Cannabis legalization in Uruguay was associated with a 52% increase in driver fatalities
An interrupted time-series analysis found that cannabis legalization in Uruguay was associated with a 52% immediate increase in light motor vehicle driver fatality rates, particularly in urban settings.
Quick Facts
What This Study Found
Following Uruguay 2013 cannabis legalization, light motor vehicle driver fatality rates showed an immediate 52.4% increase (95% CI 11.6-93.3%, p=0.012). The increase was concentrated in Montevideo (urban), not rural areas. Motorcyclist fatality rates were not significantly affected.
Key Numbers
52.4% immediate increase in light motor vehicle driver fatalities (p=0.012); Montevideo absolute increase of 0.06 per week (p=0.025); no significant change in motorcyclist or rural fatality rates.
How They Did This
Interrupted time-series analysis of weekly traffic fatalities of light motor vehicle drivers and motorcyclists in Uruguay from 2012-2017, comparing trends before and after cannabis legalization.
Why This Research Matters
As more countries legalize cannabis, understanding traffic safety implications is critical. Uruguay was the first country to fully legalize recreational cannabis, making it a unique natural experiment.
The Bigger Picture
This is one of the first studies examining traffic fatality outcomes following national-level cannabis legalization. The finding of an urban-specific effect on car (but not motorcycle) fatalities suggests a complex relationship that may involve changes in use patterns rather than simple impairment.
What This Study Doesn't Tell Us
Interrupted time-series cannot prove causation; other factors may have changed around legalization; relatively short post-legalization period (2013-2017); ecological design cannot link individual cannabis use to crashes.
Questions This Raises
- ?Did the traffic safety effect diminish over time as novelty wore off?
- ?Would different legalization frameworks (e.g., stricter impaired driving laws) mitigate the association?
Trust & Context
- Key Stat:
- 52.4% immediate increase in light motor vehicle driver fatalities after legalization
- Evidence Grade:
- Moderate: rigorous time-series methodology applied to national data, but cannot prove causation and relies on ecological data.
- Study Age:
- Published 2020.
- Original Title:
- The association between legalization of cannabis use and traffic deaths in Uruguay.
- Published In:
- Addiction (Abingdon, England), 115(9), 1697-1706 (2020)
- Authors:
- Nazif-Munoz, Jose Ignacio, Oulhote, Youssef, Ouimet, Marie Claude(2)
- Database ID:
- RTHC-02748
Evidence Hierarchy
Watches what happens naturally without intervening.
What do these levels mean? →Frequently Asked Questions
Did cannabis legalization increase traffic deaths in Uruguay?
The study found a 52% immediate increase in light motor vehicle driver fatalities after legalization, concentrated in urban areas. However, the time-series design cannot prove cannabis legalization caused the increase.
Were all types of drivers affected?
No. The increase was specific to light motor vehicle drivers. Motorcyclist fatalities and rural area fatalities were not significantly affected.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-02748APA
Nazif-Munoz, Jose Ignacio; Oulhote, Youssef; Ouimet, Marie Claude. (2020). The association between legalization of cannabis use and traffic deaths in Uruguay.. Addiction (Abingdon, England), 115(9), 1697-1706. https://doi.org/10.1111/add.14994
MLA
Nazif-Munoz, Jose Ignacio, et al. "The association between legalization of cannabis use and traffic deaths in Uruguay.." Addiction (Abingdon, 2020. https://doi.org/10.1111/add.14994
RethinkTHC
RethinkTHC Research Database. "The association between legalization of cannabis use and tra..." RTHC-02748. Retrieved from https://rethinkthc.com/research/nazif-munoz-2020-the-association-between-legalization
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.