Dennis V. Canfield

Kurt M. Dubowski

James E. Whinnery

Russell J. Lewis

Roxane M. Ritter

Civil Aerospace Medical Institute

Federal Aviation Administration

Oklahoma City, OK 73125

June 2009

Final Report

Increased Cannabinoids Concentrations

Found in Specimens From Fatal Aviation

Accidents Between 1997 and 2006

DOT/FAA/AM-09/12

Office of Aerospace Medicine

Washington, DC 20591

OK-09-0434-JAH

Federal Aviation

Administration
NOTICE

This document is disseminated under the sponsorship 

of the U.S. Department of Transportation in the interest 

of information exchange. The United States Government 

assumes no liability for the contents thereof.

___________

This publication and all Office of Aerospace Medicine 

technical reports are available in full-text from the Civil 

Aerospace Medical Institute’s publications Web site: 

www.faa.gov/library/reports/medical/oamtechreports


Technical Report Documentation Page 

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. 

DOT/FAA/AM-09/12 

4. Title and Subtitle 5. Report Date 

Increased Cannabinoids Concentrations Found in Specimens From Fatal June 2009 

Aviation Accidents Between 1997 and 2006 6. Performing Organization Code 

 

7. Author(s) 8. Performing Organization Report No. 

Canfield DV, Dubowski KM, Whinnery JE, Lewis RJ, Ritter RM 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 

 

11. Contract or Grant No. 

FAA Civil Aerospace Medical Institute 

P.O. Box 25082 

Oklahoma City, OK 73125 

12. Sponsoring Agency name and Address 13. Type of Report and Period Covered 

 

 

 

Office of Aerospace Medicine 

Federal Aviation Administration 

800 Independence Ave., S.W. 

Washington, DC 20591 14. Sponsoring Agency Code 

15. Supplemental Notes 

Work was accomplished under approved task AM-B-09-TOX-206. 

16. Abstract 

The Civil Aerospace Medical Institute’s toxicology laboratory receives biological specimens from more than 90% 

of all fatal aviation accidents that occur in the United States and its territories. As a part of the routine analysis of 

pilot specimens, the laboratory tests all cases for the presence of marijuana (cannabis). The National Institute on 

Drug Abuse (NIDA) and the Office of National Drug Control Policy (ONDCP) reported a 1.5-fold increase in 

the delta-9-tetrahydrocannabinol (THC) content of street cannabis seizures from1997-2001 to 2002-2006. This 

study was conducted to compare the changes, over those years, in blood and urine cannabinoid concentrations 

with the potency of THC reported in the cannabis plant. In our laboratory, cannabinoids are screened using 

radioimmunoassay (RIA) for blood and fluorescence polarization immunoassay (FPIA) for urine and confirmed 

using GC/MS. A total of 95 individuals were found to be using cannabis from a total number of 2769 (3.4%) 

individuals tested over the period 1997 through 2006. Blood was received for analysis from 1676 fatally injured 

individuals. Urine was received for analyses from 1650 fatalities. Cannabinoids were found in 88 of the 1676 

(5.3%) blood specimens received for analysis, and 64 of the 88 were from pilots. Cannabinoids were found in 68 

of the 1650 (4.1%) urine specimens received for analysis, and 57 of the 68 were from pilots. Other impairing 

drugs were found in 39% of the cannabinoids-positive individuals. The mean concentration of THC in blood 

for 1997-2001 was 2.7 ng/mL; for 2002-2006, it was 7.2 ng/mL, a 2.7-fold increase in the mean THC 

concentration of specimens from aviation fatalities, compared to a 1.5-fold increase in cannabis potency reported 

by the NIDA and ONDCP over the 10 years of this study. The median age for cannabis users was 42 years 

(range 18-72) for aviation fatalities. For all blood and urine specimens tested from aviation fatalities, the mean 

age of the individuals with negative test results was 50 years (range 14-92). More than half of the fatalities tested 

were 50 years or older, whereas 80% of the positive cannabis users were under 50. THC concentrations in blood 

ranged from 0 ng/mL to 68 ng/mL, with a mean concentration of 5.5 ng/mL. Concentrations of 11-nor-9-

carboxy-THC (THC-COOH) found in blood ranged from 0 ng/mL to 179 ng/mL, with a mean concentration 

of 17.5 ng/mL. Urine concentrations for THC-COOH ranged from 2 to 1,113 ng/mL, with a mean 

concentration of 137.9 ng/mL. 

