Safety Research Report
SRR-XX/XX

December 13, 2022

Safety Research Report SRR-22-02

Alcohol, Other Drug, and Multiple Drug UseAmong Drivers
Abstract: This safety research report examines the crash risk associated with different
drugs, including alcohol, and the prevalence of their use among drivers; it also
discusses countermeasures to reduce impairment-related crashes. To do this, theNational Transportation Safety Board (NTSB) conducted a literature review ofimpaired driving research, examined drug reporting in the National Highway Traffic
Safety Administration’s Fatality Analysis Reporting System, and performed an
independent analysis of the presence of potentially impairing drugs in driver
specimens submitted to four US laboratories that met strict standards for collecting
high-quality toxicology data.
The NTSB identified the following safety issues: (1) the need to implement provencountermeasures for alcohol-impaired driving; (2) the need to address the growing
problems of cannabis-, other drug-, and multiple-drug-impaired driving; (3) the needto improve drug-impaired driving laws and enforcement; (4) the need to ensure thatdriving safety is considered in the evaluation of prescription and over-the-counter
drugs; and (5) the need to enhance systems for documenting and tracking theincidence of drug use and driving.
As a result of this safety research, the NTSB makes new recommendations to the
National Highway Traffic Safety Administration; the US Food and Drug
Administration; and the 50 states, the District of Columbia, and the Commonwealthof Puerto Rico. The NTSB also classified two previous recommendations.

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Contents
Contents ................................................................................................................. i
Figures ................................................................................................................. iv
Tables .................................................................................................................... v
Acronyms and Abbreviations ............................................................................... vi
Executive Summary.............................................................................................viii
Safety Research Topic ................................................................................................... viii
What We Found ............................................................................................................. viii
What We Recommended ................................................................................................ x
1. Introduction ...................................................................................................... 1
1.1 Drug Impairment and Use Among Drivers ........................................................... 2
1.2 Scope ......................................................................................................................... 6
1.3 Goals .......................................................................................................................... 7
1.4 Challenges in Researching Drugs and Drug-Impaired Driving ......................... 7
1.4.1 Characteristics of Drugs.................................................................................. 8
1.4.2 Characteristics of the User.............................................................................. 9
1.4.3 Circumstances of Drug Use ............................................................................ 9
1.4.4 Documenting Drug Use and Drug-Related Driving Impairment............. 10
2. Methodology .................................................................................................. 15
2.1 Literature Review .................................................................................................... 15
2.2 FARS Analysis ......................................................................................................... 15
2.3 Prevalence Data from Jurisdictions with Advanced Testing
Programs ................................................................................................................. 16
2.4 Data Analysis Approach ........................................................................................ 19
2.4.1 Development of Drug Categories and Subcategories ............................. 19
2.4.2 Metabolite Coding ........................................................................................ 22
2.4.3 Identification of Potentially Impairing Drugs ............................................. 23
2.4.4 Analysis Approach ......................................................................................... 23
2.4.5 Interpretation ................................................................................................. 24
3. Results ............................................................................................................. 25iSafety Research Report
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3.1 Literature Review .................................................................................................... 25
3.1.1 Estimates of How Various Drugs Affect Driving Performance ................. 25
3.1.2 Crash Risk Associated with Individual Drugs or Drug
Categories ............................................................................................................... 27
3.1.3 Crash Risk Associated with Multiple Drug Use .......................................... 30
3.1.4 Summary of Drugs that Impair Performance and Increase
Crash Risk................................................................................................................. 33
3.2 FARS Analyses ........................................................................................................ 33
3.3 Toxicology Analyses from Four Jurisdictions ..................................................... 36
3.3.1 Overall Drug Prevalence .............................................................................. 38
3.3.2 Results by Subcategory ................................................................................ 40
3.3.3 Results by Sex................................................................................................. 42
3.3.4 Driving with Multiple Categories of Drugs ................................................. 43
3.3.5 Likelihood of Testing Positive for Other Drugs Based on BAC ............... 49
3.3.6 Time to Test .................................................................................................... 49
3.4 Summary of Drug Prevalence Results ................................................................. 50
4. Safety Issues .................................................................................................... 53
4.1 Need to Implement Proven Countermeasures for Alcohol-Impaired
Driving ..................................................................................................................... 53
4.1.1 Effective Laws and Enforcement .................................................................. 55
4.1.2 In-Vehicle Technologies ............................................................................... 56
4.1.3 Actions Needed to Reduce Alcohol-Impaired Driving Crashes .............. 57
4.2 Need to Address the Growing Problem of Cannabis-, Other Drug-,and Multiple-Drug-Impaired Driving ................................................................... 58
4.2.1 Public Campaigns.......................................................................................... 60
4.2.2 Prescription and OTC Drug Labeling ......................................................... 61
4.2.3 Cannabis Labeling ......................................................................................... 64
4.3 Need to Improve Drug-Impaired Driving Laws and Enforcement .................. 66
4.3.1 Oral Fluid for Impaired Driving Enforcement ............................................ 66
4.3.2 Impairing Drug Definitions in Impaired Driving Statutes ......................... 70
4.3.3 Electronic Warrants ....................................................................................... 71
4.3.4 State Efforts to Address Drug-Impaired Driving ....................................... 72ii

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4.4 Need to Ensure that Driving Safety Is Considered in the Evaluationof Prescription and OTC Drugs ............................................................................ 74
4.4.1 Evaluating Potential Effects on Driving Safety During Drug
Development........................................................................................................... 74
4.4.2 Continued Surveillance of Prescription and OTC Drugs .......................... 76
4.5 Need to Enhance Systems for Documenting and Tracking theIncidence of Drug Use and Driving ..................................................................... 78
4.5.1 BAC Testing and Reporting ......................................................................... 79
4.5.2 Other Drug Testing and Reporting ............................................................. 79
4.5.3 Sentinel Surveillance Systems to Track Drug Use in
Crash-Involved Drivers ........................................................................................... 86
4.5.4 Driver Pretrial Services, Monitoring, Specialty Courts, andTreatment ................................................................................................................ 87
5. Conclusions ..................................................................................................... 89
5.1 Findings ................................................................................................................... 89
6. Recommendations .......................................................................................... 92
6.1 New Recommendations ........................................................................................ 92
6.2 Previously Issued Recommendations Classified in This Report ....................... 94
Board Member Statement ................................................................................... 96
Appendixes ......................................................................................................... 97
Appendix A: NTSB Impairment-Related Recommendations ................................... 97
Appendix B: Impairment-Related NTSB Investigations Since 2012 ...................... 129
Appendix C: NTSB Drug Category and Subcategory Descriptions...................... 132
Appendix D: Summary of the DRUID Meta-Analysis Results ................................. 137
Appendix E: List of Drug Compounds Tested by Laboratory................................ 139
References......................................................................................................... 146iii

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FiguresFigure 1. Number and rate of fatalities involving an alcohol-impaired driver, per 100
million VMT, 1982–2020. ....................................................................................................... 3
Figure 2. Time course of standardized THC concentration in blood, subjective high,and negative performance on a divided attention task after smoking cannabis (Source
data: Spindle and others 2018; Spindle and others 2019). ............................................ 14
Figure 3. Relative crash risk associated with different BACs (Source: Blomberg andothers 2005). ......................................................................................................................... 28
Figure 4. Percentage of drivers in fatal crashes tested for drugs by state, reported to
FARS, 2020. ........................................................................................................................... 35
Figure 5. Percentage of drivers testing positive for each drug category by laboratory
dataset.................................................................................................................................... 39
Figure 6. Percentage of drivers testing positive for each drug category by sex in the
Orange County laboratory dataset. ................................................................................... 42
Figure 7. Percentage of drivers testing positive for multiple drug categories in eachlaboratory dataset. ............................................................................................................... 43
Figure 8. Distribution of alcohol and cannabis in the Orange County laboratory dataon drivers arrested for impaired driving and the Wisconsin laboratory data on crashinvolved drivers arrested for impaired driving. ................................................................ 45
Figure 9. Distribution of drivers with different BACs from the Orange County
laboratory dataset. ............................................................................................................... 47
Figure 10. Distribution of drivers with different blood THC concentrations from theOrange County laboratory dataset. ................................................................................... 48
Figure 11. Oral fluid collection laws for impaired driving enforcement (Source: Moore
and others 2022)................................................................................................................... 69iv

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TablesTable 1. NTSB potentially impairing drug categories and subcategories used for drugclassification and analysis. ................................................................................................... 21
Table 2. Meta-analysis findings from Elvik 2013, unless otherwise indicated;
statistically significant crash risk findings are indicated with an asterisk. ...................... 29
Table 3. Proportions of fatally injured and surviving drivers in fatal crashes in the
United States with BACs reported in FARS. ...................................................................... 34
Table 4. Proportions of fatally injured and surviving drivers in fatal crashes in the
United States that were reportedly drug tested based on FARS data........................... 34
Table 5. Summary of characteristics of the laboratories and datasets included in thisresearch. ................................................................................................................................ 37
Table 6. Prevalence of potentially impairing drugs in the five driver populations
studied. .................................................................................................................................. 38
Table 7. Drug category and subcategory prevalence for drivers arrested for impaired
driving from the Orange County laboratory and crash-involved impaired driving fromthe Wisconsin laboratory. .................................................................................................... 41
Table 8. Frequency of commonly observed drug categories and drug category
combinations in the Orange County laboratory dataset. ................................................ 44
Table 9. The prevalence of alcohol alone, in combination with other drugs, andoverall for each driver population. ..................................................................................... 46
Table 10. The prevalence of cannabis alone, in combination with other drugs, andoverall for each laboratory sample driver population. .................................................... 46
Table 11. Varying warning labels about driving after use of diphenhydramine sleep
aids for three different brands on the FDALabel website. .............................................. 63
Table 12. Minimum drugs to be tested for according to ANSI/ASB Standard 120,
adapted from the NSC ADID Tier I Compounds (D’Orazio and others 2021). ............ 81
Table A-1. NTSB impairment-related recommendations. ............................................... 97
Table B-1. NTSB-investigated highway crashes in which alcohol-, other drug-, or
multiple-drug impairment was a cause or contributing factor since 2012. ................ 129
Table D-1. Degree of impairment sorted in ascending order within different
substance classes. .............................................................................................................. 137
Table E-1. List of drug compounds tested by each of the four laboratories. ............. 139v

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Acronyms and Abbreviations
ANSI/ASB Standard 120

American National Standards Institute/American Academyof Forensic Sciences Standards Academy Board Standard
for the Analytical Scope and Sensitivity of Forensic
Toxicological Testing of Blood in Impaired Driving
Investigations, ANSI/ASB Standard 120

ARIDE

Advanced Roadside Impaired Driving Enforcement

BAC

blood alcohol concentration

CFR

Code of Federal Regulations

DNA

deoxyribonucleic acidDOT

US Department of Transportation

DRE

drug recognition expert

DRUID

Driving Under the Influence of Drugs, Alcohol andMedicines

DUI

driving under the influence

FARS

Fatality Analysis Reporting System

FBI

Federal Bureau of Investigation

FDA

US Food and Drug Administration

g/dL

grams per deciliter

GHSA

Governors Highway Safety Association

ICADTSInternational Council on Alcohol, Drugs, and Traffic Safety

IIJA

Infrastructure Investment and Jobs Act

MDA

3,4-methylenedioxyamphetamine

MDMA

3,4-methylenedioxymethamphetamine

ng/mL

nanograms per milliliter

NHTSA

National Highway Traffic Safety Administrationvi

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NRS

National Roadside Survey

NSC ADID

National Safety Council Alcohol Drugs, and Impairment
Division

NTSB

National Transportation Safety Board

OTC

over-the-counter

SFST

standardized field sobriety test

THC

tetrahydrocannabinol

VMT

vehicle miles traveled

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Executive Summary
Safety Research Topic
Alcohol-impaired driving is involved in nearly one in three traffic fatalities, andthe problem of driving while impaired by other drugs alone or combined together
continues to create harm on our roadways. Alcohol and other drugs, including illicit,
prescription, and over-the-counter drugs, can negatively affect driving performanceand increase crash risk. Taking multiple drugs at the same time, sometimes referred
to as polydrug or polysubstance use, can have similar effects on drivers and is an
emergent concern for roadway safety. Over the past 5 decades, the National
Transportation Safety Board (NTSB) has documented drug impairment from alcohol,
other drugs, or a combination of drugs as a cause of numerous highway crashes andhas issued more than 150 safety recommendations to address impaired driving. ThisNTSB safety research report examines the crash risk associated with different drugs,
including alcohol, and the prevalence of their use among drivers; it also discusses
countermeasures to reduce impairment-related crashes.
To conduct this research, the NTSB reviewed scientific literature about
impaired driving, examined drug reporting in the National Highway Traffic Safety
Administration’s (NHTSA) Fatality Analysis Reporting System, and performed an
independent analysis of the presence of potentially impairing drugs in driver
specimens submitted to four US laboratories that met strict standards for collecting
high-quality toxicology data. These specimens were from fatally injured drivers anddrivers arrested for or suspected of impaired driving.

What We FoundA literature review found that multiple drugs and drug categories areassociated with impaired performance and increased crash risk. (A drug categoryrefers to a group of drugs that have similar effects, such as stimulants or sedatives.)
We confirmed that drug data in national-level databases continue to be unreliable
and cannot be used to estimate drug prevalence among drivers. Consequently, we
analyzed the best available toxicological data from five populations of drivers,
including drivers arrested for impaired driving and fatally injured drivers, from theOrange County, California, Crime Laboratory; the Wisconsin State Laboratory ofHygiene, which provided data for two populations of drivers; the New York State
Police Forensic Investigation Center; and the San Francisco Office of the Chief
Medical Examiner.
Between 71% and 99% of drivers in the five populations studied tested positive
for one or more potentially impairing drugs, and about half of drivers tested positive
for more than one category of drug. Alcohol and cannabis were the two mostviii

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commonly detected drugs across all populations studied. We must address those.
Alcohol was most often detected alone, whereas cannabis was most often detected in
combination with alcohol or other drugs. Alcohol continues to be the drug with themost detrimental impact on traffic safety; however, cannabis and other potentially
impairing drugs contribute to the problem of impaired driving crashes.
The research also found that reducing the time between an impaired driving
event and biological specimen collection increases the likelihood that toxicologicaltest results will reflect drug presence at the time of an event. Also, because there is nocommon standard of practice for the collection, testing, and reporting of driver drug
toxicology data in the United States, critical information that could improveunderstanding of drug trends and prevalence, assist with the evaluation ofcountermeasures, and better guide treatment options for impaired driving offenders
is not being captured or analyzed. For this reason, widespread adoption ofstandardized drug testing and reporting is needed to improve our understanding of
the prevalence of drug use among crash-involved drivers and drivers arrested for
impaired driving. Efforts are also needed to increase the reporting of blood alcohol
concentrations among drivers involved in fatal crashes.
Currently, some policies halt further drug testing when a blood alcohol
concentration over a certain threshold is detected. However, if we limit further
testing for drivers whose blood alcohol concentrations exceed a certain threshold,
we miss important information about what else may be impairing them and ways tointervene, including, but not limited to, improving the safety of prescription andover-the-counter drugs and treatment interventions for drug addictions. A standard
toxicology testing approach will allow us to implement appropriate countermeasures
widely and to identify developing problems with impairment. However, testing is only
a part of the solution. We must also work on laws, enforcement, education, andtreatment interventions.
Our research indicated several areas where improvements could be made to
reduce the incidence of drug-impaired driving, including the following:•

Implementing proven countermeasures for alcohol-impaired driving.

•

Addressing the growing problems of cannabis-, other drug-, andmultiple-drug-impaired driving, for example, by including
driving-related warnings on cannabis products, improving prescription
and over-the-counter drug labeling, and continuing efforts to increase
drivers’ awareness of the risks of drug-impaired driving.

•

Improving drug-impaired driving laws and enforcement by authorizing theuse of electronic warrants and oral fluid testing to expedite the collection of
biological specimens and by using the NHTSA-developed Drug-Impaired
Driving Criminal Justice Evaluation Tool to guide improvements toix

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addressing drug-impaired driving. Additionally, specifying a prescribed setof drugs that are impairing can limit enforcement efforts.
•

Ensuring that driving safety is considered in the evaluation of prescription
and over-the-counter drugs both during new drug development and after
drugs have gone to market.

•

Enhancing systems for documenting and tracking the incidence of drug use
and driving both to better our understanding of the problem and to
customize early intervention and post-conviction intervention treatments,
which can be effective for reducing impaired driving recidivism.

What We Recommended
As a result of this research, the NTSB issued 12 new recommendations andclassified 2 previously issued recommendations. Six recommendations were issued tovarious states, the District of Columbia, and the Commonwealth of Puerto Rico. Those
recommendations call on them to do the following:•

Require a warning label on cannabis products advising users to not drive
after cannabis use due to its impairing effects.

•

Modify laws to allow for oral fluid collection, screening, and testing for thedetection of drug use by drivers.

•

Allow the use of electronic warrants to obtain biological specimens during
impaired driving arrests.

•

Enact laws specifying that drivers under the influence of a drug or multiple
drugs that may impair driving are considered to be impaired under thedefinition of drug-impaired driving.

•

Assess drug-impaired driving efforts using a tool developed by NHTSA
and, based on the results, apply for NHTSA funds to establish programs to
reduce drug-impaired driving.

•

Require government-funded toxicology laboratories to adopt and routinely
apply (regardless of driver blood alcohol concentration) standard practices
for the toxicological testing of biological specimens and provide fundingfor equipment, personnel, and training to facilitate that testing. (This newrecommendation supersedes Safety Recommendation H-22-23, which wasclassified Closed—Superseded.)xSafety Research Report
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The NTSB issued three recommendations to NHTSA to do the following:•

Disseminate a common standard of practice to state officials for drug
toxicology testing. (This new recommendation supersedes Safety
Recommendation H-12-33, which was classified Closed—Acceptable
Action/Superseded.)•

Establish a program to support toxicology laboratories’ compliance with astandard practice for the toxicological testing of biological specimens.

•

Establish a trauma center-based sentinel surveillance system; that is, acollection of reporting sites that provide timely and high-quality data tomeasure trends in the prevalence of drug use among crash-involved
drivers.

Lastly, the NTSB issued three recommendations to the US Food and Drug
Administration (FDA) to do the following:•

Conduct a study to understand how drug labels could be modified toincrease user understanding and compliance with driving-related warnings
and publish the study findings.

•

Develop a system to audit drugmaker compliance with FDA guidance toevaluate drug effects on the user’s ability to operate a motor vehicle.

•

Incorporate additional data and research concerning drug use and driving
to improve FDA drug safety surveillance systems.

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1. Introduction
Drug-impaired driving, including impairment from alcohol, other drugs, or
multiple drugs, is not a new problem.1 The National Transportation Safety Board(NTSB) has investigated numerous crashes involving drug-impaired driving,
conducted safety research on the topic, and held public forums to discuss varying
dimensions of the issue. As a result, over the past 5 decades, the NTSB has issued
more than 150 related safety recommendations.2 “Prevent Alcohol- and Other
Drug-Impaired Driving” is an issue area on the NTSB’s 2021–2023 Most Wanted Listof Transportation Safety Improvements, and impaired driving has been an area ofconcern on most of the NTSB’s Most Wanted Lists since its inception in 1990.3
Between 2012 and 2013, the NTSB held two Board meetings and apublic forum addressing impaired driving, subsequently issuing a total of
19 recommendations with the goal of eliminating impaired driving crashes (NTSB
2012a, 2012b, 2012c, 2013a). In its 2013 report, Reaching Zero: Actions to Eliminate
Alcohol-Impaired Driving, the NTSB focused primarily on alcohol-impaired driving
because its association with crash risk and the countermeasures to address it were
well understood. Other drugs were also recognized as a potential problem for roadsafety; however, because less was known about the scope of their use by drivers, the
NTSB called for improvements in identifying other drug use among crash-involved
drivers.
Since that time, the NTSB has continued to document drug impairment fromalcohol, other drugs, or a combination of drugs―sometimes referred to as polydrug
or polysubstance use―as a cause of highway crashes.4 This safety research reportexamines the crash risk associated with different drugs, including alcohol, and theprevalence of their use among drivers; it also discusses countermeasures to reduce

Alcohol is a drug. However, it is sometimes considered as distinct from other drugs. In thisreport, the terms drug, drug-impaired driving, and drug prevalence will include alcohol unless clearlystated otherwise.
1

Appendix A lists all NTSB impairment-related recommendations related to the highway
mode. Additional information about safety recommendations referenced in this report is also available
via the CAROL Query.
2

3

Impaired driving has been highlighted on the NTSB’s Most Wanted List for 28 of 34 years.

See appendix B for a list of recent NTSB-investigated highway crashes in which drug use wascited as the probable cause or a contributing factor.
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impairment-related crashes.5 To do this, the NTSB conducted a literature review ofimpaired driving research, examined drug reporting in the National Highway Traffic
Safety Administration’s (NHTSA) Fatality Analysis Reporting System (FARS), andperformed an independent analysis of the presence of potentially impairing drugs indriver specimens submitted to four US laboratories that met strict standards forcollecting high-quality toxicology data.6
This research focused specifically on identifying drugs that may impair driving
and determining their prevalence of use among drivers. Although a primary focus
was given to alcohol and cannabis due to their documented prevalence and negative
impacts on traffic safety, numerous other drugs, including illicit, prescription, andover-the-counter (OTC) drugs, were examined.7 Any drug that may impair driving
performance may result in traffic harm and adverse legal consequences for the driver,such as an arrest for driving under the influence (DUI). Yet, many drivers may be
unaware of the risks certain drugs present to the safe operation of a motor vehicle.
This includes drugs that are prescribed by a doctor or used according to the druglabeling. This should not discourage the proper medical use of drugs or stigmatize
the underlying medical conditions they are intended to treat. However, a better
understanding of driving risk and prevalence of all drugs is critical to promoting
traffic safety and providing all drivers with necessary information regarding potential
risks to their safety and the safety of all road users.

1.1 Drug Impairment and Use Among Drivers
The best available national-level drug-impaired driving data are limited toalcohol use by drivers in fatal crashes. NHTSA reports driver blood alcohol
concentration (BAC) in fatal crashes for FARS.8 Figure 1 depicts the number offatalities in alcohol-impaired driving crashes per year and fatalities per 100 million
vehicle miles traveled (VMT) based on FARS estimates. Beginning in the 1980s, there
Visit ntsb.gov to find additional information in the public docket for this NTSB safety research(case number DCA21SS003). Use the CAROL Query to search safety recommendations and othersafety research.
5

6

See section 2.3 for a description of the standards for inclusion in this safety research.

Cannabis is a plant commonly referred to as “marijuana.” This report uses the term “cannabis”
except in instances where the term “marijuana” is used by the author or organization being cited.
7

NHTSA uses a statistical technique known as multiple imputation, which refers to the practiceof “filling in” missing data with plausible values. Between 2018 and 2020, more than one-third ofdrivers in fatal crashes did not have BAC reported. Multiple imputation in FARS involves estimating
10 simulated BAC values for each missing value, then using statistical averages for subsequent
analyses (Subramanian 2002).
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was a substantial reduction in both the number of impaired driving fatalities and thefatality rate. However, since 2010 there has been little change, except in 2020, when
there was a notable increase, which coincided with the COVID-19 pandemic.9 NHTSA
estimated that 11,654 people died in crashes involving an alcohol-impaired driver in
2020, accounting for nearly 1 in 3 traffic fatalities (NCSA 2022a; NCSA 2022b).10

Figure 1. Number and rate of fatalities involving an alcohol-impaired driver, per 100 million
VMT, 1982–2020.

FARS also contains information about other drug use; however, because ofinconsistencies in the collection, testing, coding, and reporting of these data acrossand within jurisdictions, NHTSA has issued broad cautions against the use of its data
about other drug use, including to examine trends over time or to make comparisonswith alcohol use (Berning and Smither 2014; Berning and others 2022). Despite thelimitations of national fatal crash data concerning other drug use and driving, there isevidence of major societal trends in drug prescribing and drug use over the past2 decades that may have affected the prevalence of drug use among drivers anddrug-related crashes. This includes a significant increase in prescription drug
use―including potentially impairing benzodiazepines, muscle relaxants, and opioid
analgesics―among adults of all ages in the United States (Kantor and others 2015;
The COVID-19 pandemic began in late 2019. See the Centers for Disease Control andPrevention’s “CDC Museum COVID-19 Timeline” and “Basics of COVID-19” sites for further
information.
9

NHTSA defines an alcohol-impaired driver as one with a BAC of 0.08 grams per deciliter(g/dL) or higher, which is consistent with the per se impairment threshold in 49 states. In 2018, Utahbecame the first state to lower its per se BAC limit to 0.05 g/dL.
10

3

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Schepis and McCabe 2016; Hirschfeld 2017). Also, there has been a proliferation ofnovel psychoactive substances, which are chemicals designed to mimic the effects ofillicit drugs.11 Common examples include “spice” and “bath salts,” which are designed
to mimic cannabis and illicit stimulants, respectively.12 Research has shown increases
in novel psychoactive substance use in the United States and may not capture the full
extent of its use because such drugs are difficult to detect using conventional
methods (Neicun and others 2020).
Additionally, there has been a general movement to decriminalize or legalize
cannabis use over the past decade.13 Since 2012, 21 states, the District of Columbia,
and two US territories have legalized recreational cannabis use.14 Other states havemade cannabis legal for medical use or have decriminalized it by reducing thepenalties associated with its possession. Research about the effects of such measureson the prevalence of cannabis use among the driving population and traffic safety
have shown mixed results (Ramirez and others 2016a; Tefft and Arnold 2020; Farmer,
Monfort, and Woods 2022; Aydelotte and others 2019; Monfort 2018; Eichelberger
2019; Highway Loss Data Institute 2020).
In addition to increases in potentially impairing drug use overall, there is also
evidence that people are using impairing substances while driving. For example, the2013–2014 National Roadside Survey (NRS), a nationally representative study in whichbiological specimens were collected from volunteer drivers and tested for alcoholand 98 other drugs or drug metabolites, estimated that 22.3% of daytime drivers and22.5% of nighttime drivers tested positive for potentially impairing drugs (Ramirez
and others 2016b; Kelley-Baker and others 2017).15 Their results also showed asignificant increase in drug use by nighttime drivers compared to 2007, the first year
in which the NRS tested for drugs other than alcohol. The prevalence of both11

Novel psychoactive substances are also referred to as “synthetic drugs” or “designer drugs.”

See the US Drug Enforcement Administration’s “Designer Drugs” webpage for more
information.
12

Cannabis is a plant commonly referred to as “marijuana.” This report uses the term“cannabis” except in instances where the term marijuana is used by the author or organization being
cited. Also, since 2019, two states (Oregon and Colorado) and several cities have legalized or
decriminalized psilocybin, commonly known as “magic mushrooms.”
13(a) See the National Conference of State Legislatures’ “State Medical Cannabis Laws”
webpage for more information. (b) Additionally, the Agriculture Improvement Act of 2018, Public Law
115–334, 132 Stat. 4490 (2018), contained language that ended federal control over cannabis plants
and derivatives containing no more than 0.3% tetrahydrocannabinol (THC) on a dry weight basis.
14

15

A drug metabolite is a compound formed by the body processing, or metabolizing, a drug.

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cannabis alone and cannabis in combination with other drugs increased significantly
between the 2007 and the 2013–2014 NRS periods (Kelley-Baker and others 2017).
The National Survey on Drug Use and Health, an annual survey conducted by
the Substance Abuse and Mental Health Services Administration, found that, in 2020,
more than 1 in 10 respondents reported driving under the influence of alcohol
and/or an illicit drug or illicit drugs in the past year (SAMHSA 2021). The two mostcommonly reported drugs were alcohol at 7.2% and cannabis at 4.5%. About 1% of
respondents reported driving under the influence of other selected illicit drugs,
including cocaine, heroin, hallucinogens, inhalants, and methamphetamine. A
nationally representative survey of drivers conducted by the AAA Foundation for
Traffic Safety in 2020 found that 5.9% admitted to driving when they were over thealcohol limit in the past month, 4.4% admitted to driving within an hour of using
marijuana, and 3.4% admitted to driving when using potentially impairing
prescription drugs (AAA FTS 2021).
Tracking the prevalence of potentially impairing drug use amongcrash-involved drivers is a necessary component of determining crash risk,
understanding trends, and evaluating the effectiveness of countermeasures. A recent
NHTSA-sponsored study examined drug prevalence among seriously and fatally
injured road users who were taken to certain trauma centers beginning in
September 2019. The COVID-19 pandemic occurred during the study period, so thestudy reported findings for the periods before and after the March 16, 2020,declaration of a public health emergency (Thomas and others 2020).16
Before the COVID-19 public health emergency declaration, 50.8% of seriously
or fatally injured drivers tested positive for at least one potentially impairing drug
category, and 17.6% tested positive for two or more.17 For the 4 months studied after
the declaration, the proportions increased significantly to 64.7% and 25.3%,
respectively. Alcohol and cannabis were the most common drugs detected (Thomas
and others 2020). Two subsequent publications noted that drug prevalence in thethird and fourth quarters of 2020, while still higher than prepandemic levels, had
begun to recede (Office of Behavioral Safety Research 2021a, 2021b). The NHTSA
study provides important insights but cannot be considered representative of all
crash-involved drivers in the United States because it only included seriously or fatally
injured drivers and its data collection varied somewhat over time and locations.

The researchers reported that they were able to modify testing protocols to continue
collecting data during the pandemic.
16(a) A drug category refers to a group of drugs that have similar effects, such as stimulants or
sedatives. (b) The drug categories were alcohol, cannabis, stimulants, sedatives, opioids/narcotic
analgesics, antidepressants, OTC, and other drugs.
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Because alcohol-impaired driving is involved in nearly one in three traffic
fatalities and because of the growing problem of driving while impaired by otherdrugs or multiple drug use, the NTSB has undertaken this research effort. The NTSB is
not alone in its efforts to understand and address issues relating to drug-impaired
driving. For example, the Infrastructure Investment and Jobs Act (IIJA) included
several sections on multiple substance-impaired driving prevention.18 Also, in recent
years, many groups have undertaken efforts to address this issue, including NHTSA,
the Centers for Disease Control and Prevention, the Transportation Research Board,
the National Safety Council, the Governors Highway Safety Association (GHSA), theNational Governors Association, the Foundation for Advancing Alcohol
Responsibility, the Society of Forensic Toxicologists, and many others. This safety
research aims to add to the current literature and other work that has been done or iscurrently underway to understand and address the problem of drug and multiple
drug use among drivers.

1.2 ScopeThis research focuses on drug and multiple drug use among drivers; however,there are no reliable national-level data available on the topic. Therefore, to conduct
this research, the NTSB relied on an extensive review of relevant scientific literature to
inform its analytical approach and used the best data available from four
US laboratories that met strict standards for collecting high-quality toxicology data.
Analyzing these data allowed the NTSB to gain current, detailed, and comprehensive
results about the types of drugs and drug combinations drivers are using when they
are fatally injured or arrested for impaired driving.
This research does not assess the effects of all potentially impairing drugs or all
possible drug combinations. The laboratory data used are not representative of all
impaired drivers and could not be aggregated due to differences amonglaboratories. Still, the data selection process was criteria based, and the sample driver
populations are examined in parallel to determine drug prevalence.
Although the documented prevalence and traffic harm from alcohol andcannabis created a special focus on these two substances, other potentially impairing
drugs were included in this research. Much less is known about the prevalence ofother potentially impairing drugs, including many illicit, prescription, and OTC drugs.
The unique toxicology data and methodology used in this research allowed for an

IIJA, Public Law 117–58, 135 Stat. 429 (2021). See the following sections: 24105, “National
Priority Safety Programs”; 24106, “Multiple Substance-Impaired Driving Prevention”; 24107, “Minimum
Penalties for Repeat Offenders for Driving While Intoxicated or Driving Under the Influence”; 24220,“Advanced Impaired Driving Technology”; and 25025, “Drug-Impaired Driving Data Collection.”
18

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innovative assessment of the prevalence of many of these potentially impairing drugs
and drug combinations.
Therefore, it is important to note that the following points informed andguided the scope of this research:•

Alcohol and cannabis were key focus areas, but other potentially impairing
drugs were examined to better understand the prevalence of drug use anddrug combinations among drivers. This included the combinations of otherpotentially impairing drugs with alcohol and cannabis.

•

Only potentially impairing drugs were included in the analysis. Many drugs
may improve driving performance, including by treating potentially
impairing medical conditions.

1.3 Goals
The goals of this research are to (1) better understand the prevalence ofpotentially impairing drug use among drivers; (2) summarize what is known about
how different drugs, including alcohol, and drug combinations may affect driving
safety; and (3) recommend measures to reduce the likelihood of drug-impaired
driving and to improve our ability to track its prevalence.

1.4 Challenges in Researching Drugs and Drug-Impaired Driving
Understanding the problem of drug-impaired driving is challenging andcomplex for a variety of reasons. There are hundreds of potentially impairing drugs
and thousands of potential drug combinations. For most drugs, with the notable
exception of alcohol, there is no clear correlation between measurable drugconcentrations from biological specimens and the level of impairment experienced
by a driver. Also, different drugs may affect people differently depending on thecharacteristics of the drug, the characteristics of the user, and the circumstances inwhich the drug is used. This section is designed to provide readers a basic overview
of some of the many factors that need to be considered to fully understand andaddress the problem of drug-impaired driving and to interpret the results of thepresent research.

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1.4.1 Characteristics of Drugs
This research focuses on alcohol and other drugs with psychoactive effects that
could potentially impair driving.19 Alcohol’s negative effects on driving performanceand crash risk are well understood and have been described in detail in other reports(NTSB 2013a; NASEM 2018). Illicit drugs generally refer to drugs that are illegal topossess and have no medical use; they are considered impairing with a highpropensity for abuse.20 Additionally, some drugs that are prescribed for medical
conditions or sold OTC have the potential to be impairing by, for example, increasing
drowsiness, affecting judgment, slowing reaction time, or blurring vision. Such drugs
may carry labels that warn users to avoid driving or using heavy machinery while
taking the drug or that caution them not to drive until they know how the drug affects
them. In these cases, a drug may impair driving even if prescribed by a doctor andtaken as recommended.21
Characteristics of a drug’s chemistry can also lead to different effects on users.
For example, a stimulant drug will have a very different effect than a depressant drug.
Additionally, when drugs are taken in combination, their impairing effects may
increase, or new effects may develop. For example, many drugs with depressive
effects, such as opioids and benzodiazepines, contain warnings that users should notconsume alcohol while taking those drugs because of the potential for combined
effects. The US Food and Drug Administration (FDA) has cautioned that druginteractions can make certain drugs less effective, increase the action of a drug, orlead to unexpected side effects that may be harmful to health.22 Further, in somecases, drug users may not be aware that they are consuming more than one drug; forexample, if an illicit drug contains a contaminant or cutting agent that also has
psychoactive properties.23

Psychoactive drugs affect the brain or nervous system functioning in ways that can alter
perception, behaviors, or performance.
19

The US Drug Enforcement Administration categorizes a subset of drugs in five “Schedules”
based on their potential for abuse. Schedule I drugs are considered to have no medical use and are
generally not available legally. Although cannabis is classified as a Schedule I drug, several states havelaws that allow its medical or recreational use.
20

Many OTC and prescription drugs are medically necessary. The objective is not todiscourage the consumption of drugs used as a part of medical treatment or to cast a negative light on
individuals taking these drugs or any underlying medical condition. Rather, the potentially impairing
effects of these drugs must be understood and communicated to drivers to mitigate traffic harm.
21

22

See the FDA’s “Drug Interactions: What You Should Know” webpage for more information.

23

A cutting agent refers to a less expensive substance added to dilute or adulterate a drug.

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1.4.2 Characteristics of the User
Drugs may affect people differently depending on genetic or physicalcharacteristics or medical conditions. For example, the drug zolpidem, commonlymarketed as Ambien and prescribed as a sleep aid to treat insomnia, is metabolized
slower by females than by males. For drivers with certain medical conditions, drugs
may reduce crash risk. Drugs used to treat epilepsy or narcolepsy are examples ofdrugs that have the potential to reduce crash risk for individuals who have thosediseases (Devlin and others 2012; Donjacour and others 2016).

1.4.3 Circumstances of Drug Use
Some drugs may be relatively non-impairing at low doses but may havesignificant effects on performance at higher doses. For example, dextromethorphan,commonly marketed as Robitussin, is commonly used as a cough suppressant. At
recommended doses, it has little to no effect on performance for most people, but athigh doses, it can result in dissociative effects and hallucinations, increasing crash risk
(Couper and Logan 2004).24
The route of administration, such as eating, inhaling, or injecting, can affect theway a drug is absorbed into the body. For example, cannabis that is inhaled via
vaporization, or “vaping,” results in stronger drug effects and higher peak blood
tetrahydrocannabinol (THC) concentrations compared to an equivalent amount ofsmoked cannabis (Spindle and others 2018). Compared to vaping or smoking, inwhich psychoactive effects are reported almost immediately after inhalation, whencannabis products are eaten, the psychoactive effects may not begin until 30 to
60 minutes later (Borodovsky and others 2016).
Some drugs may cause impairment immediately following use, but for others
the onset may be delayed. Additionally, the duration of a drug’s effects can vary
greatly depending on the rate at which a drug is metabolized. Further, althoughmany drugs are impairing while the drug is actively circulating in the user’s system,some drugs may affect users in different ways over the course of their metabolism
and elimination. For example, after certain stimulants are metabolized, there is awithdrawal phase, which involves extreme fatigue, depression, and drug craving,even when drug levels are low (Couper and Logan 2004).

