Marijuana use increases throughout the calendar year, with use up 13 percent on average at the end of each year (2015-2019) compared to the beginning, according to a new study published in the journal Drug and Alcohol Dependence.
“We found that marijuana use is consistently higher among those surveyed later in the year, peaking during late fall or early winter before dropping at the beginning of the following year.
We think this may be due, in part, to a ‘Dry January’ in which some people stop drinking alcohol or even stop using marijuana as part of a New Year’s resolution,” said Joseph Palamar, Ph.D., MPH, an associate professor of population health at NYU Grossman School of Medicine, an affiliated researcher with the Center for Drug Use and HIV/HCV Research (CDUHR) at NYU School of Global Public Health, and the study’s lead author. “We’re now in the time of year when people are the least likely to use marijuana.”
Prior research shows that alcohol and drug use vary by time of year, with drug use often increasing during summer months, possibly due, in part, to social events.
These seasonal variations can inform interventions – for instance, studies show that programs to reduce heavy drinking among college students should begin during the summer.
To better understand seasonal trends in marijuana use, Palamar and his colleagues analyzed data from 282,768 adolescents and adults who responded to the National Survey on Drug Use and Health from 2015 to 2019. The survey asked participants about their past-month use of marijuana and other substances, and the researchers estimated their use within each calendar quarter: January through March, April through June, July through September, and October through December.
Each year, as the calendar year progressed, marijuana use grew, increasing in summer and fall months before dropping as each new year began. While 8.9 percent reported using marijuana in January through March, 10.1 percent reported using in October through December, a 13-percent relative increase.
These seasonal trends occurred independently of annual growth in marijuana use and were seen across nearly all groups surveyed, regardless of sex, race/ethnicity, and education level. Teens were one exception; their marijuana use grew in the summer but declined in the fall months back to winter and spring levels.
Recreational use may be driving the growth throughout the year, as similar small increases occurred among those living in states with and without legal medical marijuana, and among those without a prescription for medical marijuana.
Seasonal marijuana use also increased among those who reported using other substances, including alcohol, nicotine, and especially LSD.
The researchers note that the consistent dip in marijuana use during winter months could be a result of a variety of factors: a lower supply this time of year from cannabis harvests, colder weather keeping people inside who usually smoke outdoors, or people quitting marijuana as a New Year’s resolution.
“Ultimately, we hope that these findings can be utilized by researchers and clinicians alike,” said study coauthor Austin Le, DDS, a research associate at NYU Langone Health and orthodontic resident at NYU College of Dentistry.
“Researchers studying marijuana use should consider seasonal variation, as surveys administered at the end of the year may yield different results than at the beginning of the year. And for those who wish to reduce marijuana use, it appears the best time for such targeting may be later in the year—when use is highest.”
In addition to Palamar and Le, Benjamin Han of the University of California, San Diego’s Department of Medicine, Division of Geriatrics co-authored the study. The research was supported by the National Institute on Drug Abuse, part of the National Institutes of Health (grants R01DA044207 and K23DA043651).
Cannabis is a genus belonging to the Cannabaceae family. Cannabis includes three species, Cannabis sativa, Cannabis indica, and Cannabis ruderalis. However to date, there are still disagreements regarding whether or not cannabis is a single species (monotypic) or multiple species (polytypic) (Hartsel et al., 2016).
In addition, Cannabis sativa and Cannabis indica are frequently crossbred to produce hybrid phenotypes with desired characteristics (Hartsel et al., 2016). As the focus of this review is not the taxonomy of cannabis, the monotypic name will be used for the review for the simplicity of the text.
Cannabis, which is also known as marijuana, is the most frequently used recreational/illicit drug in Asia (Dargan and Wood, 2012), Australia (AIHW, 2016), Canada (Health Canada and Canada, 2012, Health Canada and Canada, 2017), the European Union (EMCDDA, 2018), the United States (CBHSQ, 2018; Cerdá et al., 2012), or in general, the most commonly abused drug globally (UNODC, 2019).
In 2017 it was estimated that the consumption of cannabis was 187 tons in the single state of Colorado (Adam et al., 2018). From March 2018 to February 2019, approximately 370 tons of cannabis were consumed nationwide in Canada (Werschler and Brennan, 2019).
The cultivation and use of cannabis are prohibited in most countries, as it is classified as an illicit drug (Sharma et al., 2012). However, the shift in perspective on cannabis has resulted in the legalization of cannabis (e.g., Canada and some U.S. states) for medical use and recreational purposes.
While the cultivation of Cannabis indica is illegal in many countries, the cultivation of hemp (Cannabis sativa L.), which consists of less than 0.2 or 0.3% Δ9-tetrahydrocannabinol (THC) by dried weight (Schluttenhofer and Yuan, 2017) for non-drug uses, is legal in more than 30 countries such as France and Australia (Schluttenhofer and Yuan, 2017), with China being the largest cultivator of hemp (Amaducci et al., 2015; The Economist, 2019).
It is predicted that the market share for cannabinoid-based drugs will expand up to 700% by 2020 (Saleh et al., 2019). The global cannabis market is also predicted to increase to US$ 40.6 billion by 2024 (George-Cosh, 2019).
After the legalization of cannabis for medical and recreational uses in October 2018, Canada saw an increase in the consumption of cannabis in the population above the age of 15 from 14% to 18% (STATCAN, 2019). After legalization in October 2019, cannabis edibles, extracts, and topical products are estimated to have a Canadian market of CAD$ 2.7 billion (The Canadian Press, 2019).