 

17. Key Words 18. Distribution Statement 

 

 

Cannabis, Cannabinoids, Trends, Aviation, Potency, 

Concentration

Document is available to the public through the 

Defense Technical Information Center, Ft. Belvoir, VA 

22060; and the National Technical Information 

Service, Springfield, VA 22161 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price 

Unclassified Unclassified 16 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

iii

Acknowledgments

We thank the Federal Aviation Administration Office of Aviation Accident Investigation and the 

Office of Aerospace Medicine for sponsoring this research.

Contents

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Materials and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Increased Cannabinoids Concentrations Found in Specimens

From Fatal Aviation Accidents Between 1997 and 2006

Introduction

Although it remains the most commonly used illicit 

drug in the United States cannabis use has declined 

slightly over the past 10 years.1, 2 However, the potency 

of cannabis, as measured by delta-9-tetrahydrocannabinol 

(THC) concentrations, has nearly doubled from 1997 

to 2006.3 This increased potency could result in higher 

concentrations of THC and incidence of impairment in 

persons working in the transportation industry. It has 

also been reported that marijuana use disorders among 

cannabis users, which are already the most prevalent illicit substance use disorders in the population, increased 

significantly (P=0.002) between 1991-1992 and 2001-

2002 in the absence of increased frequency and quantity 

of cannabis use, suggesting that concomitant increased 

cannabis potency may have contributed to the rising rates 

of cannabis use disorders.4

Recent studies have shown that cannabis users choose 

to smoke high-potency cannabis more often than lowpotency cannabis.5 High-potency cannabis users will 

generally increase their average THC intake.6 There are 

contradictory reports that subjects do not regulate their 

cannabis smoke intake in response to changes in cannabis 

potency7 and that they do titrate their intake.8 If cannabis 

users do titrate the amount of cannabis used based on its 

potency, one would not expect a significant increase in the 

concentration of cannabinoids found in blood samples 

collected over a 10-year period during which the potency 

of the cannabis significantly increased. 

Most of the earlier performance studies used lowpotency cannabis, compared to the potency of cannabis 

available today, and probably do not reflect the performance impairment potential of high-potency cannabis.9

Studies conducted with high-potency cannabis have 

demonstrated consistent impairment of executive function, tracking performance, and motor impulse control.6

The impairment was shown to last for up to 6 hours after 

smoking. There is other recent evidence that the use of 

cannabis is not harmless.4,10,11

Research has shown that THC concentrations in blood 

between 3.5-5.0 ng/mL (plasma 7-10 ng/mL) have an 

impairing effect on drivers equivalent to a blood alcohol 

concentrations 0.05%.12 The FAA prohibits pilots from 

operating an aircraft with blood alcohol concentrations 

at or above 0.04%. That raises the question of how many 

aviation accidents are found with pilots having blood 

THC concentrations at or above the impairing range, 

compared to fatal aviation accidents that occurred prior 

to the availability of high-potency cannabis.

This study was undertaken to compare the change 

in reported cannabis potency with changes in the concentrations of THC and its 11-nor-9-carboxy-THC

(THC-COOH) metabolite found in urine and blood 

from fatal aviation accidents during the period from 

1997 to 2006.

Materials and Methods

The Civil Aerospace Medical Institute (CAMI) receives biological fluids and tissues for toxicology analysis from all aviation accidents that occur nationwide. 