Dissociative effects refer to a sense of disconnection from the self or the surrounding
environment.
24

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Some prescription drugs can cause severe impairment in new users, but after aperiod of use, tolerance develops, and driving performance may return to baseline.25
For example, experimental studies examining the antidepressant mirtazapine,commonly marketed as Remeron, found that users in a driving simulator showedsome evidence of performance impairment (variability in lane position) after 2 days ofuse but that performance returned to normal after about 2 weeks of use (Theunissen
and others 2013). For other drugs, such as benzodiazepines, which are central
nervous system depressants commonly prescribed for anxiety, tolerance may takemuch longer (Hansen and others 2015; van der Sluiszen and others 2019).
For some drugs, long-term habitual use has been linked to performancedecrements even after a period of abstinence. For example, one study found thatpsychomotor performance of chronic daily cannabis smokers improved over a
3-week period of abstinence but did not recover to the point that it was equivalent to
the performance of a control group comprised of occasional users (Bosker and others2013).26

1.4.4 Documenting Drug Use and Drug-Related Driving Impairment
The ability to detect whether a driver has used specific drugs can support
research, crash investigation, enforcement of impaired driving laws, and more
effective education and intervention, all of which have the potential to reduce theincidence of impairment-related crashes and improve roadway safety.
On an individual level, identifying potentially impairing drugs can facilitate
impaired driving arrests and prosecution. However, it may also help to develop
customized interventions to reduce the likelihood of recidivism. Better understanding
the drugs in a driver’s system can help shape the most effective treatment options.
For example, for a driver impaired only by alcohol, an alcohol ignition interlock may
be a successful tool for preventing recidivism, whereas identifying the use of otherdrugs or multiple drug use could lead to changes in a driver’s prescriptions ortreatment for a substance use disorder. A number of education and treatment tools
also exist, including pretrial services, early intervention services, monitoring,supervision, and treatment.
From a community perspective, understanding which drugs are being used bydrivers and their prevalence can enhance understanding of the association of drugs
Use of a certain drug may also produce tolerance to other drugs, a phenomenon known ascross-tolerance.
25

Psychomotor performance refers to physical movement in coordination with the cognitive
processing of information, such as a driver’s speed of reaction when steering a vehicle.
26

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and crash risk and can be used to direct resources toward systemic countermeasures,such as awareness campaigns and training for law enforcement or medical
professionals.
Most law enforcement officers learn about detecting signs of alcohol use andimpairment during their initial training, but fewer have detailed training on detecting
and identifying impairment from other drugs. The current tools used by law
enforcement officers rely largely on interviews, behavioral observations, andphysiological assessments. Law enforcement assessments seek to evaluate anddocument both whether a driver is demonstrating signs of impairment and whether
the driver has consumed drugs that are consistent with the observed signs of
impairment; these assessments include the following:•

The standardized field sobriety tests (SFSTs) are designed to detect drivers
with BACs at or above 0.08 grams per deciliter (g/dL). There are three
SFSTs: one-leg stand, walk and turn, and horizontal gaze nystagmus.27 Most
law enforcement officers learn to conduct the SFSTs during basic academy
training. There is some evidence that some SFSTs could be used to screen
for certain drugs or drug categories, including stimulants, depressants,
cannabis, and narcotic analgesics (Porath-Waller and Beirness 2014).
However, the SFSTs are likely not sufficient to identify drivers impaired by
all potentially impairing drugs, and NHTSA has not validated the SFSTs forany drugs other than alcohol.

•

The Advanced Roadside Impaired Driving Enforcement (ARIDE) program isa 16-hour training program that educates law enforcement officers about
how to observe, identify, and articulate the signs of impairment related toboth alcohol and other drugs. Since the program’s inception in 2009, morethan 141,000 law enforcement officers, prosecutors, and toxicologists havereceived this training (IACP 2021).

•

The Drug Evaluation and Classification program, developed by theInternational Association of Chiefs of Police and NHTSA, trains law
enforcement officers to become experts in identifying the signs andsymptoms of impairment by various categories of drugs. In 2021,
8,115 drug recognition experts (DREs) were in the United States,
representing about 1.2% of law enforcement officers (IACP 2021).28 This
program includes 72 hours of classroom training and 40 to 60 hours of fieldtraining. Law enforcement officers who complete the Drug Evaluation and27

Horizontal gaze nystagmus refers to a rapid side-to-side motion of the eye.

According to the US Bureau of Labor Statistics’ “Occupational Employment and Wage
Statistics” webpage, there were 665,380 police and sheriff’s patrol officers in the United States in 2021.
28

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Classification program are certified to perform a 12-step evaluation
protocol to assess subjects for drug impairment, which includes
psychophysical tests and physical examinations. DREs are required toregularly perform and document their evaluations under specific conditions
to maintain certification.
In some cases, a law enforcement officer who has arrested a driver for
impaired driving will request or, depending on the circumstances, compel a driver tosubmit a biological specimen to screen or test for the presence of alcohol and otherdrugs. Biological specimens may include breath, urine, blood, or oral fluid.
Toxicological analyses of biological specimens may also be conducted as a part of apostmortem investigation for drivers who are fatally injured in motor vehicle crashes
or in support of research.
1.4.4.1 Breath
Breath specimens are routinely collected during impaired driving arrests whenalcohol impairment is suspected because they can provide reliable estimates of BAC.
Portable breath-testing devices are commonly used at the roadside as part of theSFSTs. Evidential breath testing devices, that is, those that meet NHTSA-establishedmodel specifications, are typically used in police departments after an arrest has
occurred.29 Breath testing is not currently used to reliably test for drugs other thanalcohol, although some research has been conducted to explore its future feasibility(Beck, Ullah, and Kronstrand 2019; Johnson, Miskelly, and Rindelaub 2022).30
1.4.4.2 Urine
Urine is a commonly used biological specimen for drug testing. Title 49 Codeof Federal Regulations (CFR) Part 40 requires employers to conduct urine drug testingfor commercial motor vehicle drivers under several circumstances, including fatal
crashes or serious crashes in which citations are issued. In some states, urine
specimens are used for impaired driving investigations in which drugs other thanalcohol are suspected.31 Urine can provide information about historical use of or
exposure to drugs. However, urine can be challenging to collect, it can also be
29

See NHTSA’s “Alcohol Measurement Devices” webpage for more information.

See also the National Institute of Standards and Technology’s “Chemical Foundations for a
Cannabis Breathalyzer” webpage for more information.
30

For example, in Florida, urine is commonly collected during arrests for driving under the
influence of drugs because Florida statute does not allow for the collection of blood except in cases
when using breath or urine is impossible or impractical and serious bodily injury or death is involved.
See the Florida Senate’s 2017 Florida Statutes, Title XXIII, chapter 316, section 1932, for more
information.
31

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susceptible to substitution or tampering, and it may not provide evidence of recent
drug use (Niedbala and others 2001). In general, urine tests cannot identify the
specific concentration of a drug acting on the body or the timing of its use relative tothe timing of a crash or driving violation. In its 2021 recommendations for
toxicological investigation for drug-impaired driving and motor vehicle fatalities, theNational Safety Council’s Alcohol, Drugs, and Impairment Division (NSC ADID) noted
these limitations and concluded that it would sunset its guidance concerning urine as
an appropriate testing specimen for impaired driving investigations (D’Orazio andothers 2021).
1.4.4.3 Blood
Blood is generally considered to be an optimal biological specimen for
toxicological analyses to determine the presence of drugs that were psychoactive at
the time of collection. Blood is very useful, but its collection requires transport to afacility for a blood draw, during which time drugs in a driver’s system continue to be
metabolized.32 As a result, the toxicological analysis may not reflect the drug levels
present in a driver’s blood at the time of an event or a drug may even completely
metabolize out of a driver’s system by the time of collection.
1.4.4.4 Oral Fluid
Oral fluid, which is comprised of saliva and other substances found in themouth, such as cell debris and particles of ingested materials, may be collected withrelative ease and swiftness compared to blood and urine (White and Moore 2018).
Oral fluid drug testing has long been used in clinical and workplace settings, but its
use for drug-impaired driving enforcement is relatively new. Some law enforcement
agencies have begun using oral fluid screening devices at the roadside during
impaired driving arrests to provide rapid qualitative (positive or negative) information
about a predetermined panel of drugs or drug categories. Oral fluid specimens canalso be used for confirmatory testing by toxicology laboratories, which typically
includes a larger panel of drugs and provides information about the quantity of drugs
detected in the specimen. However, currently only one state, Alabama, routinely
conducts confirmatory testing on oral fluid specimens.33

In some communities, law enforcement personnel or contractors with phlebotomy
training―that is, training in drawing blood samples―are used to expedite blood collection. For
example, police departments in Arizona, Idaho, Minnesota, and Washington have such phlebotomy
programs (NHTSA 2019).
32

The Alabama Department of Forensic Sciences also encourages law enforcement to collectblood specimens to provide a more complete picture of recent drug use. See its “Toxicology Oral
Fluid Drug Testing Program” webpage for more information.
33

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1.4.4.5 Challenges in Using Biological Specimens to Document Impairment
Toxicological testing can provide information about whether a drug was
consumed, but for most drugs, a measured concentration alone cannot indicate
whether a driver was impaired by that drug at the time of a crash or a traffic stop. In
the case of alcohol, as a driver’s BAC increases, their performance degrades and theircrash risk increases, and this has provided the rationale for illegal per se BAC limits.34
However, for many drugs, this is not the case. For example, as shown in figure 2,
when a person smokes cannabis, their blood THC levels rise with the peak occurring
shortly after smoking ends. The THC levels in blood drop rapidly thereafter, but the
subjective high and performance decrements remain after THC levels have receded(Compton 2017).

Figure 2. Time course of standardized THC concentration in blood, subjective high, andnegative performance on a divided attention task after smoking cannabis (Source data:
Spindle and others 2018; Spindle and others 2019).
Note: In the figure, ng/mL refers to nanograms per milliliter.

Per se BAC laws establish the BAC level at which it is illegal per se (in itself) for a driver tooperate a vehicle, regardless of the driver’s apparent condition or actions.
34

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2. Methodology
This section discusses the methods the NTSB used to conduct this research:(1) a literature review of impaired driving research, (2) an examination of drug
reporting in NHTSA’s FARS, and (3) an independent analysis of high-quality
toxicology data of fatally injured drivers and drivers arrested for or suspected of
impaired driving from four laboratories that met strict data standards for inclusion.
These methods worked together to improve our understanding of the effects drugs
have on drivers, the current state of national data on drug use and driving, and theprevalence of drugs and drug combinations in fatally injured drivers or drivers
arrested for or suspected of impaired driving on US roadways.

2.1 Literature Review
The literature review focused on meta-analyses of epidemiological andexperimental studies that have been conducted over several decades to assess theperformance effects and crash risk of various drugs and drug combinations.35 Whenmeta-analyses were not available, the report describes the findings from individual
studies.

2.2 FARS Analysis
As a census of all fatal crashes on US roadways, FARS is a prominent source oftraffic safety data.36 FARS collects data on both alcohol and other drugs. However, in
2014, NHTSA issued a report cautioning that the drug data in FARS had significant
limitations and were insufficient to answer many important questions about theprevalence and risk of drug-impaired driving (Berning and Smither 2014). Since thattime, NHTSA has put out a renewed call for caution using drug data in FARS while
also highlighting steps taken to improve drug data in FARS (Berning and others2022). For example, beginning in 2018, the agency expanded FARS to allow for theentry of all available drug tests and results, thereby allowing for the documentation of
more than three drugs per driver, which had been the previous FARS limit.
Because of its well-documented shortcomings, the NTSB did not use FARS tocharacterize drug prevalence among drivers in fatal crashes. However, the NTSB did
conduct analyses of FARS drug data to determine the following:

A meta-analysis is a statistical study design used to systemically summarize and combine theresults of multiple previous independent studies relevant to an issue.
35

FARS includes motor vehicle crashes on public roadways that involve the death of a vehicle
occupant or nonoccupant within 30 days of the crash.
36

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whether alcohol and other drug testing/reporting, for both fatally injured
and surviving drivers, has increased in recent years•

reporting rates for drug testing by state in which the crash occurred•

whether the 2018 FARS change from a limit of three nonalcohol drugs per
driver to unlimited drug reporting increased reporting of drivers positive
for more than three drugs

2.3 Prevalence Data from Jurisdictions with Advanced Testing
Programs
There are severe limitations with existing national data on drug-involved
driving (Berning and others 2022; NTSB 2012c). These limitations often stem frominconsistencies in drug testing procedures and reporting in both state databases andat toxicology laboratories. For example, in many jurisdictions, laboratories first
determine BAC in their toxicology testing programs, and, if that level is above thestate’s per se limit, additional testing for other drugs is not performed.37 This type of“stop-testing” protocol provides information on alcohol-impaired driving but little tono information on circumstances where alcohol is combined with other drugs.38 There
are also large amounts of missing data due to the lack of toxicology testing and major
inconsistencies in drug testing protocols, including which drugs are tested for andunder what circumstances. Because of missing data and inconsistent testing
protocols, it is difficult to assess the prevalence of drug use and to assess crash risk
associated with different drugs.
Thus, to address the severe limitations of current national drug data, the NTSB
took a targeted approach to soliciting high-quality data from leading laboratories
across the country. Specifically, we sought out laboratories that performed consistentand comprehensive drug testing of all driver specimens received. These laboratories
provided data that exceeded the known limitations of most impaired driving
databases and provided unique and previously unexplored insights into the drug useof drivers in those communities.

The process of first testing for BAC levels may be based on the costs associated with acomprehensive drug panel or because of complexities in the legal system when positive BAC levels
are reported with the presence of other drugs.
37

Stop-testing generally refers to canceling further drug tests when a driver’s BAC is above acertain threshold.
38

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Acknowledging the common limitations of toxicology data, the NTSB
developed data-inclusion standards to guide the selection of these laboratories anddata. For example, the selected laboratories had to do the following:•

consistently test all driver specimens for drugs regardless of circumstances;that is, they did not use “stop-testing” protocols for drivers above a certain
BAC•

use a comprehensive drug panel that included compounds from theAmerican National Standards Institute/American Academy of Forensic
Sciences Standards Board Standard for the Analytical Scope and Sensitivityof Forensic Toxicological Testing of Blood in Impaired Driving
Investigations, ANSI/ASB Standard 120 (ANSI/ASB 2021)39•

use blood as a testing specimen to reflect a closer association to time of
drug usage•

maintain data management systems that allow for the electronic transfer ofdeidentified toxicology data

The NTSB conducted outreach to identify and contact toxicology experts forthis data collection effort. The purpose of this outreach was twofold. First, the NTSB
sought to identify data from jurisdictions with laboratories that met the above criteria.
Second, the NTSB elicited subject matter expert input from the toxicology community
to understand the steps laboratories or jurisdictions took to expand and improvetheir testing programs and the obstacles they faced or continue to face when
conducting and reporting on comprehensive testing.
The NTSB spoke with subject matter experts from the following organizations:•

Alabama Department of Forensic Sciences•

California Department of Justice Bureau of Forensic Services•

Colorado Department of Public Safety(a) A drug compound refers to drugs or drug metabolites. (b) The ANSI/ASB Standard 120
compounds include THC, carboxy-THC, 11-hydroxy-THC, methamphetamine, amphetamine,
3,4-methylenedioxyethylamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), cocaine,benzoylecgonine, cocaethylene, carisoprodol, meprobamate, zolpidem, alprazolam, clonazepam,
7-aminoclonazepam, lorazepam, diazepam, nordiazepam, oxazepam, temazepam, codeine,
6-acetylmorphine, buprenorphine, norbuprenorphine, fentanyl, hydrocodone, methadone, morphine,
oxycodone, tramadol, and O-desmethyltramadol (ANSI/ASB 2021).
39

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Florida (multiple organizations represented)40•

Houston Forensic Science Center•

NSC ADID•New York State Police•

North Louisiana Criminalistics Laboratory•

NMS Labs41•

Orange County, California, Crime Laboratory•

San Francisco Office of the Chief Medical Examiner•

San Diego County, California, Sheriff’s Department•

Wisconsin State Laboratory of Hygiene

The subject matter experts provided valuable input about their experiences
concerning driver toxicology testing. Four organizations identified by these subject
matter experts had laboratory protocols and data that met the inclusion criteria andagreed to share data with the NTSB:•

Orange County, California, Crime Laboratory•

Wisconsin State Laboratory of Hygiene•

New York State Police Forensic Investigation Center•

San Francisco Office of the Chief Medical Examiner42

Forensic Toxicology Laboratory at the University of Florida, Palm Beach County Sheriff’s
Office, Forensic and Clinical Toxicology Laboratory of the University of Miami School of Medicine,
Florida Department of Law Enforcement Orlando Regional Laboratory and Tallahassee Regional
Laboratory, Pinellas County Forensic Laboratory, Hillsborough County Medical Examiner’s Office,Florida Department of Transportation, Florida Traffic Safety Resource Prosecutor, and Florida Impaired
Driving Coalition.
40

41

NMS Labs was formerly known as National Medical Services.

For simplicity, throughout the remainder of this report, the Orange County Crime Laboratory
will be referred to as the Orange County laboratory, the Wisconsin State Laboratory of Hygiene will bereferred to as the Wisconsin laboratory, New York State Police Forensic Investigation Center will bereferred to as the New York laboratory, and the San Francisco Office of the Chief Medical Examiner will
be referred to as the San Francisco laboratory.
42

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Many of the other organizations NTSB spoke with shared summaries or
published data from their laboratories that provided insight into the procedures andfindings of those laboratories (Harper 2020; Lee and Stout 2020; Lee, Stout, andEgdorf 2021; Rosenthal and Reed 2022).

2.4 Data Analysis Approach
The amount of data NTSB acquired for this research was substantial;
specimens from many drivers were tested at each of these laboratories and thosespecimens were tested for a large number of drugs for each driver. A structured
approach to coding and analyzing the toxicology data was necessary to guide theanalysis and interpretation. This approach was developed through discussions with
the NTSB medical officers and review of the drug toxicology literature; thetoxicologists who provided data for this research also provided a technical review of
the approach.

2.4.1 Development of Drug Categories and Subcategories
Drugs are complex, and many toxicology laboratories test for hundreds, if not
more than a thousand, different drug compounds. The development of a drugclassification scheme that comprehensively and accurately classifies drugs and their
metabolites is helpful for interpretation of results and discussion. There is nouniversal method for classifying drugs, and numerous varying approaches exist in the
traffic safety literature and field.43 Based upon review of the existing drugclassification schemes, and in close coordination with NTSB medical officers, the
NTSB developed a novel method for drug classification and analysis.

See the following for a few examples of these approaches: NHTSA’s 2013–2014 National
Roadside Study of Alcohol and Drug Use by Drivers: Drug Results (Kelley-Baker and others 2017); theInternational Association of Chiefs of Police’s “7 Drug Categories” webpage; the NTSB’s 2013–2017
Update to Drug Use Trends in Aviation (NTSB 2020a); the FDA’s “Pharmacologic Class” webpage.
43

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A full list of individual drugs and metabolites that were assessed within eachcategory and subcategory is available in the NTSB public docket.44 The drug
categories and, when appropriate, subcategories resulting from the classification arelisted in table 1. (Appendix C provides descriptions of the NTSB’s drug categories
and subcategories.) It should be noted that ethanol was differentiated from othernon-ethanol alcohols in this categorization scheme and analysis. In the remainder ofthe report, ethanol will simply be referred to as alcohol.45 Furthermore, thisclassification approach was designed to only categorize potentially impairing drugs.
“Potentially impairing” was added before the “neuropsychiatric medications” and the“other” categories for extra clarity because many of these types of medications would
not generally be impairing. However, all categories should be understood to only
include examples of impairing drugs for this report.

44

See the NTSB public docket, case number DCA21SS003.

(a) Ethanol is the alcohol present in alcoholic beverages such as beer, wine, and spirits.
(b) Non-ethanol alcohols tested for by the four laboratories included acetone, isopropanol, andmethanol.
45

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Table 1. NTSB potentially impairing drug categories and subcategories used for drugclassification and analysis.
Drug Category

Drug Subcategory

Alcohol (Ethanol)
Non-Ethanol Alcohols
Cannabis――
THC

Cannabis

Other Cannabinoids

Potentially Impairing
Neuropsychiatric Medications

AntidepressantsPotentially Impairing Neuropsychiatric Medications

Antiepileptics

Potentially Impairing Neuropsychiatric Medications

Antipsychotics

Potentially Impairing Neuropsychiatric Medications

Other Anxiolytics

Potentially Impairing Neuropsychiatric Medications

Other Potentially Impairing
Neuropsychiatric Medications

Hallucinogens
Inhalants
Dissociative Anesthetics
Sedatives―――
Barbiturates
Benzodiazepines

Sedatives
Sedatives

Muscle Relaxants

Sedatives

Sedating Antihistamines

Sedatives

Sleep Aids

Sedatives

Other Sedatives

Stimulants

Amphetamines
CocaineStimulants
Stimulants

Methamphetamines

Stimulants

Piperazines

Stimulants

Other Stimulants

Narcotic Analgesics

Non-Fentanyl Opioids

Narcotic Analgesics

Fentanyls

Novel Psychoactive Substances

Synthetic Cannabinoids

Novel Psychoactive Substances

Synthetic Cathinones

Other Potentially Impairing
Drugs

Anticholinergics

Other Potentially Impairing Drugs

Antiemetics

Other Potentially Impairing Drugs

Blood Pressure Medications

Other Potentially Impairing Drugs

Methorphan

Other Potentially Impairing Drugs

Migraine Medications

Other Potentially Impairing Drugs

Mitragynine

Other Potentially Impairing Drugs

Other Alkaloids

Other Potentially Impairing Drugs

Other (for example, butane)

Note: The em dash means not applicable.

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2.4.2 Metabolite Coding
As drugs are metabolized by the human body, they break down into newcompounds (that is, metabolites). The original drug taken by the user can often be
identified by the detection of the parent drug, that is, the original drug taken, or its
metabolites. For example, cannabis usage is often detected by the identification of
the parent drug delta-9-THC or one of its common metabolites, such as
11-hydroxy-delta–9-THC or 11-nor-delta-9-carboxy-THC. In this case, testing positive
for any of these compounds is evidence of cannabis usage, but the presence of all
three of them should not be treated as multiple drug usage because they are theresult of taking a single drug. This is critical because many parent drugs, such as
cocaine, are rapidly metabolized below detectable levels and are often best detected
through their metabolites. Further complicating analyses is that some parent drugs
metabolize into active compounds that may also be taken as a parent drug; forexample, codeine metabolizes into morphine.
As a part of this research, a comprehensive examination of drug metabolite
pathways was conducted to capture the complexity of drug metabolism.46
Specifically, the following coding and analysis rules were developed for the treatmentof drugs and metabolites:•

The detection of a parent drug’s metabolite(s) was coded as testing positive
for use of the parent drug, even if the parent drug was not detected.

•

The presence of multiple metabolites of a drug was not treated as multiple
drug usage.

•

Metabolites were generally coded as the highest detected parent drug. For
example, if both diazepam and nordiazepam were detected, then they
were solely coded as diazepam for analysis and reporting.

46

See the NTSB public docket, case number DCA21SS003, for more information.

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2.4.3 Identification of Potentially Impairing Drugs
The purpose of this research was to identify drugs that may potentially be
impairing an individual’s performance at the time of driving. There are numerous
drugs that may be tested for by toxicology laboratories and included in common
datasets, but many of those drugs are unlikely to actually influence or degrade an
individual’s driving performance. For example, many toxicology laboratories test for
non-impairing drugs, such as nicotine, caffeine, and acetaminophen (commonlymarketed as Tylenol). These and many other likely non-impairing drugs are includedin FARS, and, without proper care, analyses of such data could lead to a significant
overreporting of the prevalence of drug or multiple drug use that may impair driving.
Another key consideration, especially in a crash context, is that potentially
impairing drugs may be given as a part of standard medical treatment following acrash. Although such drivers would clearly not have been influenced by these drugs
at the time of driving, specimens drawn for drug testing after the administration ofthese drugs, as is often the case, would show the driver testing positive for thesepotentially impairing drugs. To address this concern, the NTSB identified drugs thatwere likely to be administered as a part of postcrash treatment. Both drugs that arelikely non-impairing and likely administered as a part of postcrash medical treatment
were removed from analysis for the present research. A full list of these drugs isavailable in the NTSB public docket.47

2.4.4 Analysis Approach
The laboratories that provided data for this research conduct drug testing thatis more extensive than tests conducted for crash-involved drivers or impaired driving
investigations in most US toxicology laboratories. The populations tested and the
toxicology test protocols followed in the four laboratories were similar, but not
identical. Therefore, the data could not be accurately combined for analysis. Eachlaboratory’s dataset provides a meaningful snapshot of its particular population, but
key differences in populations, drug panels, and testing protocols do not facilitate
accurate aggregation of these data for combined analyses. Instead, each laboratory’s
data were analyzed and reported separately, and common themes across the results
are discussed.

47

See the NTSB public docket, case number DCA21SS003.

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2.4.5 Interpretation
Several keys to interpretation and research limitations must be understoodwhen discussing the toxicology results. The detection of a drug in these populationsof drivers is evidence of recent usage of that drug but does not definitively
demonstrate the driver was impaired at the time of driving or that other drugs notdetected were not influencing the driver. Many drugs remain at detectable levels
even after their influence on a driver’s performance has dissipated. Alternately, many
drugs that may have been influencing an individual at the time of driving may havemetabolized out a driver’s system by the time a specimen was taken for testing. Thatis, it is important to understand that long delays can occur between when a driver isarrested or involved in a crash and when a biological specimen is collected for
toxicology testing. Every feasible step was taken to minimize these challenges, forexample, using appropriate testing specimens, considering metabolites, andremoving drugs that were likely administered postcrash.
The actual population of drivers tested must also be considered. For example,
a set of drivers that were tested for impaired driving cases may not represent theentire population of impaired drivers in a locality because not all impaired drivers arearrested and not all arrested drivers are tested. Possible effects from these factors
were not explored in the present research. Additionally, many law enforcement
officers may not be as familiar with impaired driving that does not involve alcohol. It is
possible that drivers impaired by other drugs are not arrested if they do not test at or
above the legal limit on a breath testing device. Some individuals originally arrested
for impaired driving may also have been suffering from a medical condition rather
than drug impairment. These are important considerations for future research, butthey are beyond the scope of the present research.

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3. Results
This section discusses the results of the methods described in the previous
section.

3.1 Literature Review
The literature review conducted in support of this research concentrated on
two key areas: (1) the ways that certain drugs affect driving performance and (2) crashrisk associated with drug and multiple drug use among drivers. The review focusedon large-scale meta-analyses that combined the results from multiple high-quality
peer-reviewed studies. Information gathered from the literature review provided
context for many of the discussions throughout this report.

3.1.1 Estimates of How Various Drugs Affect Driving Performance
Driving is complex and requires attention and the simultaneous performanceof several tasks. Researchers interested in how drugs may impair driving performance
have measured different variables, such as lane weaving or lane departures, vehicle
speed or speed variation, reaction times to environmental stimuli, and performanceon divided-attention tasks. A given drug may affect some but not all
driving-performance-related variables. Also, a drug may affect a driver in indirectways that can affect performance. For example, if a drug increases risk-taking
behaviors, such as speeding, a driver may lose control of the vehicle. Or if a drugcauses drowsiness, a driver’s reaction time may be slower.
Research in this area generally involves dosing participants and then assessing
driving- or driving-related performance in controlled environments. For example,
researchers may measure visual acuity or divided attention in laboratory settings ormeasure lane keeping, speed variability, or reaction time to hazards in simulated or
actual driving environments. A strength of this type of research is that by using
controlled doses and performance testing, a study may provide a detailed
understanding of the ways a given drug may affect various types of driving-related
performance. However, there are also limitations because researchers may be unable
to test illicit drugs due to legal or ethical restrictions. Also, the controlled dosing andtesting environments may not be reflective of real-world drug use or real-world
driving conditions.
Significant work has been done to document which drugs may impair driving
performance. For example, in 2004, NHTSA published a set of “Drugs and Human
Performance Fact Sheets” for 16 different drugs or drug groups that were commonly25Safety Research Report
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used at the time (Couper and Logan 2004).48 The fact sheets were developed by apanel of international experts on drug-impaired driving and included information
about each drug’s chemistry, how it affects the body, its usage and dosage, and its
performance effects. The fact sheets also included scientific references andrecommended reading. In 2018, NHTSA began a project to update the 2004 fact
sheets and to expand the number of drugs described.49
The Driving Under the Influence of Drugs, Alcohol and Medicines (DRUID)
project, a 5-year effort involving 18 European countries, comprised numerous studies
to assess the prevalence of use and risk of various drugs (Hels and others 2011). The
project also conducted meta-analyses on data from 450 published papers on alcoholand 605 publications concerning medicines and illicit drugs to estimate the overall
effects of different drugs and drug categories on performance. The DRUID project
found that alcohol and several other drugs, including cannabis, and several
benzodiazepines, sleep aids, antidepressants, and antihistamines, significantly andnegatively affected fitness to drive.50 Using these analyses, the project estimated thedegree of impairment for different drugs and drug doses. However, the resulting
report acknowledged that there was not enough information to fully assess all drugs
or drug combinations (EMCDDA 2012).
More recent meta-analyses have confirmed and expanded the findings fromthe DRUID project. One meta-analysis demonstrated impairment in several
driving-related tasks after cannabis use and that the impairment was greater foroccasional users compared to regular users (McCartney and others 2021). Anotherfound that alcohol, cannabis, and the combination of both drugs had a significant
impairing effect on certain driving performance measures, and that the combinationof the two drugs was more detrimental than either drug alone (Simmons and others2022). Two meta-analyses that examined the effects of sleep aids on driving
performance found that certain sleep aids, including zopiclone and zolpidem, wereassociated with impaired driving performance the morning after use (Roth and others
2014; McElroy and others 2021).

The drugs were carisoprodol, cocaine, dextromethorphan, diazepam, diphenhydramine,
gamma-hydroxybutyrate (GHB), ketamine, lysergic acid diethylamide (LSD), marijuana (cannabis),methadone, methamphetamine, MDMA, morphine, phencyclidine (PCP), toluene, and zolpidem.
48

For more information, see the US Department of Transportation’s (DOT) webpage “Update
NHTSA’s Drugs and Human Performance Fact Sheets.”
49

50

See appendix D for a summary of the DRUID meta-analysis results.

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3.1.2 Crash Risk Associated with Individual Drugs or Drug
Categories
In general, epidemiological studies that aim to assess the crash risk for
different drugs compare the presence of drugs in populations of drivers involved incrashes of varying severity to a control group of comparable drivers who were not
involved in crashes. These are referred to as case-control studies. By contrast, in
responsibility studies, researchers compare drug presence in drivers deemed
responsible for a multivehicle crash to drug presence in those drivers deemed not
responsible. Drug presence is typically measured using toxicological analysis or
driver self-report. Many studies also account for factors that may be related to both
drug use and crash risk, such as driver age, sex, or other drug use.
Because of challenges in conducting this type of research, most studies have
only assessed the crash risk associated with the presence of a drug, as opposed toconcentrations of a drug or actual impairment from that drug. By contrast, researchon alcohol has been able to quantify the crash risk associated with different BACs
compared to drivers with a BAC of 0.00 g/dL. One case-control study used data from
more than 10,000 crash- and non-crash-involved drivers in California and Florida; itfound that a statistically significant elevated crash risk began at a BAC of 0.04 g/dL
and rose steeply at higher BACs (Blomberg and others 2005). As shown in figure 3, at
a BAC of 0.08 g/dL, the per se impairment level in most states, the crash risk was
more than 2.5 times higher, and at a BAC of 0.10 g/dL, the crash risk was nearly
5 times higher. A separate meta-analysis, which combined data from eight studies ofalcohol and crash risk, found a similar dose-risk curve (Taylor and others 2010).

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Figure 3. Relative crash risk associated with different BACs (Source: Blomberg and others2005).

For other drugs besides alcohol, table 2 documents findings from several
meta-analyses.51 Most of the findings come from a meta-analysis conducted by Elvik(2013) that included 264 risk estimates from 66 studies published between 1976 and2011. In this table, relative risk indicates the likelihood of a crash or the likelihood thata driver was deemed responsible for a crash with a drug present compared to drivers
without a drug present.

The meta-analyses referenced in table 2 combined multiple studies that may have defineddrugs or drug categories differently.
51

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Table 2. Meta-analysis findings from Elvik 2013, unless otherwise indicated; statisticallysignificant crash risk findings are indicated with an asterisk.
Drug or Drug Category

Crash Severity or Responsibility

Odds Ratiof

95% ConfidenceIntervalg

Amphetamine
Amphetamine
Amphetamine
Analgesics
Antiasthmatics
AntidepressantsAntidepressantsAntihistamines
Benzodiazepines
Benzodiazepines
Benzodiazepines
Benzodiazepines
Benzodiazepines

Fatal crashes
Injury crashes
Property damage crashes
Injury crashes
Injury crashes
Injury crashes
Property damage crashes
Injury crashes
Fatal crashes
Injury crashes
Property damage crashes
All crashesa
All crashesa

5.17*
6.19*
8.67*
1.02
1.31*
1.35*
1.28
1.12*
2.30*
1.17*
1.35*
1.59*
1.81*

2.56–10.42
3.46–11.06
3.23–23.32
0.89–1.16
1.07–1.59
1.11–1.65
0.90–1.80
1.02–1.22
1.59–3.32
1.08–1.28
1.04–1.76
1.10–2.31
1.35–2.43

Benzodiazepines

Crash responsibility a

1.41*

1.03–1.94

Cannabis
Cannabis
Cannabis
Cannabis
Cannabis
Cannabis
CocaineCocaineCocaine
Opiates
Opiates
Opiates
Opioids (prescription)
Opioids (prescription)
Penicillin
Zopiclone
Zopiclone
Zopiclone

Fatal crashes
Injury crashes
Property damage crashes
All crashesb
All crashesc
All crashesd
Fatal crashes
Injury crashes
Property damage crashes
Fatal crashes
Injury crashes
Property damage crashes
All crashese
Crash responsibilitye
Injury crashes
Fatal crashes
Injury crashes
Property damage crashes

1.26
1.10
1.26*
2.66*
1.32*
1.92*
2.96*
1.66
1.44
1.68*
1.91*
4.76*
2.29*
1.47*
1.12
2.60
1.42
4.00*

0.88–1.81
0.88–1.39
1.04–1.76
2.07–3.41
1.09–1.59
1.35–2.73
1.18–7.38
0.91–3.02
0.93–2.23
1.01–2.81
1.48–2.45
2.10–10.80
1.51–3.48
1.01–2.13
0.91–1.39
0.89–7.56
0.87–2.31
1.31–12.21

a. The source for this information is Dassanayake and others 2011.
b. The source for this information is Li and others 2012.
c. The source for this information is Rogeberg, Elvik, and White 2018.
d. The source for this information is Asbridge, Hayden, and Cartwright 2012.
e. The source for this information is Chihuri and Li 2017.
f. The odds ratio estimates the odds of crash involvement or crash responsibility when a drug is present
compared to when it is not present. An estimate greater than 1 indicated that a drug increased risk,
and an estimate less than 1 would indicate that a drug reduced risk.

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g. A 95% confidence interval is a range of values above and below an estimate used to interpret theestimate’s accuracy and precision. The estimates with 95% confidence intervals that did not include 1
were considered significant and predictive in terms of changes in risk.

The results from the studies described above suggest that several drugs or
drug categories are associated with significantly increased crash risk or increased
likelihood of responsibility in a multivehicle crash. There was a clear pattern ofsignificantly increased risk associated with alcohol, amphetamine, benzodiazepines,
and opioids. For several other drugs and drug categories, one or more meta-analyses
indicated increased risk for certain types of crashes. However, an association between
a drug category and crash risk does not mean that every drug within that category
necessarily increases crash risk. For example, tricyclic antidepressants are generally
considered to be more impairing than selective serotonin reuptake inhibitors, which
are also used as antidepressants. Further, many antidepressants may not only
improve an individual’s overall health but may indeed help with potentially impairing
medical conditions, such as depression (Aduen and others 2018).

