Stable Isotope Ratios of Marijuana. I. Carbon and Nitrogen Stable Isotopes Describe Growth Conditions

• NCJ Number: 225891
• Journal: Journal of Forensic Sciences Volume: 54 Issue: 1 Dated: January 2009 Pages: 84-89
• Author(s): Jason B. West Ph.D.; Janet M. Hurley M.S.; James R.. Ehleringer Ph.D.
• Date Published: January 2009
• Length: 6 pages
• Contract Number(s): HHSP23320046100ZC
• Sponsoring Agency: Office of National Drug Control Policy
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

This report presents the results of a large survey of the stable isotope ratios of marijuana cultivated within the United States and suggests a framework for interpreting these results, with the goals of providing data on the cultivation sources of marijuana supplying particular areas as well as the temporal changes in distribution and cultivation practices for seized samples.

Abstract

The results provide strong evidence that C and N isotope ratios record important aspects of marijuana cultivation, yielding a record with a rich potential to aid forensic investigations and drug intelligence. Samples identified as outdoor-grown by delta13(superscript)C were generally recorded as such by the Drug Enforcement Administration (DEA). DEA-classified indoor-grown samples had the most negative delta13C values, consistent with indoor cultivation, although many were also in the outdoor-grown domain. Delta15(superscript)N indicated a wide range of fertilizers across the dataset. There was clear evidence of indoor-grown plants being supplemented with carbon dioxide based on the low delta13C values. The delta15N results suggested that plants grown in the United States were fertilized with a wide range of nitrogen fertilizers, dominated by inorganic fertilizers or perhaps no fertilizer application; however, many were derived from organic sources. Samples seized at the single location suggested multiple sources. Northwest border delta13C values suggested indoor growth; whereas, outdoor growth was indicated from the Mexican and Colombian samples. This study analyzed the delta13C and delta15N of 508 domestic samples from 30 U.S. States and 218 U.S. counties, 31 seized from a single location, 5 samples grown in Mexico and Colombia, and 10 northwest-border seizures. The samples were seized by the DEA between 2003 and 2006. For a subset of samples, inflorescences and leaves were analyzed separately. 7 figures and 35 references