Blood specimens received from pilots are screened for 

THC-COOH by radioimmunoassay (RIA) and urine 

specimens by fluorescence polarization immunoassay 

(FPIA). Solid phase extraction is used to isolate THC and 

THC-COOH from blood and urine. The confirmation 

and quantitation of THC-COOH in urine is performed 

using gas chromatography and electron impact mass spectrometry (GC/MS). THC and THC-COOH in blood 

are confirmed and quantitated by negative-ion chemical 

ionization GC/MS, based on a modification of a procedure published in 1983.13The procedure used to analyze 

cannabinoids includes deuterated internal standards and 

has a limit of detection and a limit of quantitation of 1 

ng/mL in blood and urine. 

A 10-year period from 1997 to 2006 was selected for 

this study to correlate with data reported by the National 

Institute on Drug Abuse (NIDA) and the Office of 

National Drug Control Policy (ONDCP) on cannabis 

potency.3Cannabinoids concentrations in blood and urine 

were compared with the reported potency of cannabis 

during the same time period.

Results

The principal findings of this study are contained 

in Tables 1-6. From 1997 through 2006, a total of 95 

(3.4%) individuals where found to have used cannabis 

of 2769 individuals tested. Of the 95 cannabinoids-
Table 1. Demographics of the Study Subjects and Number of 

Cannabinoids-Positive and Negative Results.

Category N Age Mean SD Age Median Age Range

Males Positive 87 40 12 42 18-72

Males Negative 2543 50 15 51 14-92

Total 2630 50 15 50 14-92

Females Positive 8 36 9 39 24-45

Females Negative 120 44 15 44 17-77

Total 128 44 15 44 17-77

Undesignated Positive 0 NA NA NA NA

Undesignated Negative 11 36 9 39 19-44

Total 11 36 9 39 19-44

All Total Positive 95 40 12 42 18-72

All Total Negative 2674 50 15 51 14-92

All Total 2769 49 15 50 14-92

Table 2. Cannabinoids-Positive Results in Blood by Year of Study.

ǻ9 THC ng/mL Blood TCH-COOH ng/mL Blood

Year N Mean SD Median Span Mean SD Median Span

1997 9 1.3 2.6 0.0 0.0-8.0 11.6 13.0 9.0 1.0-41.0

1998 7 0.9 1.9 0.0 0.0-5.0 4.7 4.2 2.0 1.0-11.0

1999 7 3.1 4.3 2.0 0.0-12.0 14.7 15.5 11.0 1.0-42.0

2000 8 3.9 4.7 2.0 0.0-13.0 9.1 16.2 2.0 1.0-48.0

2001 9 4.2 7.3 1.0 0.0-19.0 18.1 21.1 6.0 1.0-53.0

2002 6 1.0 2.0 0.0 0.0-5.0 3.8 4.8 1.0 0.0-11.0

2003 19 7.8 16.3 2.0 0.0-68.0 11.0 7.4 12.0 1.0-22.0

2004 7 9.9 15.4 2.0 0.0-37.0 20.9 32.5 10.0 1.0-92.0

2005 7 2.7 2.4 2.0 0.0-7.0 25.9 44.1 8.0 1.0-122.0

2006 9 14.8 20.5 5.0 2.0-65.0 56.0 67.3 28.0 8.0-179.0

Totals 88 5.5 11.7 1.5 0.0-68.0 17.5 30.6 8.5 0.0-179.0

Table 3. Cannabinoids-Positive Results in Urine by Year of Study.

TCH-COOH ng/mL Urine

Year N Mean SD Median Span

1997 10 98.0 211.8 26.0 2.0-695.0

1998 6 31.5 36.6 14.0 3.0-100.0

1999 8 98.5 161.5 43.5 10.0-493.0

2000 5 68.0 57.2 37.0 18.0-147.0

2001 6 142.0 131.1 83.0 40.0-388.0

2002 6 52.2 47.1 41.5 9.0-142.0

2003 11 113.9 178.6 29.0 3.0-600.0

2004 3 316.7 465.1 86.0 12.0-852.0

2005 6 182.2 203.8 87.0 31.0-543.0

2006 7 373.9 382.7 308.0 8.0-1113.0

Totals 68 137.9 218.9 45.5 2.0-1113.0
Table 4. Summary of Results in Urine for Cannabinoids and Other Impairing

 Drugs by Year of Study.