3.1.3 Crash Risk Associated with Multiple Drug Use
The research challenges for understanding the effects of a single drug are
greatly multiplied when examining drug combinations. There are nearly unlimited
combinations of drugs that may each affect a given driver differently. This may limit
the availability of meta-analyses that rely on multiple studies addressing the same
research question. Yet, one such meta-analysis found that the drug combination of
alcohol and benzodiazepines was associated with a greater than 7-fold increased
crash risk compared to drivers who tested negative for all drugs (Dassanayake andothers 2011).52
For drug combinations not assessed through meta-analysis, findings can bederived from epidemiological studies. For example, the DRUID project compareddrug presence from crash-involved drivers (cases) to non-crash-involved drivers(controls) to assess the crash risks of individual drugs as well as the risks associatedwith combining alcohol with other drugs and multiple drug use that did not include(a) The odds ratio was 7.69, and the 95% confidence interval was 4.33–13.65.
(b) Benzodiazepines and alcohol are known to have additive effects due to both drugs acting on
gamma-aminobutyric acid (GABA) receptors. This means taking benzodiazepines will increase theimpairing effects of alcohol. Other drugs interact differently with alcohol, which will impact both thequantity of alcohol required for impairment as well as the strength of the impairing effects of a given
quantity of alcohol.
52

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alcohol (Hels and others 2011).53 The aggregated results showed that the odds ofdrivers being seriously injured in a crash, compared to drivers who tested negativefor drugs, were more than 28 times higher for drivers who tested positive for alcohol
combined with other drugs and 8 times higher for drivers who tested positive formore than one nonalcohol drug.54 The aggregated results from fatally injured drivers
showed similar results. Drivers who tested positive for alcohol combined with otherdrugs had a crash risk more than 31 times higher than drivers who tested negative forthe presence of drugs or alcohol.55 For drivers who tested positive for more than one
nonalcohol drug, the risk was more than 18 times higher.56 A separate analysis of asubset of the DRUID project data collected in Belgium examined drug category
combinations, including alcohol and sedatives, alcohol and stimulants, multiple
sedatives, and stimulants and sedatives (Kuypers and others 2012). The crash risk
associated with each of the combinations was found to be significant and ranged
from 13 to 210 times greater for drivers who tested positive for these drug
combinations than for drivers with negative drug tests.57 However, the authors notedthat a study limitation was the small sample sizes of drivers who tested positive forcertain drugs and drug combinations. Additionally, a limitation of both studies was
the fact that some individuals in the control group population refused to participate. If
those who refused were more likely to have used alcohol or other drugs, the risk
estimates could be inflated.

53
The drugs studied in the DRUID project included alcohol, 6-acetylmorphine (6-AM),
alprazolam, amphetamine, benzoylecgonine, cannabis, clonazepam, cocaine, codeine, diazepam,
flunitrazepam, lorazepam, MDA, 3,4-methylenedioxy-N-ethylamphetamine (MDEA), MDMA,
methadone, methamphetamine, morphine, nordiazepam, oxazepam, zolpidem, and zopiclone.
Tramadol, 7-amino-clonazepam, and 7-amino-flunitrazepam were tested for in most but not all
countries (Hels and others 2011).

For drivers who tested positive for alcohol combined with other drugs, the odds ratio was
28.82, and the 95% confidence interval was 18.41–45.11. For drivers who tested positive for more than
one nonalcohol drug, the odds ratio was 8.01, and the 95% confidence interval was 5.34–12.01.
54

55

The odds ratio was 31.52, and the 95% confidence interval was 16.83–59.05.

56

The odds ratio was 18.51, and the 95% confidence interval was 10.84–31.63.

For alcohol and sedatives, the odds ratio was 67.19, and the 95% confidence interval was
23.91–188.84. For alcohol and stimulants, the odds ratio was 20.34, and the 95% confidence interval
was 4.93–83.82. For multiple sedatives, the odds ratio was 13.70, and the 95% confidence interval was
2.95–63.66. For stimulants and sedatives, the odds ratio was 210.97, and the 95% confidence interval
was 4.90–9088.71.
57

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A study using data from 3,398 fatally injured drivers from the Australian statesof Victoria, New South Wales, and Western Australia found that drivers with both a
BAC ≥0.05 g/dL and the presence of THC in their blood were nearly three times more
likely to be deemed responsible for a crash than drivers with a BAC ≥0.05 g/dL alone(Drummer and others 2004).58 A similar study using US data found that drivers with a
combination of THC and a BAC >0.00 g/dL but <0.05 g/dL were 3.42 times more
likely to be found responsible for a crash than drivers with no alcohol or other drugs
detected in their system (Romano, Voas, and Camp 2017). The same study did not
find a significant likelihood of crash responsibility for drivers with a BAC >0.00 g/dL
but <0.05 g/dL and no other drugs present, suggesting that it was the combination of
alcohol and cannabis that led to the elevated risk. However, it is important to interpret
this US study with caution because it relied on FARS drug data, which has significant
limitations. Further, it is important to note that not all case-control studies haveidentified significant risk associated with multiple drug use. For example, a
NHTSA-sponsored study conducted in Virginia Beach, Virginia, involving more than
3,000 crash-involved drivers and 6,000 matched controls, found a significant crashrisk for alcohol but not for other drugs or drug combinations when controlling for
demographic variables (Lacey and others 2016).
Epidemiological studies, such as those described in this section, are valuable
because they can provide insights about overall association between drug use andcrash risk. However, an epidemiological link between a drug or class of drugs andcrashing does not necessarily mean that a drug is dangerous to use while driving
under all circumstances. For example, epidemiological studies do not generally lookat the dose or whether a driver was using a drug as directed by their health careprovider. Nonetheless, when findings from epidemiological research, and particularly
meta-analyses of epidemiological studies, are considered alongside studies of how
drugs or drug combinations affect driving-related performance, they can provide amore nuanced understanding of how different drugs affect driving safety.

58

The odds ratio was 2.9, and the 95% confidence interval was 1.1–7.7.

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3.1.4 Summary of Drugs that Impair Performance and Increase
Crash Risk
In summary, many studies have been conducted to assess (1) how various
drugs affect driving and driving-related performance and (2) the association between
the use of various drugs and either crash risk or crash responsibility. Both of thesefactors are important to consider when evaluating how a given drug or drug
combination may affect driving safety. A review of these studies as well as several
meta-analyses, which systemically combine the results of multiple previous
independent studies relevant to an issue, allowed for the identification of some of thedrugs and drug categories that can affect driving safety. The NTSB concludes thatmultiple drugs and drug categories―including alcohol, cannabis, and numerous
illicit, prescription, and OTC drugs―can impair driving performance and areassociated with increased crash risk. As shown in table 2, some of these drugs areriskier and affect performance more than others. It is also important to recall thatsome drugs are medically necessary and may make drivers safer than not taking the
drugs, and in some cases, an underlying condition a drug is treating may also
increase crash risk independent from the drug effects.

3.2 FARS Analyses
In 2012, the NTSB issued recommendations to states to increase collection,
documentation, and reporting of BAC results using NHTSA best practice guidance,with a goal of achieving BAC reporting rates of at least 80% of fatally injured drivers
and at least 60% of surviving drivers in fatal crashes (H-12-34, H-12-35).59 At the time,
the national BAC reporting rates were 69% for fatally injured drivers and 28% forsurviving drivers in fatal crashes. For the present research, we compiled data from the
3 most recent years with available data: 2018, 2019, and 2020. As shown in table 3,
the rates of BAC reporting were on average about 5 percentage points lower in themost recent 3 years than in 2012 for both fatally injured and surviving drivers (NCSA
2014, 2019, 2020, 2021, 2022a).

Each individual state received a classification based on its response to Safety
Recommendations H-12-34 and H-12-35. Both recommendations have an overall classification of
Open—Acceptable Response. See appendix A for more information.
59

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Table 3. Proportions of fatally injured and surviving drivers in fatal crashes in the
United States with BACs reported in FARS.
Year

2012

2018

2019

2020a

Fatally Injured

69%

65%

65%

58%

Surviving

28%

23%

24%

22%

a. The COVID-19 public health emergency took place in 2020, which may have affected testing rates
during this period.

Additional analyses were conducted to examine testing rates for drugs otherthan alcohol.60 As shown in table 4, the proportions of drivers reported as drug tested
were also lower, on average, over the most recent 3 years tested compared to 2012.
Table 4. Proportions of fatally injured and surviving drivers in fatal crashes in the
United States that were reportedly drug tested based on FARS data.
Year

2012

2018

2019

2020a

Fatally Injured

61%

65%

60%

54%

Surviving

21%

19%

18%

17%

a. The COVID-19 public health emergency took place in 2020, which may have affected testing rates
during this period.

The availability of drug test results varied greatly by state in 2020, as shown infigure 4. For example, for Montana, FARS reported drug testing for more than 80% ofdrivers in fatal crashes. By contrast, there were eight states with drug tests reported
for less than 20% of drivers in fatal crashes, and for two states, the proportion was lessthan 5%. The availability of this information in FARS does not necessarily reflect theactual testing rates within each state; it may reflect the level of test reporting to FARS
analysts.

60

FARS maintains alcohol and other drug data in separate data files.

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Figure 4. Percentage of drivers in fatal crashes tested for drugs by state, reported to FARS,
2020.

The review of FARS data showed that for the majority of drivers, there are noreported test results for drugs other than alcohol and that reporting rates vary greatly
across states. Further, reports from NHTSA, the agency that maintains FARS, cautions
against the usage of drug data in FARS for prevalence analyses (Berning and Smither
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2014; Berning and others 2022). Therefore, the NTSB concludes that drug data innational-level databases continue to be unreliable and cannot be used to estimate
drug prevalence among drivers.

3.3 Toxicology Analyses from Four Jurisdictions
As noted previously, four laboratories met the inclusion criteria for thisresearch and agreed to share data with the NTSB for independent analysis. Separate
analyses were conducted on each of these datasets. Data from each laboratory wereunable to be reasonably aggregated into a single analysis due to key differencesamong laboratories. This included the population of drivers being tested, the numberof drugs tested at each laboratory, and other differences in laboratory protocols.
However, the results across laboratories may be examined in parallel to draw
conclusions regarding drug prevalence.
The four laboratories and the type of data they provided are described below.
•

The Orange County laboratory provided 2 years of data between
August 1, 2018, and July 30, 2020, on 14,051 drivers arrested for impaired
driving offenses.

•

The Wisconsin laboratory provided a database that included two
populations of drivers that were comprehensively and consistently tested
for drugs. The first population was fatally injured drivers. The second
population was crash-involved drivers arrested for impaired driving
offenses. Data were provided from January 1, 2019, to March 31, 2021, forboth populations. This resulted in 9,569 crash-involved arrested drivers and406 fatally injured drivers.

•

The San Francisco laboratory provided over 3 years of data between
March 20, 2015, and December 31, 2018, from 2,075 drivers arrested for
impaired driving. All 2,075 drivers were tested for alcohol locally by the
San Francisco Office of the Chief Medical Examiner. Blood specimens ofthese drivers were analyzed by NMS Labs for all other drugs.

•

The New York laboratory provided 11 months of data between
May 7, 2020, to June 8, 2021, from drivers suspected of impaired driving ina crash that involved a fatal or serious physical injury. All drivers were tested
for alcohol and other drugs. Due to the sample size (217 total drivers), bothof these populations were analyzed together for this research.61(a) Throughout the remainder of this report, these will be referred to as arrest cases forcomparison as these cases usually involve an arrest. (b) All cases received by the New York laboratory
involving a crash with a fatality or a serious injury are comprehensively tested for all drugs.
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Table 5 provides an overview of the data provided by each of the four
laboratories. It shows the number of compounds tested, number of drivers tested,
and key data characteristics. For a full list of compounds tested by each laboratory,
see appendix E.
Table 5. Summary of characteristics of the laboratories and datasets included in this research.
Data Provided

DriverPopulation
Potentially
Impairing
Compounds
TestedData Start
Date
Data End Date
Sample Size
Age
Sex
Incident Date
Time Between
Arrest andBlood
Collection

Orange County
Laboratory

Wisconsin
Laboratory

Wisconsin
Laboratory

San Francisco
Laboratory

New York
Laboratory

Impaired
driving arrests

Crash-involved
impaired driving
arrests

Crashinvolved
fatally injured

Impaired
driving arrests

Crash-involved
suspected
impaired drivingcases involving
fatality or serious
injury

183

136

136

54

39

8/1/2018

1/1/2019

1/1/2019

3/20/2015

5/7/2020

7/30/2020
14,051
Yes
Yes
No

3/31/2021
9,569
Yes
Yes
Yes

3/31/2021
406
Yes
Yes
Yes

12/31/2018
2,075
Yes
No
Yes

6/8/2021
217
Yes
Yes
Yes

No

Yes

No

Yes

Yes

Analyzing substance usage across categories represents the most likely andprominent effects of mixing drugs, aids interpretations, and provides clear areas forpotential countermeasure development. For this reason, the analyses in this section
were primarily focused on drug categories and subcategories rather than individualcompounds or drugs. To reduce redundant reporting of results across laboratories,
such as detailed demographic breakdowns, results are reported using the best suiteddataset(s) for the specific analysis.

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3.3.1 Overall Drug Prevalence
Across all data from the four laboratories, the vast majority of drivers arrested
for impaired driving tested positive for at least one potentially impairing drug, asdetailed in table 6.
Table 6. Prevalence of potentially impairing drugs in the five driver populations studied.

Total Sample
Drivers Testing
Positive
Percentage ofDrivers Testing
Positive

OrangeCountyLaboratory

Wisconsin
Laboratory
Crash-Involved
Impaired
Driving Arrests

Wisconsin
Laboratory
Crash-Involved
Fatally Injured

San Francisco
Laboratory

New York
Laboratory

14,051

9,569

406

2,075

217

13,903

9,073

289

2,040

171

98.9%

94.8%

71.2%

98.3%

79.8%

It would be expected that drivers arrested for impaired driving offenses would
be highly likely to test positive for at least one potentially impairing drug sincesuspected driver impairment led to the impaired driving arrest. By contrast, the factthat 71.2% of drivers in the fatally injured population tested positive for at least one
potentially impairing drug could be considered high knowing that not all fatally
injured drivers are responsible for crashes.
Figure 5 shows the percentages of drivers testing positive by drug category
across all laboratories and populations. Note that the percentages in the figure sum
to more than 100% because some drivers were positive for multiple drug
categories.62 Alcohol was by far the most commonly detected drug. It was detected in
between 55% and 78% of the drivers in the impaired driving datasets. Alcohol was
also the most commonly detected drug for the fatally injured drivers, with a positivity
rate of about 44%. The second most commonly detected drug in all datasets wascannabis. Cannabis was detected in over 30% of drivers in the impaired driver arrest
populations and in 20% of the fatally injured drivers. The next most common
categories of detected drugs were stimulants, sedatives, and narcotic analgesics.

See section 3.3.4 of this report for further discussion of the combinations of drug categories
that drivers tested positive for in each population examined.
62

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These categories varied slightly in the order in which they were most commonly
detected by laboratory.63

Figure 5. Percentage of drivers testing positive for each drug category by laboratory dataset.
Note: PINM refers to potentially impairing neuropsychiatric medications, OPID refers to otherpotentially impairing drugs, and NPS refers to novel psychoactive substances.

Differences in the detection of drug categories across laboratories may reflect regional
differences in drug prevalence or variance in laboratory testing procedures. Not all laboratories tested
for the same number of drugs within each category and fewer drugs tested in a category would resultin a lower prevalence for that category. For example, the New York laboratory did not test for any
potentially impairing neuropsychiatric medications
63

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3.3.2 Results by Subcategory
The prevalence of subcategories of drugs was also explored. This provides amore granular analysis of drugs that were detected in each of the driver populations.
Table 7 shows the frequency and percentage of drivers testing positive for drug
categories and subcategories for the impaired driving arrest population from theOrange County laboratory and the crash-involved impaired driving arrest populationfrom the Wisconsin laboratory. These laboratories are highlighted due to theircomparatively large sample sizes and extensive drug panels that best allow for
examining subcategory prevalence. Looking at these two populations demonstrates
some consistencies in drug subcategory prevalence, as well as variations that could
be attributable to differences in drug use patterns by region or variance in overalltesting protocols. For example, in both populations, benzodiazepines were the mostcommonly detected sedative. Similarly, methamphetamine and cocaine wereconsistently the most commonly detected stimulants. However, methamphetamine
was more than 2.5 times more likely to be detected in the Orange County laboratory
data (13.2%) than in the Wisconsin laboratory data (5.2%). It should be noted many ofthese similarities extended to all five laboratory populations. This includes
benzodiazepines consistently emerging as the most common sedative subcategory
and methamphetamine and cocaine emerging as the most common stimulant
subcategories.

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Table 7. Drug category and subcategory prevalence for drivers arrested for impaired drivingfrom the Orange County laboratory and crash-involved impaired driving from the Wisconsin
laboratory.
Drug Category and
Subcategory
Alcohol (Ethanol)
Non-Ethanol Alcohols
Cannabis
THC
Other Cannabinoids
Potentially Impairing
NeuropsychiatricMedications
AntidepressantsAntiepileptics
Antipsychotics
Anxiolytics
Other Potentially Impairing
Neuropsychiatric Medications
Narcotic Analgesics
Non-Fentanyl Opioids
Fentanyls
Hallucinogens
Inhalants
Dissociative Anesthetics
Sedatives
Barbiturates
Benzodiazepines
Muscle Relaxants
Sedating Antihistamines
Sleep Aids
Other Sedatives
Stimulants
Amphetamines
CocaineMethamphetamine
Piperazines
Other Stimulants
Novel Psychoactive
Substances
Synthetic Cathinones
Synthetic Cannabinoids
Other Potentially Impairing
Drugs
Anticholinergics
Antiemetics
Methorphan
Migraine Medications
Mitragynine

Orange County
Laboratory

Orange County
Laboratory

Wisconsin
Laboratory

Wisconsin
Laboratory

Frequency

Percent

Frequency

Percent

10,827
13
4,623
4,613
10

77.1%
0.1%
32.9%
32.8%
0.1%

7,112
3
3,090
3,090
not tested

74.3%
<0.1%
32.3%
32.3%
―

975

6.9%

1,198

12.5%

451
410
348
5

3.2%
2.9%
2.5%
<0.1%

347
795
310
11

3.6%
8.3%
3.2%
0.1%

2

<0.1%

3

<0.1%

1,030
860
303
19
596
80
2,084
33
1,374
225
813
96
―
3,000
324
978
1,856
5
39

7.3%
6.1%
2.2%
0.1%
4.2%
0.6%
14.8%
0.2%
9.8%
1.6%
5.8%
0.7%
―
21.4%
2.3%
7.0%
13.2%
<0.1%
0.3%

1,135
650
737
7
33
127
1,461
22
1,172
47
317
100
4
1,478
229
840
501
1
11

11.9%
6.8%
7.7%
0.1%
0.3%
1.3%
15.3%
0.2%
12.3%
0.5%
3.3%
1.1%
<0.1%
15.5%
2.4%
8.8%
5.2%
<0.1%
0.1%

not tested

―

2

<0.1%

not tested
not tested

―
―

0
2

0.0%
<0.1%

207

1.5%

102

1.1%

23
6
121
6
56

0.2%
<0.1%
0.9%
<0.1%
0.4%

0
15
45
not tested
43

0.0%
0.2%
0.5%
―
0.5%

Note: (a) Subcategories do not sum to categories because a person who tested positive for multiple
subcategories within one category would only be counted once at the category level. (b) The em dashmeans no data available.

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3.3.3 Results by Sex
Information on the sex of the driver was provided to the NTSB by all of thelaboratories except for the San Francisco laboratory. This allowed for the examinationof differences in the prevalence of various drug categories by sex. Figure 6 displays
the percentage of drivers testing positive for each drug category by sex in the
Orange County laboratory dataset. This laboratory was chosen as an exemplar due to
its large sample size and the representativeness of these results across other datasets.
Out of the 13,942 drivers with a recorded sex in the Orange County laboratory
dataset, 10,840 (77.8%) were male and 3,102 were female (22.2%).
Although alcohol and cannabis were the most commonly detected drugs forboth sexes in all datasets, there were significant differences between sexes observedin which other drug categories were most prevalent. In the Orange County laboratory
dataset, males were significantly more likely to test positive for cannabis andstimulants. Females were significantly more likely to test positive for alcohol,
sedatives, potentially impairing neuropsychiatric medications, non-ethanol alcohols,
and other potentially impairing drugs. Across all datasets, there was a tendency formales to test positive at a higher rate for drugs that are commonly used illicitly, andfor females to test positive for drugs that are most commonly used legally and/or witha prescription.

Figure 6. Percentage of drivers testing positive for each drug category by sex in the
Orange County laboratory dataset.
Note: (a) The asterisk symbol indicates that the group difference between the sexes from thechi-square test was statistically significant at p <0.05. (b) PINM refers to potentially impairing
neuropsychiatric medications, and OPID refers to other potentially impairing drugs. (c) Females weresignificantly more likely to test positive for non-ethanol alcohols (0.23%) as compared to males(0.06%).

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3.3.4 Driving with Multiple Categories of Drugs
Multiple drug presence was determined by examining the combinations ofdrug categories that drivers tested positive for in each population. Combinations ofdrug categories were examined rather than combinations of individual drugs or drug
subcategories to assess the most common drug combinations and for easierinterpretability of results.64 For example, the Orange County laboratory alone had
266 distinct combinations of drug categories in its sample of 14,051 drivers. This
number would have been exponentially greater for combinations of individual drugs
and would have made meaningful interpretation of the results more difficult.
3.3.4.1 Overall Prevalence of Multiple Drug Categories
Figure 7 shows the percentage of drivers who tested positive for varying
numbers of drug categories. For the impaired-driving arrest populations, about halftested positive for two or more drug categories. In the Wisconsin fatally injured driver
population, about 28% tested positive for two or more drug categories.

Figure 7. Percentage of drivers testing positive for multiple drug categories in eachlaboratory dataset.
Note: The asterisk on the category “Wisconsin Laboratory – Arrest” refers to crash-involved
drivers arrested for impaired driving.
As a result, if a driver tested positive for multiple drugs within one category, that driver wasclassified as using a single drug category.
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3.3.4.2 Specific Combinations of Multiple Category Drug Presence
There were hundreds of combinations of drug categories within the drivers
tested. Table 8 shows the most common drug categories (where only one category of
drug was detected) and combinations of drug categories from the Orange County
laboratory dataset. This dataset highlights the wide variety of drug combinations
detected in drivers in this research. There was significant variance in the prevalenceof these combinations across the datasets. However, the most frequently detectedcombination of multiple drug categories across all datasets was alcohol andcannabis. No other combination of drug categories had a prevalence greater than
10% across any of the datasets analyzed.
Table 8. Frequency of commonly observed drug categories and drug category combinationsin the Orange County laboratory dataset.
Drug Categories andFrequency

Combinations of Drug Categories

Overall
Percent

Alcohol Only

5,926

42.17

Alcohol and Cannabis

2,022

14.39

Alcohol and Stimulants

739

5.26

Cannabis Only

685

4.88

Stimulants Only

455

3.24

Alcohol, Cannabis, and Stimulants

376

2.68

Alcohol and Sedatives

356

2.53

Cannabis and Stimulants

264

1.88

Cannabis and Sedatives

175

1.25

Alcohol, Cannabis, and Sedatives

166

1.18

Narcotic Analgesics and Stimulants

157

1.12

No Alcohol or Other Drugs Detected

148

1.05

Alcohol and Inhalants

143

1.02

143

1.02

2,296

16.34

14,051100.00Alcohol and Potentially Impairing NeuropsychiatricMedications
All Other Single Drug Categories or Combinationsof Drug Categories
Total

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3.3.4.3 Alcohol and Cannabis
Alcohol and cannabis, as well as their combined use with each other and otherdrugs, were further examined because they were the most frequently observed
combination of drug categories across all laboratories. Figure 8 shows the
distribution of drivers from the Orange County laboratory and the Wisconsin
laboratory datasets on impaired driver arrests relative to the presence of alcohol,
cannabis, or both. These two datasets are highlighted for their relatively large sample
sizes as well as the representativeness of the results across the other datasets. Strong
similarities can be seen between these datasets. In both the Orange County
laboratory and the Wisconsin laboratory datasets, the vast majority of drivers―89% in
the Orange County data on impaired driving arrests and 84% in the Wisconsin dataon crash-involved impaired driving arrests―tested positive for alcohol and/or
cannabis. Over half of drivers tested positive for alcohol, but not cannabis. Over 20%
had both alcohol and cannabis while about 10% tested positive for cannabis, but notalcohol. Although cannabis was the second most commonly detected drug behind
alcohol, cannabis was often detected in combination with alcohol.

Figure 8. Distribution of alcohol and cannabis in the Orange County laboratory data on
drivers arrested for impaired driving and the Wisconsin laboratory data on crash-involved
drivers arrested for impaired driving.

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Table 9 further examines the prevalence of alcohol and multiple drug
combinations among all potentially impairing drugs included in the present research.
Results show that these drivers were slightly more likely to only have alcohol in theirsystem as compared to alcohol plus at least one other potentially impairing drug. Thiswas observed in four of the five laboratory populations, with the New York laboratory
as the exception.
Table 9. The prevalence of alcohol alone, in combination with other drugs, and overall foreach driver population.

Alcohol

Alcohol Only
Alcohol andOther Drugs
Alcohol Total

OrangeCountyLaboratory

Wisconsin
Laboratory

Wisconsin
Laboratory(Crash-Involved
Impaired Driving
Arrests)(CrashInvolved
Fatally Injured
Drivers)

San Francisco
Laboratory

New York
Laboratory

42.2%

39.7%

26.9%

43.6%

22.6%

34.9%

34.6%

17.4%

34.1%

32.3%

77.1%

74.3%

44.3%

77.7%

54.9%

Table 10 further explores the prevalence of cannabis detected alone, in
combination with alcohol, and in combination with other drugs (excluding alcohol).
Despite nearly one-third of drivers testing positive for cannabis across all populations,cannabis alone was infrequently detected in these populations, ranging from 2.9% to
8.8%. Cannabis was most frequently found in combination with alcohol, but it wasalso found in combination with additional drugs other than alcohol.
Table 10. The prevalence of cannabis alone, in combination with other drugs, and overall foreach laboratory sample driver population.

Drug Category

Cannabis Only
Cannabis andAlcohol Only
Cannabis, Alcohol,
and Other Drugs
Cannabis andOther Non-Alcohol
Drugs
Cannabis Totala

OrangeCountyLaboratory

Wisconsin
Laboratory(Crash-Involved
Impaired
Driving Arrests)

Wisconsin
Laboratory(CrashInvolved
Fatally Injured
Drivers)

San Francisco
Laboratory

New York
Laboratory

4.9%

2.9%

5.2%

5.5%

8.8%

14.4%

15.6%

6.7%

16.1%

17.1%

5.0%

6.8%

3.2%

6.6%

5.5%

8.6%

7.0%

4.9%

7.0%

5.1%

32.9%

32.3%

20.0%

35.2%

36.4%

a. The percentages in this row may not reflect the exact column totals due to rounding.

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The consistency of quantification of alcohol and THC concentrations also
allowed for an examination of these concentrations in these data. In particular, theOrange County laboratory provided a large sample size with consistent quantificationof both BAC and THC. Figure 9 shows a histogram of BAC values from the
10,804 drivers that had positive BACs. The average BAC of these drivers was
0.17 g/dL. This is similar to data from other laboratories with consistent BAC
reporting, such as the Wisconsin laboratory data on crash-involved drivers arrested
for impaired driving, for which the average BAC of drivers with alcohol in their system
was 0.19 g/dL.

Figure 9. Distribution of drivers with different BACs from the Orange County laboratory
dataset.

The average BAC of drivers who only tested positive for alcohol and no otherdrugs was further explored. In particular, BAC comparisons were made to determine
the number of drivers arrested for impaired driving in the Orange County laboratory
dataset that tested below the commonly established per se limits of 0.05 g/dL (Utah)and 0.08 g/dL (all other states and territories). There were 5,492 drivers who tested
positive for alcohol and no other substances. The average BAC of these individuals
was 0.17 g/dL. Out of these 5,492 drivers, there were 339 (6.2%) drivers with a
BAC below 0.08 g/dL and 105 drivers (1.9%) with a BAC below 0.05 g/dL. This
indicates that while a large majority of the drivers suspected of impaired driving inthis sample had BACs above common per se legal limits in the United States, there
were numerous drivers suspected of impaired driving with BACs below these levels.
Concentrations of THC were also explored due to the relative consistency ofquantification and overall prevalence of cannabis in the drivers in the laboratory47

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datasets analyzed for this research. Again, the Orange County laboratory data
provided an ideal set of drivers for analysis due to the large sample size andconsistent reporting of THC values. Figure 10 shows the THC concentrations fordrivers in the Orange County laboratory dataset. There were 4,015 (28.6%) drivers
with detectable levels of THC. The average THC concentrations of these drivers was
6.9 nanograms per milliliter (ng/mL) with a median of 4.6 ng/mL.

Figure 10. Distribution of drivers with different blood THC concentrations from theOrange County laboratory dataset.

Analyses were also conducted examining drivers who only tested positive for
THC. This was done to further explore the effects of cannabis on the driver without
the influence of other drugs or drug interactions. The Orange County laboratory had
666 drivers that only tested positive for THC. The average THC concentrations ofthese drivers was 10.2 ng/mL.
Several US states and Canada have per se values for THC ranging from
2 ng/mL to 5 ng/mL.65 As shown in figure 10, many drivers arrested for impaired
driving tested below these levels. The 666 drivers who tested positive for THC, andonly THC, in the Orange County laboratory dataset were examined to determine how
According to the National Conference of State Legislatures’ “Drugged Driving:
Marijuana-Impaired Driving” webpage, five states (Illinois, Montana, Nevada, Ohio, and Washington)
have specific per se limits for THC in blood ranging from 2 ng/mL to 5 ng/mL. Colorado’s law statesthat it is permissible to assume a driver was under the influence if their blood THC level is 5 ng/mL or
higher. Twelve states (Arizona, Delaware, Georgia, Indiana, Iowa, Michigan, Oklahoma, Pennsylvania,
Rhode Island, South Dakota, Utah, and Wisconsin) have zero tolerance laws for driving with THC, andthe remaining states do not specify a threshold for impairment.
65

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many of these drivers had toxicology results below 5 ng/mL.66 Nearly one-third ofthese drivers (215 or 32%) had THC values below this value.

3.3.5 Likelihood of Testing Positive for Other Drugs Based on BAC
The size and quality of the Orange County laboratory dataset was ideal forfurther examining the prevalence of varying BACs in drivers and possible
relationships between BAC and the prevalence of other drugs. This also shows themagnitude of drug data that is lost with stop-testing procedures. Out of the
14,051 drivers in the Orange County laboratory dataset who were arrested for
impaired driving, 3,247 (23.1%) had a BAC of 0.00 g/dL, 994 (7.1%) had a
BAC >0.00 g/dL but <0.08 g/dL, and 9,810 (69.8%) had a BAC ≥0.08 g/dL. Among
drivers who tested positive for alcohol, the average BAC was 0.17 g/dL with amaximum BAC of 0.46 g/dL.
The relationship between BAC and the likelihood of testing positive fornonalcohol drugs was examined. Out of the 3,247 drivers with a BAC of 0.00 g/dL,
3,099 (95.4%) tested positive for at least one category of nonalcohol drug. Out of the
994 drivers with a BAC >0.00 g/dL but <0.08 g/dL, 65.0% (646) had at least one
category of drug other than alcohol detected. Over 40% of the 9,810 drivers with a
BAC ≥0.08 g/dL (4,232 or 43.1%) had at least one other category of drug detected intheir system in addition to alcohol. This means that if stop-testing protocols for drugs
were in place for drivers with BACs ≥0.08 g/dL, just over 30% (4,232 or 30.1%) of the
14,051 drivers in this sample who tested positive for at least one category of drugother than alcohol would have been recorded as only positive for alcohol.

3.3.6 Time to Test
Certain potentially impairing drugs can quickly metabolize below detectablelevels in a driver’s system. Therefore, collecting biological specimens as soon as
possible after an impaired driving arrest increases the likelihood that the presence ofpotentially impairing drugs will be detected.67 The delay between the time of an
impaired driving event and the collection of a blood specimen for toxicology testing
was available for both the Wisconsin laboratory and the San Francisco laboratory
sample populations. The Wisconsin and San Francisco laboratory populations werechosen for analysis because of their collection and reporting of both time of event
There were 666 drivers with quantified levels of THC. The 685 drivers testing positive for“cannabis only” in table 8 included drivers that tested positive for any cannabinoid, which could
include testing positive for a metabolite of THC but not a quantified and positive value for THC.
66

For example, as shown in figure 2, within 30 minutes of smoking cannabis, blood THC levels
had decreased by more than half their peak level.
67

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and time of sample collection as well as the similarity of both datasets not being
limited to severe crashes, which would potentially bias the time it takes to collect asample. Out of the 9,569 drivers in the Wisconsin laboratory impaired driving arrest
sample, there were 9,046 drivers with complete data for elapsed time between theevent and sample collection. To control for possible data entry errors and outliers,
elapsed times less than 15 minutes or greater than 24 hours were excluded from thisanalysis. This left 8,969 cases for analysis.
The average time between the crash-involved impaired driving event and theblood draw was 1 hour 51 minutes in the Wisconsin laboratory sample population.
Less than 20% of drivers had a time to test of less than 1 hour. Just over half of drivers
were tested after 1 hour 40 minutes.
A similar protocol was used for the San Francisco laboratory sample
population and any drivers with an elapsed time less than 15 minutes or greater than
24 hours were excluded from the analysis. There were 2,023 of the 2,075 drivers with
time-to-test data that met these criteria.
The average time between a blood draw and the impaired driving event in the
San Francisco laboratory sample population was 2 hours 4 minutes. Over half ofdrivers had a delay greater than 1 hour 40 minutes. Less than 15% of drivers had atime to test of less than 1 hour.
Many drugs can be metabolized completely out of an individual’s system or
below laboratory-detection thresholds in the average of about 2 hours that it took to
conduct a blood draw after the traffic event in the Wisconsin and San Francisco
laboratories. Ultimately, long delays between the time of the traffic event andspecimen collection decreases the probability a drug will still be detected in a driver,which may impact the prosecution of the case. Thus, it is critical to identify andimplement programs that reduce the delay in obtaining a specimen for drug testing.

3.4 Summary of Drug Prevalence Results
Because there is no reliable national-level data available concerning drug use
among crash-involved drivers, the NTSB analyzed the best available data fromlaboratories in four jurisdictions that employ protocols that meet or exceed ANSI/ASB
Standard 120 (ANSI/ASB 2021). These data provided a unique look at the full rangeof drugs and drug combinations present in the driver populations examined, which
included both crash-involved and non-crash-involved drivers arrested for impaired
driving as well as fatally injured drivers.
The research employed a novel drug classification scheme, developed by
NTSB in consultation with toxicology experts, to ensure a consistent and responsible
approach to assessing multiple-drug presence. Presence alone does not indicate that50

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drivers were impaired. However, on a population level, for drugs with known
impairing effects, an increase in prevalence among drivers arrested for impaired
driving or crash-involved drivers may point to a need for countermeasures.
Population-level data can also be used along with exposure data to identify drugs or
drug combinations that may increase the likelihood of a driver being arrested for
impaired driving or increase a driver’s crash risk.
Some overall results emerged from the NTSB’s analyses:•

Alcohol was the most commonly found drug across all populations, withpositivity rates ranging from 44% to 78%.

•

Cannabis was the second most common drug identified, with positivity
rates ranging from 20% to 36% across the five laboratory sample
populations. Cannabis was typically found in combination with alcohol orother drugs.

•

The most commonly detected categories of drugs, besides alcohol andcannabis, were sedatives, stimulants, and potentially impairing
neuropsychiatric medications. In general, both sedatives and stimulants
were more likely to be detected than narcotic analgesics and dissociative
anesthetics.

•

About half of drivers across all four laboratory sample populations arrested
for impaired driving tested positive for more than one category of drug. In
the population of fatally injured drivers, about 28% tested positive for morethan one category of drug.

•

Multiple-category drug prevalence was diverse, and hundreds of
combinations of drug categories were observed in this research.

•

The most common drug combination was alcohol and cannabis. No othercombination of drug categories besides alcohol and cannabis had agreater than 10% prevalence across any of the five populations.

•

Alcohol was often detected alone, whereas cannabis was most frequently
detected in combination with alcohol or other drugs.

•

Across all five laboratory sample populations, there were common
subcategories of drugs that were most frequently observed within eachdrug category. The most commonly observed sedatives werebenzodiazepines. The most frequently observed stimulants were cocaine
and methamphetamines.

•

Different drug presence patterns were found to be sex-based. Males weremore likely to test positive for illicit drugs, whereas females were more
likely to test positive for drugs that are legally available, such as alcohol orprescription drugs.
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Policies that limit drug testing, such as those that use stop-testing protocols
when a driver’s BAC is over a certain level, result in a loss of information.
Results from the Orange County laboratory showed that if this laboratory
had implemented a stop-testing protocol at a BAC of 0.08 g/dL then 4,232
of 14,051 (30.1% of the entire sample) drivers would not have been
identified as testing positive for other drugs despite having detectablelevels in their system.

•

Delays in specimen collection for toxicology testing after an impaired
driving arrest or crash can result in critical loss of evidence of impaired
driving as drugs can rapidly metabolize out of a driver’s system.
Laboratories that collected information on the time between the impaired
driving event and specimen collection showed a large time delay in
specimen collection. The Wisconsin laboratory data showed the average
specimen took 1 hour 51 minutes to collect after an arrest. The
San Francisco laboratory showed the average time to collect a specimen
was 2 hours 4 minutes after an arrest.

