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State Cannabis Policies Significantly Impacted the Scale of their EVALI Outbreak, Study Finds

By Alexander Beadle

Published: Oct 14, 2021   
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States with legal recreational cannabis markets were less likely to report large numbers of ​​e-cigarette or vaping-associated lung injury (EVALI) cases during the 2019 vaping crisis, a new study has found.

This new research, funded by the National Institute on Drug Abuse (NIDA) and published in the journal Drug and Alcohol Dependence, also found that the relationship between medical cannabis laws and EVALI cases depended heavily on individual policy attributes. For example, in states where home cultivation was permitted, EVALI cases were reduced by more than 60 percent compared to those which forbade it.

In light of these results, the researchers say that lawmakers may wish to reflect on current cannabis policies as a way to reduce the scale of such outbreaks should they happen again. Additionally, states that are thinking about implementing a new cannabis program may wish to consider how their proposed restrictions might affect cannabis consumption habits, and what impact this consequently might have on illicit market product consumption and other risk factors.

Recreational cannabis laws linked to fewer EVALI cases

The study, conducted by researchers at the Yale School of Public Health and the Yale School of Medicine, codified the status of state cannabis laws during 2019 and compared this information against the confirmed plus probable EVALI cases reported by each state during the same year. Survey data from the Behavioral Risk Factor Surveillance System’s 2016-2019 cannabis supplements were also used to analyze how state policy might relate to residents choosing vaping as their primary cannabis consumption method.

They found that, despite the broad variation in cannabis laws across the United States, the majority of states that permitted recreational cannabis use fell into the lower two quintiles for EVALI prevalence. In contrast, those states in the highest quintile tended to either enforce blanket cannabis prohibition or have a strict medical cannabis program with no provision to allow home cultivation.

Overall, EVALI incidence was around 40 percent lower in states with recreational cannabis laws and operational recreational markets.

“Given that EVALI cases stemmed primarily from informally-sourced vaporizable marijuana concentrates, these results are consistent with crowd-out, whereby introduction of one market (legal marijuana) displaces utilization of another (informally-sourced marijuana products),” the study authors wrote.

“Simply put, if the public can obtain products legally from reputable sources, there is less demand for illicit market products. Thus, RM [recreational marijuana] legalization could have dampened market penetration of tainted marijuana concentrates by reducing consumption of informally-sourced marijuana products more generally.”

This finding tracks with other similar studies that have examined the height of the EVALI outbreak. For example, in another previous study authored by Abigail Friedman, the first author of this latest research and an assistant professor at the Yale School of Public Health, it was found that higher rates of cannabis use in a state were not associated with higher EVALI case rates. Another analysis carried out last year by researchers at Indiana University also observed that states with legal recreational cannabis laws saw fewer EVALI cases per million population.

Medical cannabis’ association with EVALI depends on specific policy elements

While the relationship between legal recreational cannabis and lower EVALI prevalence is quite clear in this latest study, the findings regarding medical cannabis legalization are slightly more nuanced.

Overall, there was no significant association seen between medical cannabis access and EVALI cases. However, since there is such a large variety in medical cannabis schemes, the researchers also elected to run additional analyses that adjusted for specific policy attributes.

Once this adjustment was applied, it was found that EVALI incidences were more than 60 percent lower in the medical cannabis states where the home cultivation of cannabis was permitted. Additionally, medical cannabis states that forbade the use of combustibles and did not sell smokable cannabis flower within their state dispensaries saw an increase in hospitalized EVALI cases when compared to other medical-use states that permitted smoking.

The researchers theorize that since vaping is the second-most popular cannabis consumption method behind smoking, these bans on combustible use may have led to increases in the use of vaporizable cannabis concentrates. They also suggest that non-medical cannabis users in these states might have seen this as an endorsement of the safety of vape products and also followed suit, putting themselves at a greater risk of encountering the vape products thought to have been responsible for the EVALI outbreak.

Home cultivation may also have helped to protect some cannabis users in the states which permitted the practice, the researchers say, by ending their reliance on commercial cannabis vape products and thus reducing their likelihood of exposure to illicit market products. Indeed, the Behavioral Risk Factor Surveillance System data on cannabis consumption methods appear to support the idea that allowing home cultivation leads to reduced odds of reporting vaping as a primary mode of cannabis use.

The researchers say that this variation in terms of medical cannabis policy and its impact on both EVALI case count and cannabis use mechanisms demonstrates the importance of understanding the final implications of different cannabis policy decisions. It also suggests that rather than repealing existing cannabis laws – a move which may not be popular with voters – minor policy changes could be implemented through legislative amendments that may still have the power to significantly alter the extent of the illicit cannabis product market and potential for future outbreaks in the state. While the findings of this study are not causal, the researchers note, they may provide good direction for states that are considering implementing a medical cannabis program.


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