CasesTested Negative Positive Cannabinoids

Year for Cannabinoids Cannabinoids Cannabinoids & Other Drugs

1997 191 181 10 5

1998 176 170 6 2

1999 162 154 8 2

2000 163 158 5 2

2001 162 156 6 1

2002 150 144 6 1

2003 187 176 11 4

2004 159 156 3 3

2005 163 157 6 3

2006 137 130 7 3

Totals 1650 1582 68 26

Table 5. Summary of Results in Blood for Cannabinoids and Other 

Impairing Drugs by Year of Study.

Positive

CasesTested Negative Positive Cannabinoids

Year for Cannabinoids Cannabinoids Cannabinoids & Other Drugs

1997 178 169 9 5

1998 140 133 7 2

1999 165 158 7 2

2000 163 155 8 3

2001 157 148 9 1

2002 168 162 6 1

2003 197 178 19 9

2004 179 172 7 5

2005 167 160 7 2

2006 162 153 9 5

Totals 1676 1588 88 35

Table 6. Ratio of Blood to Urine Cannabinoids.

Urine-Range Mean Blood Mean Blood Mean Urine Blood/Urine Blood THC

ng/mL THC THC-COOH THC-COOH THC-COOH /Urine

THC-COOH

0-9.0 0.8 3.5 4.9 1 6 8

10-14.0 5 4 12.1 3 2 8

Mean 2.9 3.8 8.5 2 4 8

SD 3.0 0.4 5.1 1.4 2.8 0

15.0-30.0 1.9 1.9 21.8 11 11 8

31.0-60.0 1 6.4 40.5 6 41 12

61.0-100.0 1.1 10.6 82.2 8 75 13

100.0-400.0 3.4 17.4 201.1 12 59 11

400.0-1113.0 13 55.4 662.3 12 51 8

Mean 4.1 18.3 201.6 9.8 47.4 10

SD 5.1 21.5 266.8 2.7 23.8 2.3

N
positive ­individuals, 39% were also found positive for 

other impairing drugs. Blood was received for analysis 

from 1676 fatalities. Urine was received for analysis from 

1650 fatally injured individuals. Cannabinoids were found 

in 88 (5.3%) of the 1676 blood specimens received for 

analysis, and 64 of these were from pilots. Cannabinoids 

were found in 68 (4.1%) of the 1650 urine specimens 

received for analysis; 57 of these were from pilots. 

The median age for cannabis users was 42 years among 

the fatally injured aviation individuals, with a range from 

18 to 72 (Figure 1). For negative cannabinoids in blood 

and urine specimens tested, the median age was 50 years, 

with a span from 14 to 92. More than half of the fatally 

injured persons tested were 50 years or older, whereas 

80% of the cannabis users were under 50.

THC concentrations in blood ranged from 0 to 

68ng/mL, with a mean of 5.5 ng/mL. THC-COOH

concentrations in blood ranged from 0 to 179 ng/mL, 

with a mean of 17.5 ng/mL. Urine concentrations of 

THC-COOH ranged from 2 to 1,113 ng/mL, with a 

mean of 137.9 ng/mL. 

Between 1997 and 2001, 8 positive THC cases of 55 

positive cannabinoids cases in blood were at or above 3.5 

ng/mL, while 20 of the reported 51 positive cannabis 

cases in blood from 2002 to 2006 were at or above 3.5 

ng/mL. This is more than a two-fold increase over those 

years with lower cannabis potency.

The data indicated an approximately 1/10 blood/urine 

THC-COOH ratio for urine THC-COOH concentrations above 15 ng/mL. For urine THC-COOH concentrations at or below 15 ng/mL, there was an approximately 

1/2 blood/urine THC-COOH ratio. The ratio of the 

mean blood THC concentration to the mean urine 

THC-COOH concentration for urine specimens with 

THC-COOH concentrations at or below 15 ng/mL was 

1/3 and 1/50 for concentrations above 15 ng/mL.