The NTSB concludes that alcohol was the most prevalent drug found among
impaired drivers in toxicology data reviewed by the NTSB, and about half of all
impaired drivers were positive for other drugs or multiple drugs, indicating that
although alcohol-related countermeasures must remain the highest priority,
countermeasures that effectively address other drugs and drug combinations are alsoneeded. The NTSB also concludes that policies that limit drug testing, such as thosethat use stop-testing protocols when a driver’s BAC is over a certain level, result in aloss of valuable information that could otherwise be used to customize policies,
treatment, and other countermeasures. The NTSB further concludes that reducing thetime between an impaired driving event and biological specimen collection increases
the likelihood that toxicological test results will reflect drug presence at the time ofthe event.

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4. Safety Issues
As a result of this research, the NTSB identified the following safety issues:(1) the need to implement proven countermeasures for alcohol-impaired driving;(2) the need to address the growing problems of cannabis-, other drug-, andmultiple-drug-impaired driving; (3) the need to improve drug-impaired driving laws
and enforcement; (4) the need to ensure that driving safety is considered in theevaluation of prescription and OTC drugs; and (5) the need to enhance systems for
documenting and tracking the incidence of drug use and driving. The sections that
follow describe these safety issues and consider countermeasures to reduce theincidence of impairment-related crashes.
Many impaired driving countermeasures are designed to deter drivers frommaking the decision to drive impaired. History has shown that changing driver
behaviors can be exceptionally hard, and additional strategies that improve safety
but do not rely on an impaired driver’s decision-making are crucial. Recognizing theinherent challenges, we need to not only advocate for these strategies, but also
support a Safe System approach. The principles underpinning the Safe Systemapproach acknowledge that humans make mistakes or make bad decisions that leadto traffic crashes, but no one should lose their life or be seriously injured as a result ofa crash; the human body has a limited physical ability to tolerate crash forces;
roadway safety is a shared responsibility; and all parts of the system must be
strengthened so that if one part fails, road users are still protected (DOT 2022).
In 2021, the NTSB hosted a roundtable series on the Safe System approachthat included consideration of vehicles, road users, roads, speeds, and postcrashcare.68 There are many safety countermeasures available or in development that do
not rely on driver behaviors or decision-making to keep the public safe. Such an
approach does not absolve drivers of responsibility but recognizes that overall safety
will be improved when we do not solely rely upon drivers to make good choices.

4.1 Need to Implement Proven Countermeasures for AlcoholImpaired Driving
Alcohol—alone and in combination with other drugs—was the most prevalent
drug found in every dataset analyzed for this research. The results showed about
one-third of drivers in each of the populations of drivers arrested for impaired driving
were positive for alcohol only, and an additional 20% to 40% were positive for alcohol
in combination with other impairing drugs. Alcohol prevalence in the Wisconsin
laboratory’s fatally injured driver sample was lower, but alcohol was still the most68

See the NTSB’s webpage on “The Safe System Approach: Roundtable Series.”

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prevalent drug, with 26.6% of drivers testing positive for alcohol only and an
additional 17.7% of drivers testing positive for alcohol and other drugs.
Alcohol’s relationship to performance decrements and crash risk are clear(Moskowitz and Fiorentino 2000; Blomberg and others 2005). At a BAC of 0.08 g/dL,
the per se limit in nearly every state, the risk of crashing is more than doubled.
Although there is less research documenting the risk of combining alcohol and otherdrugs, existing research suggests that doing so can increase crash risk significantly,
even when BACs are <0.08 g/dL (Hels and others 2011; Romano, Voas, and Camp
2017). Alcohol is also the drug for which the most is known concerning its negative
impact on roadway safety. It is consistently associated with more than 3 in 10 road
fatalities (NCSA 2022a). In 2020, NHTSA estimated that 11,654 people died incrashes involving a driver with a BAC >0.08 g/dL―an increase of 14% from 2019,
which was more than twice the overall increase of 6.8% in crash fatalities during thesame period―so it is more critical than ever to implement known countermeasures(Stewart 2022). The NTSB concludes that alcohol, both alone and in combination withother drugs, continues to be the drug with the most detrimental impact on traffic
safety.
Actions to address alcohol-impaired driving can make a difference, as
evidenced by the many efforts in the 1980s and 1990s that led to a substantial drop
in alcohol-impairment-related fatalities.69 Additionally, many of the countermeasuresdescribed in the NTSB’s 2013 Reaching Zero: Actions to Eliminate Alcohol-Impaired
Driving report remain relevant and needed. Some key recommendations are
summarized below, and a full listing of the recommendations and their overall
statuses are available in appendix A.

The advocacy efforts of groups, such as Mothers Against Drunk Driving and Remove
Impaired Drivers, contributed to numerous legislative changes and to a shift in the cultural acceptanceof alcohol-impaired driving. A 1982 law provided incentives to states based on the establishment of aper se BAC limit of 0.10 g/dL (see Alcohol Traffic Safety Programs, Public Law 97–364, 96 Stat. 1738).
This law also called for administrative license suspension/revocation for drivers arrested for driving
while impaired, mandatory jail time or community service for repeat offenders, and better enforcementof drunk driving laws. Two years later, the National Minimum Drinking Age Act of 1984 (Public Law
98-363, 98 Stat. 435, section 158), which mandated that states would receive reduced federal highway
funds if they did not raise the minimum legal drinking age to 21, went into effect. Between 1981 and1986, a total of 729 new state laws addressing drunk driving were enacted (Lerner 2011, 88–90).
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4.1.1 Effective Laws and Enforcement
Several NTSB recommendations promote effective laws and high-visibility
enforcement to combat alcohol-impaired driving. The NTSB has recommended thatstates reduce per se BAC limits for all drivers to 0.05 g/dL or lower (H-13-5) and has
called on NHTSA to seek legislative authority to award incentive grants to states toestablish such limits (H-13-1).70 Research has estimated that lowering the BAC limit inevery state would likely reduce the number of fatal alcohol crashes by 11%,potentially saving about 1,800 lives per year (Fell and Scherer 2017). In 2018, thestate of Utah lowered its per se BAC limit to 0.05 g/dL and subsequently saw
reductions in both its fatal crash and fatality rates relative to the rest of theUnited States (Thomas and others 2022). Specifically, Utah’s fatal crash rate andfatality rate reductions from 2016 to 2019 were 19.8% and 18.3%, respectively,
compared to 5.6% and 5.9% for the rest of the United States. An evaluation of the
law’s effects found that Utah drivers reported changed behaviors, such as arranging
alternate transportation when drinking away from home. The evaluation did not findany negative effects on alcohol sales, tourism, or tax revenues, nor did it find amarked increase in impaired driving arrests (Thomas and others 2022).
The NTSB has also recommended all-offender interlock laws, that is, laws
requiring alcohol ignition interlocks for all individuals convicted of alcohol-impaired
driving offenses (H-12-45).71 In 2012, the NTSB made the recommendation to
33 states, the District of Columbia, and the Commonwealth of Puerto Rico. Since thattime, four states, Alabama, Delaware, Idaho, and Tennessee, and the District ofColumbia, have enacted such laws. Additionally, a recent study that examineddifferences among three types of interlock laws between 2001 and 2019 found that
all-offender interlock laws were the most effective and were associated with 26%
fewer drivers with BACs ≥0.08 g/dL being involved in crashes compared to stateswith no law (Teoh and others 2021). Enforcement is a key element of addressing
alcohol-impaired driving, and the NTSB supports high-visibility enforcement. In 2013,
the NTSB recommended that the 50 states, the District of Columbia, and theCommonwealth of Puerto Rico include in their highway safety plans provisions for
conducting high-visibility enforcement using passive alcohol-sensing technology
during traffic stops, saturation patrols, sobriety checkpoints, and at accident scene

The overall status of Safety Recommendation H-13-5 is classified Open—Unacceptable
Response. See appendix A for more information. Safety Recommendation H-13-1 is classified
Open―Acceptable Response.
70

The overall status of H-12-45 is classified Open—Unacceptable Response. See appendix A for
more information.
71

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responses (H-13-6).72 Since that time, the NTSB has classified that recommendation
Closed—Acceptable Action for four states―Connecticut, Hawaii, Indiana, andKansas―because they have implemented such enforcement programs.73
Effective laws and enforcement are critical to combating impaired driving. It
must also be clear that this enforcement needs to be both fair and equitable.
Individuals of all identities and backgrounds must be treated with respect, dignity,and fairness from the decision to make a traffic stop through the final adjudication ofa case. As outlined in other areas of this report, enforcement is one valuable
component of reducing impaired driving, but it must also be paired with educationand evidence-based treatment.

4.1.2 In-Vehicle Technologies
The NTSB has a long history of calling for in-vehicle technologies, such as
forward collision avoidance systems, that can reduce the incidence of crashes or
mitigate their severity, and the issue is on the 2021–2023 Most Wanted List of
Transportation Safety Improvements. Such technologies can reduce the incidence ofcollisions and injury regardless of the underlying reason and, consequently, they are
an important part of a Safe System approach. In terms of preventing alcohol-impaired
crashes, alcohol ignition interlock devices can be installed in vehicles to prevent theiroperation by a driver with a positive BAC. However, such devices have historically
been installed after an alcohol-impaired driving arrest or conviction. Currently, no
in-vehicle technology is commercially available that can passively detect driver
impairment and prevent vehicle operation, although the NTSB has recommended thedevelopment and promotion of such a technology.74
In 2021, Congress passed a law requiring impaired driving prevention
technology to be deployed on all new vehicles within 3 years. Specifically, section
24220 of the IIJA included a requirement for “advanced drunk and impaired driving
prevention technology” that can (1) passively monitor the performance of a motor
vehicle driver and prevent or limit vehicle operation if impairment is detected and/or
The overall status of H-13-6 is classified Open—Unacceptable Response. See appendix A for
more information.
72

73

See appendix A for more information.

In 2013, the NTSB recommended that NHTSA and the Automotive Coalition for Traffic Safety
work together to accelerate widespread implementation of Driver Alcohol Detection System for Safety(also known as DADSS) technology “by (1) defining usability testing that will guide driver interface
design and (2) implementing a communication program that will direct driver education and promote
public acceptance” (H-12-43 and H-12-48). Both recommendations are classified
Closed―Unacceptable Action. See appendix A for more information.
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SRR-22-02(2) passively and accurately detect whether the driver’s BAC is ≥0.08 g/dL andprevent or limit motor vehicle operation if a BAC at or above this level is detected.75
In its report of the January 1, 2021, fatal crash in Avenal, California, caused by analcohol-impaired driver (NTSB 2022a), the NTSB concurred with this legislation andrecommended that NHTSA do the following:
Require that all new vehicles be equipped with passive
vehicle-integrated alcohol impairment detection systems,
advanced driver monitoring systems, or a combination thereof;
the systems must be capable of preventing or limiting vehicle
operation if driver impairment by alcohol is detected (H-22-22).76
This recommendation, if fully implemented, could have enormous lifesaving
potential. For example, one study estimated that requiring in-vehicle systems thatprevent vehicle operation by drivers with BACs of 0.08 g/dL and above would savemore than 1,000 lives annually within 3 years of the mandate (Farmer 2021). The
same study found that if all highway vehicles were equipped with such technology,
more than 9,000 lives could be saved annually.77

4.1.3 Actions Needed to Reduce Alcohol-Impaired Driving Crashes
For more than 50 years, the NTSB has advocated for changes to reduce theincidence of alcohol-impaired driving crashes, and the agency has issued more than
150 recommendations to address impaired driving. Efforts over the past several
decades have yielded meaningful reductions in the number and rate of fatalities
involving a driver with a BAC of 0.08 g/dL or higher. However, in 2020,
11,654 people died in crashes in which at least 1 driver had a BAC at or abovethat threshold, accounting for nearly 1 in 3 roadway fatalities, and alcohol was themost prevalent drug found in each of the laboratory samples analyzed for the present
research. This indicates that more must be done to address alcohol-impaired driving.
Recent efforts, including Utah’s law reducing its per se BAC limit to 0.05 g/dL;
the adoption of all-offender interlock laws in several states; and the federal law
requiring advanced drunk and impaired driving prevention technology as standard
equipment on new vehicles are important steps toward addressing this problem. Yet,
The Safeguarding Privacy in Your Car Act of 2022, S. 4647, 117th Cong. (2022), proposed torepeal section 24220 of the IIJA.
75

Safety Recommendation H-22-22 is classified Open—Await Response. See appendix A for
more information.
76

The study also found that a system that prevented drivers from operating a motor vehicle
with any BAC would save nearly 12,000 lives per year.
77

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more remains to be done. In 2022, the NTSB completed a review of state progress on
10 recommendations to address alcohol-impaired driving and sent a letter to eachstate documenting the actions needed to close any open NTSB recommendations.78
The NTSB also reviewed NHTSA’s progress on five impairment-related
recommendations and sent a letter encouraging additional action on those thatremained open.79 The NTSB will continue to advocate for adoption of all open
recommendations concerning alcohol-impaired driving through its Most Wanted Listand other advocacy efforts. The NTSB concludes that implementing countermeasures
to reduce alcohol-impaired driving must remain a high priority to reduce impaired
driving crashes overall.

4.2 Need to Address the Growing Problem of Cannabis-, Other
Drug-, and Multiple-Drug-Impaired Driving
A focus on alcohol-related countermeasures is a necessary step to eliminating
impaired driving crashes and injuries. However, if we limit the focus to alcohol, theproblem will not be fully solved. The pattern of results across all datasets analyzed forthe present research found that many other drugs, alone or in combination,
contribute to the problem. This is particularly true for cannabis, which wasconsistently the second most commonly found drug after alcohol. Between 20% and
36% of drivers across all five laboratory sample populations tested positive for it.
Compared to alcohol, cannabis was more likely to be found in combinations
with other drugs. As shown in table 9, in four of the five laboratory populations
tested, alcohol was slightly more likely to be detected alone than with one or moreother drugs. However, as shown in table 10, most drivers who tested positive forcannabis also tested positive for another potentially impairing drug.
Multiple drug presence was also common, with about half of all drivers in eachof the populations arrested for impaired driving testing positive for two or more drug
categories. For the Wisconsin laboratory sample of fatally injured drivers, about 28%
were positive for multiple categories of drugs. The most commonly found categories
of drugs after alcohol and cannabis tended to be sedatives and stimulants, whichranged in positivity across all five driver populations from 7.8% to 26.1% (see figure5). Narcotic analgesics and potentially impairing neuropsychiatric medications werealso relatively common. There are many potential reasons for variability in drug
prevalence among the datasets used for this research, including actual differences in
The letters concerned Safety Recommendations H-12-34, H-12-35, H-12-36, H-12-45, H-13-5,
H-13-6, H-13-7, H-13-8, H-13-9, and H-13-10. See appendix A for more information.
78

The letter concerned Safety Recommendations H-12-33, H-13-1, H-18-35, H-18-56, andH-18-57. See appendix A for more information.
79

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driver drug use; variability in the populations sampled, such as fatally injured drivers
versus drivers arrested for impaired driving; variances in the drug compounds tested
for; and the application of varying cutoff values for reporting results. Although there
was some variability among the datasets, the overall pattern of results was similar anddemonstrated the prevalence of numerous potentially impairing drugs and drug
combinations. The NTSB concludes that although alcohol and cannabis were both
highly prevalent in toxicology data reviewed by the NTSB, alcohol was most often
detected alone, whereas cannabis was most often detected in combination withalcohol or other drugs. The NTSB also concludes that cannabis and other potentially
impairing drugs, especially in combination with and without alcohol, contribute to the
problem of impaired driving crashes due to their prevalence and negative impacts on
driving performance.
Although cannabis and many other drugs have been shown to impair driving
performance and are associated with increased crash risk, there is evidence that,
relative to alcohol, awareness about the potential dangers of driving after using otherdrugs is lower. For example, a 2020 survey conducted by the AAA Foundation for
Traffic Safety found that 94% of respondents rated driving after drinking enoughalcohol to be over the legal limit as extremely or very dangerous. For driving within
an hour after using cannabis or after using potentially impairing prescription drugs,
the percentages were 69% and 87%, respectively (AAA FTS 2021).80
The AAA Foundation for Traffic Safety survey also found drivers perceived thatthe chance of being caught by police was higher for alcohol use than for other drug
usage. For driving after drinking enough alcohol to be over the legal limit, 66% of
drivers reported that it is very likely or somewhat likely a driver would be caught bypolice. For driving within an hour after using cannabis, 29% of drivers reported that it
is very likely or somewhat likely a driver would be caught by police, and for driving
while using potentially impairing prescription drugs, 41% of drivers reported thatperception. The NTSB considered several countermeasures that could address thegrowing problem of cannabis-, other drug-, and multiple-drug-impaired driving. Thissection considers how the problem could be addressed by raising driver awarenessof the risks of driving impaired by drugs other than alcohol. The sections that follow
discuss strengthening laws, facilitating law enforcement, and improving postmarket
surveillance of prescription and OTC drugs.
Public campaigns and drug labeling are two strategies that have the potential
to raise awareness about the hazards of cannabis- and other drug-impaired driving
and the potential consequences of doing so. In theory, if drivers have greaterawareness of the risks, they may be less likely to use drugs if they know they must

80

The survey used the term “marijuana.”

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drive or more likely to make plans for alternative forms of transportation when using
drugs, leading to a reduction in impaired driving crashes.

4.2.1 Public Campaigns
NHTSA, states, and advocacy groups have led multiple public campaigns
designed to reduce the incidence of various types of impaired driving.81 As early as
1983, NHTSA partnered with the Ad Council to develop the “Drinking and Driving
Can Kill a Friendship” campaign to prevent alcohol-impaired driving.82 In recent
years, campaigns have targeted impaired driving with messages such as “Drive Soberor Get Pulled Over,” “Drive High—Get a DUI,” and “If You Feel Different, You Drive
Different.” Additionally, the GHSA and the International Council on Alcohol, Drugs,
and Traffic Safety (ICADTS) have recently developed documents that can informcannabis messaging. The GHSA report provides guidance with the goal of facilitatingclear communications about cannabis use and roadway safety.83 ICADTS developed aseries of fact sheets that provide research consensus on topics related to cannabis
and traffic safety, including summaries of research, cannabis detection andtoxicology, and policy and legislative issues.84
NHTSA’s most recent edition of its Countermeasures That Work: A Highway
Safety Countermeasures Guide for State Highway Safety Offices rates media
campaigns as “promising” (Venkatraman and others 2021).85 Many studies haveevaluated impaired driving media campaigns over the years—mostly focused on
alcohol-related campaigns—but there is no clear consensus about their effectivenessin reducing impaired driving crashes. One systematic review of data from nineresearch papers suggested that media campaigns that are viewed by many andimplemented alongside enhanced law enforcement are effective in reducing
alcohol-impaired crashes (Elder and others 2004). However, a similar review
See NHTSA’s webpages “Drive Sober or Get Pulled Over,” “Buzzed Driving is Drunk Driving,”“If You Feel Different, You Drive Different,” and “There’s More Than One Way to Be Under the
Influence.” See also the GHSA’s webpage “Colorado ‘Drive High, Get a DUI’ Drugged Driving
Campaign.”
81

See the Association of National Advertisers Educational Foundation’s webpage “Drunk
Driving Prevention (1983-Present): Ad Council Campaigns That Have Made a Difference.”82

See the GHSA’s 2022 report, Cannabis Consumers and Safe Driving: Responsible Messaging,for more information.
83

84

See ICADTS’s Fact Sheets on “Cannabis and Driving.”

The guide uses a 5-star rating scale. Countermeasures that receive 4 or 5 stars are deemed
effective. Countermeasures that receive 3 stars are considered promising and likely to be effective,
and those that receive 2 stars or 1 star have not been determined to be effective.
85

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conducted a decade later, which incorporated results from 19 studies, was lessconclusive (Yadav and Kobayashi 2015). Its authors noted that although some studies
found a significant impact of media campaigns on reducing alcohol-impaired driving
crashes, the pooled analysis from all studies did not yield a significant result.
Several recent and ongoing campaigns exist to raise awareness of the risks ofdriving after using cannabis or other drugs. For example, see the GHSA’s “Colorado‘Drive High, Get a DUI’ Drugged Driving Campaign” webpage, Massachusetts’s 2019
“Cannabis and Alcohol Users Tapped for State’s Impaired Driving Campaign” press
release, and the Teen Safe Driving Coalition’s “Drugged Driving—What You Should
Know” webpage. Although their link to reducing impairment-related crashes is notdefinitive, such campaigns have the potential to raise awareness, which may lead tolonger-term changes in societal norms concerning the acceptability of driving afterusing cannabis or other drugs. Therefore, the NTSB concludes that media campaigns
have the potential to raise awareness of the risk of impaired driving associated withcannabis, other drug, and multiple drug use, but it is unclear if they change driver
behavior.

4.2.2 Prescription and OTC Drug Labeling
Potentially impairing prescription and OTC drugs were found, both alone andin combination with other drugs, in all of the populations examined in this research.
For example, about 1 in 10 drivers tested positive for drugs in the sedative category.
The most prevalent subcategories within that category were benzodiazepines, which
are commonly prescribed for anxiety or insomnia, and sedating antihistamines, which
are commonly found in OTC allergy medicines and sleep aids. It is not possible toknow, based on toxicology data alone, whether drivers were using those drugs
consistent with labeling. The challenge of communicating driving risk to patientstaking prescription and OTC drugs is well documented, and the NTSB has a long
history of advocating for more effective and consistent drug labeling. Most notably,on January 13, 2000, the NTSB recommended that the FDA do the following:
Establish a clear, consistent, easily recognizable warning label for allprescription and over-the-counter medications that may interfere withan individual’s ability to operate a vehicle. Require that the label beprominently displayed on all packaging of such medications (I-00-5).
The FDA made important progress before this recommendation was classified
Closed—Reconsidered on July 13, 2017.86 The correspondence between the FDA andthe NTSB, as well as contributions by NHTSA, influenced the development of
In its 2017 correspondence closing I-00-5, the NTSB acknowledged certain limitations of the
FDA’s authority to mandate specific drug warning labels.
86

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SRR-22-02“Evaluating Drug Effects on the Ability to Operate a Motor Vehicle: Guidance forIndustry,” which provides tools for evaluating the potential of new psychoactive drugs
to impact the safe operation of a motor vehicle (FDA 2017). This guidance, which is
described in greater detail in section 4.4.1, can play a key role in better evaluating thepotentially impairing effects of drugs prior to entering the market if it is usedconsistently by the drug industry. Also in this 2017 guidance, the FDA stated that
information from such evaluations should be included in the “clinical studies” sectionof drug labeling as well as, if appropriate, in other sections, such as “warnings andprecautions” and “patient counseling information.” Safety Recommendation I-00-5
also facilitated public health awareness efforts from the FDA, which included thedevelopment of a website and podcasts on the potential driving impairment risks ofmany medications, including common OTC medications.
Since Safety Recommendation I-00-5 was closed in 2017, new research has
highlighted the prevalence of driving after using potentially impairing prescription
and OTC drugs, as well as findings related to patient education and drug labeling. In
July 2022, the AAA Foundation for Traffic Safety released results from a national
survey of US drivers on the use of potentially impairing medications in relation todriving (Arnold and Kim 2022). About half of the drivers surveyed reported taking atleast one potentially impairing medication in the past 30 days, and nearly one in fivereported taking two or more potentially impairing medications over this time frame.
Nearly half of drivers who reported using one or more potentially impairing
medications reported driving within 2 hours of using at least one of these
medications. Drivers that received a warning from a healthcare provider about thedriving risks associated with a medication were 18% less likely to report having driven
within 2 hours of using the medication (Arnold and Kim 2022).
In addition to the high prevalence of prescription and OTC use while driving,other emerging research highlights the need to reexamine shortcomings with druglabeling. For example, another study conducted by the AAA Foundation for Traffic
Safety identified current drug labeling as largely insufficient in conveying driving risk
to patients (Smith, Turturici, and Camden 2018). This research included a broad,systematic literature review, subject matter expert interviews, and an expert panelthat included impaired driving researchers, pharmacists, medical doctors, andgovernment representatives. One reported theme was thatmany Americans simply do not understand the potentially impairing
effects of medications based on the labeling and do not realize thewarning to ‘not operate heavy machinery’ applies to their personalvehicle (Smith, Turturici, and Camden 2018).
In addition to recognizing the limitations of current prescription and OTC druglabeling practices, the AAA Foundation for Traffic Safety research identified potential
solutions (Smith, Turturici, and Camden 2018). Results from this literature review
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indicated that labels that included a pictogram and graded levels of potential risk
showed particular promise as a means of improving consumer awareness of driving
risk (Emich and others 2014; Monteiro and others 2013; Smyth and others 2013).
Furthermore, the expert panel from this research identified “include asymbol/graphic on the prescription label (move toward European style)” as one if its
top five countermeasures for addressing prescription-drug- and OTC-impaired
driving. Despite the need for improved prescription and OTC drug labeling andgeneral countermeasure strategies available in published research, the current bodyof research is insufficient to point to a single strategy for improving this labeling.
Further research is needed to identify label characteristics that can reduce thelikelihood that consumers will drive while impaired by prescription or OTC drugs.
Challenges not only remain with current drug labeling effectiveness atconveying driving risk while taking potentially impairing medications, but also withthe consistency of this labeling even when a drug has known impairing effects. For
example, diphenhydramine is a sedating antihistamine available OTC that is
approved for use in treating allergies as well as for use as a sleep aid, and it has beenfound to impair driving performance (Weiler and others 2000). According to 21 CFR
341.72, when diphenhydramine is marketed as an antihistamine for the treatment ofallergies, it is required to include a label advising drivers to “use caution when driving
a motor vehicle or operating machinery.” However, as shown in table 11, when it ismarketed as a sleep aid, there is no such requirement, and the label varies (FDA2021).87
Table 11. Varying warning labels about driving after use of diphenhydramine sleep aids forthree different brands on the FDALabel website.
Brand of Diphenhydramine

Advice About Use While Driving

Label Warning

Thirty Madison Sleep Aid

Yes

Do not drive a motor vehicle oroperate machinery

Kroger EZ Nite SleepYes

Be careful when driving a motor
vehicle or operating machinery

ZzzQuil Nighttime Sleep-Aid

No―

The “FDALabel: Full-Text Search of Drug Product Labeling” website enables the public tosearch for and view drug labels.
87

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The NTSB concludes that although the FDA has provided useful guidance toindustry concerning evaluating drug effects on driving, additional effort is needed to
identify drug label characteristics that can effectively and consistently convey driving
risk to consumers. The NTSB therefore recommends that the FDA conduct a study tounderstand how prescription drug labeling and OTC drug labels could be modified
to increase user understanding and compliance with driving-related warnings;
publish the study findings.

4.2.3 Cannabis Labeling
Cannabis is generally not legal for medical or recreational use at the federal
level in the United States.88 Consequently, there is no federal requirement for labelingcannabis. By contrast, in Canada, which legalized cannabis at the federal level in
2018, all cannabis products must be labeled with health warnings, including awarning that states the following: “Do not drive or operate heavy equipment afterusing cannabis. Cannabis can cause drowsiness and impair your ability to concentrate
and make quick decisions.”
In the United States, the Alcohol Beverage Labeling Act of 1988 requires that
alcoholic beverages contain a label that includes the text “consumption of alcoholic
beverages impairs your ability to drive a car.”89 Although evidence suggests that
alcohol labeling had little effect on behavior change, some authors have suggested
that even small effects can be meaningful if a product is widely used (Kaskutas andGreenfield 1992; Greenfield, Graves, and Kaskutas 1999; Stockwell 2006).
A recent study found that among the 31 US states with medical cannabis
programs, all have some labeling requirements, and 26 have some requirement forlabeling concerning impairment, but not necessarily driving impairment (Kruger,
Korach, and Kruger 2022). For example, Maryland law requires that all medicalcannabis bear a label that includes the following warning: “Consumption of medicalcannabis may impair your ability to drive a car or operate machinery. Please use

On its “FDA and Cannabis: Research and Drug Approval Process” webpage, the FDA notesthat the agency has “not approved a marketing application for cannabis for the treatment of any
disease or condition.” It has, however, approved one cannabis-derived product, cannabidiol(marketed as Epidiolex), which is used to treat seizures associated with rare forms of epilepsy, and two
synthetic cannabinoids, dronabinol (marketed as Marinol or Syndros) and nabilone (marketed as
Cesamet), which are used to treat severe nausea and vomiting or weight loss for people with certain
conditions.
88

See the Alcohol Beverage Labeling Act of 1988, section 8001, subsection 204, of theAnti-Drug Abuse Act of 1988, Public Law 100–690, 102 Stat. 4181 (1988).
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extreme caution.”90 In comparison, Oklahoma law requires that medical cannabis
include the following warnings on labels: “keep out of reach of children” and “womenshould not use marijuana or medical marijuana products during pregnancy becauseof the risk of birth defects or while breastfeeding”; however, there are no labelingrequirements concerning driving or potential impairment of any kind.91 An NTSB
analysis of laws in the 50 states, the District of Columbia, and the Commonwealth of
Puerto Rico, identified 23 jurisdictions where cannabis sales are legal but wherecannabis label requirements are not required or are inadequate. This includes
12 jurisdictions that have no driving-related label requirements, 4 that have label
requirements for only certain cannabis products, and 7 whose labeling requirements
do not explicitly warn against driving after cannabis use.92
Although it is not clear whether the inclusion of driving-related warnings oncannabis labels would influence driver behaviors or reduce crash risk, a recent
national survey found that drivers are less likely to perceive driving after cannabis use
to be dangerous compared to driving after alcohol use (AAA FTS 2021). Additionally,
the absence of such labeling―especially when alcohol and many prescription and
OTC drugs do include warnings about driving―could lead users to believe thatcannabis does not impair driving. The NTSB concludes that including driving-related
warnings on cannabis products, similar to those on alcohol and many prescription
and OTC drugs, would increase awareness of the risks of cannabis-impaired driving.
Therefore, the NTSB recommends that the District of Columbia, the Commonwealthof Puerto Rico, and the 21 states where cannabis use is legal but driving-related
cannabis warning labels are not required or are inadequate require a warning label
on cannabis products advising users not to drive after cannabis use due to its
impairing effects. The Canadian labeling requirements or requirements from theseveral states that do include driving-related warnings may be useful references for
those states without such labeling. Additionally, an international standards-setting

See the Maryland Code of Regulations, 10.62.24.01, “Packaging of Medical Cannabis
Finished Product.”90

See Title 310, Oklahoma State Department of Health, Chapter 681, Medical Marijuana
Regulations.
91

The 12 jurisdictions with no driving-related label requirements are Arkansas, the District ofColumbia, Florida, Louisiana, Mississippi, Missouri, Ohio, Oklahoma, Oregon, Puerto Rico,
Rhode Island, and Virginia. The 4 states that have label requirements for only certain cannabis
products are Illinois, Maine, New Jersey, and New York. The 7 states whose labeling requirements do
not explicitly warn against driving after cannabis use are Alabama, Arizona, California, Colorado,
Maryland, Pennsylvania, and West Virginia.
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organization recently adopted a symbol to indicate the presence of “intoxicating
cannabinoids” in consumer products.93

4.3 Need to Improve Drug-Impaired Driving Laws and Enforcement
Having strong laws and enforcement can help in detecting and removing
impaired drivers from the road. It can also foster a general deterrent effect if people
recognize that there is a strong likelihood of being caught. All states have laws
against driving impaired by alcohol and other drugs, but some laws may be outdated
and may not address the complexities of the current environment. Additionally,certain aspects of laws, such as limiting the definition of drug impairment to a certain
subset of drugs, may create barriers to swift and effective enforcement. This can
impede the ability of a community to address impaired driving through the criminal
justice process. This section focuses on laws and policies that could be improved tostrengthen and expedite the criminal justice process to reduce the likelihood of
impaired driving and impaired driving crashes.

4.3.1 Oral Fluid for Impaired Driving Enforcement
To test for drugs other than alcohol, blood and oral fluid are optimal
specimens because they are most likely to provide a snapshot of drugs that were in
the system and potentially influencing driving at the time when the
impairment-related behaviors were observed. Such specimens are not collected until
after an impaired driving arrest has been made. When law enforcement officers
conduct a traffic stop for suspected impairment, they first document and assess signsof impairment before making an arrest, including driving behaviors, such as weavingor speeding; driver behaviors, such as slurred speech or stumbling; driverappearance, such as bloodshot eyes or smell of cannabis or alcohol; andperformance on standardized tests, such as the SFSTs. When an officer determinesthat a driver is impaired and makes an arrest, the officer then requests a biological
specimen to test for the presence of alcohol and/or other drugs.

(a) See ASTM International’s “Standard Specification for International Symbol for Identifying
Consumer Products Containing Intoxicating Cannabinoids,” ASTM D8441/D8441M-22, for more
information. ASTM International was formerly known as the American Society for Testing and Materials.
(b) See the Doctors for Cannabis webpage “Universal Cannabis Symbol” for examples of various
intoxicating cannabis product symbols.
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Collecting blood can be challenging because it may require a search warrant
and transportation to a facility where a trained phlebotomist can draw a specimen.94
This can lead to delays, and by the time the blood specimen is collected, drug
metabolism may have taken place (Wood, Brooks-Russell, and Drum 2016). In thepresent research, the elapsed time between arrest and blood collection averaged
about 2 hours, and there was considerable variability in the times.
Because drug metabolism is typically not linear and can vary greatly between
individual drivers suspected of being impaired, it is not possible to calculate
backward to know the amount of drug present at the time of an arrest or a crash or toknow if a parent compound was present if only metabolites are found. Consequently,
obtaining a biological specimen near to the time of the event is valuable tounderstand what drugs were in a driver’s system while driving and to facilitate
impaired driving prosecution. Some law enforcement organizations have developed
specialized phlebotomy programs, which may expedite the collection of blood
specimens. In 2019, NHTSA published a Law Enforcement Phlebotomy Toolkit tohelp law enforcement agencies wishing to implement such programs, and the agency
has also established a program to assist with their funding (NHTSA 2019). Other law
enforcement agencies have begun collecting oral fluid at the roadside when drivers
are arrested for impaired driving.
There are two ways that oral fluid collected at the roadside may be used. First,
it may be analyzed with an on-site screening device that provides rapid
qualitative―that is, positive or negative―information about the likely presence ofdifferent drugs or drug categories. Similar to a preliminary breath test for alcohol, apositive oral fluid drug screen would likely lead to the collection of an evidentiary oral
fluid or blood specimen. For example, Indiana began a roadside oral fluid screening
program in 2020, and pilot programs have been conducted in several other states(Michigan State Police 2019; Edwards, Smith, and Savage 2017; Moore and others2022).95
Second, evidentiary oral fluid specimens can be sent to a toxicology laboratory
for screening and confirmatory testing, which can provide information about specificdrugs and may also include information about the quantity of a drug detected in a(a) A phlebotomist is someone trained to collect and prepare blood specimens for testing.
(b) In the past decade, there have been multiple Supreme Court decisions concerning thecircumstances under which search warrants may or may not be required for the collection of blood
during an impaired driving arrest. For example, see Mitchell v. Wisconsin, 588 US (2019); Missouriv. McNeely, 569 US (2013); and Birchfield v. North Dakota, 579 US (2016).
94

See the Indiana Criminal Justice Institute’s “Roadside Oral Fluid Program” webpage for more
information.
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specimen. Alabama is currently the only state that routinely collects oral fluid in
addition to blood for evidentiary purposes.
The potential benefits are that oral fluid collection allows for rapid and lessinvasive biological specimen collection, and it is less likely to be susceptible toalteration compared to urine. Because it can be collected at the roadside, oral fluid ismore likely to provide an accurate snapshot of the presence of psychoactive drugs ina driver’s system at the time of an event. It is increasingly recognized as a biological
specimen that can provide valid information about driver drug use. For example, inFebruary 2022, the US Department of Transportation (DOT) proposed to allow oral
fluid testing as an alternative to urine testing for safety-sensitive transportation
employees who are subject to regulatory drug testing.96
In 2018, the NTSB recommended that NHTSA develop and disseminate bestpractices, identify model specifications, and create a conforming products list for oral
fluid drug screening devices (H-18-56).97 In response, NHTSA conducted a study toevaluate on-site oral fluid drug screening technology (Buzby and others 2021). It
found variability in the performance of the devices evaluated and affirmed theimportance of accuracy and reliability in oral fluid screening devices. In 2022, NHTSA
committed to working with the National Institute of Standards and Technology todevelop performance standards and testing procedures for oral fluid screening
devices.
Also in 2022, AAA published a comprehensive toolkit for the use of oral fluid todetect drugged drivers (Moore and others 2022). The toolkit describes the benefits oforal fluid for use in drug-impaired driving enforcement. It also provides guidance onoral fluid legislation and policy considerations, the tools for oral fluid field screening,laboratory oral fluid confirmation, oral fluid pilot programs, and education for the
judiciary on the consideration of oral fluid evidence.
Although there is increasing recognition that oral fluid can provide valid results
and is less invasive, easier, and quicker to collect, several states do not authorize its
use. As shown in figure 11, as of February 2022, 15 states’ implied consent laws
allowed for the collection of oral fluid.98 In 28 states and the District of Columbia, it
See DOT’s notice of proposed rulemaking titled “Procedures for Transportation Workplace
Drug and Alcohol Testing Programs: Addition of Oral Fluid Specimen Testing for Drugs,” published at
87 Federal Register 11156 on February 28, 2022.
96

Safety Recommendation H-18-56 is classified Open—Acceptable Response. See appendix A
for more information.
97

Implied consent laws generally state that when drivers apply for a license to drive, they agree
to comply with requests from law enforcement officers to collect certain specimens for alcohol or otherdrug testing.
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was not authorized. In six states, it was authorized by an impaired driving statute but
not mentioned as part of the implied consent laws, and in one state (Alabama), it was
authorized both in its implied consent law and impaired driving statute.

