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The Exaggerated Hazards of Marijuana & Driving
 

The Exaggerated Hazards of Marijuana & Driving

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    The Exaggerated Hazards of Marijuana & Driving The Exaggerated Hazards of Marijuana & Driving Presentation Transcript

    • The Exaggerated Hazards of 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! 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!
      Peak in THC Oral Dose
    • Odds Ratios of Accident Culpability for THC and Alcohol Culpability Odds Ratios Location #N Study Alcohol (>.08-.1%) THC ( only ) 1= Low Risk; 2-3 Moderate; >5 High Risk 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
    • 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 Initiative Will 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
    • Fatal Accident Rates by State - 2008 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 Marijuana Use Soars (Prop. 215) (Prohibition Repealed) => Fears of slaughter on the highway due to marijuana are unwarranted!