The mean concentration of THC in blood for the 

period 1997-2001 was 2.7 ng/mL it was 7.2 ng/mL for 

2002-2006, a 2.7-fold increase in the mean THC concentration of specimens from aviation fatalities. The annual 

mean THC concentration found in blood increased from 

1.3 ng/mL in 1997 to 14.8 ng/mL in 2006, an 11.3-fold 

increase. The annual maximum THC concentration 

found in blood increased from 8 ng/mL in 1997 to 65 

ng/mL in 2006, an 8.1-fold increase.

The mean concentration of THC-COOH in blood 

for the period 1997-2001 was 11.6 ng/mL, and for 2002-

2006 it was 23.5 ng/mL, a 2.0-fold increase in the mean 

THC-COOH concentration of specimens from aviation 

fatalities. The annual mean THC-COOH concentration 

found in blood increased from 11.6 ng/mL in 1997 to 

56.0 ng/mL in 2006, a 4.8-fold increase. The annual 

maximum THC-COOH concentration found in blood 

increased from 41 ng/mL in 1997 to 179 ng/mL in 2006, 

a 4.4-fold increase.

Urine specimens were received from 740 fatally injured 

pilots designated as airline transport or commercial pilots, 

and 14 (1.9%) of the commercial pilot cases exceeded 

the DOT workplace drug testing urine THC-COOH

confirmation threshold (15 ng/mL).14

No cannabinoids were found in specimens from the 

airline transport pilots tested. Eight (57%) fatally injured 

commercial pilots (including agricultural pilots) found 

with a urine THC-COOH in excess of the DOT workplace drug testing urine threshold were flying private 

planes. Urine specimens from fatally injured agricultural 

pilots (Part 137) were found to exceed the DOT workplace drug testing threshold THC-COOH in 5 (36%) 

Figure 1. Graphic display of age distribution for all fatal pilots and cannabis users. 

0

100

200

300

400

500

600

700

800

10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-92 Unk

Age

Neg

0

5

10

15

20

25

30

35

Pos Neg

Pos
of the THC-COOH positive cases. One fatally injured 

commercial air taxi pilot (Part 135) was found to exceed 

the DOT workplace drug testing urine threshold for 

THC-COOH.

In the present study, 61 of 2,769 cases (2.2%) were 

found to have ethanol at or above 40 mg/dL (0.04%) 

in blood or urine.

Discussion

The 2.7-fold increase in the mean blood THC concentration found in this study for the 1997-2001 and 

2002-2006 periods compares to a 1.5-fold increase in 

the mean THC concentration of cannabis reported by 

the National Drug Intelligence Center (NDIC) for the 

1997-2001 and 2002-2006 periods. The reasons for 

this difference are presently unknown. The analytical 

toxicology procedures for THC and THC-COOH used 

at CAMI remained the same during the period of this 

study, as did the quality assurance and quality control 

procedures, including internal and external “blind” performance testing.

In 2006, 0.05 % of the individuals (flight crewmembers) tested in the FAA aviation industry random drug 

testing program were found to be positive for marijuana;15

6.0% of the commercial pilots tested in the CAMI forensic 

drug testing laboratory (fatal aviation accident pilots) were 

positive for THC-COOH at or above the threshold of 15 

ng/mL THC-COOH in urine . The commercial pilots 

tested in the CAMI forensic toxicology department for 

2006 were flying private planes (Part 91) or crop dusters 

(Part 137). Not all commercial pilots (agricultural pilots, 

for example) are required to participate in the random 

drug testing program. 

