Lung Diseases and Infections

An infographic used by A Healthier Michigan as part of Lung Cancer Awareness month.

Many people feel that because marijuana is a plant, that it is “all natural” and good for them. But marijuana can have similar health consequences to tobacco, especially among those who use it regularly. Frequent marijuana users have been found to suffer from chronic bronchitis, coughing on most days, excess phlegm production, shortness of breath, wheezing, and chest sounds without a cold, according to one US study. Marijuana plants can also have mold and fungi on them, as well as remnants of any chemicals used to grow them, and it is possible for users to ingest up to 70 percent of these while smoking, creating increased risks of infection and poisoning. Marijuana, like tobacco, also carries tar, which is associated with lung cancer, though this link has not been definitively proven for marijuana users. Because marijuana smokers keep smoke in their lungs longer than tobacco smokers, their lungs actually face greater exposure to tars, chemicals, and contaminants. In addition, smoking marijuana compromises the overall resistance of the lungs to disease, increasing rates of infection.  For a good summary of all the potential health hazards of marijuana, see this article from the National Institute of Drug Abuse.

Changes in the Brain and Decreases in IQ

Photo from

There are conflicting studies about whether or not marijuana use can create physical changes in the brain or even lower people’s IQs.  But even if there are no physical changes to the brain, most agree that there are noticeable changes in the behavior of those who use marijuana.  Studies have found that those who began using marijuana during adolescence had lower IQs, and did not recover lost IQ points after discontinuing their marijuana use.  For those who did not start until adulthood, no IQ points were lost.

But this does not mean there are no side effects; other studies have shown that marijuana has negative effects on attention, memory, and learning, and that these negative effects can last for days or weeks after use. Understandably, these effects are also especially problematic for students as they negatively impact the processing and retention of knowledge.  In school, missing or not understanding even a few lessons can hurt a student’s overall performance since lessons are generally cumulative.

For those interested in reading about these effects in action, look at the links attached to the post on potential marijuana addiction.  There are two stories there of people who realized they were dependent on marijuana and the tolls it was taking on their lives.

Depression and Anxiety

Photo from

There has been a lot of discussion surrounding whether marijuana use contributes to or affects mental illness, particularly depression and anxiety. Most studies have shown that those who use marijuana, particularly beginning in adolescence, are more likely to suffer from depression and/or anxiety later on. Frequent use further raises this likelihood. Interestingly, those who suffer from depression and/or anxiety are not any more likely to use marijuana. Causality has not been definitively proven as to whether marijuana use causes depression and/or anxiety, but the relationship has been shown consistently.

Another related, possible consequence of marijuana use, especially for those who use marijuana often, is that it may damage the brain’s ability to process enjoyment. Studies have shown that people who use marijuana produce the same amount of dopamine (the brain chemical tied to pleasure and reward) as non-users, but that it does not create the same physical reaction for them that it does for non-users. And this lack of physical response indicates that marijuana users may have damaged the areas of their brains responsible for creating the feeling of enjoyment. Again, whether marijuana use causes the damage, or whether people use it to make up for existing damage, is unclear.

Effects on Mental Illness

drugs and mental illness
A chart on mental illness and drug use from SAHMSA.

Some contend that marijuana has become a growing cause of mental illness. In truth, this has not been proven and it is clear that not all people who use marijuana will become mentally ill. There is evidence that supports the idea that marijuana use in adolescents is tied to an increased likelihood of developing depression or psychotic disorders, particularly schizophrenia and bipolar disorder. Use by those with congenital predispositions or certain genes is also tied to development of these disorders; marijuana can exacerbate the disorders’ symptoms and possibly bring them out sooner. Frequent marijuana use among teenagers is believed to be especially problematic because their brains are not yet fully developed; it is also linked to poor school performance. Whether marijuana use contributes to mental illness or not, recent studies have shown that marijuana use in those with mental illness can exacerbate the problem especially by derailing treatment efforts.

For more detailed reading:

Potential for Addiction

addiction photo
Photo from

Though it is uncommon, it is possible for people to become addicted to marijuana. The National Institute on Drug Abuse estimates that between nine and ten percent of marijuana users will become addicted. For those who begin regularly using marijuana as adolescents, it is around 17 percent, and for those who use the drug everyday, it is between 25 and 50 percent. As mentioned in another post, average THC levels in marijuana have been on the rise in recent years, further contributing to an increased likelihood of addiction, especially for those who use concentrated forms of marijuana.

Many still contend that it is only possible to be psychologically, not physically, addicted to marijuana. Even if that’s true, in the long run it can be harmful to one’s mind, body, and life; even a psychological dependence involves changes in the brain. In a recent Vice article, the author gives her personal account of realizing she was addicted to marijuana and the negative impacts it had on her. Another article, an op-ed from the LA Times, gives the personal account of the impact that marijuana had on the writer’s life, and of what she understands now that she has removed it from her life. Both writers realized that there was more to life than what they had and that it was marijuana that was preventing them from attaining those things. Whether it was only psychologically or not, they both dependened on marijuana just to make it through the day, and eliminating it improved their lives. Without it, they were more productive, and focused more on the people and goals they had been neglecting.

