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Table 1 Legal Δ9-tetrahydrocannabinol (THC) thresholds for drivers in states with per se laws

From: Establishing legal limits for driving under the influence of marijuana

State Legal THC limit Collected specimen Year effective
Colorado 5.0 μg/L in blood Blood, urine, or OF 2013
Iowa THC-COOH: 50.0 μg/L in urine Blood or urine 2010
Montana 5.0 μg/L in blood Blood 2013
Nevada THC: 10.0 μg/L in urine, 2.0 μg/L in blood THC-COOH: 15.0 μg/L in urine, 5.0 μg/L in blood Blood, urine, or other bodily substance 2003
Ohio THC: 10.0 μg/L in urine, 2.0 μg/L in blood THC-COOH: 35.0 μg/L in urine, 50.0 μg/L in blood THC-COOH in combination with alcohol or other drugs: 15.0 μg/L in urine, 5.0 μg/L in blood Blood, urine, or other bodily substance 2006
Pennsylvania THC or THC-COOH: 1.0 μg/L in blood or urine Blood or urine 2011
Washington 5.0 μg/L in blood Blood 2013
  1. Abbreviations: OF oral fluid, THC Δ9-tetrahydrocannabinol, THC-COOH carboxy-Δ9-tetrahydrocannabinol.
  2. Sources: (NORML). Drugged Driving. Washington, D.C. 2014a. http://norml.org/legal/drugged-driving. Accessed July 15 2014.; Lacey J, Brainard K, Snitow S. Drug Per Se Laws: A Review of Their Use in States. Washington, D.C.: National Highway Traffic Safety Administration (NHTSA). 2010. Accessed July 15 2014.; Avila EN. Minimum Levels of Controlled Substances or Their Metabolites in Blood to Establish Presence of Controlled Substance. Pennsylvania Bulletin. [2011] April 30. Accessed July 23 2014.; [Wash Rev Code § 46.61.502]); Walsh JM. A State-by-State Analysis of Laws Dealing With Driving Under the Influence of Drugs. Washington, D.C.: National Highway Traffic Safety Administration (NHTSA). 2009. Accessed July 12 2014.