Government agencies and the scientific literature repeatedly reported that the potency of cannabis has been 

increasing over the 10 years of this study.3, 16, 17The mean 

concentration of THC in blood specimens from fatal 

aviation accidents tested by CAMI has also increased 

over the last 10 years, but at a greater rate than marijuana 

potency (Figure 2). Research conducted in Sweden also 

found an increase in the mean concentration of THC in 

blood from 1.8 to 2.3 ng/mL in a 10-year (1995-2004) 

study of drug impaired drivers.18

Controlled laboratory experiments on driving-related 

skills reported in the literature have shown that THC

concentrations between 2 and 5 ng/mL in whole blood 

are associated with driver impairment.19 Serum THC

concentrations between 7-10 ng/mL (whole blood, approximately 3.5-5.0 ng/mL) have been compared to a 

blood alcohol concentration of 0.05%,12 which exceeds 

the DOT alcohol threshold of 0.04% (BAC) for transportation workers in safety-sensitive positions. It is clear 

that the use of high-potency cannabis could significantly 

alter the performance of an individual, assuming the blood 

THC concentrations increase correspondingly.

In a study in Norway, 589 (2.0%) samples of approximately 30,000 samples from impaired drivers were 

found to contain only THC as the impairing drug.20The 

Norway epidemiological study indicated an association 

of driving impairment in individuals at or above 2.5 ng/

mL THC in blood and found no impairment at blood 

THC concentrations at or below 1.9 ng/mL in suspected 

drugged drivers.20This is consistent with earlier findings 

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

ng/mL and % THC

Plant THC

Blood THC

 Note: Blood THC results for 2002 and 2005 were removed as outliers from this graph. 

Figure 2. Increase in blood THC (ng/mL) and cannabis potency (% THC) 1997-2006. 
of a linear, dose-related, physiological response to THC.

21

“Furthermore, drivers with blood THC concentrations 

above 3 ng/mL had an increased risk for being judged 

impaired compared to drivers with lower concentration 

ranges . ”20 In our research, we found that approximately 

46 % (22/48) of the blood samples positive for THC

from 2002-2006 had concentrations of THC greater 

than 3.5 ng/mL, whereas only 25 % (10/40) exceeded 

that concentration between 1997 and 2001. 

Although there were only 95 cannabinoids-positive 

cases reported in this study, cannabis use may be more 

prevalent in the driving population and in other modes 

of transportation. A 10-year study from 1995 to 2004 of 

drug impaired drivers in Sweden found that 8,794 drivers had THC in their blood;18 constituting a proportion 

rising from 18 to 29 % of all tested specimens during 

that decade. This suggests that the prevalence of THC

in the driving population is far higher than we found in 

aviation fatalities. 

A study of 1,079 commercial tractor-trailer drivers in 

the State of Washington found that 4.3% of the drivers 

were using cannabis, while 1.3 % of the drivers were 

using alcohol;22 cannabis use in truck drivers was 3.3 

times as prevalent as alcohol use in this 2002 report.22

In our study of aviation fatalities cannabis use was found 

to be 1.7 times greater than alcohol use at or above 40 

mg/dL in blood or urine. These findings are contrary to 

the widely held perception that alcohol is the most commonly abused drug in transportation. It is also important 

to recognize that some of the alcohol positive cases found 

in aviation fatalities in this study could have been the 

result of postmortem ethanol formation.23

Cannabis use in conjunction with other impairing substances such as alcohol has been reported to significantly 

increase the driving impairment of an individual and to 

cause impairment by cannabis at much lower concentrations than 3.5 ng/mL of THC in whole blood.24 This 

study found that 39% of the positive cannabinoids cases 

were also positive for other impairing substances. 

In a study of THC positive drivers in Sweden, the 

mean age was reported as 33 years, with a range of 15-66 

years.18 In our study, the mean age for cannabis users was 

40 years for aviation fatalities, with an age range of 18-

72. For all blood and urine specimens tested at CAMI, 

the mean age was 50 years with a range of 14-92. More 

than half of all fatally injured individuals tested were 50 

years, or older; however, 80% of the cannabinoids users 

were under 50. It appears from these data that younger 

individuals were more likely to be using cannabis in 

aviation, just as in the general population. The driving 

population is younger than the flying population, and 

would be more likely to use cannabis and be subject to 

impairment from the effects of high-potency cannabis. 

The percentage of cannabis users in motor vehicle accidents could be greater than that found in fatal aviation 

accidents because of the age differences between drivers 

and pilots, among other factors.

