cognitive function as chronic heavy alcohol use does (1998, p. 1614). Like tobacco smoke, the carcinogenic smoke of marijuana is linked to a higher risk of respiratory cancer, but addiction rates differ; one tenth of marijuana users become dependent while one third of tobacco users become addicted (1998, p. 1614).
Clearly, chronic, prolonged marijuana use harms the body in some way, but if that standard of prohibition is applicable to all goods, one would expect the government to prohibit the sale of tobacco and alcohol as well. Thus marijuana’s remaining implicit costs, the impact on human capital creation and the gateway effect, deserve careful consideration when considering legalization.