Figure 11. Oral fluid collection laws for impaired driving enforcement (Source: Moore andothers 2022).

The NTSB concludes that oral fluid is a valuable but underutilized biological
specimen for the detection of drug use by drivers and can support the enforcementof impaired driving laws. Therefore, the NTSB recommends that the District ofColumbia and the 28 states that do not currently explicitly allow oral fluid collection
and testing modify their impaired driving laws to allow for oral fluid collection,screening, and testing for the detection of drug use by drivers.99

The states are Alaska, California, Connecticut, Delaware, Florida, Hawaii, Idaho, Iowa,
Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Montana, Nebraska,
New Hampshire, New Jersey, New Mexico, Oregon, Pennsylvania, South Carolina, Tennessee, Texas,
Virginia, Washington, West Virginia, and Wisconsin.
99

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4.3.2 Impairing Drug Definitions in Impaired Driving Statutes
Certain states’ impaired driving laws only allow drug-impaired driving
violations when a driver is using certain drugs. By contrast, most states have a broad
definition that includes any drug that may impair driving. In a state that defines alimited set of drugs, a driver who is arrested and found to be impaired by a drug thatis not explicitly listed in the statute will likely not be prosecuted. For example, one
report describes several case studies from Florida in which drivers who exhibited
clear signs of impairment were not prosecuted for impaired diving because they had
used several prescription drugs that were not identified in the Florida statute(Tiscione and others 2018).100 A similar problem could result from drivers impaired bynovel psychoactive substances, as new and unique formulations of those drugs
continue to be developed. This can severely limit the ability for the criminal justicesystem to address drug-impaired driving.
Statutes should define drug-impaired driving as driving that is caused by
impairment from any drugs rather than limiting their statutes to illicit drugs or to a setof drugs presently associated with impairment. Some states and other organizations
have recently made efforts to address this issue. For example, in 2022, the New YorkState Senate and Assembly sponsored bills to modify its laws related todrug-impaired driving.101 The bills, which did not ultimately pass, proposed several
changes, including broadening the definition of “drug” to include any drug that
impairs a driver rather than a specific list of drugs.
The NTSB concludes that laws that specify only certain drugs that can impair
driving restrict the ability to prosecute drivers impaired by other drugs or drug
combinations that are not specified in the statute, thereby limiting the ability to fully
address drug-impaired driving. Therefore, the NTSB recommends that the five statesthat restrict drug-impaired driving statutes to a limited set of drugs enact laws
specifying that drivers under the influence of a drug or multiple drugs that may impair
driving are considered to be impaired under the definition of drug-impaired
driving.102

Other drivers had used a combination of drugs, some of which were included in the statuteand others that were not; however, because prosecutors could not demonstrate that the drugs
specifically covered in the statute caused the impairment, they were unable to support prosecution for
impaired driving.
100

101

See the New York State Senate Bills S8913 and A9554 for more information.

The states that restrict drug-impaired driving statutes to a limited set of drugs are Alaska,
Florida, Massachusetts, New York, and Oregon.
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4.3.3 Electronic Warrants
Analyses from the crash-involved impaired driving arrest population in the
Wisconsin laboratory dataset and the impaired driving arrest population in the
San Francisco laboratory dataset found that the average elapsed time between traffic
violation and blood specimen collection was about 2 hours. Such delays, and theresulting drug metabolism that takes place, can make enforcement particularly
problematic in jurisdictions where laws specify a certain drug per se limit (Wood,
Brooks-Russell, and Drum 2016). This was evidenced in the Orange County
laboratory dataset where nearly one-third of drivers arrested for impaired driving,
who only tested positive for cannabis, had THC levels below 5 ng/mL, which is a
per se or permissible inference threshold for cannabis impairment in 4 states.103
However, many other drugs can also quickly metabolize below detectable levels in adriver’s system, and all toxicological evidence of drug use may metabolize out of adriver’s system with delays in collection of a biological specimen for testing. Indeed,
one advantage of blood testing is the ability to detect recent use. This, unfortunately,
also means these specimens need to be collected efficiently to detect usage.
Countermeasures described in earlier sections, including programs that train
law enforcement officers to become phlebotomists and facilitating the collection oforal fluid as an alternative biological specimen both have the potential to overcome
this challenge. The use of electronic search warrants is another countermeasure thatcan potentially facilitate and improve drug-impaired driving enforcement. A
traditional process for obtaining a search warrant may involve an arresting officercompleting affidavit and warrant forms, contacting an on-call prosecutor or judge,
faxing forms for review and signature, and, if granted, awaiting the return of thesigned forms (Berning and others 2007). By contrast, electronic warrant systems,
which allow for the requesting and transmitting of search warrants through online
management systems, can streamline the impaired driving arrest process and lead tomore timely collection of biological specimens from impaired driving suspects.
There are a number of published resources on implementing expedited
warrants. In 2018, the Foundation for Advancing Alcohol Responsibility published areport, Improving DUI System Efficiency: A Guide to Implementing Electronic
Warrants, which provides detailed guidance for communities wishing to implement
an electronic warrant system (Borakove and Banks 2018). The guide includes sections
on model legislation, stakeholder engagement, funding, policy and operations,training, and measuring effectiveness. It also includes several case studies ofcommunities that successfully implemented electronic warrant systems. Additionally,in 2021, NHTSA published a similar report, Practices for Implementing Expedited
Search Warrant Programs for Obtaining Evidence from Impaired Drivers, which
103

The four states are Illinois, Montana, Washington, and Colorado.

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provides best practices for implementing expedited warrants (Symoun and others2021). NHTSA has also established a funding support program to assist agencies intheir efforts to implement or enhance electronic warrant programs.
The use of electronic warrants is a straightforward process that can expedite
the collection of biological specimens during drug-impaired driving arrests, but theiruse is not authorized by certain states. Reviews of state legislation and practices
concerning the use of electronic warrants for impaired driving enforcement haveyielded varied findings. A Foundation for Advancing Alcohol Responsibility analysis
concluded that 26 states and the District of Columbia have specific legislation
authorizing the use of electronic warrants, and an additional 8 states have court rulesthat authorize their use (Borakove and Banks 2018). In 2019, the AAA Foundation for
Traffic Safety published the results of a survey that asked states to report on policies
and practices related to drug-impaired driving (Taylor, McKnight, and Treffers 2019).
Of the District of Columbia and the 44 states that responded, 5 reported regularly
using electronic warrants statewide, 26 reported some use, and 14 reported notusing them. Of the 14 states that reported not using electronic warrants, 12 did nothave legislative authority to use electronic warrants, and 2 states reported
administrative obstacles to implementing a program.104 Although both reports notedthat the presence of explicit legislative authority may not be necessary to establish an
electronic warrant program, such policies can be useful for encouraging uniform
practices and to guard against legal challenges (Borakove and Banks 2018; Taylor,
McKnight, and Treffers 2019).
The NTSB concludes that the use of electronic warrants during the impaired
driving arrest process can expedite the collection of biological specimens, thereby
increasing the likelihood that impairing drugs present at the time of driving will be
detected. Therefore, the NTSB recommends that the Commonwealth of Puerto Ricoand the 17 states that have not established electronic warrant programs for impaired
driving enforcement allow the use of electronic warrants to obtain biological
specimens during impaired driving arrests by modifying laws or removing
administrative barriers.

4.3.4 State Efforts to Address Drug-Impaired Driving
Modifying laws to allow for any impairing drug to be included in the definitionof drug-impaired driving and to authorize the use of oral fluid testing and electronic
The 14 states that reported not using electronic warrants were Alabama, Connecticut,
Georgia, Hawaii, Idaho, Iowa, Maine, Massachusetts, Mississippi, New Mexico, North Carolina,
Rhode Island, Virginia, and West Virginia. The NTSB contacted the Commonwealth of Puerto Rico andthe six states that did not respond to the AAA FTS survey and determined that three additional states,
Alaska, New York, and South Carolina, do not use electronic warrants. Puerto Rico did not respond.
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warrants are important steps toward addressing drug-impaired driving. However, tofully realize the potential benefits of strong laws, states need to invest in establishingsystems or programs to facilitate their enforcement. Establishing and maintaining
such programs requires commitment from multiple stakeholders as well as financial
resources. Furthermore, there are many different approaches that states andcommunities might take to address these issues. For instance, to expedite thecollection of biological samples, one state might invest in providing phlebotomy
training to law enforcement while another might establish an evidentiary oral fluid
program. A state may need to consider many factors to customize an approach that ismost likely to lead to reductions in impaired driving.
As part of its efforts to address drug-impaired driving, NHTSA recently
developed and published a Drug-Impaired Driving Criminal Justice Evaluation Tool.
The tool is comprised of a series of worksheets addressing many facets ofdrug-impaired driving prevention. It is designed to be used by state, local, territorial,or tribal government agencies to “assist with identifying program strengths andopportunities for improvements.” The worksheet topics include law enforcement,
prosecution, judiciary, community supervision, toxicology, treatment, emergency
medical services, data, legislation, and program and communications.105 Aftercompleting a self-evaluation using the Drug-Impaired Driving Criminal JusticeEvaluation Tool, agencies may submit applications to NHTSA for financial support ofprojects designed to address challenges identified through the tool’s use.
As of October 2022, within 4 months of launching the tool, NHTSA reported
that 10 states or other agencies had submitted applications based on using the tooland that about 10 others had indicated that they were using the tool to conduct anevaluation and intended to apply for funding.106 The NTSB concludes that NHTSA’s
Drug-Impaired Driving Criminal Justice Evaluation Tool can provide valuableguidance to help states and communities identify opportunities to improve efforts toaddress drug-impaired driving. Therefore, the NTSB recommends that the 50 states,
the District of Columbia, and the Commonwealth of Puerto Rico complete anassessment using NHTSA’s Drug-Impaired Driving Criminal Justice Evaluation Tool,
and, if gaps are identified, apply to NHTSA for support in establishing programs to
reduce drug-impaired driving.

See NHTSA’s “Drug-Impaired Driving Criminal Justice Evaluation Tool” webpage for more
information and to download the tool and review the worksheet topics.
105

106

Jennifer Davidson, NHTSA, personal communication, October 26, 2022.

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4.4 Need to Ensure that Driving Safety Is Considered in the
Evaluation of Prescription and OTC Drugs
As new drugs are developed and evaluated, an opportunity exists to consider
potential impairing effects on driving. This section discusses the current efforts
underway to evaluate how prescription and OTC drugs may affect driving safety andthe importance of continued postmarket surveillance of the effects of drugs on
driving safety.

4.4.1 Evaluating Potential Effects on Driving Safety During Drug
Development
In 2008, in response to a 2000 NTSB recommendation to the DOT, NHTSA
convened an expert panel to identify drugs that were safe for driving and those thatwere hazardous so that transportation operators could make safer choices about
drug use (I-00-2).107 The panel agreed that drivers need better information about how
drugs affect their ability to operate motor vehicles but noted that there wasincomplete information available to make a definitive classification for many drugs.
The panel instead proposed a protocol to assess the driving impairment potential ofvarious drugs (Kay and Logan 2011). The protocol includes three components:•

pharmacology/toxicology review, which refers to the evaluation of thelikelihood that a drug or drug combination will affect brain functions used
for driving•

epidemiology review, which refers to the examination of the association
between drug presence and crashes, such as studies that compare drug
use between crash-involved drivers and non-crash-involved drivers•

standardized behavioral assessment, which refers to experimental
research on how drugs affect behaviors needed for safe vehicle operation,such as studies that employ dosing protocols and evaluate performance incontrolled settings, such as driving simulators or test tracks. A standardized
behavioral assessment is designed to be undertaken if the potential for
impairment is identified in the other components

In 2017, the FDA published guidance for the drug industry, “Evaluating Drug
Effects on the Ability to Operate a Motor Vehicle: Guidance for Industry,” based on
NHTSA’s expert panel’s protocol (FDA 2017). The guidance states that all drugs
should be evaluated for potential central nervous system-impairing effects during thefirst phase of drug development. If there is evidence of impairing effects, additional
107

Safety Recommendation I-00-2 is classified Closed—Unacceptable Action.

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research in subsequent trials should examine potential impairment over the full rangeof drug exposure that may occur.108 The guidance suggests the use of dedicateddriving studies if the initial evaluation indicates a potential for driving impairment.
Such targeted studies could be particularly important because research has indicatedthat drug-impaired drivers are not able to accurately predict their levels of
impairment prior to driving (Verster and Roth 2012).
There is evidence that some drugmakers have applied the 2017 FDA
guidance. For example, in January 2022, the FDA approved daridorexant (marketed
as QUVIVIQ) to treat insomnia in adults. Its patient package insert includes a sectionthat describes a driving study that was conducted to evaluate the effects of nighttime
dosing on next-morning driving performance.109 The study examined next-day driving
performance in a driving simulator among 60 participants ages 50 to 79 years.
Statistically significant driving performance impairment was observed the day after
the first dose. After 4 consecutive nights of treatment, there was no overall significant
driving impairment; however, driving remained impaired for some participants. As aresult, the daridorexant drug labeling calls on prescribers to caution patients about
the potential for next-morning driving impairment after taking daridorexant.110 It alsosuggests that patients should not drive after taking the drug if a higher thanrecommended dose is taken or if it is taken with less than a full night of sleep
remaining.
The 2017 FDA guidance is useful; however, this guidance does not appear to
be used regularly by drug manufacturers. The FDA reviews about 50 new drug
applications each year.111 A NHTSA study that sought information about publishedreports and clinical trials that used the tiered assessment protocol was only able tofind four examples since 2017 in which driving studies were conducted.112 It is
possible that, for the remaining drugs, initial reviews did not suggest a need for
driving studies. Also, considering that it may take years to develop a new drug, it ispossible that some drug sponsors did not have an opportunity to incorporate driving
The guidance also noted that even some non-psychoactive drugs, for example, those that
could impair vision or result in loss of consciousness from hypoglycemia, could impair driving ability
and should therefore be considered.
108

See the daridorexant patient package insert, section 14.2, “Special Safety Studies, Effects on
Driving,” for more information.
109

For more information about the effectiveness of prescription and OTC drug labeling, seesection 4.2.2.
110

See the FDA’s “New Drugs at FDA: CDER’s New Molecular Entities and New Therapeutic
Biological Products” webpage for more information.
111

112

DeReece Smither, NHTSA, personal communication, October 20, 2021.

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studies if their clinical programs were already underway when the 2017 guidance wasissued. However, because the FDA has not tracked whether drug sponsors are awareof or are following the guidance, it is not possible to know whether it is being
followed consistently.
In an effort to help drug developers and the FDA identify drugs that could
pose a risk to safe driving early in the drug development process, NHTSA has alsosponsored a study designed to validate a simulator-based “drug-impaired driving
scenario.”113 The drug-impaired driving scenario study will evaluate cannabis, thebenzodiazepine alprazolam, and a placebo during a simulated drive in which thestandard deviation of lateral position, lane exceedances, and reaction time will bemeasured. If the study can demonstrate a link among drug use, performance on the
scenario, and crash risk, it could be a very valuable tool for drug safety evaluation.
The NTSB concludes that the FDA has recognized the importance ofevaluating the potential for driver impairment during the development of new drugs
and has provided guidance for a systematic method of doing so, but it is unknown if
its guidance is consistently applied. Therefore, the NTSB recommends that the FDA
develop a system to audit drugmaker compliance with its 2017 “Evaluating Drug
Effects on the Ability to Operate a Motor Vehicle: Guidance for Industry.”

4.4.2 Continued Surveillance of Prescription and OTC Drugs
In some instances, drug labeling or dosing recommendations have been
modified after the FDA became aware of driving-related safety issues. For example,
zolpidem, a drug used to treat insomnia, was approved by the FDA in 1992 under thebrand name Ambien.114 By 2006, it was the 13th highest selling brand-name drug.
Several subsequent research studies raised concerns about zolpidem, including one
that showed a 220% increase in emergency department visits involving adverse
reactions associated with its use from 2005 to 2010 (SAMHSA 2013) and an increased
risk of motor vehicle crashes the day after its use (Yang and others 2011).
In March 2007, the FDA requested that manufacturers of sedative-hypnotic
drugs, including Ambien, strengthen product labeling to describe risks of the drugs,
including “complex sleep-related behaviors which may include sleep-driving, making
phone calls, and preparing and eating food (while asleep)” (FDA 2007). In
January 2013, the FDA required manufacturers to lower their recommended bedtime
doses for certain drugs containing zolpidem, particularly for women (FDA 2013a). It
See the US National Library of Medicine’s clinical trials webpage “Validation of the Drug
Impaired Driving Scenario (DIDS) on the CRCDS-miniSim (PDID)” for more information.
113

114

In April 2007, the FDA approved zolpidem in its generic form.

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also urged health care providers to caution patients about the risks of next-morning
activities, including driving. The 2013 drug safety communication referred to driving
simulator and laboratory studies submitted to the FDA that showed an elevated riskof a motor vehicle crash after using zolpidem. In May 2013, the FDA approved
labeling changes for the new dosing recommendations. The FDA also warned thatpatients who used extended-release zolpidem should not drive or do other activities
that require alertness the day after taking the drug (FDA 2013b).
In the case of zolpidem, it took several years before its effects were fully
understood and prescribing and labeling were modified. Ideally, if drug
manufacturers are following the 2017 FDA guidance during drug development,
potentially risky driving-related drug side effects should be discovered, and druglabeling should take place before a drug goes to market. However, continued
postmarket drug safety monitoring remains a valuable tool for identifying unintended
adverse effects, particularly since the premarket evaluations cannot address all
possible types of drug use and users. For example, they cannot anticipate all possible
drug interactions.
The FDA administers several programs for postmarket monitoring of drug
safety risks. The FDA Amendments Act of 2007 directed the agency to develop a
postmarket risk identification and analysis system.115 In response, the FDA developed
its Sentinel System, which leverages electronic health records and medical billinginformation from numerous health care organizations.116 The FDA queries these data
to identify and study potential adverse drug effects. The FDA also reviews medical
literature and conducts analyses of the FDA Adverse Event Reporting System, an
FDA-sponsored database that contains adverse drug event reports, medication error
reports, and product quality complaints submitted by industry and the public (FDA
2019a).117 Industry submitters may include drug manufacturers, distributors, andothers. Public submissions may come from health care providers, consumers, orfamily members. The FDA identifies safety issues in the database using data-mining,
aggregate analysis, and case-based evaluation.
In 2019, the FDA described its 5-year strategy to expand the Sentinel System’sfoundation, including a plan to broaden its stakeholder community and its use of“real-world data” for surveillance (FDA 2019b). According to the FDA, real-world data
may come from many sources, including electronic health records, claims and billing

115

FDA Amendments Act of 2007, Public Law 110–85, 121 Stat. 823 (2007). See section 905.

116

For more information about the Sentinel System, see the “Sentinel Initiative” webpage.

See the FDA’s “FDA Adverse Event Reporting System (FAERS) Public Dashboard” webpage
for more information. A separate but analogous system is used to track vaccine safety.
117

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activities, product and disease registries, patient-generated data, and data gatheredfrom other sources.
In the present research, more than 1 in 10 drivers arrested for impaired driving
tested positive for sedatives, narcotic analgesics, or potentially impairing
neuropsychiatric medications, which are categories comprised predominantly ofprescription and OTC drugs. If the prevalence of certain drugs or drug combinations
in crash-involved impaired driving populations is higher than would be expected in
the general driving population, it may indicate a heightened crash risk associatedwith those drugs. Several epidemiological studies, including those referenced in thisreport, have already documented the crash risk associated with certain prescription
and OTC drugs, and the FDA has required warnings about driving for several of thedrugs. Incorporating transportation safety data and research into the FDA’s
postmarket drug surveillance efforts could further enhance the agency’s ability toidentify drugs that may impair driving and increase crash risk.
The NTSB concludes that the FDA’s drug safety surveillance systems have
improved the likelihood that adverse drug effects will be detected and addressed;
however, the surveillance systems could be enhanced by better incorporating
information about drug use and driving safety. Therefore, the NTSB recommends that
the FDA incorporate additional data and research concerning drug use and driving to
improve FDA drug safety surveillance systems. For example, the FDA could conduct a
review of epidemiological studies to identify drugs that may be associated withheightened crash risk, or it could examine drug prevalence data from the present
research or from NHTSA’s recent research on drug prevalence among crash-involved
drivers admitted to trauma centers.

4.5 Need to Enhance Systems for Documenting and Tracking theIncidence of Drug Use and Driving
The NTSB has a long history of advocating for improvements in the collection,
testing, and reporting of alcohol and other drug data.118 A robust data system canbenefit safety in several ways. For example, established evidence of impaired driving
paired with timely tests for a standard set of commonly used impairing drugs canfacilitate arrest and prosecution of impaired drivers. It also increases the likelihoodthat a driver’s potential drug use problems may be identified and result in treatment.
A systematic approach to collecting, testing, and reporting drug data can also
facilitate tracking trends in drug use as well as the development of data-driven
For a detailed history, see NTSB’s June 24, 2022, response to NHTSA’s request forcomments titled “Barriers and Solutions for Submitting Toxicology Data to [FARS] Pursuant to
Recommendations for Toxicological Investigation of Drug-Impaired Driving and Motor Vehicle
Fatalities,” published at 87 Federal Register 24390 on April 25, 2022.
118

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countermeasures and the evaluation of their effects. Such improvements rely on
resources and support from multiple stakeholders.

4.5.1 BAC Testing and Reporting
In 2012, the NTSB recommended that NHTSA disseminate BAC testing andreporting guidelines to the 50 states, the Commonwealth of Puerto Rico, and theDistrict of Columbia (H-12-32).119 We also made two recommendations to the
45 states with low reporting rates, the Commonwealth of Puerto Rico, and theDistrict of Columbia, to take steps to increase their BAC reporting rates (H-12-34 andH-12-35).120 Since those recommendations were issued, some states have improved
their reporting rates, but on the national level, reporting has decreased. During themost recent 3 years from 2018 to 2020, the average rates of BAC reporting wereabout 5 percentage points lower than in 2012 for both fatally injured and surviving
drivers.
In 2022, the NTSB classified Safety Recommendation H-12-34
Closed―Acceptable Action for the 2 recipients that completed the recommended
action, Open—Acceptable Response for 30 recipients, Open—Acceptable Alternate
Response for 3 recipients, and Open—Unacceptable Response for 12 recipients. The
NTSB also classified Safety Recommendation H-12-35 Closed—Acceptable Action for
2 recipients that completed the recommended action, Open—Acceptable Response
for 25 recipients, and Open—Unacceptable Response for 20 recipients.
The NTSB concludes that although a few states have taken some steps toward
improving BAC reporting rates, additional efforts by most states to improve BAC
collection, documentation, and reporting are needed to ensure accurate tracking of
national alcohol-impaired driving trends and to develop and evaluate appropriate
countermeasures.

4.5.2 Other Drug Testing and Reporting
In 2012, as a result of the NTSB Reaching Zero forum, the NTSB observed thatno standard guidance existed for states regarding a minimum set of drugs thatshould be evaluated, recommended methods for drug testing, or reporting
thresholds for crash databases. Because establishing standardized postcrash drug

Safety Recommendation H-12-32 is classified Closed—Acceptable Action as ofDecember 13, 2021. See appendix A for more information.
119

Safety Recommendations H-12-34 and H-12-35 have an overall classification ofOpen―Acceptable Response. See appendix A for more information.
120

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testing and reporting is a needed first step toward improving our understanding of
the problem of drug-impaired driving, the NTSB recommended that NHTSA
Develop and disseminate to appropriate state officials a common
standard of practice for drug toxicology testing, including (1) the
circumstances under which tests should be conducted, (2) a minimum
set of drugs for which to test, and (3) cutoff values for reporting theresults (H-12-33).121
In its letter to NHTSA concerning that recommendation, the NTSB
acknowledged the efforts of ICADTS and of the NSC ADID as examples of sources forstandard practices. In 2016, NHTSA provided support for an effort to review andupdate the NSC ADID recommendations for the toxicological investigation of
drug-impaired driving cases and motor vehicle fatalities. The resulting NSC ADID
report, which was part of a regularly produced survey of forensic toxicology
laboratories in the US and Canada, provided a set of recommendations concerningwhich drugs should be routinely tested for, as well as screening and confirmation
cutoffs for analyses in blood, urine, and oral fluid (Logan and others 2018).
In 2018, NHTSA established an expert working group on toxicology datacollection to improve overall understanding of the national scope and prevalence ofdrug-impaired driving. The working group drafted guidance for the forensic
toxicology community; however, the draft guidance was never shared with the public,
and the working group stopped meeting in 2019.122 In the meantime, the NSC ADID
group published an updated set of recommendations (D’Orazio and others 2021),
and many of those recommendations were codified in ANSI/ASB Standard 120(ANSI/ASB 2021).
The NSC ADID recommendations and ANSI/ASB Standard 120 provide
guidance on the scope of testing; the recommended matrix to be tested, such as
blood or oral fluid; and the minimum laboratory detection cutoffs for the testing ofthese drugs. The NSC ADID recommendations go one step further by suggesting theelimination of stop-testing procedures, where further drug testing is cancelled if adriver has a BAC over a certain threshold. The standardization of the drug panel,meaning which specific drugs are tested, is valuable because there are potentiallythousands of drugs that could be tested, and testing of additional drugs can add cost
and time constraints. Table 12 shows the drugs included in ANSI/ASB Standard 120.

Safety Recommendation H-12-33 is classified Open—Acceptable Response. See appendix A
for more information.
121

122

See the NTSB’s June 24, 2022, comments to the docket.

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Table 12. Minimum drugs to be tested for according to ANSI/ASB Standard 120, adaptedfrom the NSC ADID Tier I Compounds (D’Orazio and others 2021).
Drug Category

Drugs Tested

Cannabinoids
Cannabinoids
Cannabinoids
EthanolNarcotic Analgesics
Narcotic Analgesics
Narcotic Analgesics
Narcotic Analgesics
Narcotic Analgesics
Narcotic Analgesics
Narcotic Analgesics
Narcotic Analgesics
Narcotic Analgesics
Narcotic Analgesics
Narcotic Analgesics
CNS Stimulants
CNS Stimulants
CNS Stimulants
CNS Stimulants
CNS Stimulants
CNS Stimulants
CNS Stimulants
CNS Depressants
CNS Depressants
CNS Depressants
CNS Depressants
CNS Depressants
CNS Depressants
CNS Depressants
CNS Depressants
CNS Depressants
CNS DepressantsTHC
11-nor-delta-9-carboxy-THC
11 hydroxy delta–9-THC—
Morphine
Codeine6-acetylmorphine
Hydrocodone
Oxycodone
Methadone
Fentanyl
Buprenorphine
Norbuprenorphine
TramadolO-desmethyltramadol
Amphetamine
Methamphetamine
MDA
MDMA
CocaineCocaethylene
Benzoylecgonine
Carisoprodol
Meprobamate
Zolpidem
Alprazolam
Clonazepam
7-aminoclonazepam
Lorazepam
Nordiazepam
OxazepamTemazepam

In March 2022, NHTSA published a report providing a detailed exploration of
the challenges in driver drug testing and reporting in the United States to “lay thegroundwork for improving the data collection and reporting” (Berning and others2022). The report describes numerous problems and challenges at all stages of thecurrent process, including obstacles in obtaining toxicological specimens andordering drug tests, inconsistencies in testing and reporting procedures, and delays
and challenges in transferring toxicology findings into crash databases. It also
describes some of the measures that NHTSA has taken, or plans to take, to address
those problems. For example, NHTSA has expanded the number of drugs that can beentered into FARS. Additionally, in April 2022, in response to a congressional
mandate in section 25025 of the IIJA, NHTSA issued a request for comments titled“Barriers and Solutions for Submitting Toxicology Data to [FARS] Pursuant to
Recommendations for Toxicological Investigation of Drug-Impaired Driving andMotor Vehicle Fatalities,” published at 87 Federal Register 24390. In its response to81

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this request, the NTSB strongly encouraged NHTSA to use the information it gathered
to take steps to improve BAC and other drug reporting for all drivers in fatal
crashes.123
The NTSB’s FARS analysis confirmed that national-level reporting of
nonalcohol drugs continues to be inadequate. Drug tests were reportedly conducted
for an average of 60% of fatally injured drivers and 18% of surviving drivers in fatal
crashes between 2018 and 2020, which is 1 to 2 percentage points less than in 2012.
There is also substantial variability among reported testing rates by state. Even if
reporting rates increased, the variability in testing and reporting protocols thatcurrently exist would not allow for meaningful summaries of the reported data.
Importantly, these standards and improvements to the consistency of
toxicology testing not only enhance traffic data, which may then be used to evaluate
drug trends and evaluate countermeasures, but they are also invaluable for helping
individuals arrested for impaired driving get appropriate treatment. For example, if adriver is arrested for a DUI with alcohol and other drugs in their system, but theirblood sample is never tested for drugs other than alcohol because of stop-testingprocedures or because the specific drugs influencing them were not included in the
drug panel, then this driver may only receive treatment and countermeasurestargeted toward alcohol. The many substance abuse challenges stemming from otherdrugs may not be addressed, denying them the treatment help they need andincreasing their likelihood of recidivating. The NTSB concludes that because there isno common standard of practice for the collection, testing, and reporting of driver
drug toxicology data in the United States, critical information that could improveunderstanding of drug trends and prevalence, assist with the evaluation ofcountermeasures, and better guide treatment options for DUI offenders is not being
captured or analyzed. Additionally, the NTSB concludes that widespread adoption of
ANSI/ASB Standard 120 would improve our understanding of the prevalence of drug
use among crash-involved drivers and drivers arrested for impaired driving.
Therefore, the NTSB classifies Safety Recommendation H-12-33 Closed—Acceptable
Action/Superseded and recommends that NHTSA disseminate ANSI/ASB
Standard 120 to state officials for use as the common standard of practice for drug
toxicology testing (Safety Recommendation H-22-33).
NHTSA has recently taken steps to support improvements in toxicology
testing. In 2021, NHTSA funded a task order to support state drug-impaired driving
toxicology meetings in up to 10 states for the purpose of increasing communication
among state and local laboratories and partners, providing training for toxicologists
and prosecutors on courtroom testimony, standardizing testing procedures amongstate agencies, and coordinating data collection and reporting to state partners and123

See the NTSB’s June 24, 2022, comments to the docket.

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FARS to strengthen state drug-impaired driving testing and reporting within eachdemonstration state. The agency also established a Toxicology Liaison Program tosupport liaisons in three NHTSA regions.124 These liaisons provide a knowledge
resource to states and toxicology laboratories to help them strengthen their drug
testing programs. The NHTSA toxicology liaisons are in a good position toaccomplish Safety Recommendation H-22-33 by sharing information about ANSI/ASB
Standard 120 with relevant state officials.
Toxicology laboratories will also likely need resources to meet the standard.
For example, some laboratories will need upgraded instruments for drug testing,which will necessitate training on the new instruments and protocols. They may also
require additional staff to address the increased workload. Forensic toxicology
laboratories are already strained. A report from the National Institute of Justice
showed a 26% increase in expenditures for toxicology from fiscal year 2015–2016 to
fiscal year 2016–2017, which it attributed in part to the opioid crisis (NIJ 2019). The
report also noted that, compared to deoxyribonucleic acid (DNA) testing, otherforensic disciplines, including toxicology, receive considerably less federal funding.125
NHTSA is well-positioned to provide funding and other support to help
toxicology laboratories meet ANSI/ASB Standard 120. The agency has recently
established three reimbursement-based drug-impaired driving funding programs,
including one to support implementation of law enforcement phlebotomy programs,
one to support electronic warrant implementation, and the aforementioned
Drug-Impaired Driving Criminal Justice Evaluation Tool, which enables support forvarious programs. The funding for these three programs must be expended byMarch 2023, July 2023, and September 2023, respectively.126 NHTSA has
demonstrated a dedication to helping states improve toxicology testing, and the
newly developed programs and funding provide important resources. Yet, more isneeded to help states address increased toxicology demands while meeting
ANSI/ASB Standard 120. As NHTSA continues its efforts to support improvements to
toxicology testing, creating a reimbursement program dedicated to funding
laboratory improvements would further foster widespread adoption of ANSI/ASB
Standard 120. NHTSA could also assist toxicology laboratories with achieving thisgoal by seeking authority to remove restrictions that may make it difficult to obtain
124

Tara Kelley-Baker, NHTSA, personal communication, August 15, 2022.

Much of the federal funding for DNA testing stemmed from a movement in the 1990s toestablish and promote a standard approach to DNA analysis. The DNA Identification Act of 1994,
Public Law 103–322, 108 Stat. 2065, required that the Federal Bureau of Investigation ensure that all
DNA laboratories that received federal grant funds or participated in the National DNA Index Systemdemonstrate compliance with the quality assurance standards.
125

126

Tara Kelley-Baker, NHTSA, personal communication, September 9, 2022.

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needed toxicology equipment, such as, the restrictions described in section 165 of
the Surface Transportation Act of 1982, commonly referred to as the Buy America
Act.127 Therefore, the NTSB recommends that NHTSA establish a program to support
toxicology laboratories’ compliance with ANSI/ASB Standard 120.
States can also play an important role in promoting the adoption of standardpractices for drug toxicology testing. In its 2022 report on the fatal Avenal, California,
collision involving a driver who tested positive for alcohol and cannabis, the NTSB
noted that the county where the crash occurred does not routinely test fatally injured
drivers for cannabis. The report also described the efforts of the California Highway
Patrol’s Impaired Driving Task Force. The task force, formed in 2017, met multiple
times over several years and, in January 2021, released a report containing
recommendations to prevent impaired driving as well as to reduce and mitigate its
effects (CHP 2021). Several recommendations addressed improvements to forensic
toxicology testing, including improving standardization of the conduct of tests andallocating funds for toxicology testing equipment and personnel.
In the Avenal report, the NTSB recommended that the state of California enact
legislation to require forensic toxicology laboratories to follow the standards
recommended by the NSC ADID. The recommendation also called for a provision in
the legislation to require laboratories to update the testing protocol if additional
federal guidance is provided (H-22-23).128
Enacting legislation requiring that laboratories follow ANSI/ASB Standard 120
regardless of driver BAC is one way to achieve this goal. Another way would be toprovide incentives to states or laboratories that commit to meeting the standard. For
example, in 2022, the California Highway Patrol established a grant program for the(a) The Surface Transportation Act of 1982, Public Law 97–424, 96 Stat. 2097 (1983). (b) For
example, NHTSA’s September 15, 2022, notice of proposed rulemaking titled “Uniform Procedures forState Highway Safety Grant Programs,” published at 87 Federal Register 56756, stated that the
Buy America Act requires its grant recipients “to purchase with federal funds only steel, iron, andmanufactured products produced in the United States, unless the Secretary of Transportation
determines that such domestically produced items would be inconsistent with the public interest, thatsuch materials are not reasonably available and of a satisfactory quality, or that inclusion of domestic
materials will increase the cost of the overall project contract by more than 25 percent.”
127

On August 29, 2022, the California governor approved a law which will require coroners or
medical examiners to perform alcohol and other drug screening and confirmation tests on people who
die while driving a motor vehicle. See California Senate Bill 925, Chapter 223 (2022).
128

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improvement and standardization of practices in toxicology laboratories supporting
impaired driving efforts.129
California Highway Patrol’s Impaired Driving Task Force provides an exampleof how key stakeholders can work together to develop recommendations that canlead to meaningful progress in improving and standardizing drug toxicology testing.
Therefore, the NTSB recommends that the 50 states, the District of Columbia, and theCommonwealth of Puerto Rico require government-funded laboratories that conduct
forensic toxicology testing to adopt and routinely apply (regardless of driver BAC)ANSI/ASB Standard 120, and provide funding for equipment, personnel, andtraining, to facilitate testing meeting that standard. Consequently, the NTSB alsoclassifies Safety Recommendation H-22-23 Closed―Superseded by Safety
Recommendation H-22-40.130
It should be noted the goal of these recommendations is not to expand thenumber of people subjected to blood testing. Rather, these recommendations seek
to standardize the testing that does occur. This not only improves the quality of datathat can be used for research and countermeasure development but would also assist
with guiding treatment. Applying consistent standards for toxicological testing, rather
than allowing individual variability in testing—for example, law enforcement
requesting the scope of the drug panel for each individual case—may also facilitate
more equitable testing outcomes.
Standardizing testing and reporting protocols will lead to a substantial
improvement in the understanding of drug use among drivers. Progress in this area
can be further augmented if those who analyze drug prevalence data, such aspolicymakers and researchers, adopt a standardized approach to classifying andtracking drug prevalence, which may improve the comparability of results. The
classification scheme used in this research provides one example of an approach that
could be adopted by others. A full list of the drugs, metabolites, and classifications
used in this research is available in the NTSB public docket.131

See the California Grants Portal webpage “Toxicology Driving Under the Influence/Driving
Under the Influence of Drugs: Crime Laboratories.”
129

The NTSB recognizes that Safety Recommendation H-22-23 is currently classified
Open―Await Response but contends that superseding it with Safety Recommendation H-22-40 better
clarifies the intent of the recommendation for all states, the District of Columbia, and theCommonwealth of Puerto Rico.
130

131

See the NTSB public docket, case number DCA21SS003.

