Comparing nicotine and marijuana is not straightforward. Nicotine is so closely associated with tobacco and smoking that assessing the compound on its own is difficult. Marijuana is making the transition from evil to medicinal but is still the subject of scrutiny.

Usage figures make for interesting reading. In 2016, according to the CDC, 17.5% of men and 13.5% of women smoked a tobacco-based product, with the highest number (18%) falling into the age band of 45 to 64. Studies published by NIH indicate that Marijuana is also used more by men than women. Unlike with nicotine, though, most marijuana users are adolescents or young adults with 35.6% of 12th graders using the drug regularly.

A discussion of nicotine and marijuana’s history, the nature of the compounds, their effects, issues around legality, and the way both are currently viewed by society are useful ways of comparing them.

History

Both nicotine and marijuana have been through various stages in terms of their identification, classification, usage, and perception.

Nicotine:

Nicotine is a naturally occurring organic compound and an alkaloid (i.e. a substance with a high nitrogen content). These compounds have marked physiological effects on people. Most of us equate nicotine exclusively with tobacco. This isn’t an unreasonable association given the tobacco plant contains high levels of this very addictive compound. However, it’s also found in extremely small amounts in potatoes, tomatoes, eggplant, and red peppers all of which are part of the nightshade family.

In “Everything you need to know about nicotine”, Adam Felman points out that the indigenous tobacco plant has been used as a stimulant and medicine in the States for millennia.  Cigars and pipes were in fairly widespread use from the 1600’s. It’s interesting to note that even that long ago, “Some saw tobacco as medicinal, while others saw it as toxic and habit-forming”.

The first identification of crude nicotine was in 1571, and its pure form was first distilled as far back as 1828. After the molecular formula was established in 1843, this alkaloid could be synthesized in the laboratory. Prior to this, nicotine was used as an insecticide and poison. By the end of the 1800’s, despite the recognized toxic and addictive nature of nicotine, cigarettes were being mass produced.

It was this process that led to the virtually inextricable connection of nicotine with smoking, the primary source or delivery method of nicotine.

Marijuana:

While nicotine is found in a family of plants, marijuana (also known as cannabis, grass, pot, weed, or dope) is the product of only two: Cannabis indica and Cannabis sativa. The stems, leaves, seeds, and flowers are used, usually in dried form although extracts are also sometimes produced. These plants contain over 100 cannabinoids – mind-altering chemicals – with Tetrahydrocannabinol or THC the principal psychoactive constituent.

The history of marijuana also stretches back many centuries. The first written record dates to China in 2727 B.C. The dateline provided by PBS indicates that hemp was grown commercially in America in the 1600’s for its fiber. However, it wasn’t until the 1800’s that the plant was used for medicinal purposes by non-native individuals in the U.S.

After the Mexican Revolution in 1910, recreational cannabis was introduced into the U.S. The hostility towards these migrants extended to the marijuana that came with them. During the 1930’s and the Depression antagonism and fear increased, and marijuana use was linked to criminal, violent, and deviant behaviors. Come 1939 marijuana was illegal in 29 states, beginning with those in the south west.

Photo by Get Budding / Unsplash

Another reason for the demonization of marijuana is that it was believed to be a gateway drug. In other words, using cannabis led to the use of much harder illegal drugs. An article published by Drugabuse.gov cites findings from a study that shows that rodents exposed to THC when they are young show “enhanced” reactions to other addictive substances due to changes in their brains and pleasure responses. However, there is further evidence that most marijuana users do not move to hard drugs.

A CBS News report compiled by by Anthony Salvanto, Fred Backus, Jennifer De Pinto, and Sarah Dutton states that 43% of Americans used marijuana regularly in 2015, and this figure increased to 51% in 2016. Usage amongst the young is widespread. The fact that the statistics with school-goers and young adults are still high is ascribed to the change in perceptions of the drug linked to discussion of, and changes to, its legal status. A poll in 2017 indicated that 56% of Americans believe that marijuana should be legal, a huge shift since the 27% in 1979.

The Pharmacology of Nicotine and Marijuana

There are chemical reactions in our bodies caused by nicotine and compounds within marijuana. These explain why and how both are addictive.

Nicotine:

Nicotine is a unique compound in that it has a biphasic effect. This means that it can have either a tranquilizing or a stimulating effect. The former is the result of taking deep drags and the latter by taking in smoke in quick, short puffs.

While nicotine is the largest and most addictive component of tobacco smoke, it is only one of more than 4000 compounds. However, consensus is that nicotine is the one that impacts on the body more than any other, and its effects are profound.