For further reading on potential addiction to marijuana:

Hash Oil Explosions

hash oil fire
Photo from

Particularly in states that have legalized recreational marijuana use, there has been an increase in production of marijuana extract, usually called hash oil, in the past few years, causing concern among law enforcement personnel, as discussed in a recent piece by USA Today and one from its affiliate, Statesman Journal. Hash oil is made by pouring a solvent (often butane) over marijuana leaves. The mixture is then heated, to evaporate the solvent. Users like this process because it allows them to create the much more THC-potent oil from what otherwise would be unusable parts of the plant. The potential danger comes from the fact that butane sinks; it is heavier than air and will descend, where stove pilot lights or even the motors in refrigerators can ignite it. People also store hash oil in their refrigerators, where the butane continues to evaporate, which can create flammable build-ups of the solvent.

In addition to its explosive potential, hash oil often has residual butane, as well as the lubricants used to ensure butane moves smoothly through lighters. It can also often contain pesticides (which are more concentrated than when found in marijuana that is smoked), and plant waxes that may be safe to eat but are not considered safe to inhale. Plus, even in most places that allow recreational marijuana use, it is still illegal to produce hash oil. A recent profile by BuzzedNews provides an in-depth discussion of the drug’s potential hazards.

Possible Inhalation of Contaminants and Pesticides

Recent testing and studies have showed that the drug can often contain pesticides as well as pathogens, including mold, mildew, E. coli and Salmonella. A study published in the Journal of Toxicology revealed that as much as 70 percent of the pesticides present in marijuana may be inhaled when the drug is smoked. These hazards are in addition to historically high THC levels and lower than normal levels of cannabidol, the chemical thought to give marijuana therapeutic properties.

While marijuana has become legal in several places, legislation regulating its production and safety is still catching up to legalization movements. And because it is still illegal at the federal level, the EPA has not created any regulations relating to which chemicals may be used to grow marijuana or their proper storage and usage. Using more concentrated forms of marijuana, such as hash oil also concentrates any pesticides in them, making the contaminants, often banned for human consumption by the EPA, that much more potent.

Increasing DUIs

Photo from

There has been great concern that with increases in the number of places that allow legal marijuana use, incidents of people driving while under the influence of marijuana would see a corresponding increase. A study in New Zealand found that people who frequently used marijuana, especially before driving, were more likely to be injured in car accidents than those who did not. Another study in France showed that, even controlling for accidents in which alcohol played a part, marijuana users were twice as likely to cause fatal accidents than non-users.

A newer study, done by the National Highway Traffic Safety Administration and released in February 2015, concluded that there is no definitive link between using marijuana and an increased chance of being in an auto accident. When the study controlled for demographic variables, its results showed that marijuana users had a probability of being in an accident equal to that of drivers who had not used alcohol or other drugs. Regardless, the study still concluded that marijuana users have an overall 25 percent higher likelihood of being in auto accidents than non-users.

Guidelines regarding what level of THC is considered a DUI vary by state, and traces of THC may stay in the body for days or weeks after use (especially for frequent users). So avoiding driving soon after marijuana use is still a good idea.

Illicit Water Use

California Drought Water School
This May 1, 2014, photo shows irrigation water runs along a dried-up ditch between rice farms in Richvale, Calif. California is in the third year of the state’s worst drought in recent history. (AP Photo/Jae C. Hong)

Marijuana is a water-intensive crop to grow, using approximately six gallons of water per plant per day. Grow sites often illegally divert water from rivers and streams, and lay miles of illegal irrigation tubes. At just one illegal grow in northern California, law enforcement officials found a set of seven sites with a total of eight and a half miles of irrigation piping.

The water needs of these sites are high enough to totally deplete some streams and rivers, harming fish and wildlife in the areas, as well as official efforts to revitalize their populations. Made worse by California’s severe drought, there are cases of streams literally being sucked dry by marijuana farms, and the state has several large rivers at historically low water levels. In addition to using a lot of water, marijuana growers also often pollute water. The insecticides, fertilizers, and other chemicals they use not only seep into soil and ground water, but can also enter streams and rivers, harming the fish and wildlife that rely on them.

Deforestation and Erosion

Photo from the Texas State Aquarium.

Many people illegally growing marijuana place their grow sites in forests, particularly in California. These areas, often public lands, are difficult to reach and hard for law enforcement to monitor, making them good for concealing the growers’ activities. But to plant crops in these remote, often hilly or mountainous, locations, growers must first clear away trees to create enough open land. They also often clear away the under-growth, both of which contribute to increased soil erosion because there are fewer plants holding soil in place. Ultimately, this also increases the risk of landslides.

Individual growing areas can be up to several acres or even square miles and can be spread over multiple sites. In northern California alone, the amount of land used for illegally growing marijuana has doubled in the last five years. This illegal land use is contributing to deforestation and eliminating animal habitats, which are discussed further in other posts.