Is Risk of Fatal Crashes Increased on 4/20 Counterculture Holiday Celebrating Marijuana?

Bottom Line: The popular counterculture holiday “4/20” that celebrates marijuana was associated with an increased risk of fatal traffic crashes.

Why The Research Is Interesting: Studies suggest cannabis intoxication increases crash risk while driving. Many cannabis activists and enthusiasts gather at public celebrations on April 20 to consume marijuana.

Who and When: 1.3 million drivers involved in 882,483 crashes causing 978,328 fatalities over a 25-year study period following the popularization of “4/20” in a magazine (1992 through 2016)

What (Study Measures): Compared the number of drivers involved in fatal traffic crashes between 4:20 p.m. and 11:59 p.m. on April 20 each year with the number of drivers in fatal traffic crashes during the same time interval one week earlier and one week later to examine the relative risk, which is a statistical measure of probability, of a traffic crash happening on April 20

How (Study Design): Analysis of publicly available statistical data. Researchers were not intervening for purposes of the study and cannot control all the natural differences that could explain the study findings.

Authors: John A. Staples, M.D., M.P.H., of the University of British Columbia, Canada, and Donald A. Redelmeier, M.D., M.S.S.R., of the University of Toronto, Canada

Results: The risk of a fatal traffic crash was higher after 4:20 p.m. on April 20 compared with the identical time on other days used for comparison.

Study Conclusions:


For more details and to read the full study, please visit the For The Media website.