  • The neurotransmitter acetylcholine: One area that is affected within seconds are neurotransmitters. This is particularly marked with the neurotransmitter acetylcholine and the receptors that it binds to. The relationship between transmitter and receptor is disrupted and this can lead to addiction.

Acetylcholine transmitters and their receptors are not only found in one part of the brain but in several cerebral areas and in many organs. They carry vital messages that govern muscle movement, heart rate, respiration, and even memory. A further significant aspect is that nicotine, thanks to its similar shape, mimics acetylcholine. It fits the receptors and acts the same way as acetylcholine. This makes nicotine an agonist or a chemical that binds and activates a receptor.

The result is that the receptors are being fired too often by both nicotine and acetylcholine. The brain behaves as though there is too much acetylcholine by reducing receptor numbers and the quantity of acetylcholine. Without adequate naturally released acetylcholine the brain depends on the imposter – nicotine – to function properly. Nicotine is needed to feel ‘normal’; this is the essence of addiction.

  • Dopamine release: Another neurotransmitter acted on by nicotine is dopamine which carries signals that stimulate the reward system that in turn generates feelings of well-being and pleasure. The reward system involves several regions of the brain. Furthermore, the levels of the enzyme that breaks down dopamine are decreased by nicotine. As a result, dopamine levels in the brain are higher than normal leading to increased feelings of pleasure. This, too, explains why nicotine is so addictive.
Photo by Riccardo Fissore / Unsplash

Marijuana:

The primary compound in marijuana is tetrahydrocannabinol or THC. Like nicotine, it can mimic aspects of body chemistry. This has several effects and consequences.

  • THC has a chemical structure that is very similar to anandamide which is a neurotransmitter and a naturally occurring cannabinoid. Its function is to send messages from one neuron to the next throughout the body’s nervous system.  THC, thanks to its similar structure, can attach to molecules know as cannabinoid receptors that are found on neurons.

This means that the body alters normal brain communication because it mistakes THC for anandamide. THC activates neurons and disrupts normal physical and cognitive function as a result. These functions include co-ordination, movement, thinking, memory, concentration, and even how we perceive time and sensations.

  • As nicotine does, THC activates the brain’s reward system. The resultant flood of dopamine leads to the “high” associated with marijuana and the subsequent desire to use it again to feel those levels of pleasure.  

Unlike with nicotine levels in cigarettes, the potency of marijuana has increased due to a rise in THC levels. A report by Drugabuse.gov indicates the quantity of THC rose from 3.8% in the 1990’s to 12.2% in 2014. This increases the possibilities of users sustaining harm. The risk is especially great for young people whose brains are still developing.

Their Respective Impacts On Health

There has been a great deal said and written about the effects of both nicotine and marijuana on health. Not only is there a lot of information, it can sometimes be contradictory or partisan or both.

Nicotine:

The impact of nicotine on our bodies and minds is much more of a mixed bag than you’d expect. We’re exposed to data, images, and statistics about the dangers of smoking including the fact that it is the leading cause of preventable death in the U.S.

What is hard – if not impossible – is to state what the mortality rates for nicotine are. The statistics available are for “smoking-related” illness and death rates. Are they down to the smoke, the tobacco, nicotine, or one of the thousands of other compounds, or a combination?

The negative effects of nicotine

According to Drugabuse.gov, nicotine affects heart rate and blood pressure within 8 seconds of smoke inhalation. The article states that although nicotine is the addictive compound, it’s the tobacco that is carcinogenic and cites the fact that smoking and chewing tobacco both cause mouth, throat, and lung cancer. Nicotine on its own has been identified as causing tumors in rats but can’t be linked to cancer in humans yet.

As discussed earlier, what makes nicotine so highly addictive are its effects on acetylcholine neurotransmitters and dopamine levels. When nicotine is removed, withdrawal symptoms are often experienced. These range from the cravings so often mentioned to anxiety, irritability, poor concentration, and even depression.

In addition to the effects on neurons and dopamine, nicotine stimulates the adrenal glands which release adrenalin. This is responsible for the ‘rush’ experienced as the hormone causes a rise in blood glucose and breathing levels, heart rate, and blood pressure. The pancreas reduces the amount of insulin it produces which also increases blood sugar. Nicotine has been linked to hardening of the arteries. Finally, it inhibits the production of the anti-inflammatory protein called interleukin-10.