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4.5.3 Sentinel Surveillance Systems to Track Drug Use in
Crash-Involved Drivers
It will take time for jurisdictions to meet ANSI/ASB Standard 120. In themeantime, efforts like the development of sentinel surveillance systems are needed
to monitor changing trends in driver drug use in the United States. In the publichealth community, the term sentinel surveillance system is used to describe acollection of reporting sites that provide timely and high-quality data concerning a
potential public health issue. Sentinel surveillance systems are most commonly used
to track health issues, such as infectious disease outbreaks and trends. Sentinel
surveillance systems can also be used to measure trends in the prevalence of drug
use and driving.
In 2019, the AAA Foundation for Traffic Safety published a study examining
potential strategies for developing a sentinel surveillance system of drug use bydrivers (Kelley-Baker, Smith, and Dunn 2019). The authors examined if existing
databases could be used for such a system and put forward several optimal
standards for data that could form such a system, such as the inclusion of drug test
results that were based on a consistent drug-testing protocol, the inclusion ofdriving-related data, and the representativeness and timeliness of data. The study
assessed 10 transportation-related and 10 trauma-related data sources using thosestandards and determined that trauma centers could potentially form the basis of asentinel surveillance system for drug use and driving.
Since this AAA Foundation for Traffic Safety study was published in 2019,several studies have been conducted using a similar trauma center approach(Brubacher and others 2022; Esther and others 2022; Thomas and others 2020). Most
notably, research begun by NHTSA in September 2019 tracked drug use among
drivers at several Level I trauma centers in the United States; continued efforts such asthese could provide useful information to guide drug-impaired driving
countermeasures (Thomas and others 2020). For example, the NHTSA trauma center
study was able to document substantial increases in potentially impairing drug
presence among drivers admitted to trauma centers after the declaration of the
COVID-19 public health emergency.132 Another potential benefit of trauma center
research is that, by employing comprehensive toxicological testing that goes beyond
ANSI/ASB Standard 120, such research could identify the emergence of new
potentially impairing drugs that are not included in the standard.
A drawback of the NHTSA trauma center work was that the population
sampled was not representative, meaning its findings could not be generalized to thebroader national population. Ideally, if the network of trauma centers contributing132

See section 1.1 of this report for further discussion of this study.

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driver toxicology data could be expanded, it could allow for improved tracking ofdriver drug use trends and better identification of new drugs or drug combinations
that may impair drivers. The NTSB concludes that a trauma center-based sentinel
surveillance system could provide important information to understand drug
prevalence in crash-involved drivers, to identify new drugs or combinations of drugs
that may impair drivers, and to assist in the development of policy to reduce impaired
driving crashes. Therefore, the NTSB recommends that NHTSA establish a trauma
center-based sentinel surveillance system to track drug use among crash-involved
drivers.

4.5.4 Driver Pretrial Services, Monitoring, Specialty Courts, andTreatment
Effective countermeasures to impaired driving must not only reflect
enforcement and testing, but also recognize the need for education, support, andtreatment intervention. These types of countermeasures appreciate that impaired
driving is often not a single event, but rather may be intricately linked with substanceabuse, addiction, and other at-risk behavioral patterns. This is highlighted by the highrecidivism rates associated with impaired driving offenses.133 Unfortunately, a trafficstop or crash may be how drivers are first identified as suffering from a condition,such as substance use disorder, or informed that their medication may be impairing
their driving performance.
Effective treatment and services rely on fully understanding the driver and thenature of their impaired driving offense. In this way, comprehensive toxicology
procedures, such as refraining from stop-testing procedures, and other forms ofscreening not only generate critical data for countermeasure development andevaluation, but also help identify the substances being abused by drivers to develop
effective treatment strategies for that individual. For example, a driver with an opioid
addiction who is arrested with a BAC over the stop-testing limit may never be tested
for other drugs. In this case, the driver may be ordered to install an ignition interlock
that would address alcohol impairment but would not address the impairment
caused by opioid use. Importantly, the failure to identify other drug usage andaddictions beyond alcohol also would not allow for treatment to target the different
patterns of behavior and addiction caused by different drugs.
There are a number of approaches to address recidivism, such as pretrial
services, early intervention services, monitoring, supervision, and treatment courts(Casanova Powell 2020). These are generally programs designed to better screen
Recidivism refers to an individual repeating the same offense. It is estimated that recidivism
rates are 25.0% for impaired driving arrests and 29.5% for convictions (Warren-Kigenyi and Coleman2014).
133

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and monitor drivers for increased risk, for example, by monitoring alcohol or drug
abuse; to provide effective supervision of these drivers; and to process these cases
through specialized treatment courts, such as DUI courts or drug courts. Many ofthese programs, including court monitoring, alcohol problem assessment andtreatment, alcohol ignition interlocks, DUI offender monitoring, alcohol screening,and brief interventions, are listed in NHTSA’s Countermeasures that Work(Venkatraman and others 2021).134
Such programs are designed to address the unique needs and risks of drivers.
Furthermore, these programs can also be tailored to specifically help vulnerable
populations with high rates of risk, recidivism, or incarceration. These approaches aredesigned to maximize outcomes by providing culturally competent treatment
options. For example, the state of Missouri has a program called Habilitation
Empowerment Accountability Therapy. This program is an Afro-centric,
strength-focused, and trauma-informed cognitive behavioral therapy designed to
improve outcomes for Black men in treatment court.135 Another program is Justice for
Vets, which focuses on the unique needs and circumstances of veterans through aspecialized treatment court.136
There is a growing recognition of the need for treatment approaches that are
rehabilitative as opposed to strictly punitive. The ICADTS recently launched a working
group on pretrial services that will document international best practices and develop
training materials for early intervention and post-conviction programs. Thesematerials will provide valuable tools for documenting evidence-based programs andhelping communities adopt these programs.
The NTSB concludes that early intervention and post-conviction intervention
treatments can be effective tools for reducing impaired driving recidivism. The NTSB
will continue to monitor the research in this area and will advocate for those
programs that are demonstrated to reduce impaired driving crashes or recidivism.

Brief interventions focus on quickly screening an individual to identify the severity of
substance use and needed level of treatment. A brief intervention can increase insight, awareness, andmotivation to change and can involve referral to more extensive treatment and specialty care. See theSubstance Abuse and Mental Health Services Administration’s webpage on “Screening, Brief
Intervention, and Referral to Treatment (SBIRT)” for more information.
134

For more information, see Missouri Commissioner Casey Clevenger’s presentation,“Improving Access and Outcomes for High Risk Participants in Your Courts,” at the 2022 Lifesavers
National Conference on Highway Safety Priorities in Chicago, Illinois.
135

136

See the Justice for Vets website for further information.

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5. Conclusions
5.1 Findings
1. Multiple drugs and drug categories―including alcohol, cannabis, andnumerous illicit, prescription, and over-the-counter drugs―can impair driving
performance and are associated with increased crash risk.
2. Drug data in national-level databases continue to be unreliable and cannot be
used to estimate drug prevalence among drivers.
3. Alcohol was the most prevalent drug found among impaired drivers intoxicology data reviewed by the National Transportation Safety Board, andabout half of all impaired drivers were positive for other drugs or multiple
drugs, indicating that although alcohol-related countermeasures must remain
the highest priority, countermeasures that effectively address other drugs anddrug combinations are also needed.
4. Policies that limit drug testing, such as those that use stop-testing protocols
when a driver’s blood alcohol concentration is over a certain level, result in aloss of valuable information that could otherwise be used to customize
policies, treatment, and other countermeasures.
5. Reducing the time between an impaired driving event and biological
specimen collection increases the likelihood that toxicological test results willreflect drug presence at the time of the event.
6. Alcohol, both alone and in combination with other drugs, continues to be thedrug with the most detrimental impact on traffic safety.
7. Implementing countermeasures to reduce alcohol-impaired driving mustremain a high priority to reduce impaired driving crashes overall.
8. Although alcohol and cannabis were both highly prevalent in toxicology data
reviewed by the National Transportation Safety Board, alcohol was most often
detected alone, whereas cannabis was most often detected in combination
with alcohol or other drugs.
9. Cannabis and other potentially impairing drugs, especially in combination withand without alcohol, contribute to the problem of impaired driving crashes
due to their prevalence and negative impacts on driving performance.

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10. Media campaigns have the potential to raise awareness of the risk of impaired
driving associated with cannabis, other drug, and multiple drug use, but it isunclear if they change driver behavior.
11. Although the US Food and Drug Administration has provided useful guidance
to industry concerning evaluating drug effects on driving, additional effort isneeded to identify drug label characteristics that can effectively andconsistently convey driving risk to consumers.
12. Including driving-related warnings on cannabis products, similar to those on
alcohol and many prescription and over-the-counter drugs, would increaseawareness of the risks of cannabis-impaired driving.
13. Oral fluid is a valuable but underutilized biological specimen for the detectionof drug use by drivers and can support the enforcement of impaired driving
laws.
14. Laws that specify only certain drugs that can impair driving restrict the ability toprosecute drivers impaired by other drugs or drug combinations that are notspecified in the statute, thereby limiting the ability to fully address
drug-impaired driving.
15. The use of electronic warrants during the impaired driving arrest process can
expedite the collection of biological specimens, thereby increasing the
likelihood that impairing drugs present at the time of driving will be detected.
16. The National Highway Traffic Safety Administration’s Drug-Impaired Driving
Criminal Justice Evaluation Tool can provide valuable guidance to help states
and communities identify opportunities to improve efforts to address
drug-impaired driving.
17. The US Food and Drug Administration has recognized the importance ofevaluating the potential for driver impairment during the development of new
drugs and has provided guidance for a systematic method of doing so, but it isunknown if its guidance is consistently applied.
18. The US Food and Drug Administration’s drug safety surveillance systems have
improved the likelihood that adverse drug effects will be detected andaddressed; however, the surveillance systems could be enhanced by better
incorporating information about drug use and driving safety.

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19. Although a few states have taken some steps toward improving blood alcohol
concentration (BAC) reporting rates, additional efforts by most states toimprove BAC collection, documentation, and reporting are needed to ensure
accurate tracking of national alcohol-impaired driving trends and to develop
and evaluate appropriate countermeasures.
20. Because there is no common standard of practice for the collection, testing,and reporting of driver drug toxicology data in the United States, criticalinformation that could improve understanding of drug trends and prevalence,
assist with the evaluation of countermeasures, and better guide treatment
options for driving-under-the-influence offenders is not being captured oranalyzed.
21. Widespread adoption of the American National Standards Institute/American
Academy of Forensic Sciences Standards Board Standard for the AnalyticalScope and Sensitivity of Forensic Toxicological Testing of Blood in Impaired
Driving Investigations, ANSI/ASB Standard 120, would improve ourunderstanding of the prevalence of drug use among crash-involved drivers
and drivers arrested for impaired driving.
22. A trauma center-based sentinel surveillance system could provide important
information to understand drug prevalence in crash-involved drivers, toidentify new drugs or combinations of drugs that may impair drivers, and toassist in the development of policy to reduce impaired driving crashes.
23. Early intervention and post-conviction intervention treatments can be effective
tools for reducing impaired driving recidivism.

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6. Recommendations
6.1 New Recommendations
As a result of this investigation, the National Transportation Safety Board
makes the following new safety recommendations.
To the National Highway Traffic Safety Administration:
Disseminate the American National Standards Institute/American
Academy of Forensic Sciences Standards Board Standard for the
Analytical Scope and Sensitivity of Forensic Toxicological Testing of
Blood in Impaired Driving Investigations, ANSI/ASB Standard 120, tostate officials for use as the common standard of practice for drug
toxicology testing. (H-22-33) [This new recommendation supersedes
Safety Recommendation H-12-33.]
Establish a program to support toxicology laboratories’ compliance with
the American National Standards Institute/American Academy ofForensic Sciences Standards Board Standard for the Analytical Scopeand Sensitivity of Forensic Toxicological Testing of Blood in Impaired
Driving Investigations, ANSI/ASB Standard 120. (H-22-34)
Establish a trauma center-based sentinel surveillance system to track
drug use among crash-involved drivers. (H-22-35)
To the US Food and Drug Administration:
Conduct a study to understand how prescription drug labeling andover-the-counter drug labels could be modified to increase user
understanding and compliance with driving-related warnings; publish
the study findings. (H-22-36)
Develop a system to audit drugmaker compliance with your 2017
“Evaluating Drug Effects on the Ability to Operate a Motor Vehicle:
Guidance for Industry.” (H-22-37)
Incorporate additional data and research concerning drug use anddriving to improve US Food and Drug Administration drug safetysurveillance systems. (H-22-38)

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To the 50 states, the District of Columbia, and the Commonwealth of
Puerto Rico:
Complete an assessment using the National Highway Traffic Safety
Administration’s (NHTSA) Drug-Impaired Driving Criminal JusticeEvaluation Tool, and, if gaps are identified, apply to NHTSA for support
in establishing programs to reduce drug-impaired driving. (H-22-39)
Require government-funded laboratories that conduct forensic
toxicology testing to adopt and routinely apply (regardless of driver
blood alcohol concentration) the American National Standards
Institute/American Academy of Forensic Sciences Standards Board
Standard for the Analytical Scope and Sensitivity of Forensic
Toxicological Testing of Blood in Impaired Driving Investigations,
ANSI/ASB Standard 120, and provide funding for equipment,
personnel, and training, to facilitate testing meeting that standard.
(H-22-40) [This new recommendation supersedes Safety
Recommendation H-22-23.]
To the District of Columbia and the states of Alaska, California,
Connecticut, Delaware, Florida, Hawaii, Idaho, Iowa, Kentucky, Maine,
Maryland, Massachusetts, Michigan, Minnesota, Montana, Nebraska,
New Hampshire, New Jersey, New Mexico, Oregon, Pennsylvania,
South Carolina, Tennessee, Texas, Virginia, Washington, West Virginia,
and Wisconsin:
Modify your impaired driving laws to allow for oral fluid collection,screening, and testing for the detection of drug use by drivers. (H-22-41)
To the District of Columbia, the Commonwealth of Puerto Rico, and thestates of Alabama, Arizona, Arkansas, California, Colorado, Florida,
Illinois, Louisiana, Maine, Maryland, Mississippi, Missouri, New Jersey,
New York, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island,
Virginia, and West Virginia:
Require a warning label on cannabis products advising users not todrive after cannabis use due to its impairing effects. (H-22-42)

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To the Commonwealth of Puerto Rico and the states of Alabama, Alaska,
Connecticut, Georgia, Hawaii, Idaho, Iowa, Maine, Massachusetts,
Mississippi, New Mexico, New York, North Carolina, Rhode Island,South Carolina, Virginia, and West Virginia:
Allow the use of electronic warrants to obtain biological specimens
during impaired driving arrests by modifying laws or removing
administrative barriers. (H-22-43)
To the states of Alaska, Florida, Massachusetts, New York, and Oregon:
Enact laws specifying that drivers under the influence of a drug or
multiple drugs that may impair driving are considered to be impaired
under the definition of drug-impaired driving. (H-22-44)

6.2 Previously Issued Recommendations Classified in This Report
To the National Highway Traffic Safety Administration:
Develop and disseminate to appropriate state officials a common
standard of practice for drug toxicology testing, including (1) the
circumstances under which tests should be conducted, (2) a minimum
set of drugs for which to test, and (3) cutoff values for reporting theresults. (H-12-33)
The classification of Safety Recommendation H-12-33 is changed from
Open―Acceptable Response to Closed―Acceptable Action/Superseded by new
Safety Recommendation H-22-33 in section 4.5.2 of this report.
To the state of California:
Enact legislation that requires forensic toxicology laboratories to follow
the standards recommended by the National Safety Council’s Alcohol,
Drugs, and Impairment Division; the legislation should include a
provision requiring laboratories to update the testing protocol if
additional federal guidance is provided. (H-22-23)
The classification of Safety Recommendation H-22-23 is changed from
Open―Await Response to Closed―Superseded by new Safety Recommendation
H-22-40 in section 4.5.2 of this report.

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BY THE NATIONAL TRANSPORTATION SAFETY BOARDJENNIFER HOMENDY
Chair

MICHAEL GRAHAM
Member

BRUCE LANDSBERG
Vice Chairman

THOMAS CHAPMAN
MemberReport Date: December 13, 2022

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Board Member Statement
Member Chapman filed the following concurring statement on December 13,
2022.
Thomas B. Chapman
Statement of Concurrence
Safety Research Report—Alcohol, Other Drug, and Multiple Drug Use Among
Drivers
I concur and join in the Board’s unanimous adoption of the safety research report.
Congratulations to our team for the fine job done on this report. It is an important
contribution in an area of great challenge and exemplifies the quality work typical of
NTSB’s outstanding staff. Especially impressive is the innovative approach toanalyzing the presence of potentially impairing drugs in driver specimens submitted
to four US laboratories.

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Appendixes
Appendix A: NTSB Impairment-Related Recommendations
Table A-1 provides the number; classification as of December 13, 2022; dateclosed; and recommendation text for all NTSB impairment-related recommendations
related to the highway mode. For recommendations issued to multiple recipients,
such as states or associations, the classification status shown in the table below
reflects the overall status and is annotated as such. Each individual recipient receives
a classification based on their specific response to the recommendation; the overall
classification is determined by the plurality status of the open recipients. Further
information about the recommendations in this table can be found using the CAROL
Query or by clicking on the hyperlinks provided below.
Table A-1. NTSB impairment-related recommendations.
NumberClassification

H-22-23

Closed in this reportH-22-22

Open—Await
Response

H-18-61

Closed—Acceptable
ActionH-18-60

Open—Await
Response

Date Closed

December 21,
2020

97

Recommendation
To the state of California: Enact legislationthat requires forensic toxicology
laboratories to follow the standards
recommended by the National Safety
Council’s Alcohol, Drugs, and Impairment
Division; the legislation should include a
provision requiring laboratories to update
the testing protocol if additional federal
guidance is provided. (Superseded by
Safety Recommendation H-22-40)
To the National Highway Traffic Safety
Administration: Require that all new
vehicles be equipped with passive
vehicle-integrated alcohol impairment
detection systems, advanced drivermonitoring systems, or a combination
thereof; the systems must be capable ofpreventing or limiting vehicle operation if
driver impairment by alcohol is detected.
To the Texas Department ofTransportation: Promote the importanceof attending drug-impaired driving
enforcement training and increase
training access to meet the demands of
local and state law enforcement.
To the State of Texas: Conduct an
executive-level review of your impaired
driving program and implement datadriven strategies that result in a downward
trend in the number of fatalities, injuries,
and crashes involving alcohol- and otherdrug-impaired drivers.

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NumberClassification

H-18-57

Closed—Acceptable
ActionH-18-56

Open—Acceptable
Response

H-18-35

Open—Acceptable
Response

H-16-8

Open—Unacceptable
Response

H-15-43

Open—Await
Response(overall)

H-15-39

Open—Acceptable
Response

Date Closed

September 20,
2022

98

Recommendation
To the National Highway Traffic Safety
Administration: Evaluate best practices
and countermeasures found to be themost effective in reducing fatalities,
injuries, and crashes involving drugimpaired drivers and provide additional
guidance to the states on drug-impaired
driving in Countermeasures That Work: A
Highway Safety Countermeasure Guide
for State Highway Safety Offices.
To the National Highway Traffic Safety
Administration: Develop and disseminate
best practices, identify model
specifications, and create a conforming
products list for oral fluid drug screening
devices.
To the National Highway Traffic Safety
Administration: Examine the influence ofalcohol and other drug use on motorcycle
rider crash risk compared to that ofpassenger vehicle drivers, and develop
guidelines to assist states in implementing
evidence-based strategies andcountermeasures to more effectively
address substance-impaired motorcycle
rider crashes.
To the Federal Motor Carrier Safety
Administration: Disseminate information
to motor carriers about using hair testing
as a method of detecting the use ofcontrolled substances, under theappropriate circumstances.
To American Bus Association, American
Trucking Associations, Commercial
Vehicle Safety Alliance, Owner-Operator
Independent Drivers Association, United
Motorcoach Association: Inform yourmembers about the dangers of driver useof synthetic drugs and encourage them totake steps to prevent drivers from using
these substances.
To the Federal Motor Carrier Safety
Administration: Work with motor carrier
industry stakeholders to develop a plan toaid motor carriers in addressingcommercial motor vehicle driver use of
impairing substances, particularly those
not covered under current drug-testing
regulations such as by promoting bestpractices by carriers, expanding
impairment detection training andauthority, and developing performancebased methods of evaluation.

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NumberClassification

H-15-38

Open—Acceptable
Alternate Response

H-13-10

Open—Acceptable
Response(overall)

H-13-9

Open—Unacceptable
Response(overall)

H-13-8Closed—Acceptable
Action(overall)Date Closed

June 21, 2022

99

Recommendation
To the Federal Motor Carrier Safety
Administration: Determine the prevalenceof commercial motor vehicle driver use of
impairing substances, particularly
synthetic cannabinoids, and develop aplan to reduce the use of such
substances.
To the 9 States (Kentucky, Montana,Michigan, New Jersey, Pennsylvania,
Rhode Island, South Carolina, South
Dakota, and Tennessee) that do not haveadministrative license suspension or
revocation laws and the Commonwealthof Puerto Rico: Establish administrative
license suspension or revocation laws that
require drivers arrested for driving while
intoxicated (DWI) to use an alcohol
ignition interlock on their vehicle for aperiod of time before obtaining fulllicense reinstatement.
To the 41 states that have administrative
license suspension or revocation laws andthe District of Columbia: Incorporate into
your administrative license suspension or
revocation laws a requirement that drivers
arrested for driving while intoxicated(DWI) use an alcohol ignition interlock on
their vehicle for a period of time before
obtaining full license reinstatement.
To the 50 states, the Commonwealth of
Puerto Rico, and the District of Columbia:
Take the following steps to move toward
zero deaths from impaired driving: (1) set
specific and measurable targets for
reducing impaired driving fatalities andinjuries, (2) list these targets in yourimpaired driving prevention plan or
highway safety plan, and (3) provide amechanism for regularly assessing the
success of implemented countermeasuresand determining whether the targets havebeen met.

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NumberClassification

Date Closed

H-13-7

Open—Acceptable
Response(overall)

H-13-6

Open—Unacceptable
Response(overall)

H-13-5

Open—Unacceptable
Response(overall)

H-13-4Closed—Acceptable
Alternate Action

November 13,
2017

H-13-3

Closed—Acceptable
ActionJuly 30, 2014

H-13-2

Closed—Exceeds
Recommended Action

July 30, 2014100

Recommendation
To the 50 states, the Commonwealth of
Puerto Rico, and the District of Columbia:
Include in your impaired driving
prevention plan or highway safety planelements to target repeat offenders andreduce driving while intoxicated (DWI)
recidivism; such elements should include
measures to improve compliance withalcohol ignition interlock requirements;
the plan should also provide a mechanism
for regularly assessing the success ofthese efforts. [This recommendation
supersedes Safety Recommendation
H-00-26.]
To the 50 states, the Commonwealth of
Puerto Rico and the District of Columbia:
Include in your impaired driving
prevention plan or highway safety plan
provisions for conducting high-visibility
enforcement of impaired driving laws
using passive alcohol-sensing technology
during law enforcement contacts, such as
routine traffic stops, saturation patrols,
sobriety checkpoints, and accident scene
responses.
To the 50 U.S. states and theCommonwealth of Puerto Rico and theDistrict of Columbia: Establish a per seblood alcohol concentration (BAC) limit of
0.05 or lower for all drivers who are notalready required to adhere to lower BAC
limits.
To the National Highway Traffic Safety
Administration: Develop and disseminate
to the states best practices for driving
while intoxicated (DWI) courts.
To the National Highway Traffic Safety
Administration: Create incentives forstates to adopt the alcohol ignitioninterlock best practices developed in
response to Safety Recommendation
H-13-2.
To the National Highway Traffic Safety
Administration: Develop and disseminate
to the states best practices for increasing
alcohol ignition interlock installation andcompliance that are based on recent
National Highway Traffic Safety
Administration research.

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NumberClassification

H-13-1

Open—Acceptable
Response

H-12-48

Closed—Unacceptable
ActionH-12-45

Open—Unacceptable
Response(overall)

H-12-43

Closed—Unacceptable
ActionH-12-37

Open—Await
Response(overall)

H-12-36

Open—Unacceptable
Response(overall)Date Closed

September 20,
2022

September 20,
2022

101

Recommendation
To the National Highway Traffic Safety
Administration: Seek legislative authority
to award incentive grants for states toestablish a per se blood alcohol
concentration (BAC) limit of 0.05 or lower
for all drivers who are not alreadyrequired to adhere to lower BAC limits.
To the Automotive Coalition For Traffic
Safety: Work with the National Highway
Traffic Safety Administration to accelerate
widespread implementation of Driver
Alcohol Detection System for Safety(DADSS) technology by (1) defining
usability testing that will guide driverinterface design and (2) implementing acommunication program that will directdriver education and promote public
acceptance.
To 33 states, the Commonwealth of
Puerto Rico, and the District of Columbia:
Enact laws to require the use of alcohol
ignition interlock devices for all
individuals convicted of driving while
intoxicated (DWI) offenses.
To the National Highway Traffic Safety
Administration: Work with the Automotive
Coalition for Traffic Safety, Inc., toaccelerate widespread implementation ofDriver Alcohol Detection System for Safety(DADSS) technology by (1) defining
usability testing that will guide driverinterface design and (2) implementing acommunication program that will directdriver education and promote public
acceptance.
To the International Association of Chiefsof Police and the National Sheriffs’
Association: Inform your members of thevalue of collecting place of last drink(POLD) data as part of any arrest or
accident investigation involving an
alcohol-impaired driver.
To the 50 states, the Commonwealth of
Puerto Rico, and the District of Columbia:
Require law enforcement agencies tocollect place of last drink (POLD) data aspart of any arrest or accident investigation
involving an alcohol-impaired driver.

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NumberClassification

H-12-35

Open—Acceptable
Response(overall)

H-12-34

Open—Acceptable
Response(overall)

H-12-33

Closed in this report

H-12-32

Closed—Acceptable
ActionDate Closed

December 13,
2021

102

Recommendation
To the 45 states, the Commonwealth of
Puerto Rico, and the District of Columbia,
which have low reporting rates for BAC
testing: Once the National Highway Traffic
Safety Administration has developed theblood alcohol concentration (BAC) testing
and reporting guidelines recommended
in Safety Recommendation H-12-32,
incorporate the guidelines into astatewide action plan to achieve BAC
reporting rates of at least 80 percent of
fatally injured drivers and at least 60
percent of drivers who survived fatal
crashes.
To the 45 states, the Commonwealth of
Puerto Rico, and the District of Columbia,
which have low reporting rates for BAC
testing: Increase your collection,
documentation, and reporting of blood
alcohol concentration (BAC) test results by
taking the following actions, as needed, toimprove testing and reporting rates:(1) enact legislation, (2) issue regulations,and (3) improve procedures used by law
enforcement agencies or testing facilities.
To the National Highway Traffic Safety
Administration: Develop and disseminate
to appropriate state officials a common
standard of practice for drug toxicology
testing, including (1) the circumstances
under which tests should be conducted,(2) a minimum set of drugs for which totest, and (3) cutoff values for reporting theresults. (Superseded by Safety
Recommendation H-22-33)
To the National Highway Traffic Safety
Administration: Develop and disseminate
to the 50 states, the Commonwealth of
Puerto Rico, and the District of Columbia
blood alcohol concentration testing andreporting guidelines based on the 2012
report State Blood Alcohol Concentration
Testing and Reporting for Drivers Involved
in Fatal Crashes: Current Practices, Results,
and Strategies, 1997–2009.

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Number

H-09-18

H-04-48

H-04-47Classification

Closed—Acceptable
ActionClosed—Acceptable
Alternate Action

Closed—Acceptable
Alternate Action(overall)Date Closed

February 1, 2017

June 22, 2006

April 2, 2014103

Recommendation
To the Federal Motor Carrier Safety
Administration: Establish a regulatory
requirement within 49 Code of Federal
Regulations 382.405 that provides the
National Transportation Safety Board, inthe exercise of its statutory authority,
access to all positive drug and alcohol test
results and refusal determinations that are
conducted under the U.S. Department ofTransportation testing requirements.
To the Federation of State Medical
Boards: Work with member organizations
to ensure that continuing medical
education requirements in all States
include a course addressing the driving
risks associated with certain medical
conditions and medications, as well as theexistence and function of State reporting
laws and procedures regarding medically
impaired drivers.
To the Association of American Medical
Colleges, the American Osteopathic
Association, and the Liaison Committee
on Medical Education: Require medical
schools to teach students about thedriving risks associated with certain
medical conditions and medications, theexistence and function of State reporting
laws regarding medically high-risk drivers,
and the methods and resources forcounseling such drivers.

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Number

H-04-41Classification

Closed—Unacceptable
ActionDate Closed

Recommendation

November 13,
2017

To the National Highway Traffic Safety
Administration: Once the most effective
reporting methods and licensing
countermeasures have been determined,
develop a model comprehensive medical
oversight program for States to use tooversee medically impaired drivers. Sucha program should include, as a minimum:
a. Methods to provide information to the
public on resource availability and on the
medical oversight laws and procedures toassist medically high-risk drivers.
b. Plans and strategies to simplify andmaximize reporting of potential driver
medical impairment to medical evaluation
units of State driver licensing
organizations by law enforcement officers,
health care providers, emergency services
providers, and the public.
c. Methods to capture all cases of motor
vehicle incidents or accidents potentiallyrelated to driver medical impairment.
d. Standardized methods of driverevaluation for potentially medically
impaired drivers incorporating medical
records review, systematic testing, andon-road appraisals, as needed.
e. Methods for timely and appropriate
restriction of driving privileges for drivers
found to have medical conditions ortreatments that impair their ability tosafely operate a motor vehicle.

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NumberClassification

Date Closed

H-04-16

Closed—Acceptable
Alternate Action

December 28,
2021

H-04-13

Closed—Unacceptable
Action(overall)February 3, 2021

H-04-12Closed—Unacceptable
Action(overall)February 3, 2021

105

Recommendation
To the National Association for the
Education of Young Children: As part ofyour accreditation program, establish atransportation safety accreditation that
requires applicants to implement thefollowing elements:
Use of vehicles built to school bus
standards or of multifunction school
activity buses;
A regular vehicle maintenance andinspection program;
A requirement that occupants wear
age-appropriate restraints at all times;
A requirement that drivers receive a
criminal background check and have a
medical examination to determine fitness
to drive;
Preemployment, random, postaccident,
and "for cause" drug testing for all childcare transportation providers and theprohibition of anyone who tests positivefor drugs from transporting children;
Review by an oversight agency of periodic
driver background checks, medical
examinations, and drug test results; andA requirement that child care vehicles belabeled with the child care center's andoversight agency's names and phone
numbers.
To the states and the District of Columbia
child care transportation oversightagencies: Implement an oversightprogram for child care transportation that
includes the following elements: Review
by an oversight agency of periodic driverbackground checks, medical
examinations, and drug test results.
To the states and the District of Columbia
child care transportation oversightagencies: Implement an oversightprogram for child care transportation that
includes the following elements:
Preemployment, random, postaccident,
and "for cause" drug testing for all childcare transportation providers and theprohibition of anyone who tests positivefor drugs from transporting children.

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NumberClassification

Date Closed

H-01-27

Closed—Acceptable
ActionMarch 17, 2003

H-01-25

Closed—Acceptable
ActionFebruary 1, 2017

H-00-27

Closed—Acceptable
Alternate Action

October 6, 2003

106

Recommendation
To the National Conference of State
Legislatures: Inform State legislatures
about this accident and make them awareof the importance of establishing
immunity laws for the good-faith reportingof potentially impaired commercial drivers
by all individuals and of ensuring that the
medical community and the commercial
transportation industry are familiar withthese laws.
To the Federal Motor Carrier Safety
Administration: Develop a system thatrecords all positive drug and alcohol test
results and refusal determinations that are
conducted under the U.S. Department ofTransportation testing requirements,
require prospective employers to query
the system before making a hiring
decision, and require certifying authorities
to query the system before making acertification decision.
To the United States Department ofTransportation: Evaluate modifications to
the provisions of the Transportation Equity
Act for the 21st Century so that it can be
more effective in assisting the states toreduce the hard core drinking driverproblem. Recommend changes toCongress as appropriate. Considerations
should include (a) a revised definition of"repeat offender" to include
administrative actions on DWI offenses;(b) mandatory treatment for hard core
offenders; (c) a minimum period of
10 years for records retention and DWI
offense enhancement; (d) administratively
imposed vehicle sanctions for hard coredrinking drivers; (e) elimination ofcommunity service as an alternative toincarceration; and (f) inclusion of homedetention with electronic monitoring as analternative to incarceration.

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NumberClassification

Date Closed

H-00-26

Closed—Superseded(overall)June 3, 2013

H-00-15

Closed—Unacceptable
ActionMay 1, 2012

H-00-14

Closed—Unacceptable
ActionMay 1, 2012

H-00-13

Closed—Unacceptable
ActionMay 1, 2012107

Recommendation
To the 50 states and the mayor andcouncil of the District of Columbia:
Establish a comprehensive program that isdesigned to reduce the incidence ofalcohol-related crashes and fatalities
caused by hard core drinking drivers andthat includes elements such as thosesuggested in the National Transportation
Safety Board's model program.
(Superseded by Safety Recommendation
H-13-7, H-00-26 was superseded to all theaddressees except: Virginia, California,
Nebraska, New Hampshire, Ohio, andUtah)
To the Federal Motor Carrier Safety
Administration: Establish, in coordination
with the U.S. Department ofTransportation, the Federal Railroad
Administration, the Federal Transit
Administration, and the U.S. Coast Guard,
comprehensive toxicological testing
requirements for an appropriate sample
of fatal highway, railroad, transit, andmarine accidents to ensure theidentification of the role played bycommon prescription and over-thecounter medications. Review and analyze
the results of such testing at intervals not
to exceed every 5 years.
To the Federal Motor Carrier Safety
Administration: Establish and implement
an educational program targeting
highway vehicle operators that, at aminimum, ensures that all operators areaware of the source of information
described in Safety Recommendation
H-00-13 regarding the hazards of using
specific medications when driving.
To the Federal Motor Carrier Safety
Administration: Develop, then periodicallypublish, an easy-to-understand source of
information for highway vehicle operatorson the hazards of using specificmedications when driving.

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NumberClassification

Date Closed

H-00-12Closed—Unacceptable
ActionMay 1, 2012

I-00-5

Closed—Reconsidered

July 13, 2017

I-00-2

Closed—Unacceptable
ActionJuly 6, 2010

H-93-7

Closed—Acceptable
Action(overall)January 21, 1998

H-93-6

Closed—Acceptable
Action(overall)January 21, 1998

108

Recommendation
To the Federal Motor Carrier Safety
Administration: Establish, with assistancefrom experts on the effects ofpharmacological agents on humanperformance and alertness, procedures orcriteria by which highway vehicle
operators who medically require
substances not on the U.S. Dept. ofTransportation's list of approved
medications may be allowed, whenappropriate, to use those medications
when driving.
To the US Food and Drug Administration:
Establish a clear, consistent, easily
recognizable warning label for allprescription and over-the-counter
medications that may interfere with anindividual’s ability to operate a vehicle.
Require that the label be prominently
displayed on all packaging of such
medications.
To the US Department of Transportation:
Develop, with assistance from experts on
the effects of pharmacological agents onhuman performance and alertness, a listof approved medications and/or classesof medications that may be used safely
when operating a vehicle.
To the 50 states, the Commonwealth of
Puerto Rico, the territories, and the mayor
and city council of the District ofColumbia: Enact comprehensive laws thatprohibit drivers under the age of 21 fromdriving with any measurable blood
alcohol concentration (any level above
0.00 BAC), to include: public information
programs targeted to youth to enhancethe effect of the new law.
To the 50 states, the Commonwealth of
Puerto Rico, the territories, and the mayor
and city council of the District ofColumbia: Enact comprehensive laws thatprohibit drivers under the age of 21 fromdriving with any measurable blood
alcohol concentration (any level above
0.00 BAC), to include: a period ofextended license suspension/revocation(including a period of loss of driving
privileges without exemption) for
underage offenders in addition to any
criminal sanctions that may be specified.

