The Exaggerated Hazardsof Marijuana & Driving

NORML Conference Denver, April 23, 2011

By Dale Gieringer, Ph.D.

Director, California NORML

“Legalizing marijuana would mean slaughter on the highways”- Harry Anslinger, Federal Bureau of Narcotics Commissioner

Adverse Effects on Driving

Studies show MJ can impair:

Concentration

Complex reaction time

Peripheral vision

Steadiness of speed, distance

Decision making skills

Driving Tests Show Impairment from THC

Berghaus meta-analysis of 761 driving study tests:

• > 50% showed impairment from THC

• 3 showed improvement• Effects strongest for 2.5 hrs• Weaker effects to 4 hrs

70% impaired after 20-40 min.

Urine Tests Don’t Measure Impairment!

Excretion of THC-COOH in Urine (Immunoassay)

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From GM Ellis et al., Excretion patterns of cannabinoid metabolites after last use in a group of chronic users. Clin Pharmacol Ther 1985;38(5):572-578.)

Cannabis Doesn’t Show in Urine For Several Hours

Standard Cutoff= 50 ng/ml

High Blood THC Shows Recent Use

• Sharp THC peak in first <1 hour after smoking

• THC detectable >12 hrs at 1-3 ng

(6+ days in regular users)

• Oral THC slowly reaches low plateau of 5-10 ng/ml

• Blood THC does not track subjective effects!

Blood Levels of THC & Metabolite THC-COOH

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Peak in THC

Oral Dose

Odds Ratios of Accident Culpability for THC and Alcohol

New York 497 Terhune & Fell (1982) 5.7 2.1

California 440 Williams et al (1985) 5.0 0.2

U.S. 1,882 Terhune et al (1992) 5.7 0.7

Australia 1,045 Drummer (1994) 5.5 0.7

Australia 2,500 Hunter & Longo (1998/2000)

6.8 0.36 (<1 ng)

1.8 (>2ng)

Colorado 414 Lowenstein ((2001) 3.2 1.1 (urine)

Maryland 5,573 Soderstrom (2005) 7.45 1.2 (urine)

Australia 3,398 Drummer et al (2004) 6.0 2.7 (>1 ng

6.6 (>5 ng)

France 10,748 Laumon (2005) 3.0 - 6.2 (BAC≥.10)

2.01 (BAC≤.05)

1.78

U.S. 32,543 Bédard (2007) 8.51

3.3 (BAC≤05)

1.29

Culpability Odds Ratios Location #N Study Alcohol (>.08-.1%) THC (only)

1= Low Risk; 2-3 Moderate; >5 High Risk

Interpreting Drug Tests

• Urine metabolites not correlated to risk• THC ≤ 2-3 ng = no increased risk• THC in blood = Alcohol at .05% (moderate)• THC ≥ 5 ng ~ DUI

– With exceptions! (ADD patient w/ 71 ng in blood)

• THC + alcohol = high DUI risk

=> More marijuana use could raise or lower overall accident risk depending on whether it substitutes for alcohol.

Crancer Study: “Passage of California Cannabis InitiativeWill Increase Traffic Deaths: Marijuana May Overtake

Alcohol as a Major Contributing Factor in Fatal Crashes “

Source:Alfred & Alan Crancer: The Involvement of Marijuanain California Fatal Motor Vehicle Crashes 1998-2004

Marijuana involvement in fatal accidents up from <2% to >5% in CA

Jump in 2004

CA Auto Fatality Rates 1999-2008

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Fatal Accident Rates by State - 2008Montana 1 2.12Louisiana 2 2.03South Carolina 3 1.86West Virginia 4 1.82Arkansas 5 1.81Mississippi 6 1.79Kentucky 7 1.74Wyoming 8 1.68Alabama 9 1.63Nevada 10 1.56Oklahoma 11 1.55Arizona 12 1.52Idaho 13 1.52Florida 14 1.5Tennessee 15 1.5Texas 16 1.48Missouri 17 1.41North Carolina 18 1.4New Mexico 19 1.39Georgia 20 1.37Pennsylvania 21 1.36Delaware 22 1.35South Dakota 23 1.35Iowa 24 1.34North Dakota 25 1.33Kansas 26 1.29

Alaska 27 1.27Oregon 28 1.24Indiana 29 1.16Colorado 30 1.15Ohio 31 1.1Nebraska 32 1.09Maryland 33 1.07Maine 34 1.06New Hampshire 35 1.06Utah 36 1.06California 37 1.05Wisconsin 38 1.05Hawaii 39 1.04Vermont 40 1Virginia 41 1Illinois 42 0.98Michigan 43 0.96Connecticut 44 0.95Dist. Columbia 45 0.94Washington 46 0.94New York 47 0.92New Jersey 48 0.8Rhode Island 49 0.79Minnesota 50 0.78Massachusetts 51 0.67USA 1.26

State Rank Fatalities/100m mi.

Source: FARS http://www-fars.nhtsa.dot.gov/States/StatesFatalitiesFatalityRates.aspx

State Rank Fatalities/100m mi.

Green = Medical MJ States

Blue = Decrim, Non-MMJ States

U.S. Auto Fatality Rate Declined While Marijuana Use Soared in ‘60s & ‘70s

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US Auto Accident Fatality Rate 1921 - 2008Deaths/100 Million Vehicle Miles

Rate/Mile

Marijuana Use Soars

(Prop. 215)

(Prohibition Repealed)

=> Fears of slaughter on the highway due to marijuana are unwarranted!