A new study has indicated there’s a decline in the use of opioid painkillers in states where medical marijuana is permitted for pain treatment.

The study, published recently in the American Journal of Public Health, examined 69,000 fatal car accidents in 18 states from 1999 to 2013 with a focus on the differences between states where medical marijuana was legalized and those where it was not.

Researchers discovered a substantial difference in drivers between the ages of 21 and 40, in that those who died in states with medical marijuana laws were half as likely to test positive for opioids compared to those who died in states where medical marijuana was not legal.

"That's a pretty moderate-to-large reduction," lead author June H. Kim, a doctoral student in the Department of Epidemiology at Columbia's Mailman School of Public Health, told Live Science.

“We would expect the adverse consequences of opioid use to decrease over time in states where medical marijuana use is legal, as individuals substitute marijuana for opioids in the treatment of severe or chronic pain.”

h/t ReutersLive Science