Oregon cannabis products contained high pesticide levels, including some classified as extremely hazardous
Testing of Oregon cannabis products found high levels of residual pesticides, including nine classified as highly or extremely hazardous by the WHO, with medical cannabis containing 3-12 times more pesticide residue than recreational products.
Quick Facts
What This Study Found
Both recreational and medicinal cannabis products contained high pesticide levels, with 50 different pesticides identified. Medical cannabis products had mean pesticide residue levels 3-12 times higher than recreational products. Nine pesticides found were classified as highly or extremely hazardous.
Key Numbers
50 pesticides identified in cannabis products. Medical cannabis had 3-12 times higher mean residual pesticide levels than recreational. 9 of 50 pesticides were classified as WHO Class Ia (extremely hazardous) or Ib (highly hazardous).
How They Did This
Analysis of Oregon state pesticide testing data for both recreational and medicinal cannabis products. The Oregon Department of Agriculture developed testing regulations and a list of approved pesticides following legalization in 2014.
Why This Research Matters
The finding that medical cannabis, used by patients with health conditions, contained significantly more pesticide contamination than recreational products highlights a regulatory gap that could put vulnerable consumers and cannabis workers at risk.
The Bigger Picture
The disparity between medical and recreational cannabis pesticide levels likely reflects differences in testing requirements, suggesting that stricter and more uniform regulation is needed across all cannabis product categories.
What This Study Doesn't Tell Us
The study used state testing data, which may not capture all products on the market. Pesticide testing methods and detection limits evolved during the study period. The health effects of pesticide exposure via cannabis consumption are not well characterized.
Questions This Raises
- ?Are cannabis workers being exposed to dangerous pesticide levels?
- ?Why were medical products more contaminated than recreational ones?
- ?Have pesticide levels changed since stricter regulations were implemented?
Trust & Context
- Key Stat:
- Medical cannabis had 3-12x more pesticide residue than recreational
- Evidence Grade:
- Moderate: systematic analysis of state testing data, though limited by evolving testing standards and unknown health impact of inhalation exposure.
- Study Age:
- Published in 2020 in Annals of Work Exposures and Health.
- Original Title:
- Evaluation of Pesticides Found in Oregon Cannabis from 2016 to 2017.
- Published In:
- Annals of work exposures and health, 64(7), 770-774 (2020)
- Authors:
- Evoy, Richard, Kincl, Laurel
- Database ID:
- RTHC-02543
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Why did medical cannabis have more pesticides?
The study suggests this may reflect different regulatory oversight. At the time, recreational cannabis in Oregon faced different testing requirements than medical cannabis, potentially allowing more contamination in medical products.
What kinds of pesticides were found?
Fifty different pesticides were identified, including some not legally allowed on cannabis. Nine were classified by the WHO as highly or extremely hazardous to human health.
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Cite This Study
https://rethinkthc.com/research/RTHC-02543APA
Evoy, Richard; Kincl, Laurel. (2020). Evaluation of Pesticides Found in Oregon Cannabis from 2016 to 2017.. Annals of work exposures and health, 64(7), 770-774. https://doi.org/10.1093/annweh/wxz075
MLA
Evoy, Richard, et al. "Evaluation of Pesticides Found in Oregon Cannabis from 2016 to 2017.." Annals of work exposures and health, 2020. https://doi.org/10.1093/annweh/wxz075
RethinkTHC
RethinkTHC Research Database. "Evaluation of Pesticides Found in Oregon Cannabis from 2016 ..." RTHC-02543. Retrieved from https://rethinkthc.com/research/evoy-2020-evaluation-of-pesticides-found
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.