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Barry K Logan
Chief of Forensic Toxicology
NMS Labs
Willow Grove PA
Marijuana and its Effects on Driving
Medical Versus Recreational Cannabis
• Typical Recreational Doses (Ramaekers)
• 200-300ug/Kg THC
• ~14-21mg THC in a 150lb person
• ~0.1 - 0.2g 10% THC plant material
• Medical dosing guidelines (Aggarwal, Kahan)
• Federal Single Patient Dosage 8.24g/day
• ~0.2g THC/dose QID (Aggarwal)
• ~0.02g THC/dose QID (Kahan)
Cannabinoid Effects
Cannabinoid Pharmacology
• Cannabis used >4000 yrs for
euphoric & therapeutic effects
• Marijuana, hashish, sinsemilla
• >500 chemicals & at least 109
cannabinoids:
• THC (major psychoactive component)
• cannabinol (10% as psychoactive as THC)
• cannabidiol (non-psychoactive)
• Ratios of cannabinoids & potency vary
based on age, geographical origin, genus
& method of cultivation (hydroponics) M Huestis
The CB-1 Receptor
Creative Commons
CerebellumMovement
Basal GangliaMovement Cerebral Cortex
Higher cognitive function
HippocampusLearning. Memory, stress
Spinal cordPeripheral sensation/pain
HypothalamusAppetite
MedullaNausea/vomiting, CTZ
Cannabinoid Pharmacology
Acute Physiological Effects
• Rapid Heart Rate
• Bloodshot Eyes
• Dry Mouth
• Increased appetite
• Decreased respiratory rate
• Analgesia
• Vasodilation
• Bronchodilation
Cannabinoid Pharmacology
Acute Psychoactive Effects
• Euphoria
• Relaxation/Stress Reduction
• Enhanced Perception
• Music, Humor, Arts
• Increased Creativity/Abstract Thinking/Sensuality
• Illusions/Pseudohallucinations
• Time Distortion
• Ataxia
• Anxiety, Paranoia, Illusions, Depersonalization
Cannabis and Impairment
Acute Cognitive Effects:
�Concentration and sustained attention/vigilance.
�Fatigue, sleepiness, lethargy, memory problems.
�Reaction time
�Difficulty in thinking and
problem-solving.
�Difficulty in registering,
processing, and using
information.
Cannabis and Impairment
Psychomotor Aspects
�Decreased motor coordination
�Slurred speech
�Dizziness
�Impairment in reaction time
and tracking.
Cannabis and Driving
Driving Deficits
�Attention
�Vigilance
�Arousal
�Weaving
� Impulsivity
�Reaction Time
Cannabis and Driving
• Experimental Evidence• THC’s impairing effects increase with task complexity.
• Unexpected circumstances and choice during otherwise
monotonous driving cause increased risk for errors over
non-cannabis using controls.
• Reaction time, road tracking, weaving, steering wheel
variability, and brake latency all increase with recent
cannabis exposure.
• THC effects on cognitive performance following smoking
include immediate recall, executive functioning, working
memory and attention.
• Crash risk results are mixed
Hartman RL, Huestis MA. Cannabis effects on driving skills. Clin Chem. 2013 Mar;59(3):478-92.
Cannabinoid Pharmacokinetics
Route of Administration
• Products:
• Plant material
• Hashish
• Concentrates: Oil/BHO/Glass Shatter
• Route:
• Cigarettes/Joints/Blunts
• Smoking/Vaping – Pens, Volcano, etc
• Oral – Capsules, Syringes, Baked Goods, candy, etc
Smoked/Vaped Cannabis
Smoked THC Time-Concentration Curve
Courtesy Marilyn Huestis, Borkenstein Drug Course, 2012
• THC Concentrations peak within minutes of last inhalation, and fall rapidly as the drug distributes.