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NumberClassification

Date Closed

H-93-5

Closed—Acceptable
Action(overall)January 21, 1998

H-93-4Closed—Acceptable
Action(overall)

November 4,
2003

H-93-3

Closed—Acceptable
Action(overall)

November 4,
2003

H-93-2

Closed—Acceptable
Action(overall)

November 4,
2003

H-93-1

Closed—Acceptable
Action(overall)

September 20,
2005

109

Recommendation
To the 50 states, the Commonwealth of
Puerto Rico, the territories, and the mayor
and city council of the District ofColumbia: Enact comprehensive laws thatprohibit drivers under the age of 21 fromdriving with any measurable blood
alcohol concentration (any level above
0.00 BAC), to include: provisions foradministrative license revocation.
To the 50 states, the Commonwealth of
Puerto Rico, the territories, and the mayor
and city council of the District ofColumbia: Vigorously enforce theminimum drinking age laws by taking
driver license action against underagepurchasers and vendor license action
against those who sell to person underthe minimum purchase age.
To the 50 states, the Commonwealth of
Puerto Rico, the territories, and the mayor
and city council of the District ofColumbia: Vigorously enforce youth
drinking and driving laws to increases thepercentage of alcohol-impaired drivers
who are arrested.
To the 50 states, the Commonwealth of
Puerto Rico, the territories, and the mayor
and city council of the District ofColumbia: Vigorously enforce theminimum drinking age laws to achieve asignificant reduction in the rate of alcoholpurchase by underage persons.
To the 50 states, the Commonwealth of
Puerto Rico, the territories, and the mayor
and city council of the District ofColumbia: Review your drinking age (age21) laws to determine if they prohibit
persons under the age of 21 fromattempting to purchase, purchasing,publicly possessing, or consuming
alcoholic beverages and prohibits the saleof alcoholic beverages to persons under
the age of 21. Enact laws to include theseprovision and to eliminate deficiencies
that may exist.

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NumberClassification

Date Closed

H-92-41

Closed—Acceptable
ActionJune 2, 2004

H-91-37

Closed—Acceptable
Action(overall)

November 21,
2003

H-91-32

Closed—Acceptable
ActionAugust 3, 1994

H-91-29

Closed—Acceptable
Action/ Superseded

August 31, 1992

H-90-55

Closed—Reconsidered(overall)December 13,
2004

110

Recommendation
To the Federal Highway Administration:
Conduct research to identify designchanges in work zones that will aid drivers
with degraded sensory perceptions
resulting from aging, inattentiveness, or
impairment. Use the results of thisresearch to design better and moremeaningful work zone traffic advisories
and safety features. (Supersedes Safety
Recommendations H-91-27, H-91-29, andH-91-30)
To the states, the District of Columbia, theCommonwealth of Puerto Rico, theVirgin Islands, the U.S. territories: Requirepostaccident toxicological testing foralcohol and drug impairment ofcommercial vehicle operators involved
with the intrastate transportation of
hazardous materials in bulk.
To the Federal Highway Administration:
Require postaccident toxicological testing
for alcohol and drug impairment ofcommercial vehicle operators involved
with the intrastate transportation of
hazardous materials in bulk.
To the Federal Highway Administration:
Encourage the use of the "design driver"concept, which assumes that some drivers
are impaired or inattentive, in designingwork zone safety features and signing.
(Superseded by H-92-41)
To the National Association of Trade andTechnical Schools, National Home Study
Council, and the Professional Truck Driver
Institute of America: Encourage yourmembership to disseminate information
to the commercial trucking industry andcommercial vehicle operators regarding:
The effects of fatigue, alcohol and otherdrug use;
The interaction of alcohol, drugs andfatigue;
The differences between truck driverperception of fatigue and actual onset of
fatigue;
Methods of minimizing conditions whichlead to commercial vehicle operators
driving while fatigued.

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NumberClassification

Date Closed

H-90-54

Closed—Acceptable
Action(overall)April 9, 2001

H-90-53

Closed—Acceptable
Action(overall)April 9, 2001

H-90-51

Closed—No Longer
Applicable(overall)April 9, 2001

H-90-50

Closed—No Longer
Applicable(overall)April 9, 2001

H-90-49

Closed—No Longer
Applicable(overall)April 9, 2001

111

Recommendation
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Enact legislation to establish
0.01 percent (the practical scientific level
which allows for instrument sensitivity andindividual differences) as the per seoffense blood alcohol concentration for
operators of commercial vehicles in yourstate.
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Enact legislation or adopt
regulations, as appropriate, to define thealcohol concentration level that
constitutes driving a commercial motor
vehicle "under the influence" at the lowest
possible level consistent with thecapability of testing equipment tomeasure any ingested alcohol.
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Develop a coordinatedstatewide program to conduct selective
alcohol and other drug enforcement
operations at times and locations of highlevels of truck accidents- specifically attimes of high incidence of commercial
truck accidents involving alcohol and/or
other drugs.
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Provide drug recognition
expert training to personnel in state andlocal police agencies and in other public
safety/ law enforcement agencies who
have commercial truck and truck driver
enforcement and oversight
responsibilities.
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Disseminate safety information
to commercial truck drivers in your state
regarding the effects of fatigue, alcoholand other drug use, and the interaction ofdrugs and fatigue.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-90-47

Closed—No Longer
Applicable(overall)April 9, 2001

H-90-46

Closed—No Longer
Applicable(overall)April 9, 2001

H-90-45

Closed—No Longer
Applicable(overall)April 9, 2001

H-90-44

Closed—No Longer
Applicable(overall)April 9, 2001

H-90-43

Closed—Unacceptable
Action/No Response
Received(overall)April 9, 2001

H-90-42

Closed—Unacceptable
Action(overall)April 9, 2001

112

Recommendation
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Require intrastate motor
carriers in your state to: require close
supervision, including frequent
unannounced drug testing, for an
appropriate period, of commercial truck
drivers with an identified alcohol or otherdrug abuse problem. Such testing should
be sufficiently frequent to create thelikelihood of detection if the person uses
drugs of abuse.
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Require intrastate motor
carriers in your state to: obtain proof thatapplicants seeking work as commercial
truck drivers, who have had a history ofalcohol/drug abuse, have successfullycompleted a certified treatment programand obtained a physician's evaluation ofsubstance abuse and dependency.
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Require intrastate motor
carriers in your state to: review thealcohol/drug abuse treatment history of
all applicants seeking work as commercial
truck drivers.
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Require intrastate motor
carriers in your state to: perform
pre-employment alcohol and other drug
tests for all applicants seeking to work as
drivers of commercial trucks weighing
over 10,000 pounds GVWR.
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Report alcohol and other drug
toxicological tests requested and results
obtained in fatal accidents to the fatal
accident reporting system operated by
the National Highway Traffic Safety
Administration.
To the states, the Commonwealth of
Puerto Rico, the Virgin Islands, and theterritories: Enact legislation or issue
regulations to require the collection ofblood samples for alcohol and other drug
toxicological testing from all vehicle
operators involved in fatal commercial
truck accidents.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-90-41

Closed—Unacceptable
Action/No Response
Received

March 6, 1995

H-90-40

Closed—Unacceptable
Action/No Response
Received(overall)March 6, 1995

H-90-39

Closed—Acceptable
Action(overall)March 18, 2004

H-90-38

Closed—Acceptable
Action(overall)March 18, 2004

H-90-37

Closed—No Longer
Applicable(overall)March 18, 2004

H-90-36

Closed—No Longer
Applicable(overall)March 18, 2004

H-90-35

Closed—No Longer
Applicable(overall)March 18, 2004

113

Recommendation
To the National Governors' Association:
Develop a program for the reporting of allaccident toxicological results to the
National Commercial Truck Database
System.
To the National Governors' Association:
Coordinate development of national
programs for state implementation ofstandardized testing for alcohol and otherdrugs.
To the International Association of Chiefsof Police, International Association of
Directors of Law Enforcement Standards
and Training, and the Commercial Vehicle
Safety Alliance: Encourage your members
to provide training in drug recognition for
those personnel with commercial truck
and truck driver enforcement andoversight responsibilities.
To the International Association of Chiefsof Police, International Association of
Directors of Law Enforcement Standards
and Training, and the Commercial Vehicle
Safety Alliance: Disseminate to yourmembers information regarding theprevalence of alcohol and other drug
use/abuse and fatigue amongprofessional commercial truck drivers.
To the various trucking industry
associations, drivers associations, theTeamsters Union, and the Commercial
Vehicle Safety Alliance: Encourage yourmembership to participate in educationand public information programs
regarding: scheduling and its impact on
driver fatigue; and the effects of alcoholand other drug use; and, the interaction ofdrugs and fatigue.
To the various trucking industry
associations, drivers associations, theTeamsters Union, and the Commercial
Vehicle Safety Alliance: Encourage yourmembership to participate in alcohol andother drug education and information
programs aimed at commercial drivers.
To the various trucking industry
associations, drivers associations, theTeamsters Union, and the Commercial
Vehicle Safety Alliance: Actively promoteand encourage your members to use or
support: pre-employment tests for alcoholand other drugs; driver violation history
checks; and alcohol or other drug abuse
treatment history checks.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-90-34

Closed—No Longer
Applicable

July 23, 2007

H-90-33

Closed—Acceptable
ActionJuly 20, 2007

H-90-31

Closed—Unacceptable
ActionAugust 3, 1994

H-90-30

Closed—Unacceptable
ActionAugust 3, 1994

H-90-29

Closed—Unacceptable
ActionJuly 7, 1998

H-90-23

Closed—Acceptable
Alternate Action

April 29, 1996

114

Recommendation
To the U.S. Department of Health andHuman Services: Establish, with the
Department of Transportation and otherorganizations as appropriate, a post
accident alcohol and other drug analytic
test plan for tests to be conducted on awide range of impairing drugs with results
reported at state-of-the-art sensitivity
levels.
To the U.S. Department of Health andHuman Services: Assist the Department ofTransportation, the states, the American
Academy of Forensic Sciences, theNational Safety Council Committee on
Alcohol and Drugs, and otherorganizations as appropriate, instandardizing procedures for
postaccident toxicological specimen
collection, chain of custody, testing, andreporting among the states for accidents
involving medium and heavy trucks.
To the Federal Highway Administration:
Revise 49 CFR parts 391 and 392 toestablish violation of the commercial
vehicle operation alcohol offense (49 CFR
392.4, 392.5) as a reasonable cause
requiring a drug test of the driver. Amend
the regulations and provide notice todrivers of these revised regulations.
To the Federal Highway Administration:
Revise 49 CFR parts 391 and 395 toestablish driver hours of service violations,logbook irregularities, or the presence ofmultiple logbooks as a reasonable cause
requiring a drug test of the driver. Amend
the regulations and provide notice todrivers of these revised regulations.
To the Federal Highway Administration: As
part of the FHWA on-going study offatigue and loss of alertness amongcommercial vehicle operators, investigate
the interactions of fatigue and drug
usage.
To the Federal Highway Administration:
Establish and fund a program to train
instructors to provide drug recognition
expert training to federal agency
inspectors/investigators, police, and otherpublic service personnel with commercial
truck and truck driver oversight
responsibilities.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-90-22

Closed—Acceptable
ActionApril 21, 1994

H-90-21

Closed—Acceptable
ActionJuly 7, 1998

H-90-20

Closed—Acceptable
ActionAugust 3, 1994

H-90-19

Closed—Acceptable
Alternate Action

August 3, 1994

H-90-18

Closed—Acceptable
ActionAugust 3, 1994

H-90-17

Closed—Acceptable
Alternate Action

August 2, 1994

115

Recommendation
To the Federal Highway Administration:
Establish a demonstration project(s) todeter the use of alcohol and other drugs
by drivers of medium and heavy trucks
that includes alcohol and other drug
testing at special roadside sobriety
checkpoints, truck inspection lanes, andtruck weigh stations.
To the Federal Highway Administration:
Disseminate safety information tonational, state, and local police agencies,
public service and safety agencies,
professional truck driver groups andindividual truck drivers, regarding: theeffects of fatigue, alcohol and other druguse; the interaction of alcohol, drugs andfatigue; the prevalence of drug andalcohol abuse among professionalcommercial vehicle operators; and,methods of minimizing conditions whichlead to commercial vehicle operators
driving while fatigued.
To the Federal Highway Administration:
Require close supervision, including
frequent, unannounced drug testing, for
an appropriate period, of commercial
truck drivers with an identified alcohol orother drug abuse problem. Such testingshould be sufficiently frequent to create
the likelihood of detection if the person
uses drugs of abuse.
To the Federal Highway Administration:
Require commercial truck driverapplicants with a prior history of drug
and/or alcohol abuse to complete a
certified treatment program and obtain aphysician's evaluation of substance abuseand dependency.
To the Federal Highway Administration:
Amend 49 CFR 391.21 "application for
employment" and 391.23 investigations
and inquiries to include a complete
review of alcohol and other drug abuse
treatment history prior to employment as
a commercial truck driver.
To the Federal Highway Administration:
Require pre-employment alcohol andother drug tests on all drivers ofcommercial trucks with a gross vehicle
weight rating of 10,000 pounds andabove as a condition of employment.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-90-16

Closed—Acceptable
ActionNovember 24,
1998

H-90-15

Closed—Unacceptable
ActionApril 1, 2005

H-90-14

Closed—Unacceptable
ActionApril 1, 2005

H-90-13

Closed—Acceptable
ActionApril 1, 2005

H-90-12Closed—Acceptable
ActionApril 1, 2005

116

Recommendation
To the National Highway Traffic Safety
Administration: Revise the fatal accident
reporting system to include standardized
drug toxicological tests requested in eachfatal accident and results, both single andmultiple drug, which would include anestimating system similar to that now used
to estimate national alcohol involvementin fatal accidents.
To the United States Department ofTransportation: Provide funding
incentives, guidance and assistance to thestates to obtain complete toxicologicaltests and report results (including drug
tests requested) to DOT on all vehicle
operators involved in fatal commercial
vehicle accidents.
To the United States Department ofTransportation: Establish, with the
Department of Health and Human
Services and other organizations as
appropriate, a postaccident alcohol andother drug analytic test plan for tests to be
conducted on a wide range of impairing
drugs with results reported at state-of-theart sensitivity levels.
To the United States Department ofTransportation: With the assistance of the
Department of Health and Human
Services, the states, the American
Academy of Forensic Sciences, theNational Safety Council Committee on
Alcohol and Other Drugs, and otherorganizations as appropriate, standardize
procedures for postaccident toxicological
specimen collection, chain of custody,
testing, and reporting among the states
for accidents involving medium and heavy
trucks.
To the United States Department ofTransportation: Develop a program tomerge elements concerning commercial
vehicle operations of the separate DOT
operated and supported highway
accident databases. These elements
should include, but not be limited to,driver history, carrier, vehicle and roadway
characteristics, hazardous materials
transportation, and alcohol and otherdrug involvement.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-90-11

Closed—Unacceptable
ActionApril 1, 2005

H-90-10

Closed—Acceptable
Alternate Action

April 1, 2005

H-89-14

Closed—Acceptable
ActionAugust 20, 1990

H-89-13

Closed—Acceptable
ActionAugust 20, 1990

H-89-12Closed—Acceptable
ActionMarch 18, 2004

H-89-11

Closed—Acceptable
ActionAugust 20, 1990

117

Recommendation
To the United States Department ofTransportation: Assess and revise, as
appropriate, the reporting and accuracyof existing database elements regarding
toxicological tests for DOT operated andsupported highway accident databases
and trucking operations databases toprovide complete and accurate reportingof toxicological tests requested andresults obtained.
To the United States Department ofTransportation: With the assistance of the
Department of Labor, Occupational Safety
and Health Administration and theInterstate Commerce Commission,
conduct a detailed review of, and reporton, trucking industry structure, operations,and conditions, especially shipping,dispatching, and receiving requirements,
shipment broker operations, just-in-time
shipments, and truckload/less-thantruckload operations which may create
incentives for drivers to violate hours ofservice regulations and to use drugs ofabuse.
To the Commonwealth of Kentucky:
Expand efforts to make the public awareof increased emphasis on deterring
impaired driving.
To the Commonwealth of Kentucky:
Renew state efforts to publicize andencourage citizens to participate in the"Report a Problem Intoxicated Driver"program.
To the Commonwealth of Kentucky:
Expand the use of sobriety checkpoints by
the Kentucky State Police, and encourage
and assist local law enforcement agencies
to do the same.
To the Commonwealth of Kentucky:
Expand the use by the Kentucky State
Police of preliminary breath test devices
and the three-part field sobriety test
recommended by the National Highway
Traffic Safety Administration, including thehorizontal gaze nystagmus test, and urge
and assist all other traffic law enforcement
agencies in Kentucky to do the same.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-89-10

Closed—Acceptable
ActionMarch 18, 2004

H-89-9Closed—Acceptable
ActionMarch 18, 2004

H-89-8Closed—Acceptable
ActionMarch 18, 2004

H-89-2

Closed—Acceptable
Action(overall)March 18, 2004

118

Recommendation
To the Commonwealth of Kentucky:
Review all aspects of the plea bargaining
prohibitions of the 1984 driving-underthe-influence law to determine if persons
charged with alcohol-related offenses arebeing allowed to plea bargain the charge
to a non-alcohol-related offense, and if so,take administrative or legislative action tocorrect the situation.
To the Commonwealth of Kentucky:
Amend the current driving-under-theinfluence laws to prohibit the reduction or
elimination of a licensing penalty if aconvicted offender enrolls in an education
or treatment program. Participation inthese programs should be required inaddition to appropriate licensing or otherpenalties.
To the Commonwealth of Kentucky: Enact
the recommendations made by thedriving-under-the-influence (DUI)
committee formed by the governor toassess the current DUI laws. These
recommendations cover administrative
license revocation, illegal per se, implied
consent and testing, chemical analysis,
suspended licenses, and alcohol driver
education.
To all the states except Kentucky and theDistrict of Columbia: Convene orreconvene a committee or task force toreview your state's driving-under-the
influence (DUI) legislation and its
implementation, in light of the problems
discussed in the accident report on the
pickup truck/church activity bus head-on
collision and fire near Carrollton,
Kentucky, on May 14, 1988. Particularattention should be paid toimplementation of administrative license
revocation programs, improved
evaluations of convicted DUI offenders,and enhanced public awareness andenforcement programs. Based on thisreview, take appropriate action to improveyour state's DUI prevention program.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-85-50

Closed—Acceptable
Action(overall)February 14,
1994

H-85-49

Closed—Acceptable
Action(overall)February 14,
1994

H-85-48

Closed—Acceptable
ActionJune 7, 1993

H-85-47

Closed—Acceptable
ActionJune 7, 1993

H-84-94

Closed—Acceptable
Action(overall)June 27, 2003

H-84-92

Closed—Reconsidered

December 4,
2002

119

Recommendation
To the governors and legislative leadersof the 50 states and Puerto Rico and themayor and council chairman of the Districtof Columbia: Establish formal procedures
to ensure that quantitative tests of theblood alcohol concentration of all drivers
involved in fatal highway crashes are
performed and reported to the stateagency responsible for maintaining suchrecords.
To the governors and legislative leadersof the 50 states and Puerto Rico and themayor and council chairman of the Districtof Columbia: Initiate legislation or take thenecessary administrative action to require
alcohol testing of all drivers involved in
fatal highway crashes.
To the National Highway Traffic Safety
Administration: Urge states with deficient
programs to increase the allocation of
highway safety grant program funds andstate matching funds to improve themeasurement and reporting of alcohol
involvement in fatal highway crashes.
To the National Highway Traffic Safety
Administration: Undertake a more
extensive and aggressive program toprovide direct technical support to states
to improve alcohol testing and reportingof all drivers involved in fatal highway
crashes.
To the Arkansas State Police and the
Arkansas State Crime Laboratory: Instructstate police officers to request that two
separate vials of blood containing 5 mleach be collected for alcohol and drug
analysis in serious and fatal accident
investigations and that the samples berefrigerated until they can be transported
to a laboratory for analysis and not beheld in an officer's possession except for
direct transportation to the laboratory.
To the International Association of Chiefsof Police, Inc.: Develop a recommended
policy to the states which will prompt law
enforcement personnel to request
medical testing for the presence ofalcohol in the blood of all truck drivers
involved in serious accidents.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-84-90

Closed—Acceptable
Action(overall)May 31, 1985

H-84-89

Closed—Unacceptable
ActionNovember 19,
1985

H-84-88

Closed—Acceptable
Alternate Action

September 23,
1993

H-84-87

Closed—Acceptable
ActionSeptember 23,
1993

H-84-86

Closed—Acceptable
Action(overall)March 18, 2004

H-84-85

Closed—Acceptable
Action(overall)March 18, 2004

120

Recommendation
To the American Bar Association, theNational Association of Judicial Educators,
and the National Judicial State College:
Work with state governments, state
judicial organizations, and the National
Highway Traffic Safety Administration tovigorously promote initial and recurrent
training for judges in alcohol issues and
DWI case adjudication and to develop
more sources of funds for financing thistraining.
To the Veterans Administration: Develop
and implement a national policy making
VA hospital alcohol dependence
treatment programs more consistently
available to local traffic court rehabilitation
programs for convicted DWI defendants
who are veterans.
To the National Highway Traffic Safety
Administration: Incorporate the salientfeatures of such court records systems as
the court reporting network in
Pennsylvania and the PROMIS System inColorado in the Model Case Management
Information System; ensure that themodel system incorporates motor vehicle
licensing records and court records of
drunk driving-related violations andconvictions.
To the National Highway Traffic Safety
Administration: Evaluate the effectivenessof license actions against juveniles who
violate alcohol laws, such as the laws
recently enacted in Oregon, Washington,
North Carolina, Maryland, and Maine.
To the governors of the 50 states and themayor of the District of Columbia: Takeaction to increase the availability andquality of alcohol treatment services
designed specifically for juvenile alcoholabusers, especially to provide services at
low cost to the user.
To the governors of the 50 states and themayor of the District of Columbia: Take
steps to ensure that no diversion or
supervision program in your state is usedin place of license revocation/suspension
and that court and DMV records reflect
participation in diversion/ supervision
programs.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-84-84

Closed—No Longer
Applicable(overall)

November 2,
1995

H-84-83

Closed—Acceptable
Action(overall)March 18, 2004

H-84-82

Closed—Acceptable
Action(overall)March 18, 2004

H-84-81

Closed—Acceptable
Action(overall)March 18, 2004

H-84-80

Closed—Unacceptable
Action(overall)March 18, 2004

H-84-79

Closed—Unacceptable
Action(overall)March 18, 2004

H-84-78

Closed—Acceptable
Action(overall)

November 8,
1993

121

Recommendation
To the governors of the 50 states and themayor of the District of Columbia: Requirethat appropriate alcohol problem
evaluations of persons charged withalcohol-related traffic offenses be
conducted and made available to judges
hearing these cases.
To the governors of the 50 states and themayor of the District of Columbia: Take
steps to require that law enforcement andjudicial records systems in your stateinclude complete records of DWI
defendants' previous alcohol-related
traffic offenses, including those committed
as a juvenile, and that they are available tojudges prior to sentencing.
To the governors of the 50 states and themayor of the District of Columbia: Take
steps to develop a records system that
preserves records of alcohol related traffic
offenses committed by a juvenile after theoffender reaches adulthood.
To the governors of the 50 states and themayor of the District of Columbia:
Encourage and support initial andrecurrent training on alcohol, problem
drinking, and drunk driving caseadjudication for all judges hearing DWI
cases.
To the 50 states and the mayor of theDistrict of Columbia: Take steps topreclude reduction of an alcohol-related
charge to a non-alcohol-related charge
and to require in all cases that thedefendant's driving record reflect theoriginal charge.
To the governors of the 50 states and themayor of the District of Columbia:
Encourage detention agencies in yourstate to adopt DWI holding and release
policies that do not permit the release ofalcohol offenders until after their blood
alcohol concentration has dropped below
the lowest level specified in state law as
indicating alcohol impairment.
To the governors of the 50 states and themayor of the District of Columbia:
Propose legislation, if necessary, and/or
take other appropriate action to facilitate
the collection of DWI evidence based on
the drawing of blood for BAC test
purposes.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-84-77

Closed—Acceptable
Action(overall)December 10,
1993

H-84-27

Closed—Acceptable
Alternate Action

October 26,
1987

H-84-26

Closed—Acceptable
ActionOctober 26,
1987

H-84-25

Closed—Acceptable
Alternate Action

November 21,
1990

H-84-24

Closed—Acceptable
Alternate Action(overall)

August 24, 1993

H-84-23

Closed—Acceptable
Action(overall)December 10,
1993

H-84-22

Closed—Acceptable
Action(overall)December 10,
1993

122

Recommendation
To the governors of the 50 states and themayor of the District of Columbia:
Encourage the use, by all traffic law
enforcement agencies in your state, ofpreliminary breath test devices and the
NHTSA-recommended three-part field
sobriety test, including the horizontal gazenystagmus test.
To the mayor of the District of Columbia:
Evaluate the effectiveness of sobriety
check points and administrative license
revocation procedures implemented.
To the mayor of the District of Columbia:
Continue and expand the use of sobriety
check points on a periodic and continuingbasis by the appropriate enforcement
agencies under your jurisdiction as part ofa comprehensive driving while intoxicatedenforcement program. These checkpoints
should be conducted according toaccepted procedures and constitutionalsafeguards.
To the National Highway Traffic Safety
Administration: Evaluate the effectivenessof sobriety checkpoints and administrative
revocation procedures.
To the governors of Alaska, Indiana, Iowa,
Louisiana, Maine, Minnesota, Mississippi,
Nevada, North Carolina, North Dakota,
Ohio, Oklahoma, and West Virginia:
Evaluate the effectiveness of sobriety
check points and administrative license
revocation procedures implemented.
To the governors of Alaska, Indiana, Iowa,
Louisiana, Maine, Minnesota, Mississippi,
Nevada, North Carolina, North Dakota,
Ohio, Oklahoma, and West Virginia:
Encourage local law enforcement
agencies within your state to institutesobriety checkpoints on a similar basis.
To the governors of Alaska, Indiana, Iowa,
Louisiana, Maine, Minnesota, Mississippi,
Nevada, North Carolina, North Dakota,
Ohio, Oklahoma, and West Virginia:
Institute the use of sobriety checkpoints
on a periodic and continuing basis by theappropriate enforcement agencies under
your jurisdiction as part of acomprehensive driving while intoxicatedenforcement program. These checkpoints
should be conducted according toaccepted procedures and constitutionalsafeguards.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-84-21

Closed—Acceptable
Alternate Action(overall)

August 24, 1993

H-84-20

Closed—Acceptable
Action(overall)December 10,
1993

H-84-19

Closed—Acceptable
Action(overall)December 10,
1993

H-84-18

Closed—Acceptable
Alternate Action(overall)

August 24, 1993

H-84-17

Closed—Acceptable
Action(overall)October 13,
1993

H-84-16

Closed—Acceptable
Action(overall)December 10,
1993

123

Recommendation
To the governors of Colorado, Delaware,
Missouri, New Mexico, Oregon, Utah, andWashington: Evaluate the effectiveness ofsobriety checkpoints and administrative
license revocation procedures
implemented.
To the governors of Colorado, Delaware,
Missouri, New Mexico, Oregon, Utah, andWashington: Encourage local law
enforcement agencies within your state to
institute sobriety checkpoints on a similarbasis.
To the governors of Colorado, Delaware,
Missouri, New Mexico, Oregon, Utah, andWashington: Continue and expand theuse of sobriety checkpoints on a periodic
and continuing basis by the appropriate
enforcement agencies under yourjurisdiction as part of a comprehensive
driving while intoxicated enforcement
program. These checkpoints should be
conducted according to accepted
procedures and constitutional safeguards.
To the governors of Arizona, Arkansas,
Florida, Georgia, Idaho, Maryland,
Massachusetts, Nebraska, New Jersey,
New York, South Dakota, Vermont, andVirginia: Evaluate the effectiveness ofsobriety checkpoints and administrative
license revocation procedures
implemented.
To the governors of Arizona, Arkansas,
Florida, Georgia, Idaho, Maryland,
Massachusetts, Nebraska, New Jersey,
New York, South Dakota, Vermont, andVirginia: Enact legislation or utilize
existing authority to provide foradministrative revocation of the licensesof drivers who refuse a chemical test foralcohol or who provide a result at or
above the state presumptive limit.
To the governors of Arizona, Arkansas,
Florida, Georgia, Idaho, Maryland,
Massachusetts, Nebraska, New Jersey,
New York, South Dakota, Vermont, andVirginia: Encourage local law enforcement
agencies within your state to institutesobriety checkpoints on a similar basis.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-84-15

Closed—Acceptable
Action(overall)December 10,
1993

H-84-14

Closed—Acceptable
Alternate Action(overall)

August 24, 1993

H-84-13

Closed—Acceptable
Action(overall)October 13,
1993

H-84-12Closed—Acceptable
Action(overall)December 10,
1993

124

Recommendation
To the governors of Arizona, Arkansas,
Florida, Georgia, Idaho, Maryland,
Massachusetts, Nebraska, New Jersey,
New York, South Dakota, Vermont, andVirginia: Continue and expand the use ofsobriety checkpoints on a periodic andcontinuing basis by the appropriate
enforcement agencies under yourjurisdiction as part of a comprehensive
driving while intoxicated enforcement
program. These checkpoints should be
conducted according to accepted
procedures and constitutional safeguards.
To the governors of Alabama, California,
Connecticut, Hawaii, Guam, Illinois,
Kansas, Kentucky, Michigan, Montana,
New Hampshire, Pennsylvania, Puerto
Rico, Rhode Island, South Carolina,
Tennessee, Texas, Virgin Islands,
Wisconsin, and Wyoming: Evaluate theeffectiveness of sobriety checkpoints andadministrative license revocation
procedures implemented.
To the governors of Alabama, California,
Connecticut, Hawaii, Guam, Illinois,
Kansas, Kentucky, Michigan, Montana,
New Hampshire, Pennsylvania, Puerto
Rico, Rhode Island, South Carolina,
Tennessee, Texas, Virgin Islands,
Wisconsin, and Wyoming: Enact
legislation or utilize existing authority toprovide for administrative revocation of
the licenses of drivers who refuse achemical test for alcohol or who provide a
result at or above the state presumptive
limit.
To the governors of Alabama, California,
Connecticut, Hawaii, Guam, Illinois,
Kansas, Kentucky, Michigan, Montana,
New Hampshire, Pennsylvania, Puerto
Rico, Rhode Island, South Carolina,
Tennessee, Texas, Virgin Islands,
Wisconsin, and Wyoming: Encourage
local law enforcement agencies withinyour state to institute sobriety checkpoints
on a similar basis.

Safety Research Report
SRR-22-02

NumberClassification

Date Closed

H-84-11

Closed—Acceptable
Action(overall)December 10,
1993

H-82-36

Closed—Acceptable
Action(overall)April 17, 1983

H-82-35

Closed—Acceptable
Action(overall)July 25, 2002

H-82-18

Closed—Acceptable
Action(overall)

August 9, 1993

H-80-49

Closed—Acceptable
Alternate Action

August 8, 1988

125

Recommendation
To the governors of Alabama, California,
Connecticut, Hawaii, Guam, Illinois,
Kansas, Kentucky, Michigan, Montana,
New Hampshire, Pennsylvania, Puerto
Rico, Rhode Island, South Carolina,
Tennessee, Texas, Virgin Islands,
Wisconsin, and Wyoming: Institute the useof sobriety checkpoints on a periodic andcontinuing basis by the appropriate
enforcement agencies under yourjurisdiction as part of a comprehensive
driving while intoxicated enforcement
program. These checkpoints should be
conducted according to accepted
procedures and constitutional safeguards.
To the International Association of Chiefsof Police and the National Safety Council:
Collaborate and act as focal points forgathering information on reddi-type
programs and provide information andassistance to the interested states andlocal communities.
To the mayor of District of Columbia andthe governors of the states listed(50 states, excluding Colorado, Maryland,
Nebraska, Utah, and Washington):
Implement a citizen awareness and citizen
drunk driver reporting program such as
the reddi-type programs now used by
Colorado, Maryland, Nebraska, Utah, andWashington.
To the states of Alabama, Alaska, Arizona,
Colorado, Connecticut, Delaware, Florida,
Georgia, Hawaii, Idaho, Iowa, Kansas,
Louisiana, Maine, Massachusetts,
Minnesota, Mississippi, Montana,
Nebraska, New Hampshire, New Jersey,
New York, North Carolina, Ohio,
Oklahoma, Rhode Island, South Carolina,
South Dakota, Tennessee, Texas, Vermont,
Virginia, West Virginia, Wisconsin, andWyoming and the District of Columbia:
Raise the minimum legal age for drinking
or purchasing all alcoholic beverages to
21 years of age.
To the Oklahoma Department ofTransportation: Seek the funds necessary
to enable a renewed emphasis on alcohol
safety especially in the rural areas and theless populated communities of the state.

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NumberClassification

Date Closed

H-80-47

Closed—Acceptable
ActionAugust 21, 1986

H-80-27

Closed—Acceptable
Alternate Action

August 5, 1980

H-80-1

Closed—Unacceptable
ActionApril 30, 1984

H-78-76

Closed—Acceptable
ActionJuly 15, 1987

H-78-75

Closed—Acceptable
Alternate Action

June 13, 1983

H-76-3

Closed—Acceptable
ActionOctober 20,
1977

H-76-2

Closed—Acceptable
ActionOctober 20,
1977

126

Recommendation
To the National Highway Traffic Safety
Administration: Evaluate the effectivenessof current dram shop type laws in
reducing the number of highway
accidents involving drivers under the
influence of alcohol in states having suchlaws. If the above evaluations prove to bepositive, then incorporate the concepts ofthese laws into the existing Highway
Safety Program Standard No. 8, alcohol in
relation to highway safety.
To the Commonwealth of Pennsylvania:
Provide increased emphasis on yourstatewide enforcement program directed
toward reducing the number of persons
driving on public roads while under the
influence of alcohol. (Urgent)
To the state of Maryland: Refer thefollowing recommendation to theappropriate legislative committees: enact
legislation that will redefine the terms"intoxicated" and "impaired by alcohol" tofit current nationally accepted standard
definitions.
To the National Highway Traffic Safety
Administration: Evaluate and report to the
Safety Board those alcohol
countermeasures that the NHTSA foundto be practical and effective for the
reduction in the number ofalcohol-involved drivers.
To the city of Plant City, Florida: As part ofits Operation Lifesaver program,emphasize in its selective traffic law
enforcement program grade crossing
warning signal violators and those whodrive while under the influence of alcoholor drugs. (Urgent)
To the National Highway Traffic Safety
Administration: Develop and report more
effective systems and standards forconveying traffic information to impaired
drivers at temporary traffic control sites(e.g., railroad crossings, construction sites,etc.) and protecting those persons
controlling traffic.
To the National Highway Traffic Safety
Administration: Determine and report theeffectiveness of traffic information control
systems currently in use at railroad
crossings, considering in particular theirability to warn and achieve an appropriate
reaction from impaired drivers.

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NumberClassification

Date Closed

H-71-58

Closed—Acceptable
ActionJanuary 1, 1980

H-71-57

Closed—Acceptable
ActionJanuary 1, 1980

H-69-5

Closed—Acceptable
ActionJune 27, 1975

127

Recommendation
To the National Highway Traffic Safety
Administration: Develop new and/or
supplemental efforts in their alcohol safety
action programs specifically designed forthe young drinking driver, beyond those
now contemplated or in use.
To the National Highway Traffic Safety
Administration: Re-examine its highway
safety program efforts with a view tofocusing certain programs more sharply
on the 15 to 24 year-old group of drivers
as a means of reducing excess losses inthis group. This would pertain especiallyto driver licensing, driver education, driver
improvement, alcohol safety action
programs, and vehicle inspection. A much
more thorough set of examinations for
initial licensing of young drivers appears
highly desirable. A diagnostic approach todriver preparation, driver licensing, anddriver improvement programs designed
primarily for the new young driverappears highly justified by thedisproportionate involvement and fatality
rate of this age group.
To the United States Department ofTransportation: The Board feels that
alcohol problems in the different modesof transportation should be coordinatedby the Department of Transportation. The
role of such coordination would be (a) togive increased emphasis to study andprogram action with respect to the role ofalcohol, extending coverage of the
problem to all transportation modes,(b) to coordinate the DOT efforts withthose of the health-oriented agencies andorganizations, the various state and local
transportation authorities, and the otherfederal efforts at public education andprogram action regarding alcohol
problems, and (c) to provide a national
focal point for information on alcohol intransportation safety. This coordination
should be especially responsive to thelarge number of alcohol fatalities inhighway transportation, the researchcapability in the Federal Highway
Administration, and the need for transfer
of techniques between the highway field,
general aviation, and other modes. The
vigorous educational effort with generalaviation is worthy of careful study.

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Number

H-68-27Classification

Closed—Acceptable
ActionDate Closed

Recommendation

June 27, 1975

To the Federal Highway Administration:
Develop a program designed to produce
a sense of individual responsibility in thegeneral public to protect the nation's
highways from drinking drivers, enlistingin such a program the aid of the news
media, the producers of alcoholic
beverages, private and public agencies
concerned with highway safety, as well as
religious, educational, and civic groups to(a) support law enforcement efforts
against and the prosecution of drinking
drivers; (b) impress upon the public
individually, each person's serious social
duty not to drive while under the
influence of alcohol; and (c) individually to
accept the responsibility of preventing
other persons from driving while under
the influence of alcohol.

