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a. Drugged driving is on the scale of drunk driving

b. Drugged driving is not just an American problem

c. Which drugs do drugged drivers use?

d. How do we know that drug use causes crashes and impacts highway traffic safety?

e. The impairment conundrum

a. Drugged driving is on the scale of drunk driving

On the nation's highways, drugged driving now poses a danger on the scale of the better-known problem of drunk driving. In a national survey, drugs were present more than 7 times as frequently as alcohol among weekend nighttime drivers in the U.S., with 16% testing positive for drugs, compared to 2% testing at or above the legal limit for alcohol.i In addition, a recent study of seriously injured drivers at the Maryland Shock Trauma Center showed that 5l% of the sample tested positive for illegal drugs, compared to 34% who tested positive for alcohol.ii In 2009, 10.5 million people drove under the influence of drugs.iii
Use Among Impaired Drivers.

High School Seniors.
Young drivers are particularly at risk for being impacted by drugged driving as supported by data on youth behaviors. Monitoring the Future showed that nearly 28% of high school seniors had put themselves at risk, by being in a vehicle whose driver had been using marijuana or another illicit drug, or had drunk 5 or more alcoholic drinks, in the two weeks prior to being surveyed.iv About 1 in 8 (12.4%) of high school seniors said they drove after he or she used marijuana while 8.7% said they drove after drinking alcohol. Nearly 1 in 4 said they had recently ridden in a car with an impaired driver.

Learn more about teen drugged driving from the Traffic Safety Guy's feature on the 2014 Teen DUID Summit.

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b. Drugged driving is not just an American problem

Countries throughout the world are recognizing that their efforts to curb drunk driving are having good but still limited success pushing rates of drunk driving down while drugged driving continues to increase. In some samples drugged driving is passing alcohol-impaired driving as a highway safety threat.

Many countries are ahead of the U.S. in terms of dealing with drugged driving, especially Australia, New Zealand, Canada and Western Europe. For example, in a roadside study of drivers in British Columbia, over 10% tested positive for drug use compared to only 8% who tested positive for alcohol.v While alcohol-impaired drivers tended to be younger in age, with more positive test results occurring during weekends and later nighttime hours, drug-impaired drivers were more evenly distributed across all age groups and survey times.

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c. Which drugs do drugged drivers use?

In a study of seriously injured drivers, 26.9% tested positive for marijuana while 11.6% tested positive for cocaine, and 5.6% tested positive for either methamphetamine or amphetamine.vi These percentages are far higher than those detected among drivers in the 2007 NHTSA National Roadside Survey (NRS) which found 8.6% of weekend nighttime drivers positive for marijuana, 3.9% positive for cocaine, and 1.3% positive for methamphetamine.vii The higher statistics from the crash study compared to the NRS random driver sample are clear evidence that drugged driving is a serious threat to highway safety.

Additionally, in a recent British Columbia roadside study of drivers, 10.4% of drivers who provided an oral fluid sample tested positive for at least one drug other than alcohol.viii Cannabis and cocaine were the most commonly detected illegal substances, with 4.6% of drivers testing positive for each. 0.9% of drivers tested positive for opiates. Amphetamines, methamphetamine and benzodiazepines were detected in less than 1% of drivers.

Of the total number of positive drug tests, cannabis accounted for 49.4%. Cocaine was detected in 29.3% of positive cases while opiates were detected in 14.8%. Cannabis and cocaine was the most common polydrug combination, and accounted for 8.3% of all positive drug cases.

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d. How do we know that drug use causes crashes and impacts highway traffic safety?

The Fatality Analysis Reporting System (FARS), a census of fatal motor vehicle traffic crashes, provides data on the presence of drugs among drivers. Of the 12,055 drivers with known test results in 2009, 33% were positive for drugs. While the number of drivers killed in motor vehicle crashes has declined over the past five years, the number of drivers positive for drugs has increased by 5%. ix

The Institute for Behavior and Health, Inc. conservatively estimates that 20% of motor vehicle crashes are attributable to Drugged Driving. x Based on that figure, IBH estimates:
  • 6,761 People died in 2009 as a result of Drugged Driving xi
  • 440,000 People were injured in car crashes as a result of Drugged Driving xii
  • $59.9 billion in costs every year are attributable to Drugged Driving xiii

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e. The impairment conundrum

Unlike drugged driving, drunk driving is easily detectable through Blood Alcohol Concentration (BAC). Modern technology can measure the BAC in a portable breath test that can be used at the roadside. State laws on drunk driving are very specific with BAC cut-off levels of 0.08%. For commercial drivers, the limit is 0.04%. The cutoff levels of 0.08% and 0.04% work reasonably well with alcohol because there is a correlation between the level of impairment and the blood alcohol level (as the alcohol level increases, the behavior becomes more impaired and as the BAC falls, impairment lessens). Nevertheless, drunk driving depends on a per se determination rather than measurement of impairment. What is measured and what is illegal for a driver is the BAC. That is what the per se level means.

The relationship between illegal drug use and impairment is even more complex than for alcohol with no linear relationship between blood levels of a drug (or drug metabolities) and impairment. There are loops of impairment related to blood levels. The size and shape of these curves vary considerably depending on the drug. In most cases blood concentrations rise and fall after illegal drug use but there are different levels of impairment at the same blood levels for any person. The legal issues are different for illegal drug use than from alcohol use by drivers over the age of 21 because the use of these drugs is illegal, as underage drinking is illegal.