Factors Affecting Peak/Concentration
• Smoked Dose
• Potency of marijuana
• Amount smoked
• Duration and frequency of smoking/inhalation
• Depth of inhalation/breath holding
• Body Fat
• Co-ingestion with alcohol or other drugs
• Time between smoking and blood draw
Smoked/Vaped Cannabis
Smoked THC Time-Concentration Curve
Courtesy Marilyn Huestis, Borkenstein Drug Course, 2012
• There is substantial inter-subject variability in peak THC concentration based on smoking technique, body fat, metabolism
Smoked/Vaped Cannabis
Visual Analog Scale Composite Stoned, High, Strength (n=63)
Smoked/Vaped Cannabis
Feel-Drug Visual Analog Scale
Oral Cannabis
• Products are not
accurately
labeled for dose
• No ability to
titrate dose
• THC
concentrations
peak at 4-5 hours
• Blood THC levels
are extremely
low, while
impairment is
severe
Cone E, NSC Congress, Atlanta, 2015
THC in DUID
Cannabis and Driving
Driving Deficits
�Attention
�Vigilance
�Arousal
�Weaving
� Impulsivity
�Reaction Time
Cannabinoid Concentrations
• There is no good evidence linking specific THC
thresholds in blood to a degree of impairment
• Studies that have established effect thresholds collect
blood samples during driving or from fatally injured drivers.
• Enforcement blood samples are typically collected
45 minutes to 2 hours after alleged impaired driving.
• THC concentrations change dramatically over 30 minutes,
and can’t reliably be extrapolated to the time of driving.
• Blood concentrations do not approximate the
concentrations in the brain, especially after oral ingestion
• A threshold of 1, 2, or 5ng/mL at the time of test is not
evidence of impairment at the time of driving
Real World Cannabinoid Concentrations
Driving
Smoking
40
30
20
10
Arrested
Tested
Current Per Se Laws for Cannabis
StateStateStateState ThresholdThresholdThresholdThreshold Year PassedYear PassedYear PassedYear Passed
AZ ZT, incl mets 1990
COCOCOCO 5ng/mL5ng/mL5ng/mL5ng/mL, THC (permissible inf.) 2012
DE ZT, excl mets 2007
IL ZT, incl mets 1997
IN ZT, incl mets 2001
IA Urine per se 1998
MI ZT, excl mets 2003
MTMTMTMT 5ng/mL 5ng/mL 5ng/mL 5ng/mL THC 2013
NVNVNVNV 2ng/mL2ng/mL2ng/mL2ng/mL THC, mets 2003
NC ZT, U21, excl mets. 2003
OHOHOHOH 2ng/mL2ng/mL2ng/mL2ng/mL THC, mets 2006
OK ZT, incl mets 2013
PAPAPAPA 1ng/mL1ng/mL1ng/mL1ng/mL, incl mets 2004
RI ZT, incl mets 2006
SD ZT, U21, incl mets 1998
UT ZT, incl mets 1994
WAWAWAWA 5ng/mL 5ng/mL 5ng/mL 5ng/mL THC 2012
WI ZT, excl mets. 2003
*ZT: Zero tolerance means any
detectable amount or amount
established based on laboratory
protocol.
2014: 17 states have per se
StateStateStateState ThresholdThresholdThresholdThreshold
WA, CO, MT 5ng/mL
NV, OH 2ng/mL
PA 1ng/mL
Current Per Se Laws for Cannabis
StateStateStateState ThresholdThresholdThresholdThreshold Year PassedYear PassedYear PassedYear Passed
AZ ZT, incl mets 1990
COCOCOCO 5ng/mL5ng/mL5ng/mL5ng/mL, THC (permissible inf.) 2012
DE ZT, excl mets 2007
IL ZT, incl mets 1997
IN ZT, incl mets 2001
IA Urine per se 1998
MI ZT, excl mets 2003
MTMTMTMT 5ng/mL 5ng/mL 5ng/mL 5ng/mL THC 2013
NVNVNVNV 2ng/mL2ng/mL2ng/mL2ng/mL THC, mets 2003
NC ZT, U21, excl mets. 2003
OHOHOHOH 2ng/mL2ng/mL2ng/mL2ng/mL THC, mets 2006
OK ZT, incl mets 2013
PAPAPAPA 1ng/mL1ng/mL1ng/mL1ng/mL, incl mets 2004
RI ZT, incl mets 2006
SD ZT, U21, incl mets 1998
UT ZT, incl mets 1994
WAWAWAWA 5ng/mL 5ng/mL 5ng/mL 5ng/mL THC 2012
WI ZT, excl mets. 2003
*ZT: Zero tolerance means any
detectable amount or amount
established based on laboratory
protocol.