A further health consideration is the impact of nicotine on babies before and after birth. Research indicates that nicotine, along with various toxins inhaled while smoking, passes into the blood stream and is carried to the unborn child. The baby also receives less oxygen and there’s a greater than average chance of premature birth, low birth weight, respiratory complications, and – in rare cases – miscarriage or still birth.

Photo by Tim Bish / Unsplash

The pros of nicotine

In terms of psychodynamic effects, however, nicotine absorption can be beneficial. For example, it increases alertness, improves mood, boosts concentration and memory, and increases wakefulness or mental arousal. This is attributed to nicotine increasing levels of norepinephrine and higher levels of beta-endorphin which reduce anxiety. For some the fact that nicotine reduces appetite is also a pro.

In his article on nicotine as a smart drug, Dave Asprey goes so far as to call nicotine a powerful smart drug but only in low doses and in its pure form. He points out that in this form nicotine no longer has “toxins and carcinogens wrapped around it” and has real value as a cognitive and performance enhancer. To support his argument, Asprey mentions study findings that show that nicotine improved attentiveness, concentration, short-term memory, motor skills, and reaction times. The nicotine used by the researchers were in gum, patch, oral spray, or injection form. Recommended ‘doses’ are one to two milligrams occasionally.

Marijuana:

In “All smoke is not created equal”, Paul Armento points out that “although tobacco smoke and marijuana smoke have some similar chemical properties, the two substances possess different pharmacological activities and are not equally carcinogenic”. Various sources and studies support his assertion.

The negative effects of marijuana

As with nicotine, addiction is a reality. However, there appears to be a vast difference in the percentage of users who become addicted. Those who use pot before they are 18 years of age are more likely to become dependent. According to the National Institute on Drug Abuse (NIH), approximately 30% of all users have some degree of dependence. However, this is not the same as full-blown addiction.

Without the THC in marijuana, long-term users experience withdrawal symptoms like the ones felt by individuals addicted to nicotine: cravings, insomnia, anxiety, loss of appetite, and irritability. Nicotine is more addictive than marijuana, though. It is thought that only 9 - 10% of marijuana users are addicts unless they began in their early teens and then it rises to 17%.

Although a marijuana-induced high can be pleasurable and enhance the senses, there are less desirable consequences too: lowered inhibitions, increased appetite (the “munchies”), an altered perception of time, dizziness, nausea, anxiety, confusion, slowed reaction times, and – with very strong forms of the drug – there may even be paranoia, hallucinations, panic attacks, and affected memory. There is some indication that long-term, regular use can negatively impact the ability to concentrate and learn.

Those individuals who suffer from chronic respiratory conditions may be more affected by smoking marijuana as there may already be some lung inflammation. Other vulnerable individuals may be more at risk of developing long-terms psychiatric problems including severe illness such as schizophrenia.

As with nicotine, mothers who use cannabis during pregnancy risk harming their baby. THC negatively affects the baby’s developing brain, and babies born to users are reported to experience abnormal responses to visual stimuli, problems with attention, increased trembling, have high pitched cries, and, as they get older, difficulties with problem-solving and memory.

In terms of mortality, no deaths that are clinically and directly due to marijuana have been reported, although some individuals may sustain injuries, even fatal ones, by doing risky things or driving while under the influence of cannabis. There is currently no evidence that marijuana reduces overall life expectancy.

The pros of marijuana

There are many health benefits of cannabis including some that are counterintuitive. For instance, marijuana smoke contains many cannabinoids, and some of them minimize carcinogenic pathways. Conversely, tobacco smoke enhances some of these pathways. The fact that marijuana users inhale less smoke during a month than tobacco smokers may also have a bearing on cancer occurrence.

Furthermore, studies acknowledge that there is no positive correlation between marijuana smoke exposure and lung cancer, emphysema, or chronic obstructive pulmonary disease (COPD). This may be in part because THC has bronchodilator, immune-suppressing, and anti-inflammatory properties.

Not only is there no apparent damage to lung function with marijuana smokers, they have better lung function than both smokers and non-smokers. There have been several studies conducted by reputable organizations and institutions such as UCLA that support this. Moderate to infrequent cannabis users were found to have increased lung function. Heavy cannabis users (20 or more a month) may be impacted negatively, however. One theory is that taking the deepest possible breath and holding it, as users do, expands the lungs. Conversely, tobacco smokers progressively lose lung function.

