Even as marijuana is increasingly legalized and decriminalized in many states, including New York, it’s still a herculean task for scientists to research its effects.

Consider the recent example of a study about the dangers of secondhand cannabis smoke. About a week ago, researchers at the University of California, Berkeley released these findings, earning the attention of several news outlets. But the study’s launch was initially delayed by about four months.

The team then had to work around several restrictions due to marijuana still being classified as a Schedule 1 drug by the U.S. Drug Enforcement Administration (DEA). This label puts pot in the same category as heroin. These legal constraints make it more challenging to study the health impacts of weed even as it becomes more accessible in states like New York and New Jersey.

The Berkeley study alleges that secondhand bong smoke might be just as harmful as tobacco because of how much particulate matter gets released into the air. But given the heavy restrictions on marijuana research, this takeaway might not be completely valid. They would need a whole different class of experiments to support this idea fully.

The Berkeley researchers conducted an "observational study" — or a more hands-off approach — as a workaround. Public health researchers Patton Nguyen and Katharine Hammond could not have any interactions with the smokers or the pot, nor control the settings where people were exposed in any way, even to give instructions or guidance. The study participants had to provide their own weed to smoke with their own bongs. Nguyen was there to measure the air before and after, but not the subjects' health.

While this practice gave the experiment a real-world feeling, it likely impacted the precision and accuracy of the study. Nguyen and Hammond could not control the airflow in the room, the variety of the weed the subjects smoked, the dosage, when it was smoked and, to some extent, how it was smoked. The study’s subjects used a standard handheld water bong, and their toking happened in the living room of a college student’s apartment. The windows and doors were closed.

Dr. Alex Bekker, chair of the department of anesthesiology at Rutgers Medical School, is skeptical of observational studies — calling them not truly scientific enough. He said that anyone could watch another person, but precise data is what makes or breaks a drug.

Typically, a drug’s effect needs to be validated in a controlled experiment that includes a placebo. These studies decipher side effects and efficacy. And Bekker argues that simply measuring hazardous particles in the air, as the Berkeley study does, is not enough to corroborate a link with potential diseases.

How federal laws are holding back weed clinical trials

While cannabis is well-documented as an effective remedy for many medical conditions, Bekker said it’s very difficult to get permission to do Phase 2 and Phase 3 clinical trials — the final stages needed to understand how a drug works in humans. As a result, very few human studies exist on cannabis — a substance that can now be freely consumed by adults in New York, New Jersey, 16 other states, two territories and Washington D.C.

“It's impossible to actually conduct a randomized placebo-controlled study, which is kind of a Catch-22,” Bekker said. “[The U.S. Food and Drug Administration] would not approve this drug for medical use officially because they have no study because it’s a Schedule 1 drug.”

Schedule 1 drugs are defined as substances with no accepted medical use and a high chance for abuse. This class includes heroin, LSD, ecstasy and peyote — but not fentanyl and methamphetamine. The latter pair are Schedule 2 because they have approved medical applications.

Trying to work through the regulatory paperwork can also be time-consuming and expensive, said Margaret Haney, a neurobiology professor at the Columbia University Medical Center. She has been researching cannabis for a quarter of a century.

Haney said that it took nearly a year for her to get a research license for marijuana. As a federally funded scientist, she said she is “extremely limited” in how she can study and handle cannabis. She can’t dispense nor use it in a placebo experiment — the gold standard for legitimizing drugs.

Her lab can also only obtain marijuana from the National Institute of Drug Addiction, and these samples all come from one government-controlled farm located in Mississippi. She said the potency of the government doses lags behind the strength of street products, potentially limiting the real-world translation of these federally-backed studies.

An activist smokes out of a glass pipe during the annual NYC Cannabis Parade & Rally, May 1, 2021

An activist smokes out of a glass pipe during the annual NYC Cannabis Parade & Rally, May 1, 2021

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An activist smokes out of a glass pipe during the annual NYC Cannabis Parade & Rally, May 1, 2021
Angela Weiss / AFP via Getty Images

As the director of the Cannabis Research Laboratory at Columbia University, Haney also had to purchase a 750-pound gun safe for storage so that nobody could walk away with the weed stocks. Its lock is fingerprint-operated. Security cameras surveil the area, and a security firm monitors the safe, in case a break-in occurs. Very few people have access to where the pot is stored. After the joints are smoked, Haney must collect all the roaches from the participants in the lab and save the drugs for the DEA to pick up.

“The huge consequence of that is no one is served when there’s no data driving what is considered medication,” Haney said. “If patients aren’t served by that, nor is the field of science when marketers are telling us what’s medication.”

Bekker researches pain treatments, and some of his work examines replacing opioids with cannabis. He sees great possibilities. But federal restrictions on using marijuana in experiments make it virtually impossible to carry out studies that can get the “hardcore science data” that is needed to approve drugs or even fully educate society about the efficacy and side effects.

“Lots of paperwork and people at some point say, 'Ah, forget about it. Let me research something else because it’s so difficult to actually conduct this research and get a cannabis sample,'” Bekker said.

What the Berkeley study shows and doesn’t show

Over eight sessions, Nguyen used an aerosol monitor to measure the air contaminant levels before and after pot-smoking gatherings. He discovered significantly more contaminants after cannabis smoke than tobacco smoke, specifically particulate matter (PM2.5). According to the study, measurements taken 12 hours after smoking sessions were still above the daily exposure limits set by the U.S. Environmental Protection Agency.

The data is valuable and aligns with similar observational studies on air toxins created by pot smoke. A 2007 study found that marijuana had much higher levels of some of these compounds. Ammonia levels in weed smoke, for example, were 20 times higher than levels measured in tobacco smoke. Hydrogen cyanide, nitric oxide and nitrogen oxides were at concentrations that were three to five times higher than cigarettes. All these chemicals can exacerbate respiratory diseases.

Yet it’s unclear if these higher levels genuinely impact people’s health on par with tobacco. Cigarettes are smoked more regularly than marijuana among U.S. adults, as tracked by the Substance Abuse and Mental Health Services Administration. According to SAMHSA data, about 24.8 million adults smoked cigarettes daily or almost daily in 2020 – compared to 14.6 million adults who used marijuana regularly. So the overall exposure and danger from tobacco might still be higher than from pot.

But this relative risk might change over time as weed-smoking becomes more commonplace. American teens, for example, were already 16 times more likely to be daily users of marijuana than cigarettes in the SAMHSA data for 2020.

“It’s just to raise the awareness of a cannabis user that their secondhand smoke from their use can affect the non-smokers, and therefore, they can take some actions to reduce their exposure,” said Hammond from Berkeley.

She and Nguyen see the current moment as analogous to tobacco smoke in the 1980s – before it was discovered to be harmful.

Nguyen and Hammond plan to conduct and release more detailed studies. And the hope for many experts is that the federal government changes its view on cannabis to allow scientists to learn more about the substance. A bill, the Marijuana Opportunity Reinvestment and Expungement Act, or MORE Act, just passed the U.S. House of Representatives. The legislation would decriminalize cannabis, expunge prior convictions and make the drug more accessible for study.

“There’s a certain stigma attached to this thing and years of propaganda – that it’s reefer madness,” Bekker said. “Some doctors feel even uncomfortable even talking about this stuff.”

The House passed a similar bill in December 2020, but a vote was never taken in the Senate. Such a law would open the doors for a flood of data that could help doctors advise their patients on effective and appropriate uses.

“They're not sure whether to rub it on their skin or to swallow it, or some vaping or smoke it,” Haney said. “Clinicians don't have any advice to give because there's no data there.”