Zammit and colleagues’ findings were supported in a 3-year longitudinal study of the relationship between self-reported cannabis use and psychosis in a community sample of 4848 people in the Netherlands (van Os et al., 2002). Van Os and colleagues reported that cannabis use at baseline predicted an increased risk of psychotic symptoms during the follow-up period in individuals who had not reported psychiatric symptoms at baseline. There was a dose–response relationship between frequency of cannabis use at baseline and risk of psychotic symptoms during the follow-up period. These relationships persisted when they statistically controlled for the effects of other drug use. The relationship between cannabis use and psychotic symptoms was also stronger for cases with more severe psychotic symptoms.
According to researchers, 25 percent of all cancer patients use medical marijuana. Cancer patients are finding relief from medical cannabis. And they want to know more about it. Research conducted at St. George’s University of London, found the two most common cannabinoids in marijuana, tetrahydrocannabinol (THC) and cannabidiol (CBD), weakened the ferocity of cancer cells and made them more susceptible to radiation treatment. Other studies have shown that medical marijuana treatments can slow the growth of cancer cells and halt their spread to other parts of the body.
Pharmacologic effects of inhaled marijuana occur within minutes but rarely persist longer than 2 to 3 hours. The likelihood that an acutely intoxicated patient would come to the operating room is small. Severe tachycardia should be controlled preoperatively with labetalol or esmolol. Animal studies have demonstrated decreased dose requirements for volatile anesthetics, barbiturates, and ketamine after the intravenous injection of THC. Possible intraoperative complications include bronchospasm secondary to airway irritability by the marijuana smoke, although marijuana is a bronchodilator.
In the United States, cannabis is overall the number four value crop, and is number one or two in many states including California, New York and Florida, averaging $3,000 per pound ($6,600/kg). Some believe it generates an estimated $36 billion market. Some have argued that this estimate is methodologically flawed, and makes unrealistic assumptions about the level of marijuana consumption. Other estimates claiming to correct for this flaw claim that the market is between $2.1-$4.3 billion. The United Nations Office on Drugs and Crime claims in its 2008 World Drug Report that typical U.S. retail prices are $10–15 per gram (approximately $280–420 per ounce). Street prices in North America are known to range from about $40–$400 per ounce ($1.4–$14/g), depending on quality.
The scientific debate regarding taxonomy has had little effect on the terminology in widespread use among cultivators and users of drug-type Cannabis. Cannabis aficionados recognize three distinct types based on such factors as morphology, native range, aroma, and subjective psychoactive characteristics. Sativa is the most widespread variety, which is usually tall, laxly branched, and found in warm lowland regions. Indica designates shorter, bushier plants adapted to cooler climates and highland environments. Ruderalis is the informal name for the short plants that grow wild in Europe and Central Asia.
^ McLaren JA, Silins E, Hutchinson D, Mattick RP, Hall W (January 2010). "Assessing evidence for a causal link between cannabis and psychosis: a review of cohort studies". The International Journal on Drug Policy. 21 (1): 10–9. doi:10.1016/j.drugpo.2009.09.001. PMID 19783132. The contentious issue of whether cannabis use can cause serious psychotic disorders that would not otherwise have occurred cannot be answered based on the existing data
In 2014, President Obama signed the Farm Bill of 2014 into law. This law contained a section that removed hemp from Schedule 1 of the Controlled Substances Act. It also created a legal structure that made cultivation and research of hemp legal in states that wanted to initiate “Pilot Research Programs” into the cultivation and marketing of hemp and hemp-derived products.
Wild North American hemp is derived mostly from escaped European cultivated hemp imported in past centuries, perhaps especially from a revival of cultivation during World War II. Wild Canadian hemp is concentrated along the St. Lawrence and lower Great Lakes, where considerable cultivation occurred in the 1800s. In the US, wild hemp is best established in the American Midwest and Northeast, where hemp was grown historically in large amounts. Decades of eradication have exterminated many of the naturalized populations in North America. In the US, wild plants are rather contemptuously called “ditch weed” by law enforcement personnel. However, the attempts to destroy the wild populations are short-sighted, because they are a natural genetic reservoir, mostly low in THC. Wild North American plants have undergone many generations of natural adaptation to local conditions of climate, soil and pests, and accordingly it is safe to conclude that they harbor genes that are invaluable for the improvement of hemp cultivars. We have encountered exceptionally vigorous wild Canadian plants (Fig. 52), and grown wild plants from Europe (Fig. 53) which could prove valuable. Indeed, studies are in progress in Ontario to evaluate the agronomic usefulness of wild North American hemp. Nevertheless, present policies in North America require the eradication of wild hemp wherever encountered. In Europe and Asia, there is little concern about wild hemp, which remains a valuable resource.
In late 2017, researchers with the University of Guelph in Canada published the first-ever study to document the ideal growing conditions for cannabis. Using liquid organic fertilizer with a PKN ratio of 1.3P–1.7K-4.0N, the experiment tested five increasing rates of fertilization. They also tested two coir-based soil-less growing media, or “substrates.”