Cannabis offers another clinically valuable cannabinoid in addition to THC: cannabidiol (CBD). Both are active ingredients in medications used to relieve muscle spasms associated with multiple sclerosis or nausea and vomiting following chemotherapy. Other cannabinoid preparations are used for chronic pain relief, glaucoma, epilepsy in children, and to boost appetite in those with HIV or AIDS. Some of these are still undergoing clinical trials.

Two studies that were conducted yielded results that support the legalization of marijuana. They found a clear link between medicinal cannabis use and a reduction in deaths from overdose on pain relievers, access to legal marijuana dispensaries reduces levels of opioid prescribing and the use of nonprescription opioid for nonmedicinal purposes.

Photo by Esteban Lopez / Unsplash

Nicotine and Marijuana:

Nicotine and marijuana both affect our minds, but what about when they are combined? That question was behind a study carried out at the University of Dallas at Texas. Findings indicated that the hippocampus – the part of the brain responsible for memory and learning – is significantly smaller in those who use marijuana and those using both nicotine and marijuana.

Individuals who don’t smoke nicotine-containing products or marijuana have a clear correlation between hippocampal size and memory: the smaller the hippocampus the poorer the memory function. In users of both cannabis and nicotine, however, something unexpected happens: the smaller the hippocampus the better the memory.

Additionally, there has been a belief that cannabis and nicotine cause “popcorn lung”. According to Medical News Today, neither do. This condition is attributed to inhaling harmful particles, fumes, or toxins. One of the culprits is diacetyl which was used to flavor e-nicotine used in vaping. It is reportedly no longer used.

Nicotine and Marijuana Delivery Methods

As with other aspects of these substances, there are similarities and differences when it comes to delivery methods for both nicotine and cannabis. What is important to focus on is not only the forms both can take but how bad each is for the user.

In broad terms, it can be agreed that inhaling smoke – regardless of the toxins that it is laced with – is damaging to the lungs in several ways and to varying degrees. For instance, while marijuana smoke may not cause constriction of the airways and loss of lung function the way other smoke does, smoke still causes irritation and may result in lesions in the lungs.

Nicotine:

Cigarettes, cigars, and pipes have been with us for a very long time as have snuff and chewing tobacco. Other forms of nicotine delivery include the more recent gum, patches, lozenges, mouth spray, and vaping and e-juice. Each provides nicotine, but they are vastly different in terms of their down-sides. In order of worst / least health to least unhealthy:

  • Smoking: this delivery system delivers nicotine to the body and brain in 4 to 8 seconds. This method has no physiological upside worth risking all the dangers for.
  • Chewing tobacco: while the lungs may be spared, chewing tobacco is highly carcinogenic and releases a staggering 3 to 4 times the amount of nicotine that cigarettes do.
  • E-cigarettes / vaping: although this is less bad for you than smoking or chewing tobacco, this delivery system is already controversial with concerns over toxins and – at this stage – unknown medium- to long-term risks.
  • Gum: given the nicotine yield is low (2 – 4 micrograms) and the release time is slow (20 – 30 minutes), you get the benefit of nicotine without the negatives of the previous three forms. The disadvantages are the same as with any other gum: less than ideal artificial sweetening agents and too much chewing action which can adversely affect the jaw and trigeminal nerve in the jaw and face.
  • Patches: these release nicotine even more slowly than the gum but on the flip side they contain more nicotine. The most important factor to keep in mind is that the dose must remain low (1 to 4 micrograms) so the stronger patches should be avoided.
  • Lozenges: what is good about these is you can get low doses (so-called mini-lozenges) and, if you such them, the release rate is fairly slow. However, like many of the nicotine gums the lozenges may be packed with unhealthy artificial sweeteners and other chemicals.
  • Spray: each spray provides about 1 microgram of nicotine. Because it is sprayed under the tongue the effects are felt quickly. There doesn’t appear to be any negative effects on the digestive system.
  • Inhalers: this uncommon delivery method is chemical free and provides nicotine-scented air.  The concern is that puffing on an inhaler may be addictive in and of itself.

If you are looking for a boost, more sustained energy, and improved focus, concentration or alertness then nicotine can provide them, but only when the dose is very low and if the release is slow and controlled. Gum, patches, lozenges, and spray are the options to go for.

Marijuana:

There is an even broader range of delivery methods for marijuana although they are placed in three categories: inhalants, ingestants (or edibles), and the ever-popular “other”. Users select one based on what they enjoy and what they want from the cannabis:

  • Smoking: as with nicotine, this is the most common and fastest delivery method. It gets THC into the bloodstream and to the brain in 4 to 8 seconds. While some evidence shows that THC is not harmful to lung health in several respects, the problem is that one does not inhale pure cannabis; it is often contaminated by other plant material and usually wrapped in paper or even tobacco which are bad.