2015: 18 states have per se
StateStateStateState ThresholdThresholdThresholdThreshold
WA, CO, MT 5ng/mL
NV, OH 2ng/mL
PA 1ng/mL
IL (prop.) 15ng/mL
Cannabinoid Concentrations
% Subjects with
THC >1ng/mL
% Subjects with
THC >2ng/mL
% Subjects with
THC >5ng/mL
+ Cannabinoid
- Alcohol
- Other Drug
90.51% 78.9% 49.3%
+ Cannabinoid
+ Alcohol
- Other Drug
79.4% 56.8% 23.5%
Percentage of arrested drivers (n=4,799) with THC concentrations above various
statutory thresholds (1ng/mL(PA); 2ng/mL (OH, NV); 5ng/mL (WA, CO, MT).
Logan, Kacinko, Beirness, AAAFTS in press, 2015
Impact of 5ng/mL THC per se Law
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
0 5 10 15
[THC]blood, ng/mL[THC]blood, ng/mL[THC]blood, ng/mL[THC]blood, ng/mL
Relative Frequency %
10,144 Marijuana DUID /DRE cases testing positive for THC and/or metab.
Per Se / Zero Tolerance Pro’s and Con’s
ProProProPro ConConConCon
Raises the profile of the DUID
Issue
Based on policy, not science, but
carries an aura of scientific
authority
Creates a “black and white”
standard
Not an impairment standard
Useful tool for cases where
injuries prevent collection of
impairment evidence.
Drug users cannot be expected
to know what their blood
concentrations are.
Expedites litigation Setting a high concentration
renders the law useless; setting
a low concentration risks
including non-impaired subjects
Impact of Medical Cannabis Laws
Medical Cannabis in Canada
• “Cannabis users should be advised not to drive for at least 3 to 4 hours after smoking, for at least 6 hours after oral ingestion, and for at least 8 hours if they experience a subjective "high" (level II evidence)”.
Kahan M, Srivastava A, Spithoff S, Bromley L.
Prescribing smoked cannabis for chronic noncancer pain:
preliminary recommendations. Can Fam Physician. 2014
Dec;60(12):1083-90.
Medical Cannabis in Germany
• In summary, a low risk profile is evident from the literature available.
• However “Cannabinoids impede cognitive and psychomotor performance, resulting in impaired driving ability”.
Radbruch L, Nauck F. A review of side effects and
complications with cannabinoid treatment . Schmerz. 2003
Aug;17(4):274-9.
NORML Position
Medical Cannabis in Colorado
• “In Colorado, since mid-2009 when medical marijuana became commercially available and prevalent, the trend became positive in the proportion of drivers in a fatal motor vehicle crash who were marijuana-positive.”
• No significant changes were seen in 34 NMMS. • For both Colorado and NMMS, no significant changes
were seen in the proportion of drivers in a fatal motor vehicle crash who were alcohol-impaired.
Salomonsen-Sautel S, Min SJ, Sakai JT, Thurstone C, Hopfer C.
Trends in fatal motor vehicle crashes before and after
marijuana commercialization in Colorado. Drug Alcohol
Depend. 2014 Jul 1;140:137-44.
Cannabis Positive Traffic Deaths, CO
Salomonsen-Sautel et al, 2014
2009