128

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Appendix B: Impairment-Related NTSB Investigations Since 2012
The NTSB has documented drug impairment from alcohol, other drugs, or a
combination of drugs as a cause or contributing factor of several highway crashinvestigations over the past decade. Table B-1 provides links to the NTSB
investigation reports, a list of drugs found in those investigations, and the probablecause of each crash.
Table B-1. NTSB-investigated highway crashes in which alcohol-, other drug-, or
multiple-drug impairment was a cause or contributing factor since 2012.
Investigation Report

Box Truck Collision withGroup of Bicyclists, Near
Searchlight, Nevada,
December 10, 2020.
HIR-22-07.

Drug(s) FoundBox truck driver:methamphetamine andamphetamineSport Utility Vehicle
Centerline Crossover
Collision With Pickup Truckon State Route 33, Avenal,
California, January 1, 2021.
HIR-22/05.

Sport utility vehicle driver:alcohol, cannabis
Pickup truck driver: cannabis

Collision Between Pickup
Truck with Trailer andGroup of Motorcycles,
Randolph, New Hampshire,
June 21, 2019. HAR-20/04.

Truck driver:benzoylecgonine, fentanyl,
acetyl fentanyl, norfentanyl,
morphine, 6-MAM

Collision Between
Passenger Train and Refuse
Truck at Active Grade
Crossing, Crozet, Virginia,
January 31, 2018.
HAB-19/03.

Truck driver: THC (6.6 ng/mL),
THC carboxylic acid (59ng/mL, gabapentin (2.2 mg/L)

129

Probable Cause
The National Transportation Safety Board
determines that the probable cause of the
Searchlight, Nevada, crash was the box truck
driver’s impairment and fatigue stemmingfrom his use of methamphetamine.
Contributing to the crash was the decision
made by the bicyclists to ride in the right travel
lane of a 75-mph roadway.
The NTSB determines that the probable causeof the Avenal, California, crash was the failureof the sport utility vehicle (SUV) driver tocontrol his vehicle due to a high level ofalcohol impairment. Contributing to theseverity of the crash was the SUV driver’s
excessive speed.
The NTSB determines that the probable causeof the Randolph, New Hampshire, crash was
the pickup truck driver’s crossing thecenterline and encroaching into the oncominglane of travel, which occurred because of his
impairment from use of multiple drugs.
Contributing to the crash was Westfield
Transport’s substantial disregard for andegregious noncompliance with safety
regulations. Also contributing was the failureof the Massachusetts Registry of Motor
Vehicles to revoke the pickup truck driver’s
Massachusetts driver’s license when notified of
his loss of driving privileges in another state.
The NTSB determines that the probable causeof the crash in Crozet, Virginia, was the truck
driver’s decision to enter an active grade
crossing and his inaction when heencountered obstacles while attempting tocross the railroad tracks, most likely due to his
impairment from the combined effects of thedrugs marijuana and gabapentin. Contributing
to the severity of the injuries was the lack ofseat belt use by the truck occupants.

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Investigation ReportDrug(s) Found

Probable Cause
The NTSB determines that the probable causeof the crash in Washington, DC, was thepedestrian’s decision to cross the street
outside the crosswalk and against the traffic
signal. Contributing to his poor decisionmaking was alcohol impairment. Further
contributing to the crash was the driver’s
impairment from alcohol, which most likely
diminished her ability to detect and avoid thepedestrian.
The NTSB determines that the probable causeof the crash in the Town of Geneva, Wisconsin,
was the pedestrian’s decision to walk in thetravel lane with her back to traffic.
Contributing to her poor decision-making was
impairment from the effects of alcohol
intoxication.
The NTSB determines that the probable causeof the crash in Falls Church, Virginia, was thepedestrian’s decision to run across themultilane roadway in front of the oncomingcar. Contributing to his poor decision-making
was impairment from the effects of alcohol
intoxication and recent use of cocaine.
The NTSB determines that the probable causeof the Concan, Texas, crash was the failure of
the pickup truck driver to control his vehicle
due to impairment stemming from his use of
marijuana in combination with misuse of aprescribed medication, clonazepam.
Contributing to the severity of the injuries was
the insufficient occupant protection provided
by the lap belts worn by passengers seated in
the rear of the medium-size bus.

Fatal Pedestrian Collision
with Car, Washington, DC,
August 18, 2016.
HAB-18/15.

Pedestrian: alcohol(BAC 0.10 g/dL)
Driver: alcohol (BAC 0.09g/dL), MDMA, MDA,
benzoylecgonine.

Fatal Pedestrian Collision
with Sport Utility Vehicle,
Town of Geneva,
Wisconsin, August 16,
2016. HAB-18/12.

Pedestrian: alcohol(BAC 0.23 g/dL)
Driver: 19 ng/ml of delta-9THC, 8.2 ng/ml of 11-hydroxyTHC, 180 ng/ml of carboxyTHC, 24 ng/ml hydrocodone

Fatal Pedestrian Collision
with Pickup Truck, Falls
Church, Virginia, June 4,
2016. HAB-18/04.

Pedestrian: alcohol (BAC 0.22g/dL), cocaine,benzoylecgonine (cocaine
metabolite), cocaethylene

Pickup Truck Centerline
Crossover Collision With
Medium-Size Bus on
US Highway 83, Concan,
Texas, March 29, 2017.
HAR-18/02.

Truck driver: delta-9 THC andclonazepam

Pickup Truck Collision With
Multiple Bicycles, Cooper
Township, Michigan,
June 7, 2016. HAB-17/01.

Truck driver: THC-COOH,
methamphetamine,
amphetamine, hydrocodone,*tramadolO-desmethyltramadol,
cyclobenzaprine,* ketamine,
norketamine,* and lorazepam(* means positive in 1 of 2
independent tests)

The NTSB determines that the probable causeof the Cooper Township, Michigan, crash was
the impairing effects of the driver’s
polysubstance abuse in the hours before thecrash.

Truck driver:methamphetamine andamphetamine

The NTSB determines that the probable causeof the Chattanooga, Tennessee, crash was thetruck driver’s failure to respond to the slowmoving traffic within a work zone because of
performance decrements likely associatedwith his fatigue and methamphetamine use.
Contributing to the crash was the failure of thepre-employment screening process to identify
driver risk factors. Contributing to the severityof the crash was the truck-tractor’s high impact
speed.

Multivehicle Work Zone
Crash on Interstate 75,
Chattanooga, Tennessee,
June 25, 2015.
HAR-16/01.

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Investigation ReportDrug(s) Found

Truck-Tractor Semitrailer
Median Crossover Collision
With Medium-Size Bus on
Interstate 35, Davis,
Oklahoma, September 26,
2014. HAR-15/03.

Truck driver: Sertraline,
trazodone; Test for 5-fluoroAMB conducted, but neither
presence nor absence could
be confirmed.

School Bus and Truck
Collision at Intersection,
Near Chesterfield, New
Jersey, February 16, 2012.
HAR-13/01.

Bus driver: 7-aminoclonazepam,
desmethylvenlafaxine (O-),
tramadol

131

Probable Cause
The NTSB determines that the probable causeof the Davis, Oklahoma, crash was the failureof the truck-tractor driver to control his vehicle
due to incapacitation likely stemming from his
use of synthetic cannabinoids. Contributing to
the severity of injuries were the lack of
restraint use by the bus passengers and thelack of appropriate crashworthiness standards
for medium-size buses.
The NTSB determines that the probable causeof the Chesterfield, New Jersey, crash was theschool bus driver’s failure to observe the
Mack roll-off truck, which was approaching theintersection within a hazardous proximity.
Contributing to the school bus driver’s
reduced vigilance were cognitive decrements
due to fatigue as a result of acute sleep loss,
chronic sleep debt, and poor sleep quality, in
combination with, and exacerbated by,
sedative side effects from his use ofprescription medications. Contributing to theseverity of the crash was the truck driver’s
operation of his vehicle in excess of theposted speed limit, in addition to his failure toensure that the weight of the vehicle waswithin allowable operating restrictions. Further
contributing to the severity of the crash were
the defective brakes on the truck and its
overweight condition due to poor vehicle
oversight by Herman’s Trucking, along withimproper installation of the lift axle brakesystem by the final stage manufacturer—all ofwhich degraded the truck’s braking
performance. Contributing to the severity ofpassenger injuries were the nonuse or misuseof school bus passenger lap belts; the lack ofpassenger protection from interior sidewalls,
sidewall components, and seat frames; andthe high lateral and rotational forces in theback portion of the bus.

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Appendix C: NTSB Drug Category and Subcategory Descriptions
The NTSB created its own drug classification scheme organized by the likely
effects of a drug or similarities in drug properties. A brief description of the NTSB
drug categories and subcategories is provided below. It should be noted that thesedefinitions reflect the specific definitions used by NTSB for this research and analysis,but other sources may define each category with slight differences. Additionally, eachof these categories should be understood to only include potentially impairing drugs.
For extra clarity due to the large number of drugs within the “neuropsychiatric
medications” and the “other” categories that are non-impairing, the words“potentially impairing” were added to these category names. Here and throughout
the report, chemical or generic drug names are not capitalized, and drug brandnames are capitalized. Drug brand names are the names given by companies that sell
the drugs.
Alcohol, the common name for ethanol or ethyl alcohol, is an intoxicant that iscommonly found in beer, wine, and liquor. Alcohol is a psychoactive drug which
produces depressant effects.
Non-Ethanol Alcohols are alcohols other than ethanol. Examples include
isopropanol and methanol.
Cannabis, commonly referred to as marijuana, refers to the dried leaves, flowers,
stems, seeds, and other derived products of the Cannabis sativa or Cannabis indica
plant. Subcategories include the following:•

THC or tetrahydrocannabinol refers to the compounds that are primarily
responsible for cannabis’ psychoactive effects. This subcategory includes
Δ9-THC and Δ8-THC and their metabolites or byproducts, including
cannabinol, 11-nor-9-carboxy-THC, and 11-Hydroxy-THC.

•

Other cannabinoids are all other chemicals derived from the cannabis
plant which are not THC or the metabolites of THC but have psychoactive
properties or alter the psychoactive properties or concentrations of othercompounds. This includes cannabidiol.

Potentially Impairing Neuropsychiatric Medications include a wide variety ofprescription drugs that have impairing side effects such as dizziness, drowsiness, andincoordination. The disorders these medications are treating may also have adverse
effects on driving safety. Subcategories include the following:•

Antidepressants are drugs commonly prescribed for the treatment ofdepression. Examples include amitriptyline, bupropion (Wellbutrin), anddoxepin.
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Antiepileptics, also referred to as anticonvulsants, are a broad group of
drugs used to treat seizures or convulsions. They may also be used to treat
nerve pain and psychiatric diseases, such as bipolar disease. Examples
include carbamazepine (Tegretol), gabapentin, and oxcarbazepine.

•

Antipsychotics, also known as neuroleptics, are used to treat or reduce
symptoms of psychosis, a finding in schizophrenia and some otherneuropsychiatric conditions. Examples include aripiprazole (Abilify),
clozapine, risperidone, and ziprasidone.

•

Other Anxiolytics are drugs used to treat anxiety. This subcategory
included drugs used to treat anxiety where the mechanism of action was
other than as a central nervous system depressant such as benzodiazepinesand barbiturates. This category includes buspirone.

•

Other potentially impairing neuropsychiatric medications includes all
remaining medications used to treat neuropsychiatric disorders that are notincluded in this or other categories. Examples include ropinirole.

Hallucinogens are a diverse group of drugs that produce psychoactive effects which
may alter perceptions, thoughts, and/or feelings. They are characterized by theirtendency to produce hallucinations. Examples include LSD, mescaline, and psilocin.
Inhalants consist of a wide variety of vapors that are inhaled as their primary methodof usage. This includes many common household products such as spray paint, paintthinners, glue, and cleaning fluids. Chemical examples include acetone,
difluoroethane, and toluene.
Dissociative anesthetics create feelings of detachment or dissociation from aperson’s body or environment and may be used for general anesthesia during
surgery. Dissociative anesthetics may produce visual and auditory distortions.
Examples include ketamine, phencyclidine (PCP), and tenocyclidine.
Sedatives serve as central nervous system depressants. They produce sedating or
relaxant effects which may be used to treat a variety of conditions. Subcategories
include the following:•

Barbiturates are a group of depressants that are known as
sedative-hypnotics because they are commonly used to induce sleep
or reduce anxiety. Examples include butalbital and phenobarbital.

•

Benzodiazepines are depressants primarily used to treat anxiety, seizures,and insomnia. Examples include alprazolam (Xanax), clonazepam(Klonopin), diazepam, and lorazepam.

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Muscle relaxants effect skeletal muscle function, decrease muscle tone,
and may be used to treat muscle pain or spasms. Examples include
baclofen, carisoprodol (Soma), and cyclobenzaprine.

•

Sedating antihistamines are drugs used to treat allergic symptoms andalso cause sleepiness. Examples include diphenhydramine (Benadryl),
meclizine, and promethazine.

•

Sleep aids are used to treat problems of falling and staying asleep.
Examples include suborexant, zolpidem, and zopiclone.

•

Other sedatives are all other drugs that act as central nervous systemdepressants, but do not have properties that fit into the above
subcategories. An example is phenibut.

Stimulants serve as central nervous system stimulants and may improve alertness,create pleasure and invigoration, and produce sympathomimetic effects.
Subcategories include the following:•

Amphetamines are strong central nervous system stimulants that may be
used legally to treat attention deficit hyperactivity disorder, narcolepsy, andobesity or illicitly for its stimulant and mood-altering effects. Examples
include amphetamine, MDA, MDMA, and phentermine.

•

Cocaine is a highly addictive stimulant made from the leaves of the cocaplant. Cocaine is a Schedule II drug under the Controlled Substances Act,
meaning it has a high potential for abuse, but may also be used for medical
treatment (primarily as a topical local anesthetic).137 Examples include
cocaine and its metabolites: benzoylecgonine, cocaethylene, EME, EEE,
and AEME.

•

Methamphetamine is a powerful central nervous system stimulant that ismost commonly used illicitly but may also be used to treat attention deficit
hyperactivity disorder and obesity. Methamphetamine metabolizes into
amphetamine.

•

Piperazines are a broad group of drugs that produce stimulant effects that
may mimic amphetamine, specifically MDMA (ecstasy). Examples include
mCPP, TFMPP, and benzylpiperazine (BZP).

•

Other stimulants are drugs that act as central nervous system stimulants,
but do not have properties that fit into any of the other subcategories.
Examples include phenylpropanolamine and yohimbine.

137

Controlled Substances Act, Public Law 91–513, 84 Stat. 1242 (1970).

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Narcotic analgesics are potent drugs used primarily for pain management but havea high potential for addiction and abuse. Subcategories include the following:•Non-fentanyl opioids include a class of drugs that are naturally found in
the opium poppy plant for pain management, as well as synthetic drugs
that act to mimic these effects. This subcategory includes all opioids withthe exception of fentanyls. Examples include codeine, heroin,hydrocodone, oxycodone, and tramadol.

•

Fentanyls are synthetic opioids that are characterized by their extreme
potency. Fentanyl is 50-100 times stronger than morphine. Examples
include fentanyl, 4-ANPP, and valerylfentanyl.

Novel psychoactive substances, sometimes referred to as “designer drugs,” aredrugs that are designed to mimic the effect of established illicit drugs, but thecompounds are often created to avoid legal classification as an illicit drug.
Subcategories include the following:•

Synthetic cannabinoids are designed to mimic the effects of cannabis,
specifically Δ9-THC, by binding to the same cannabinoid receptors in thebrain. Synthetic cannabinoids may be marketed as “K2” or “Spice.”•

Synthetic cathinones are synthetic stimulants which may commonly bereferred to as “bath salts.” They most closely mimic the effects ofamphetamine. Examples include 4-FMC, methcathinone, and mephedrone.

Other potentially impairing drugs represent a broad set of drugs that do not havecharacteristics that align with any of the categories listed above. Often this will bebecause the drug may produce impairment, but the impairment is notneuropsychiatric, or because the effects of the drug may fall into multiple categories(for example, hallucinogenic and depressant). Subcategories include the following:•

Anticholinergics are drugs that inhibit nerve impulses responsible for
involuntary muscle movements. They may be used to treat chronic
obstructive pulmonary disease (COPD), bladder conditions, gastrointestinal
disorders, and symptoms of Parkinson’s disease. Examples include
benztropine (Cogentin) and dicyclomine.

•

Antiemetics are drugs used for the prevention or treatment of nausea andvomiting. An example is metoclopramide (Reglan).

•

Blood pressure medications are used to treat high blood pressure. The
majority of these drugs are non-impairing but may be indicative of apotentially impairing medical condition.

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Methorphan, due to the similarities of the chemical compounds, refers to
dextromethorphan, dextrorphan, levorphanol, and methorphan. These
drugs are commonly used as a cough suppressant but may be abused inhigh doses which produces hallucinogenic effects.

•

Migraine medications are used to treat severe headaches and migraines.
An example is sumatriptan.

•

Mitragynine, commonly referred to as Kratom by recreational users, is theprimary alkaloid isolated from the leaves of a tropical plant—Mitragyna
speciosa. It is often used for both its stimulant properties and opioid-like
effects. Examples include mitragynine and its metabolite
7-hydroxymitragynine.

•

Other alkaloids include any alkaloid that is not otherwise classified by its
other properties into another category. Alkaloids are a large group of drugs
that serve as anesthetics, cardioprotective, and anti-inflammatory agents.

•

Other refers to any drug that could not be classified into other common
categories. An example is butane.

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Appendix D: Summary of the DRUID Meta-Analysis Results
The DRUID project, a 5-year effort involving 18 European countries, comprised
numerous studies to assess the prevalence of use and risk of various drugs (Hels andothers 2011). The project also conducted a meta-analysis on data from 605
publications to estimate the overall effects of different drugs and drug categories on
performance. Using these analyses, the project was able to estimate the “degree of
impairment” for different drugs and drug doses, which it characterized as, “capturing
in a single parameter both the intensity (magnitude of impaired effects) and durationof impairment” (EMCDDA 2012). The report also acknowledged that there was notenough information to fully assess all drugs or drug combinations.
Table D-1 shows how various drugs within a certain drug class may be much
more impairing than others. For example, within the anxiolytics drug class, lorazepam
is much more impairing than other drugs in that class. The table also shows how
different dosages and different routes of administration of the same drug can affectthe degree of impairment.
Table D-1. Degree of impairment sorted in ascending order within different substanceclasses.
Class

Substance/Dose (mg)Degree of Impairment

Anxiolytics

Buspirone (10)0Anxiolytics

Buspirone (20)0Anxiolytics

Clobazam (10)0Anxiolytics

Clobazam (20)0Anxiolytics

Meprobamate (400)0Anxiolytics

Meprobamate (800)0Anxiolytics

Diazepam (5)17Anxiolytics

Diazepam (10)57

Anxiolytics

Lorazepam (1)64Anxiolytics

Oxazepam (15)104

Anxiolytics

Diazepam (15)112

Anxiolytics

Oxazepam (30)170

Anxiolytics

Diazepam (20)171

Anxiolytics

Alprazolam (1)369

Anxiolytics

Lorazepam (2)418

Anxiolytics

Lorazepam (2.5)

571

Hypnotics and Sedatives

Temazepam (10)0Hypnotics and sedatives

Zolpidem (5)0Hypnotics and sedatives

Lormetazepam (1)22

Hypnotics and sedatives

Temazepam (20)40

Hypnotics and sedatives

Zaleplon (10)

40

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Class

Substance/Dose (mg)Degree of Impairment

Hypnotics and Sedatives(Continued)

Triazolam (0.25)

89

Hypnotics and sedatives

Flunitrazepam (1)115

Hypnotics and Sedatives

Zolpidem (10)Zolpidem (20)

119
214

Hypnotics and sedatives
Hypnotics and sedatives

Zopiclone (7.5)

240

Hypnotics and sedatives

Triazolam (0.5)

247

Hypnotics and sedatives

Flunitrazepam (2)461Antipsychotics

Sulpiride (400)0Antipsychotics

Haloperidol (3)93Antipsychotics

Promethazine (27)491

AntidepressantsFluoxetine (60)0AntidepressantsParoxetine (30)0AntidepressantsImipramine (75)32

AntidepressantsTrazodone (100)87

AntidepressantsMianserin (10)185

Antidepressants

Amitriptyline (25)327

Antidepressants

Amitriptyline (50)380

Antihistamines

Fexofenadine0

Antihistamines

Loratadine (10)0Antihistamines

Terfenadine (60)0Antihistamines

Diphenhydramine (25)54

Antihistamines

Diphenhydramine (50)92Illicit Drugs

d-amphetamine (24.75)

0Illicit drugs

d-amphetamine (4.25)

0Illicit drugs

THC oral admin. (8.25)

0Illicit drugs

THC smoking (5)66Illicit drugs

THC oral admin. (13.5)

68

Illicit Drugs

THC smoking (13.5)

70

Illicit drugs

THC oral admin. (24.5)

215

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Appendix E: List of Drug Compounds Tested by Laboratory
This table shows all of the substances that were included in this research as
potentially impairing and which laboratories tested for which substances. Table E-1
shows that even in these exemplar laboratories, there are significant differences in
the quantity of tested substances. This is a key reason why laboratory results cannot
be aggregated into a single analysis. However, understanding which drugs were
tested at each laboratory helps with interpreting each laboratory’s results.

Alcohol (Ethanol)
Non-Ethanol
Alcohols

Alcohol (Ethanol)
Non-Ethanol Alcohols

Alcohol (Ethanol)•

Isoproanol••

Non-Ethanol Alcohols

Non-Ethanol Alcohols

MethanolCannabis

THC

Cannabinol

Cannabis

THC

Carboxy THC

Cannabis

THC

HydroxyTHC

•
•
•
•

Cannabis

THC

Delta-8-THC

Cannabis

THC

Delta-9-THC

Cannabis

Other Cannabinoids

Cannabidiol••

Antidepressants

Amitriptyline

•

•

•
•
•
•
•
•
•
•
•
•
•
•
•

•

Potentially Impairing
NeuropsychiatricMedications
Potentially Impairing NeuropsychiatricMedications

AntidepressantsBupropion

Potentially Impairing NeuropsychiatricMedications

AntidepressantsBupropionHydroxy

Potentially Impairing NeuropsychiatricMedications

AntidepressantsBupropion Metabolites

Potentially Impairing NeuropsychiatricMedications

AntidepressantsClomipramine

Potentially Impairing NeuropsychiatricMedications

AntidepressantsDesipramine

Potentially Impairing NeuropsychiatricMedications

Antidepressants

Doxepin

Potentially Impairing NeuropsychiatricMedications

Antidepressants

Duloxetine

Potentially Impairing NeuropsychiatricMedications

AntidepressantsImipramine

Potentially Impairing NeuropsychiatricMedications

AntidepressantsMirtazapine

Potentially Impairing NeuropsychiatricMedications

Antidepressants

Nefazodone

Potentially Impairing NeuropsychiatricMedications

AntidepressantsNorclomipramine

Potentially Impairing NeuropsychiatricMedications

AntidepressantsNordesmethylmirtazapine

Potentially Impairing NeuropsychiatricMedications

AntidepressantsNordoxepin

139

New York Laboratory

Compound Tested

San Francisco Laboratory

Drug Subcategory

Wisconsin Laboratory

Drug Category

Orange County Laboratory

Table E-1. List of drug compounds tested by each of the four laboratories.

•

•

•

•
•

•
•

•

•

•
•
•
•

•
•
•
•

•

Safety Research Report••

AntidepressantsProtriptyline

AntidepressantsTianeptine

Potentially Impairing NeuropsychiatricMedications

AntidepressantsTrazodone

Potentially Impairing NeuropsychiatricMedications

AntidepressantsVilazodone

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Carbamazepine

•
•
•
•
•

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Eslicarbazepine

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Gabapentin

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Hydroxycarbazepine

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Lacosamide

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Lamotrigine

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Levetiracetam

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Oxcarbazepine

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Phenytoin

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Pregabalin

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Primidone

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Topiramate

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

ValproicAcid

Potentially Impairing NeuropsychiatricMedications

Antiepileptics

Zonisamide

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Aripiprazole

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Cariprazine

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Chlorpromazine

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Clozapine

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Haloperidol

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Hydroxyrisperidone

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Loxapine

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Lurasidone

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Norclozapine

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Norquetiapine

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Olanzapine

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Prochlorperazine

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Quetiapine

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Risperidone

Potentially Impairing NeuropsychiatricMedications

Antipsychotics

Ziprasidone

Drug Subcategory

Potentially Impairing
NeuropsychiatricMedications(Continued)

Antidepressants(Continued)

Potentially Impairing NeuropsychiatricMedications
Potentially Impairing NeuropsychiatricMedications

140

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•
•
•
•
•
•

•
•
•
•
•
•
•
•
•
•
•

•
•
•
•
•
•
•
•
•
•
•

•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•

•

•

•

•
•
•

•

•

New York Laboratory

Wisconsin Laboratory

Nortriptyline

Drug Category

San Francisco Laboratory

Compound Tested

Orange County Laboratory

SRR-22-02

Safety Research Report

Compound Tested

Wisconsin Laboratory

Potentially Impairing
NeuropsychiatricMedications(Continued)

Anxiolytics

Buspirone••

Ropinirole••

Potentially Impairing NeuropsychiatricMedications

Narcotic Analgesics

Other Potentially
Impairing
NeuropsychiatricMedications
Non-Fentanyl Opioids

Narcotic Analgesics

Non-Fentanyl Opioids

Buprenorphine

Narcotic Analgesics

Non-Fentanyl Opioids

Buprenorphineglucuronide

Narcotic Analgesics

Non-Fentanyl Opioids

CodeineNarcotic Analgesics

Non-Fentanyl Opioids

Codeineglucuronide

Narcotic Analgesics

Non-Fentanyl Opioids

Desmetramadol

Narcotic Analgesics

Non-Fentanyl Opioids

Dihydrocodeine

Narcotic Analgesics

Non-Fentanyl Opioids

Dihydrocodeineglucuronide

Narcotic Analgesics

Non-Fentanyl Opioids

Diphenoxylate

Narcotic Analgesics

Non-Fentanyl Opioids

EDDP

Narcotic Analgesics

Non-Fentanyl Opioids

EMDP

Narcotic Analgesics

Non-Fentanyl Opioids

HeroinNarcotic Analgesics

Non-Fentanyl Opioids

Hydrocodone

Narcotic Analgesics

Non-Fentanyl Opioids

Hydromorphone

Narcotic Analgesics

Non-Fentanyl Opioids

Hydromorphoneglucuronide

Narcotic Analgesics

Non-Fentanyl Opioids

Isotonitazene

Narcotic Analgesics

Non-Fentanyl Opioids

Meperidine

Narcotic Analgesics

Non-Fentanyl Opioids

Methadone

Narcotic Analgesics

Non-Fentanyl Opioids

Morphine

Narcotic Analgesics

Non-Fentanyl Opioids

Morphineglucuronide

Narcotic Analgesics

Non-Fentanyl Opioids

Norbuprenorphine

Narcotic Analgesics

Non-Fentanyl Opioids

Norbuprenorphineglucuronide

Narcotic Analgesics

Non-Fentanyl Opioids

Norcodeine

Narcotic Analgesics

Non-Fentanyl Opioids

Norhydrocodone

Narcotic Analgesics

Non-Fentanyl Opioids

Normeperidine

Narcotic Analgesics

Non-Fentanyl Opioids

Noroxycodone

Narcotic Analgesics

Non-Fentanyl Opioids

Norpropoxyphene

Narcotic Analgesics

Non-Fentanyl Opioids

Nortramadol

Narcotic Analgesics

Non-Fentanyl Opioids

Oxycodone

Narcotic Analgesics

Non-Fentanyl Opioids

Oxymorphone

Brorphine

141

•
•
•
•
•
•
•
•
•
•
•
•
•
•

•
•
•
•

New York Laboratory

Drug Subcategory

San Francisco Laboratory

Drug Category

Orange County Laboratory

SRR-22-02

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•

•

•

•

•
•

•

•

•
•

•
•

•
•

•
•

•
•

•
•

•

•

•

•
•

•
•

•
•
•
•
•
•
•
•
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•
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Safety Research Report

New York Laboratory

San Francisco Laboratory

Wisconsin Laboratory

Orange County Laboratory

SRR-22-02

Drug Category

Drug Subcategory

Compound Tested

Narcotic Analgesics(Continued)

Non-Fentanyl Opioids(Continued)

Propoxyphene

Narcotic Analgesics

Non-Fentanyl Opioids

6-Acetylcodeine

Narcotic Analgesics

Non-Fentanyl Opioids

6-AM

Narcotic Analgesics

Non-Fentanyl Opioids

Tapentadol

Narcotic Analgesics

Non-Fentanyl Opioids

Tapentadolglucuronide

Narcotic Analgesics

Non-Fentanyl Opioids

TramadolNarcotic Analgesics

Fentanyls

Acetylfentanyl

Narcotic Analgesics

Fentanyls

Betahydroxyfentanyl

Narcotic Analgesics

Fentanyls

Carfentanil

Narcotic Analgesics

Fentanyls

Fentanyl

Narcotic Analgesics

Fentanyls

4-ANPP

Narcotic Analgesics

Fentanyls

Methoxyacetylfentanyl

Narcotic Analgesics

Fentanyls

Norfentanyl

Narcotic Analgesics

FentanylsoFF

Narcotic Analgesics

FentanylspFF

Narcotic Analgesics

Fentanyls

Valerylfentanyl

Hallucinogens

Hallucinogens

LSD

Hallucinogens

Hallucinogens

Mescaline

Hallucinogens

Hallucinogens

Psilocin

Inhalants

Inhalants

AcetoneInhalants

Inhalants

Difluoroethane

Inhalants

Inhalants

Toluene

•
•
•
•
•
•
•

Dissociative
Anesthetics

Dissociative
Anesthetics

GHB

•

•

•

Dissociative Anesthetics

Dissociative Anesthetics

Ketamine

Dissociative Anesthetics

Dissociative Anesthetics

Norketamine

Dissociative Anesthetics

Dissociative Anesthetics

Phencyclidine

•
•
•

•

•

Dissociative Anesthetics

Dissociative Anesthetics

Tenocyclidine

Sedatives

Barbiturates

Butalbital

Barbiturates

Phenobarbital

•
•
•
•
•
•
•
•

•
•
•

•
•
•

•

Sedatives
Sedatives

Benzodiazepines

Alprazolam

Sedatives

Benzodiazepines

Bromazepam

Sedatives

Benzodiazepines

Bromazolam

Sedatives

Benzodiazepines

Chlordiazepoxide

Sedatives

Benzodiazepines

Clobazam

Sedatives

Benzodiazepines

Clonazepam

142

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•
•
•
•
•
•
•
•
•
•

•
•

•

•

•
•
•
•
•
•

•
•

•
•

•

•

•
•
•
•
•

•

•
•

•
•
•
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•

Safety Research Report

Compound Tested

Wisconsin Laboratory

Sedatives(Continued)

Benzodiazepines(Continued)

Clonazolam••

Sedatives

Benzodiazepines

Delorazepam

Sedatives

Benzodiazepines

Demoxepam

Sedatives

Benzodiazepines

Diazepam

Sedatives

Benzodiazepines

Diclazepam

Sedatives

Benzodiazepines

Etizolam

Sedatives

Benzodiazepines

Flualprazolam

Sedatives

Benzodiazepines

Flubromazolam

Sedatives

Benzodiazepines

Flubromazepam

Sedatives

Benzodiazepines

Hyd-Flurazepam

Sedatives

Benzodiazepines

Hydroxyalprazolam

Sedatives

Benzodiazepines

Lorazepam

Sedatives

Benzodiazepines

Lorazepamglucuronide

Sedatives

Benzodiazepines

Lormetazepam

Sedatives

Benzodiazepines

Norchlordiazepoxide

Sedatives

Benzodiazepines

Nordiazepam

Sedatives

Benzodiazepines

Oxazepam

Sedatives

Benzodiazepines

Oxazepamglucuronide

Sedatives

Benzodiazepines

Phenazepam

Sedatives

Benzodiazepines

7-Aminoclonazepam

Sedatives

Benzodiazepines

Temazepam

Sedatives

Benzodiazepines

Temazepamglucuronide

Sedatives

Benzodiazepines

Triazolam

Sedatives

Muscle Relaxants

Baclofen

Sedatives

Muscle Relaxants

Carisoprodol

Sedatives

Muscle Relaxants

Cyclobenzaprine

Sedatives

Muscle Relaxants

Meprobomate

Sedatives

Muscle Relaxants

Metaxalone

Sedatives

Muscle Relaxants

Methocarbamol

Sedatives

Muscle Relaxants

Norcyclobenzaprine

Sedatives

Muscle Relaxants

Orphenadrine

Sedatives

Muscle Relaxants

Tizanidine

•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•

Sedatives

Sedating
Antihistamines

Brompheniramine•

Sedatives

Sedating Antihistamines

Cetirizine

Sedatives

Sedating Antihistamines

Chlorpheniramine

•
•

143

•
•
•
•
•
•

New York Laboratory

Drug Subcategory

San Francisco Laboratory

Drug Category

Orange County Laboratory

SRR-22-02

•

•

•
•

•
•

•
•

•
•
•

•
•

•
•

•
•

•
•

•
•

•

•

•

•

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•
•
•
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•
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•
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•

•

Safety Research Report

Compound Tested

Wisconsin Laboratory

Sedatives(Continued)

Sedating
Antihistamines(Continued)

Diphenhydramine••

Sedatives

Sedating Antihistamines

Doxylamine

Sedatives

Sedating Antihistamines

Hydroxyzine

Sedatives

Sedating Antihistamines

Meclizine•••

Sedatives

Sedating Antihistamines

Norchlorcyclizine

Sedatives

Sedating Antihistamines

Pheniramine

Sedatives

Sedating Antihistamines

Promethazine

Sedatives

Sleep Aids

Suborexant

•
•
•
•
•
•
•

Sedatives

Sleep Aids

Zaleplon

Sedatives

Sleep Aids

Zolpidem

Sedatives

Sleep Aids

Zopiclone

Sedatives

Stimulants

Other Sedatives(Phenibut)
Amphetamines

Stimulants

Amphetamines

Stimulants

Amphetamines

MDA

Stimulants

Amphetamines

MDMA

Stimulants

Amphetamines

Methylphenidate

Stimulants

Amphetamines

Phendimetrazine

Stimulants

Amphetamines

Phenmetrazine

Stimulants

Amphetamines

Phentermine

Stimulants

CocaineAEME

Stimulants

CocaineBenzoylecgonine

Stimulants

CocaineCocaethylene

Stimulants

CocaineCocaineStimulants

CocaineEEE

Stimulants

Cocaine

EME

Stimulants

Methamphetamines

Methamphetamine

Stimulants

Piperazines

Benzylipiperazine

Stimulants

Piperazines

mCPP

Stimulants

Piperazines

TFMPP

Stimulants

Other Stimulants

Modafinil

Other Stimulants

Phenylpropanolamine

Other Stimulants

Yohimbine

Stimulants
Stimulants••

Atomoxetine

144

•
•
•
•
•

•
•

•

•

•

•
•

•
•

•

Phenibut
Amphetamine

New York Laboratory

Drug Subcategory

San Francisco Laboratory

Drug Category

Orange County Laboratory

SRR-22-02

•
•
•
•
•
•

•
•
•
•
•

•
•
•
•
•
•
•
•
•
•
•

•

•
•

•
•
•

•
•
•

•
•
•

•

•

•

•
•

•
•

•
•

Safety Research Report

Drug Subcategory

Compound Tested

Novel Psychoactive
Substances

Synthetic
Cannabinoids

5F-MDMB-PICA•

Novel Psychoactive Substances

Synthetic Cannabinoids

Synthetic Cannabinoids•

Other Potentially
Impairing Drugs

Anticholinergics

Benztropine•

Anticholinergics

Dicyclomine

Other Potentially Impairing Drugs

Antiemetics

Metoclopramide••

Other Potentially Impairing Drugs

Methorphan

Dextromethorphan

Other Potentially Impairing Drugs

Methorphan

Dextorphan/Levorphanol

Other Potentially Impairing Drugs

Methorphan

Levorphanol

Other Potentially Impairing Drugs

Methorphan

Methorphan

Other Potentially Impairing Drugs

Migraine Medications

Sumatriptan

Other Potentially Impairing Drugs

Mitragynine

Mitragynine

Mitragynine

7-Hydroxymitragynine

Other Potentially Impairing Drugs

Other Potentially Impairing Drugs

145

•
•
•
•
•
•

•
•
•

•

•

New York Laboratory

Drug Category

San Francisco Laboratory

Wisconsin Laboratory

Orange County Laboratory

SRR-22-02

Safety Research Report
SRR-22-02

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The National Transportation Safety Board (NTSB) is an independent federal agency dedicatedto promoting aviation, railroad, highway, marine, and pipeline safety. Established in 1967, the agency is
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