Reasearh by Dr. Staples and Redelmeier published in JAMA Internal Medicine, online February 12, 2018:
Research Summary: Be Careful on Marijuana High Holiday, April 20. Acute cannabis intoxication increases vehicle crash risk. Despite this evidence, driving after cannabis consumption is surprisingly common
The 25-year study interval identified 1.3 million drivers involved in 882 483 crashes causing 978 328 fatalitiesl
After Marijuana the relative risk of a fatal traffic crash increased 12% on April 20 between 4:20 pm to 5:00 am the following day.. Risk for a fatal vehicle crash was even more pronounced for younger drivers (Figure 1).
[The April 20 Cannabis Celebration and Fatal Traffic Crashes in the United States, Staples JA, Redelmeier DA. Journal of the American Medical Association Internal Medicine, published online Feb 12, 2018. doi:10.1001/jamainternmed.2017.8298]
“”> On April 20 each year, thousands of Americans celebrate the intoxicating properties of marijuana on a popular counterculture holiday known as “4/20.”
Legal marijuana sales surge in anticipation of the “High Holiday,” and college students report
In many cities, activists and enthusiasts gather at public celebrations that feature synchronized mass consumption of cannabis at 4:20 pm.3
Driving simulation studies indicate that higher blood Δ9-tetrahydrocannabinol concentrations decrease reaction times and increase variability in speed and lane position,
while some epidemiologic studies suggest that acute cannabis intoxication increases vehicle crash risk.4
Despite this evidence, driving after cannabis consumption is surprisingly common.5
The 25-year study interval identified 1.3 million drivers involved in 882 483 crashes causing 978 328 fatalities.
In total, 1369 drivers were involved in fatal crashes after 4:20 pm on April 20 whereas 2453 drivers were in fatal crashes on control days during the same time intervals (corresponding to 7.1 and 6.4 drivers in fatal crashes per hour, respectively).
The risk of a fatal crash was significantly higher on April 20
Subgroup analysis suggested the relative risk increase on April 20 was particularly pronounced for younger drivers (Figure 1).
Geographic analysis suggested the absolute risk increases were greatest in New York (excess of 36), Texas (excess of 32), and Georgia (excess of 29).
Sensitivity analyses supported the results of the primary analysis, including evaluations of all crash-involved persons (rather than only drivers) and extended time intervals (4:20 pm to 5:00 am the following day).
As expected, the number of drivers involved in crashes earlier than 4:20 pm or on nearby dates (April 18 and April 22) was no different than corresponding controls.
Discussion: We examined a quarter-century (25 years) of national data and found a 12% increase in the relative risk of a fatal traffic crash after 4:20 pm on April 20 compared with identical time intervals on control days.
Although the vast majority of Americans do not celebrate 4/20, the observed association was comparable in magnitude to the increase in traffic risks observed on Superbowl Sunday.6
Policy makers may wish to consider these risks when liberalizing marijuana laws, paying particular attention to regulatory and enforcement strategies to curtail drugged driving. <“”
Please read the entire articls: [The April 20 Cannabis Celebration and Fatal Traffic Crashes in the United States, Staples JA, Redelmeier DA. JAMA Intern Med. Published online February 12, 2018. doi:10.1001/jamainternmed.2017.8298]