Marijuana-positive urine test results from consumption of hemp seeds in food products

J Anal Toxicol. 1997 Oct;21(6):476-81. doi: 10.1093/jat/21.6.476.


Commercially available snack bars and other foodstuffs prepared from pressed hemp seeds were ingested by volunteers. Urine specimens were collected for 24 h after ingestion of the foodstuffs containing hemp seeds and tested for marijuana using an EMIT immunoassay and gas chromatography-mass spectrometry (GC-MS). Specimens from individuals who ate one hemp seed bar demonstrated little marijuana immunoreactivity, and only one specimen screened positive at a 20-ng/mL cutoff. Specimens from individuals who ate two hemp seed bars showed increased immunoreactivity, and five specimens screened positive at a 20-ng/mL cutoff. A single specimen yielded a quantitative GC-MS value (0.6 ng/mL), but it failed to meet reporting criteria. Several specimens from individuals who ate three cookies made from hemp seed flour and butter screened positive at both 50- and 20-ng/mL cutoffs. Two specimens produced quantitative GC-MS values (0.7 and 3.1 ng/mL), but they failed to meet reporting criteria. Several specimens also tested positive with an FDA-approved on-site marijuana-screening device. Hemp seeds similar to those used in the foodstuffs did not demonstrate the presence of marijuana when tested by GC-MS. In this study, ingestion of hemp seed food products resulted in urine specimens that screened positive for marijuana. No specimens gave a GC-MS quantitative value above the limit of detection for marijuana.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial

MeSH terms

  • Adult
  • Cannabis / chemistry*
  • Dronabinol / pharmacokinetics
  • Dronabinol / urine*
  • Enzyme Multiplied Immunoassay Technique
  • Female
  • Food
  • Gas Chromatography-Mass Spectrometry
  • Hallucinogens / pharmacokinetics
  • Hallucinogens / urine*
  • Humans
  • Immunoassay
  • Male
  • Marijuana Abuse / urine*
  • Middle Aged
  • Seeds / chemistry
  • Substance Abuse Detection / methods*


  • Hallucinogens
  • Dronabinol