The range of inhalants is surprisingly broad. Joints are cannabis rolled in cigarette paper. They may contain a mix of marijuana and tobacco which is a particularly potent mix. Blunts are more substantial than joints as they contain more cannabis, are thicker, and rolled in cigar paper.

Pipes and bowls don’t require any rolling as the marijuana is placed in the bowl and lit. This is a quicker way to get high, but the cannabis must be relit for each drag. Bongs and bubblers (miniature bongs) contain are a filtration device through which the smoke is drawn. Bongs also contain water. While the smoke is less harmful as it is both filtered and cooler, this delivery method causes rapid highs.

Finally, dabs (solidified hash oil) are a very potent marijuana extract that are melted with a blowtorch as a lighter is not hot enough. The vapors are then inhaled. While this is still smoking, there is no smoke and the vapor is pure which makes it the healthiest form. However, this delivery method produces an intense high that brings dangers of its own.  

  • Vaporizers: this delivery form, as with dabs, produces a vapor that is inhaled. Unlike with smoking, the marijuana is heated rather than burnt which makes it a healthier option for the lungs. A second filling for a vaporizer is oils rather than plant material; this contains a far higher percentage of THC.
  • Ingestants / edibles: this is a good route for users who don’t want to inhale either smoke or vapor. Cannabis can be included in various foods or ingested in the form of drinks, mouth sprays, capsules, and tinctures which can be added to drinks or foodstuffs. While these are healthier than smoking, they carry other potential problems. Firstly, the effects are stronger and, secondly, it takes longer to feel them (30 to 130 minutes). Less experienced users are likely to consume more – and too much – because they think the drug isn’t working.
  • Other delivery methods: a newer method is to apply marijuana topically using creams or lotions. In addition to not affecting the lungs, this option also doesn’t produce a high as the brain is unaffected. It’s the option for those wanting relief from localized pain or inflammation. Finally, as with nicotine one can obtain marijuana via a patch applied to the skin that releases the drug slowly. The active ingredients of cannabis are absorbed through the skin into the bloodstream.

The bottom line is that with both nicotine and marijuana smoking is the unhealthiest delivery method. Gum, patches, and ingestibles such as sprays are the least unhealthy way to obtain the drug in low, sustained doses that offer some beneficial effects.

Nicotine:

It wasn’t until the end of the end of the 1800’s that the dangers of nicotine were really grasped, and by 1890 twenty-six states legally prohibited the sale of nicotine products to minors. 1964 saw the U.S. Surgeon General publishing a study which made a connection between smoking and lung cancer and heart disease. Thirty years later the Food and Drug Administration (FDA) listed nicotine as an addictive substance.

The Supreme Court granted the FDA regulatory control over nicotine in terms of marketing and production. Products that contain pure nicotine, such as patches and gum, are governed differently than tobacco-containing products like cigarettes. Nicotine possession is legal although the FDA regulates non-tobacco nicotine-containing products as they do drugs.

While Congress has not adopted a nationwide smoking ban, bans have been implemented on state, regional, or local levels. California was the first to impose a statewide ban and others followed. The bans are complex, though, as some ban smoking in all indoor spaces (25 states), others in only certain enclosed spaces (11 states), and still others in certain outdoor areas too. Selling nicotine products to minors is illegal in most states.

In “FDA moves forward on nicotine regulation in cigarettes”, the FDA’s notice of intention to implement a rule governing the maximum level of nicotine in cigarettes is discussed.  The aim is to reduce nicotine levels to non-addictive levels. The organization is seeking guidance on how to limit and measure this amount, the potential consequences, and how best to introduce the change.

Marijuana:

In the 1930’s cannabis was perceived as an evil; in 1937 it was effectively criminalized.  1944 saw the La Guardia Report which stated that marijuana was not addictive, a gateway drug, and did not cause violence or insanity. Despite this, the mid and late 1950’s saw much stricter federal anti-drug laws introduced, and marijuana was specifically included.

The 1960’s brought a change in the cultural and political climate in the U.S. With these shifts came a more open attitude to cannabis and wider use including by members of the upper middle class. It was no longer a drug only used by ‘undesirables’. On the official policy front there was a move to punishment and treatment rather than punishment alone.

