Fatal car crashes involving opioids have become rarer in the states with legalized medical cannabis, according to a recent study carried out at Columbia University's Mailman School of Public Health.
This was one of the first investigations that compared opioid consumption at the individual level and car crashes rates before and after the adoption of medical cannabis laws in American states.
During the study, scientists analyzed the data from 1999-2013 Fatality Analysis Reporting System that contained results of alcohol and drug tests in nearly 80% of the drivers who passed away within one hour of crashing in 18 states where medical cannabis was legalized. Researchers also compared the data on the presence of opioids in the blood of 21-40-year-old drivers who died in car crashes before and after marijuana legislation came into effect. The study results showed an overall decrease in the number of opioid-positive drivers that had died in car crashes after the states adopted medical cannabis laws.
June H. Kim, who led the study group, expected that these rates would fall because of medical cannabis legalization in American states, as people tend to substitute the herb for opioids to relieve chronic pain and other severe conditions.
According to the data, nearly 42% of the deceased drivers were killed in crashes in states with applicable cannabis laws, while 25% of them had died in states before medical marijuana legislation came in force, and 33% passed away in states where the medical use of weed had never been legalized. The study results were based on 68,394 cases of fatal vehicle crashes.
The surveyed age group represented the most active weed users, as medical marijuana is available to people aged 21 and over, and cannabis patients are usually younger than 45. However, the authors of the study expect that older weed patients would also show the same decrease as an increasing number of older people is choosing marijuana instead of opioids.
After California legalized medical marijuana by a voter initiative in 1996, 22 more states along with the District of Columbia also passed laws regulating cannabis for medical use. This year, North Dakota, Arkansas, Missouri, and Florida will vote on medical marijuana propositions on the ballot.
The study results revealed a tendency to the possible substitution patterns between opioids and cannabis in young adults. According to Guohua Li, the senior researcher of the study, the available information on deceased drivers showed some suggestive evidence of the substitution hypothesis in young and middle-aged cannabis patients.
Moreover, researchers suggest that future studies in states with recreational cannabis would help better evaluate the impact of marijuana laws on opioid use.