Evidence map›Paper›PMID 41731563›Full record

ArticleJournal of cannabis research2026

Comparative analysis of metals, pesticides, mycotoxins, microbial contaminants and THC potency in illegal and regulated cannabis inflorescences in Canada.

Quinton Fiering, Jordyn Mackey, Hayline Kim, Yousef Risha, Ryan Denkert, Monica Iuogovaz, Gabriela Zorila, Julia Killorn, Gayel Abi-Yaghi, Emmanuelle Bahl and 26 more

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Journal of cannabis research, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

36 authors.

Quinton FieringPesticide Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Ottawa, Ontario, K1A 0C6, Canada.
Jordyn MackeyPesticide Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Ottawa, Ontario, K1A 0C6, Canada.
Hayline KimMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Yousef RishaPesticide Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Ottawa, Ontario, K1A 0C6, Canada.
Ryan DenkertCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Monica IuogovazCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Gabriela ZorilaCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Julia KillornCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Gayel Abi-YaghiCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Emmanuelle BahlCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Josée VerreaultCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Marick GagnonCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Carl RodrigueCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Roxane ArsenaultMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Julio Bran BarreraMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Maude LordMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Jamile AhmaraniMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Diana Becerra RodriguezMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Arianne GauthierMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Diana Bran BarreraMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Cathy St-LaurentMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Guillaume MassicotteMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Roland YangMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Morgan PopplewellPesticide Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Ottawa, Ontario, K1A 0C6, Canada.
Michel BlaisPesticide Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Ottawa, Ontario, K1A 0C6, Canada.
Peter BradleyPesticide Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Ottawa, Ontario, K1A 0C6, Canada.
Cecile LePesticide Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Ottawa, Ontario, K1A 0C6, Canada.
William MohanPesticide Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Ottawa, Ontario, K1A 0C6, Canada.
André RobichaudCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Catherine DeschenesMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Isabelle DisnardMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Geneviève ClémentCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Maryse FontaineCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Irène IugovazMicrobiology Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
Julie BellemareCannabis Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Longueuil, Québec, J4K 1C7, Canada.
David R BlaisPesticide Laboratory, Regulatory Operations and Enforcement Branch, Health Canada, Ottawa, Ontario, K1A 0C6, Canada. David.Blais@hc-sc.gc.ca.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundFollowing the legalization of recreational cannabis in Canada under the Cannabis Act (2018), regulatory frameworks were implemented to ensure product safety, quality, and consistency within the legal market. Previous studies revealed significantly greater pesticide contamination in illegal cannabis than in legal products. In light of these findings, the present study expands contaminant surveillance to include the quantification of Δ⁹-tetrahydrocannabinol (THC) and a broader range of potential toxicants, including metals, pesticides, mycotoxins, and microbial agents.

methodsFifty legal cannabis products were purchased across Canadian provinces, and 50 illegal samples were obtained via law enforcement seizures. All the samples were tested via validated, accredited/attested methods. THC content was assessed using LC-UV-MS. Pesticides were analyzed via LC-MS/MS and GC-MS/MS; metals via ICP-MS/MS; mycotoxins via LC-MS/MS; and microbial contamination using MALDI-TOF.

resultsTHC levels in 48% of legal products deviated by more than 20% from their labeled concentrations. Microbiological testing revealed that 20% of legal products exceeded the European Pharmacopoeia microbial limits, prompting appropriate compliance and enforcement measures to address each of these cases. In contrast, 55% of the illegal products exceeded the aerobic plate count thresholds, and 73% surpassed the yeast and mold limits. Mycotoxins were undetected in legal products but were present in 12% of illegal samples. Pesticide residues were found at trace levels (0.01 µg/g) for myclobutanil and dichlobenil in two legal samples, whereas 94% of illegal samples contained pesticides, averaging 3.4 compounds per sample across 24 unique active ingredients. Metal analysis revealed higher levels of arsenic, cadmium, lead, and mercury in illegal products than in their legal counterparts. However, legal samples presented higher chromium concentrations, with peak values approximately threefold greater than those observed in illegal cannabis. The concentrations of arsenic, barium, chromium, copper, molybdenum, nickel, and vanadium exceeded the inhalation concentration limits found in Table 2 of USP <232> of the United States Pharmacopeia (USP) in one or both product categories.

conclusionThese findings demonstrate that legal THC levels differ from their label claims as well as that contaminants differ between legal and illegal cannabis products. The results provide evidence to inform regulatory oversight, enhance risk assessment efforts, and support informed decision-making by consumers and policymakers in the context of a legal cannabis framework.

Indexed as

ArsenicCadmiumCannabisFlowersIllegalLeadLegalMercuryMoldPesticidesTHC

Identifiers

PMID41731563
PMCPMC13045130

What OpenQuestion holds

Textmetadata
LicenceCC BY
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Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.