One-third of drivers who drink alcohol and use marijuana simultaneously report getting behind the wheel within two hours of consumption, a new study released today from the Insurance Institute for Highway Safety shows.* There’s some evidence that the combination of alcohol and marijuana worsens driving performance more than either substance by itself.**
“Alcohol impairment is associated with almost 30% of the fatalities on our roadways, and we have made very little progress to reduce this toll over the past three decades. Now we are adding another impairing substance to the mix,” IIHS President David Harkey said ahead of his presentation at the annual meeting of the Governors’ Highway Safety Association in Louisville, Kentucky.
“Policymakers, law enforcement, safety professionals and others will need to work together and implement multiple solutions to save the thousands of lives cut short every year by impaired driving in the United States,” said Harkey.
Driving under the influence of marijuana is illegal in all 50 states and D.C., but determining impairment is tough. Unlike alcohol, the amount of marijuana present in a person’s body doesn’t consistently relate to impairment. THC, or Tetrahydrocannabinol, is the primary psychoactive component of cannabis. A positive test for THC and its active metabolite doesn’t mean the driver was impaired at the time of the crash. Habitual users of marijuana may have positive blood tests for THC days or weeks after using the drug. Marijuana is still an illegal controlled substance under federal law. * (Read AutoInformed.com on: In the Weeds – Driving Under the Influence of Cannabis)
*The latest study by Angela H. Eichelberger of IIHS used telephone interviews with 3045 adult drivers in six states (Connecticut, Delaware, New York, North Carolina, South Carolina, and Virginia)** about their opinions and behaviors related to cannabis use, alcohol use, and driving. Only 1 in 10 drivers surveyed by IIHS reported using alcohol and marijuana simultaneously over the past year, compared with 7 in 10 who reported past-year drinking. But among those simultaneous users, 33% reported drinking alcohol and consuming marijuana and then getting behind the wheel within two hours. (Prevalence of alcohol, cannabis, and simultaneous use among drivers in six states)
*Self-reported substance use varied across states.
- New York and Connecticut drivers reporting the highest proportions of past-year drinking (75%), cannabis use (29% and 26%), and simultaneous alcohol and cannabis use (15% and 14%).
- North Carolina drivers reported the lowest proportions of past-year drinking (65%) and past-year simultaneous alcohol and cannabis use (9%).
- North Carolina and Virginia drivers reported the lowest proportion of past-year cannabis use (21%).
- Across the six states, past-year use of alcohol less than 2 hours before driving was more prevalent (17%–25%) than past-year use of cannabis less than 2 hours before driving (8%–11%).
- The proportion who reported using both alcohol and cannabis less than 2 hours before driving ranged from 2% to 5%.
- Of the drivers who reported using a substance within the past year, 28% of alcohol users reported drinking less than 2 hours before driving; 41% of cannabis users reported using cannabis less than 2 hours before driving;
- Among drivers who reported past-year simultaneous use, 33% reported using both alcohol and cannabis less than 2 hours before driving.
**To understand better the net impact on safety, researchers at IIHS and HLDI have conducted a series of studies since 2014 examining how legalization has affected crash rates and insurance claims in the first states to legalize recreational use. The experimental studies suggest using alcohol and marijuana simultaneously worsens driving performance more than either substance used separately.
An earlier IIHS study of patients who were at a hospital emergency room as the result of a motor vehicle crash only showed an increased crash risk associated with marijuana when it was combined with alcohol. Recent research shows that young adults are more likely to drive or take other risks after using both substances than after consuming marijuana alone. But while legalization is associated with increases in the number of people who sometimes drink alcohol and sometimes use marijuana, it’s unclear from the National Survey on Drug Use and Health how frequently they’re consuming the two substances simultaneously, according to IIHS.
The most recent of these studies from IIHS shows that injury and fatal crash rates in California, Colorado, Nevada, Oregon and Washington jumped in the months following the relaxation of marijuana laws in each state. Combined, the impact of legalization and, subsequently, retail sales in the five states resulted in a 6% increase in injury crash rates and a 4% increase in fatal crash rates compared with other Western states where recreational marijuana use was illegal during the study period. Only the increase in injury crash rates was statistically significant.
Deadly Cocktail – Marijuana and Alcohol
“Alcohol impairment is associated with almost 30% of the fatalities on our roadways, and we have made very little progress to reduce this toll over the past three decades. Now we are adding another impairing substance to the mix,” IIHS President David Harkey said ahead of his presentation at the annual meeting of the Governors’ Highway Safety Association in Louisville, Kentucky.
“Policymakers, law enforcement, safety professionals and others will need to work together and implement multiple solutions to save the thousands of lives cut short every year by impaired driving in the United States,” said Harkey.
Driving under the influence of marijuana is illegal in all 50 states and D.C., but determining impairment is tough. Unlike alcohol, the amount of marijuana present in a person’s body doesn’t consistently relate to impairment. THC, or Tetrahydrocannabinol, is the primary psychoactive component of cannabis. A positive test for THC and its active metabolite doesn’t mean the driver was impaired at the time of the crash. Habitual users of marijuana may have positive blood tests for THC days or weeks after using the drug. Marijuana is still an illegal controlled substance under federal law. * (Read AutoInformed.com on: In the Weeds – Driving Under the Influence of Cannabis)
*The latest study by Angela H. Eichelberger of IIHS used telephone interviews with 3045 adult drivers in six states (Connecticut, Delaware, New York, North Carolina, South Carolina, and Virginia)** about their opinions and behaviors related to cannabis use, alcohol use, and driving. Only 1 in 10 drivers surveyed by IIHS reported using alcohol and marijuana simultaneously over the past year, compared with 7 in 10 who reported past-year drinking. But among those simultaneous users, 33% reported drinking alcohol and consuming marijuana and then getting behind the wheel within two hours. (Prevalence of alcohol, cannabis, and simultaneous use among drivers in six states)
*Self-reported substance use varied across states.
**To understand better the net impact on safety, researchers at IIHS and HLDI have conducted a series of studies since 2014 examining how legalization has affected crash rates and insurance claims in the first states to legalize recreational use. The experimental studies suggest using alcohol and marijuana simultaneously worsens driving performance more than either substance used separately.
An earlier IIHS study of patients who were at a hospital emergency room as the result of a motor vehicle crash only showed an increased crash risk associated with marijuana when it was combined with alcohol. Recent research shows that young adults are more likely to drive or take other risks after using both substances than after consuming marijuana alone. But while legalization is associated with increases in the number of people who sometimes drink alcohol and sometimes use marijuana, it’s unclear from the National Survey on Drug Use and Health how frequently they’re consuming the two substances simultaneously, according to IIHS.
The most recent of these studies from IIHS shows that injury and fatal crash rates in California, Colorado, Nevada, Oregon and Washington jumped in the months following the relaxation of marijuana laws in each state. Combined, the impact of legalization and, subsequently, retail sales in the five states resulted in a 6% increase in injury crash rates and a 4% increase in fatal crash rates compared with other Western states where recreational marijuana use was illegal during the study period. Only the increase in injury crash rates was statistically significant.