Conclusions

Members of the transportation industry, government 

regulators, and the general public should be informed of 

the increased potential for impairment from the use of high 

potency cannabis currently available and being used.

Further research should be conducted in other modes 

of transportation to determine the full extent of this trend 

and its overall impact on transportation accidents.

The typical distribution of THC-COOH in blood/

urine for urine concentrations of THC-COOH above 15 

ng/mL is approximately 1/10. For THC-COOH urine 

concentrations at or below 15 ng/mL, the blood/urine 

distribution was approximately 1/2.

From the data in this study, the number of potentially 

THC-impaired individuals involved in fatal aviation accidents increased 1.8 times from 1997 to 2006, reflecting 

the increased number of individuals with concentrations 

above the reported impairing concentration of THC in 

blood. Together with the other literature reports cited, 

this suggests that enhanced counter-measures may be warranted to reduce the use of cannabis by persons involved 

in transportation. 

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1. Results from the 2006 National Survey on Drug Use 

and Health: National Findings. In: SAMHSA, Rockville, MD: Office of Applied Studies; 2007:16-25.

2. Marijuana: The greatest cause of illegal drug abuse. In: 

ONDCP, ed. Marijuana Sourcebook. Vol 2008:2-3.

3. National Drug Control Strategy. Data supplement 

2008. In: ONDCP, ed: Executive Office of the 

President; 2008:66.

4. Compton WM, Grant BF, Colliver JD, Glantz MD, 

Stinson FS. Prevalence of marijuana use disorders 

in the United States: 1991-1992 and 2001-2002. 

Journal of the American Medical Association. May 5 

2004;291(17):2114-21.

5. Chait LD, Burke KA. Preference for high- versus 

low-potency marijuana. Pharmacology, Biochemistry, 

and Behavior. Nov 1994;49(3):643-7.
6. Ramaekers JG, Kauert G, van Ruitenbeek P, 

Theunissen EL, Schneider E, Moeller MR. Highpotency marijuana impairs executive function and 

inhibitory motor control. Neuropsychopharmacology. 

Oct 2006;31(10):2296-2303.

7. Chait LD. Delta-9-tetrahydrocannabinol content 

and human marijuana self-administration. Psychopharmacology. 1989;98(1):51-5.

8. Reinarman C. Cannabis policies and user practices: 

Market separation, price, potency, and accessibility 

in Amsterdam and San Francisco. The International 

Journal on Drug Policy. Mar 24 2008:1-10.

9. Ashton CH. Pharmacology and effects of cannabis: a brief review. British Journal of Psychiatry. Feb 

2001;178:101-6.

10. Solowij N, Stephens RS, Roffman RA, et al. Cognitive functioning of long-term heavy cannabis users 

seeking treatment. Journal of the American Medical 

Association. Mar 6 2002;287(9):1123-31.

11. Teen marijuana use worsens depression: An analysis 

of recent data shows “self medication” could actually make things worse. In: ONDCP, ed: Executive 

Office of the President; 2008:1-7.

12. Grotenhermen F, Leson G, Berghaus G, et al. 

Developing limits for driving under cannabis. Addiction (Abingdon, England). December 

2007;102(12):1910-7.

13. Foltz RL, McGinnis KM, Chinn DM. Quantitative measurement of delta 9-tetrahydrocannabinol 

and two major metabolites in physiological specimens using capillary column gas chromatography 

negative ion chemical ionization mass spectrometry. 

Biomedical Mass Spectrometry. May 1983;10(5):316-

23.

14. What are the cutoff concentrations for initial and 

confirmation tests. In: DOT, 49CFR40.87. 10–1–

07 ed.: U.S. Federal Government; 2007:564.

15. Random drug and alcohol testing percentage rates 

of covered aviation employees for the period of 

January 1, 2008 through December 31, 2008. In: 

DOT, 72. Federal Register; 2007:67994.

16. ElSohly MA, Ross SA, Mehmedic Z, Arafat R, Yi

B, Banahan BF, 3rd. Potency trends of delta9-THC

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