The public health puzzle of legal pot

A young woman smokes marijuana.
A young woman smokes marijuana.
TeodorLazarev/Shutterstock
A young woman smokes marijuana.

The public health puzzle of legal pot

Without data, scientists aren’t sure whether to give marijuana the green light.
March 19, 2019

As the state races toward legalizing recreational marijuana, much of the discussion has revolved around the criminal justice and tax revenue aspects of the issue. Less attention has been paid to the potential public health effects of legalization. While this may be due in part to the fervor of advocates who are championing the change for social justice or economic reasons, it also is rooted in the troubling fact that the extent of marijuana’s potential harms, and its potential benefits, are still not fully understood.

Even as more states legalize marijuana or move closer to doing so, the extent of available research on the drug and its long-term effects remains minimal compared to data on other drugs. Because the federal government still categorizes marijuana as a Schedule I drug, meaning it has a high potential for abuse and no accepted medical use, U.S. scientists have faced significant roadblocks in studying the drug. Decades of prohibition has also meant that the degree of public education about some of the known effects, positive or negative, is limited, and potentially colored by anecdotal evidence. According to one 2017 survey in the Annals of Internal Medicine, respondents generally viewed marijuana more favorably than current evidence supports.

Doctors and public health professionals who want to hit the brakes on full legalization have concerns that because scientists have not been able to study the harms and benefits of marijuana as thoroughly as other drugs on the market, it could have unknown and unintended negative consequences. For example, discussion about marijuana use disorder – pot addiction – had not begun to enter the public sphere until recently. Some studies have estimated that marijuana use disorder hovers around 30 percent.

“The rationale for bringing cannabis out of the shadows and into the public health realm is the ability to regulate.” – Daliah Heller, Vital Strategies director of drug use initiatives

Some experts argue that plowing ahead with legalization could lead to another addiction epidemic like the country currently has with opioids. As with prescription painkillers, people are minimizing potential negative impacts and pushing ahead with widespread use before understanding or properly educating people on the health risks, said Dr. Thomas Madejski, president of the Medical Society of the State of New York. Growing reliance on prescription painkillers increased exposure throughout society and led to a surge in substance abuse.

“There is an experiment going on elsewhere, so we don’t need to rush to do this,” Madejski said, referring to legalization in other states. “If things get better … we’re very open to further discussion.” For now though, Madejski and his organization believe the potential risks outweigh the potential benefits of legalization. It is instead calling for further decriminalization and a recategorization of the drug to Schedule II to enable more research.

Daliah Heller, director of drug use initiatives at the global public health organization Vital Strategies, questioned drawing an analogy between marijuana legalization and the more widespread use of opioids. She pointed to the fact that opioids exist in an entirely different framework that involves rigorous testing and approval by the Food and Drug Administration before being placed on the pharmaceutical market to be prescribed by doctors. She said marijuana is more akin to alcohol and tobacco, which are sold over the counter and subject to public health regulations. “I think that comes to the same issue here – the rationale for bringing cannabis out of the shadows and into the public health realm is the ability to regulate,” Heller said. She said she is unaware of any evidence to suggest legalization would lead to a large enough increase in marijuana use among current and first-time users that would result in a significantly higher rate of abuse. She also argued that marijuana use is already ubiquitous enough that such an epidemic would already be apparent.

“There’s all sorts of behaviors that have risks attached to them that we allow because people enjoy doing it.” – Dr. Bryon Adinoff, Doctors for Cannabis Regulation board member

Many medical and public health professionals who support legalization say that while there are health risks involved with marijuana consumption – it is still a drug after all – it is safer to create a legal, regulatory framework so people know what they are putting in their bodies, rather than taking their chances buying drugs off the street. It also comes down to relative risk, in that marijuana is considered by these proponents to have a low relative risk when compared to opioids or even alcohol. When asked how a doctor could advocate for the recreational legalization of an intoxicant that poses even a small threat, Dr. Bryon Adinoff, an addiction specialist and a board member of Doctors for Cannabis Regulation, drew comparisons to gambling, which also contains inherent risks but is legal, or unhealthy food. “There’s all sorts of things we allow in our environment by way of ingestion, behaviors that have risks attached to them that we allow because people enjoy doing it,” Adinoff said. What is critical, experts say, is that marijuana legalization happen with a robust education campaign to create a well-informed society.

Marijuana use by minors is perhaps the greatest concern among health professionals on both sides of the legalization fight. Use among children and teenagers has been linked to mental health issues and the emergence of psychiatric disorders. Madejski said he had a 16-year-old patient who was being treated for depression, and when he began smoking marijuana, his condition worsened and he became suicidal. Beyond anecdotal evidence, Madejski referenced a recent study that found that while individual risk remains low, high rates of marijuana use by adolescents could lead a large number of young people to develop depression.

Of course, like alcohol, proposed legislation to legalize marijuana would do so only for adults age 21 and over. Lawmakers in New York have not entertained proposals that would allow teenagers to use the drug recreationally. Yet regulations have not prevented underage drinking, and opponents fear that easier access to marijuana could increase youth exposure, both through conscious decisions and through accidents. Data shows that calls to poison control centers about accidental marijuana ingestion by children increased in states that allow medical marijuana. However, a five-year study out of Colorado examining the effects of marijuana legalization found that adolescent consumption did not increase.

Concerns about the effects of marijuana on adolescents also raise the issue of how the drug will be marketed. Recently, New York City lawmakers introduced legislation to prohibit the sale of menthol cigarettes and flavored e-cigarettes, arguing that the flavors make the product more enticing to adolescents. Critics say the marijuana industry, following the lead of the tobacco industry, could deploy irresponsible marketing campaigns. Tobacco giants have also begun heavily investing in marijuana companies. However, Adinoff said keeping the drug illegal simply makes access to it even easier for young people.

Another potential health impact that has received less attention is the effect of marijuana smoke. Anytime a marijuana user inhales smoke, there is a risk of developing cardiovascular problems. But unlike tobacco smoke, relatively little research exists on the long-term effects of smoking marijuana, and even less on the effects of secondhand smoke. One study in rats suggests that marijuana smoke may actually have a more severe effect on blood vessel function than tobacco smoke. And another study found that being in an enclosed space with someone smoking marijuana with a high concentration of THC could result in a contact high.

Under proposals by both Gov. Andrew Cuomo and state legislators, smoking in public spaces would remain prohibited, much like drinking in public. But such prohibitions have not stopped many marijuana smokers, as anyone walking around New York City could tell you. And research has suggested that as more states decriminalize and legalize the drug, marijuana smokers in the city have gotten bolder about smoking in public. While other states have not studied the matter, it is possible that the practice will become commonplace should recreational marijuana be made legal.

Such a step is not risk-free – driving while high is yet another problem and accurate testing for marijuana intoxication levels has yet to emerge. Lack of data adds to the worry since it still poses many unknowns. While opponents remain wary and await new research, proponents say the available body of knowledge provides enough to evidence to move forward. And if more research is what opponents want, supporters say the best way to gather it is through legalization and regulation.

Rebecca C. Lewis
is a staff reporter at City & State.
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