As a result of the increase in popularity of cannabidiol and hemp derived products in food and cosmetics (Hannaford, 2019; Wallace, 2019), an increase in cannabis, or more specifically cannabinoids, is expected to be released into the water systems and the environment.
More than 421 chemicals can be extracted from cannabis (Huestis, 2007; Sharma et al., 2012). Of these, at least 113 are cannabinoids (Aizpurua-Olaizola et al., 2016). Cannabinoids are a group of diverse organic compounds that directly affect the cannabinoid receptors in the brain.
Two well-known cannabinoids are THC and cannabidiol (CBD). The primary psychoactive compound, THC, is a volatile lipophilic viscous oil that contributes to the undesirable effects on the behavior caused by consumption of cannabis. CBD is credited for the medicinal properties of cannabis.
Cannabinoids can enter the body by three main routes that include inhalation, ingestion, and through the skin. After inhalation, THC is distributed to liver, spleen, adipose tissue, and lungs (Musshoff and Madea, 2006).
When inhaled, THC quickly enters the bloodstream via the lungs and is then metabolized to 11-hydroxy-Δ9-tetrahydrocannabinol (THC-OH) by the liver. THC-OH is then converted into the main metabolite 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH), which is then excreted in human urine and feces, as a glucuronic acid conjugate (Castiglioni et al., 2008; Khan and Nicell, 2012).
When dermally absorbed, THC enters the bloodstream through the skin. In this instance, the rate of diffusion of THC through the aqueous layer of the skin is the rate determining step for dermal THC absorption (Huestis, 2007). If ingested, the THC enters the bloodstream through the liver, resulting in delayed psychoactive effect (Huestis et al., 2006).
After excretion and during wastewater treatment, beta-glucuronidases of fecal bacteria could readily hydrolyze THC-COOH back to its free acid form (Huestis, 2005). While THC-COOH is not a psychoactive compound, it can remain in the body from several days to weeks, depending on the doses of the users (Brenneisen et al., 2010).
Therefore, THC-COOH has been used in many studies as biological marker for cannabis consumption and in several sewage epidemiology studies as a surveillance tool (Balducci et al., 2016; Daughton, 2001; Khan and Nicell, 2012; Postigo et al., 2011).
Cannabidiol (Table 1 ), the main non-psychoactive cannabinoid constituent, is another dominant cannabinoid in cannabis. Like THC, it is biogenerated from cannabigerolic acid, thus it has a similar molecular structure to THC (Table 1).
With respect to the medicinal use of cannabis, CBD and synthetic cannabidiol are both used for pain relief (Hammell et al., 2016; Russo, 2008). In 2018, a cannabinoid-based pharmaceutical under the tradename of Epidiolex was approved by the US Food and Drug Administration for the treatment of seizures related to two severe types of epilepsy, Lennox-Gastaut syndrome and Dravet syndrome (USFDA, 2018). In 2019, the sales of CBD products were legalized in Canada with restriction under the Cannabis Act (Health Canada, 2019).
Table 1
Structures and molecular information of major cannabinoids and metabolites.
| Name | Δ9-tetrahydrocannabinol | 11-hydroxy-Δ9-tetrahydrocannabinol | 11-nor-9-carboxy- Δ9-tetrahydrocannabinol | Cannabidiol | Cannabinol |
|---|---|---|---|---|---|
| Abbreviation | THC | THC-OH | THC-COOH | CBD | CBN |
| Molecular formula | C21H30O2 | C21H30O3 | C21H28O4 | C21H30O2 | C21H26O2 |
| Molar mass (g mol−1) | 314 | 330 | 344 | 314 | 310 |
| Pka | 9.81a | 9.78 ± 0.60b | 4.87/9.30a | 6.43a | |
| 9.81 ± 0.60b | 4.66 ± 0.40b | ||||
| Log Kow | 7.68a | 5.36 ± 0.42b | 6.21 | 7.03a | |
| 6.84 ± 0.35b | 5.25 ± 0.38b | ||||
| Aqueous solubility (mg L−1) | 0.040a | 7.931b | 0.230a | 0.006a | |
| 0.786b | 309b | ||||
| Structure |  |  |  |  |  |
bPark et al. (2016).
Cannabinol (CBN), shown in Table 1, is a mild psychoactive compound with only 10% of THC potency (Izzo et al., 2009). CBN is another common type of cannabinoid that is a major constituent in aged or cured cannabis but only a minor constituent in fresh cannabis. CBN is formed from the degradation of THC in the presence of oxygen or heat (Hartsel et al., 2016). This cannabinoid is used as a chemical indicator of improper cannabis storage and aging.
Due to the increase in the market demand for cannabis related products, there is an increase in cannabis cultivation (Chen, 2017), cannabinoids extraction (Subramaniam, 2019), and cannabis related products production. This would therefore increase the chance of cannabinoids releases into the environment through agricultural and industrial wastes.
While the approval of cannabis as recreational drug might not significantly increase the cannabinoids release to the environment, the rapid increase in the demand for cannabinoid-based pharmaceuticals such as Epidiolex and the change in the perspective of the cannabis for medical uses would likely cause an increase in cannabinoids release into the environment.
With the recent change in legalization for the use and consumption of cannabis, it is timely to review the analytical methods and its occurrence in water systems. The toxicity and treatment of cannabinoids were also reviewed to understand the environmental impacts of cannabinoids and to address the lack of knowledge in the environmental field.
reference link : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7489229/
More information: Joseph J. Palamar et al, Quarterly Trends in Past-Month Cannabis Use in the United States, 2015-2019, Drug and Alcohol Dependence (2021). DOI: 10.1016/j.drugalcdep.2020.108494
