title: Tracing retail cannabis in the United States: geographic origin and cultivation patterns.
abstract: BACKGROUND
  Although cannabis is the most readily available and widely used illicit drug in the United States, there remains significant uncertainty about the importance of different production regions and trafficking patterns.
  
  
  METHODS
  We analysed 628 "retail" cannabis seizures from over 50 municipalities across the United States for hydrogen and carbon isotope ratios to predict their growth locations and environments.
  
  
  RESULTS
  Results are presented for 22 consolidated retail locations across the United States. Evaluation of specimens from within these retail areas suggested that cannabis seizures had region-dependent origins, often from both domestic and foreign sources, and although indoor growth was common in many areas, there was also regional dependence in the proportions cultivated under indoor versus outdoor conditions.
  
  
  CONCLUSIONS
  Street-available cannabis exhibits region-specific trafficking patterns, both Mexican- and Canadian-grown cannabis are apparently widely available, and indoor-grown cannabis appears to be cultivated and trafficked in both warm and cool weather localities throughout the United States.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112, United States. jhurley@smrtl.org
authors.forename: Janet M
authors.initials: JM
authors.lastname: Hurley
authors.forename: Jason B
authors.initials: JB
authors.lastname: West
authors.forename: James R
authors.initials: JR
authors.lastname: Ehleringer
mesh_terms: D002188:Cannabis / Q000737:chemistry* / Q000254:growth & development*; D002247:Carbon Isotopes / Q000032:analysis; D003903:Deuterium / Q000032:analysis; D004335:Drug and Narcotic Control / Q000331:legislation & jurisprudence*; D004777:Environment; D006859:Hydrogen / Q000032:analysis; D008377:Maps as Topic; D014481:United States
chemical_list: D002247:Carbon Isotopes; D006859:Hydrogen; D003903:Deuterium