In recognition of the serious problem of drugged driving for commercial drivers and for others involved in safety-sensitive jobs such as airline pilots and train engineers, in 1988 the U.S. Department of Transportation established the per se standard for illegal drug use: any evidence of recent illegal drug use was considered a violation of the law. The per se standard is not a measure of impairment but a marker of illegal driving behavior. This is exactly the standard now needed for all drivers on the U.S. roads. It is the standard widely used in most of the developed world including Western Europe. While this is controversial to some people, IBH asks if this is not a reasonable standard, why is it used for pilots and truck drivers? And if it is reasonable for commercial drivers and others, then why is it not a reasonable standard for all drivers? IBH believes this standard is not only reasonable but that widespread adoption of the per se standard for illegal drug use is important to improve highway safety.

For drivers under the age of 21, for whom alcohol is illegal, there is no legally acceptable alcohol level; any evidence of drinking is a violation. This fits with the Department of Transportation's standard for illegal drug use: when the substance use is illegal, there is no expectation of a "safe" level. This includes use of all of illegal drugs including the nonmedical use of prescription drugs. Effective public education and law enforcement using the per se standard is the way forward not only to improve highway safety for all Americans but also to reduce illegal drug use. As a bonus an effective drugged driving program will provide a new path into treatment and long-term recovery for millions of Americans.

Click here to learn more about the per se standard.

Impairment.


iRichard Compton, & Amy Berning, Results of the 2007 National Survey of Alcohol and Drug Use By Drivers. National Highway Traffic Safety Facts. Washington, DC: NHTSA's National Center for Statistics and Analysis (July 2009) DOT HS 811 175
iiJ. Michael Walsh, Ron Flegel, Randolph Atkins, Leo A. Cangianelli, Carnell Cooper, Christopher Welsh and Timothy J. Kerns, Drug and Alcohol Use Among Drivers Admitted to a Level-1 Trauma Center, Accident Analysis and Prevention, Volume 37, Issue 5, Pages 894-901 (September 2005)
iiiSubstance Abuse and Mental Health Services Administration. (2010). Results from the 2009 National Survey on Drug Use and Health: Volume I. Summary of National Findings (Office of Applied Studies, NSDUH Series H-38A, HHS Publication No. SMA 10-4856Findings). Rockville, MD.
iv O'Malley, P.M.; Johnston, L.D. Driving after drug or alcohol use by U.S. high school seniors, 20012011.American Journal of Public Health 103(11):2027-2034, 2013. Abstract.
v Beirness, D.J., & Beasley, E.E. (2009). Alcohol and Drug Use Among Drivers: British Columbia Roadside Survey 2008. Ottawa, ON: Canadian Centre on Substance Abuse.
viJ. Michael Walsh, Ron Flegel, Randolph Atkins, Leo A. Cangianelli, Carnell Cooper, Christopher Welsh and Timothy J. Kerns, Drug and Alcohol Use Among Drivers Admitted to a Level-1 Trauma Center, Accident Analysis and Prevention, Volume 37, Issue 5, Pages 894-901 (September 2005)
viiRichard Compton, & Amy Berning, Results of the 2007 National Survey of Alcohol and Drug Use By Drivers. National Highway Traffic Safety Facts. Washington, DC: NHTSA's National Center for Statistics and Analysis (July 2009) DOT HS 811 175
viiiBeirness, D.J., & Beasley, E.E. (2009). Alcohol and Drug Use Among Drivers: British Columbia Roadside Survey 2008. Ottawa, ON: Canadian Centre on Substance Abuse.
ixNational Highway Traffic Safety Administration. (2010). Drug Involvement of Fatally Injured Drivers. Traffic Safety Facts. (http://www-nrd.nhtsa.dot.gov/Pubs/811415.pdf)
x20% is a conservative estimate based on:
• 33% of fatally injured drivers with known drug test results in FARS in 2009 were positive for one or more drug
• J.M. Walsh's finding that 50% of seriously injured drivers tested positive for drugs OTA (Walsh JM, Flegel R, et al Acc Anal Prev 37, 2005)
• Barry Logan's study showing 35% of fatally-injured drivers test positive for drugs (Schwilke, dos Santos, Logan, J For Sci, 2006)
• Barry Logan's trucker drug-testing study which found 21% of truckers test positive for drugs (Couper, Logan. J For Sci, 2001)
• CDC estimates that 18% of traffic accidents are drug-related (http://www.cdc.gov/ncipc/factsheets/drving.htm, http://www.cdc.gov/MotorVehicleSafety/Impaired_Driving/impaired-drv_factsheet.html)
• NIDA & NHTSA estimate that drugs are used by 10% to 22% of drivers in collisions (http://www.nida.nih.gov/PDF/Infofacts/driving05.pdf)
• NHTSA notes that, for fatally injured drivers, cannabis is detected in 7% to 37% with a mean of 14%. Each of five other drugs can be found in about 5% or less (http://icsw.nhtsa.gov/people/injury/research/StateofKnwlegeDrugs/StateofKnwlegeDrugs/index.html)
xi • Figure based on IBH's conservative estimate that 20% of vehicle crashes are attributable to drugged driving, and recent data from the Fatality Analysis Reporting System (FARS)
• FARS Death Data 2009:
          33,808 motor vehicle deaths * .20 = 6,761.
xii Figure based on IBH's conservative estimate that 20% of vehicle crashes are attributable to drugged driving, and the most recent data from the NHTSA
• FARS Death Data 2009:
          2.2 million injuries * .20 = 440,000
xiii Figure based on IBH's conservative estimate that 20% of vehicle crashes are attributable to drugged driving, and recent data from AAA's estimate that the cost of car accidents costs $299.5 billion a year.
• (AAA Crashes vs. Congestion: What's the Cost to Society? Report Nov 2011: http://www.camsys.com/pubs/2011_AAA_CrashvCongUpd.pdf)
          $299.5 billion *.20 = $59.9 billion ($59,900,000)

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