Workplace fatalities are down by an average of 19.5 percent in the 29 US states (and the district of Columbia) that have legalised the use of medical marijuana for medical purposes. The surprising result opposes the consensus view that widespread marijuana use would cause an increase in workplace accidents.
Since 1992, 29 states and the District of Columbia have legalised the use of marijuana for medicinal purposes, and to date, little is still known about the relationship between medical marijuana laws and workplace fatalities.
The International Journal of Drug Policy study used workplace fatalities data from all states and districts and used regression models to adjust for state demographics, the unemployment rate, state fixed effects, and year fixed effects.
It found that legalising medical marijuana was associated with a 19.5% reduction in the expected number of workplace fatalities among workers aged 25–44, and that this association grew stronger over time. Five years after taking effect, medical marijuana laws were associated with a 33.7% reduction in the expected number of workplace fatalities.
On top of this, medical marijuana laws that listed pain as a qualifying condition were associated with larger reductions in fatalities among workers aged 25–44 than those that did not.
The researchers said that although more research is needed to determine the precise mechanism through which medical marijuana laws affected workplace fatalities, one explanation is that users in legalisation states use marijuana ahead of other legal drugs which might pose greater risk.
In other words, more widespread use of marijuana may lead to reductions in the consumption of alcohol and other substances that impair cognitive function, memory, and motor skills.
As said earlier, the results come amid ongoing concern that legalising medical marijuana will make workplaces more dangerous due to the drug’s effects on motor skills and cognitive function. When Canada passed full legalisation of marijuana use in 2018 (medicinal and recreational), many employers raised concerns over the impact on accidents, absenteeism and performance (see related article).