The 1970’s saw amazing shifts. Most of the mandatory minimum penalties were repealed and marijuana was placed in a separate narcotics category. The FDA established the Compassionate Use program which allowed for the medical use of cannabis. Furthermore, mandatory federal sentences were removed. By the end of the decade eleven states had decriminalized cannabis spurred on by the findings of the Shafer Commission which had recommended this action. On the flip side, 1973 brought the Drug Enforcement Agency (DEA) and several conservative, civilian, anti-cannabis organizations such as the National Institute on Drug Abuse (NIDA).

The 1980’s saw a swing in the opposite direction when President Reagan signed the Anti-Drug Abuse Act. This legislation introduced mandatory sentences for drug-related crimes and federal penalties for possessing and dealing marijuana.

In 1996 there was a swing back again when Californians voted in Proposition 215 which allows for the sale of marijuana for cancer and AIDS patients and those with other painful and serious medical conditions. This decade saw a huge surge in the amount of research being carried out on the dangers and benefits of marijuana.

In the U.S. there is currently a confusing mixture of decriminalization and legalization. In “Where is marijuana legal?”, the author provides a helpful breakdown of the situation in each state for both medical and recreational use.

THE PRESENT AND FUTURE FOR NICOTINE AND MARIJUANA

Smoking has come a long way from the days when it was perceived as macho or sexy or both. Now smokers are viewed as antisocial and anything but cool. Nicotine has been blamed – not without justification – for the hold smoking has over so many and has been painted as entirely bad for one. There is no question that nicotine is highly addictive and lethal in high doses.

However, researchers have now made strides at separating nicotine from smoking and looking at it in its own right; we are beginning to see the redemption of pure nicotine when used responsibly and very sparingly. With tobacco products being replaced by other nicotine delivery methods the situation is changing constantly. There are options now that offer the nicotine without the smoke and all the other toxins that go with tobacco. We are reaching a stage where the writing is on the wall for smoking, but is nicotine’s time still to come?

Marijuana has been rehabilitated to a large degree. While there are still real and significant concerns about the effects on brain development on the babies, very young users, and on vulnerable users, there are new health-giving and medicinal uses for cannabis being found, used, or investigated all the time. There is also a change to smokeless delivery methods.

Research has also indicated that, unlike nicotine and smoking, cannabis is not remotely as addictive, doesn’t cause cancer (and in fact has beneficial effects in this regard), and does not adversely affect lung function. While the studies and trials carried out thus far have led to the medicinal use of cannabinoid medicines and the decriminalization and medical legalization of marijuana in many states, the all-too-frequently encountered phrase is, “More research is needed”.

References

[1] Armento, Paul. All smoke is not created equal: Marijuana vs. Tobacco, January 2016. [Accessed June 2018].  

[2] Asprey, Dave. Is nicotine the next big smart drug?, December 2015. [Accessed June 2018].  

[3] CBS News. Marijuana use and support for legal marijuana continue to climb, April 2016. [Accessed June 2018].  

[4] Centers for Disease Control and Prevention. Current Cigarette Smoking Among Adults in the United States, 2018. [Accessed June 2018].

[5] Felman, Adam. Everything you need to know about Nicotine, January 2018. [Accessed June 2018].

[6] Franciosi, Anthony. The best ways to consume marijuana: a guide, June 2017. [Accessed June 2018].

[7] Huizen, Jennifer. What's to know about popcorn lung?, March 2018. [Accessed June 2018].  

[8] LaVito, Angelica and Tirrell, Meg. FDA moves forward on nicotine regulation in cigarettes, March 2018. [Accessed June 2018].  

[9] National Institute on Drug Abuse. Background on nicotine, June 2007. [Accessed June 2018].  

[10] National Institute on Drug Abuse. Monitoring the Future, December 2018. [Accessed June 2018].

[11] National Institute on Drug Abuse. What is marijuana?, June 2018. [Accessed June 2018].  

[12] National Institute on Drug Abuse. Is marijuana a gateway drug?, June 2018. [Accessed June 2018].  

[13] Szalavitz, Maia. Study: Smoking marijuana not linked with lung damage, January 2012. [Accessed June 2018].  

[14] Tetiyevsky, Charlie. Where is marijuana legal in the US? The definitive guide to weed laws by state, November 2017. [Accessed June 2018].  

[15] The Public Broadcasting Service. Marijuana Timeline. [Accessed June 2018].

[16] University of Texas at Dallas Center for Brain Health. Study finds nicotine changes marijuana's effect on the brain. [Accessed June 2018].  

Article