States That Legalize Marijuana See Reduced Tobacco Use, Study Finds

While some public health experts have expressed concerns that the legalization of marijuana could fuel a rise in the use of tobacco products, a new study instead concludes that state-level cannabis reforms are mostly associated with “small, occasionally significant longer-run declines in adult tobacco use.”

Researchers did find “consistent evidence” that the adoption of state recreational marijuana laws (RMLs) led to a slight uptick in cannabis use among adults—of between about two and four percentage points, depending on the data source—but tobacco didn’t follow that trend.

If the apparent substitution effect from cigarettes to marijuana that’s being driven by legalization were extended nationally, it could result in healthcare cost savings worth more than $10 billion per year, the study concluded.

“We find little empirical support for the hypothesis that RMLs increase the net consumption of tobacco, as measured across a wide range of combustible tobacco products as well as [e-cigarettes],” they wrote. “Rather, the preponderance of evidence points to small, occasionally significant longer-run declines in adult tobacco use.”

“We conclude that [recreational marijuana laws] may generate tobacco-related health benefits.”

Authors at Bentley, San Diego State and Georgia State universities published the findings in the Journal of Health Economics last month, calling the report “the first to comprehensively examine the impact of recreational marijuana legalization on tobacco use.” The study draws on federal data from the Population Assessment of Tobacco and Health (PATH) and the National Survey on Drug Use and Health (NSDUH).

At a time of surging public support for cannabis legalization, the researchers write, “public health experts have taken a more cautious approach, urging more research to assess the health benefits and costs of marijuana use, as well as to understand potentially unintended consequences on other health behaviors.” Some have raised concerns that reform could lead to the “renormalization” of smoking, potentially reversing nearly half a century of declining cigarette use.

Cigarette smoking rates have fallen dramatically since the first Surgeon General’s report in 1964, with rates among male adults dropping from 55 percent to 16 percent and female smoking rates declining from 35 percent to 12 percent. “While the causes of these declines are the subject of much debate,” the study acknowledges, “most public health experts seek to preserve the health gains.”

Authors of the new study acknowledge that their analysis of the NSDUH data shows that legalization has “a (largely) statistically insignificant 0.5 to 0.7 percentage-point decline in tobacco use,” which includes cigarettes, pipe tobacco, smokeless tobacco and cigars. “However, this null effect masks small, lagged tobacco effects of RMLs. Three or more years following the adoption of an RML, we find that adult tobacco use falls by approximately 1.4 to 2.7 percentage-points.”

Looking specifically at cigarette use, they continue, “Again, while the overall treatment effect is relatively small…three or more years following RML enactment, we find evidence of a statistically significant 1.1 to 1.3 percentage-point decline in cigarette use among adults.”

To check, the study also analyzed states that legalized cannabis earlier than others. “The results,” it says, “provide some support for the hypothesis that tobacco use declined in several of the earliest adopting states, most notably in Colorado and Washington, which are also those states that saw the largest increases in marijuana use following RML enactment.”

Legalization “is associated with a lagged reduction in electronic nicotine delivery systems (ENDS) use, consistent with the hypothesis that ENDS and marijuana are substitutes.”

The researches said that the reduction in tobacco use in legal states is “primarily concentrated among men and for RMLs that are accompanied by open recreational dispensaries,” findings that they say are “consistent with the hypothesis that recreational marijuana and tobacco may be substitutes for some adults.”

The paper notes that potential health care cost savings resulting from substitution away from cigarettes and toward cannabis “could be substantial.”

“[O]ur estimates suggest a reduction in smoking prevalence by as many as 5.1 million, translating into tobacco-related healthcare cost savings of about $10.2 billion per year,” it concludes.

Because most states with legal cannabis first passed medical marijuana laws (MMLs), the study notes it’s possible that “the RML effects could be conflated with the long-run effects of MMLs,” especially in light of the delays states often see between legalizing medical marijuana and actually beginning legal sales.

Analyses of PATH data, meanwhile, yielded similar conclusions. “Consistent with the NSDUH, we find no evidence that RML adoption significantly increased prior-month combustible tobacco use or [e-cigarette] use,” authors write. “While estimated lagged effects are positive in most cases for cigarette use, cigar use, and all combustible tobacco products, the effects are uniformly below a percentage-point—often under 0.5 percentage-points—and not statistically distinguishable from zero at conventional levels.”

Further, the study found “no evidence that RML adoption significantly increases initiation of tobacco products among baseline non-users or decreases cessation among baseline tobacco users.”

Legalization was associated with a 1.2 to 1.3 percentage point increase in joint use of tobacco and marijuana, however, which researchers said attributed primarily to “marijuana initiation among the sub-population of individuals who were already using tobacco prior to the policy shift.”

According to a Gallup poll published last year, more Americans now smoke marijuana than cigarettes. A Monmouth University survey from October, meanwhile, found that most Americans believe alcohol and tobacco are more dangerous than cannabis.

And a federally funded study published earlier this year found that CBD could help reduce nicotine cravings and help people quit.

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