Overview
This study quantified 29 macro and trace elements by ICP-MS in 90 hemp leaf/flower samples representing 9 cultivar varieties from 13 Greek growing regions, providing a comprehensive multi-analyte occurrence dataset for a crop with expanding applications in dietary supplements, edible oils, and herbal medicines. Of the key toxic elements, Hg, Pb, Cd, and As concentrations were below WHO 2007 recommendation limits in all but one sample (one Cd exceedance at 1.4× the limit); however, Cr exceeded the WHO limit in approximately 25% of the analyzed samples, indicating a systematic regional or soil-driven Cr enrichment issue for Greek hemp.
Key numbers
- n=90 leaf/flower samples; 9 varieties (Finola, Futura 75, Fedora 17, Gamagnola, Fellina 32, Dora, CS, Fibror 79, Compolti); 13 Greek regions; 2018–2019.
- Toxic element ranges and averages (ppm, dry weight):
- Hg: 0.006–0.107 ppm (avg 0.020); WHO limit 0.2 ppm — all below
- Cd: 0.007–0.431 ppm (avg 0.049); WHO limit 0.3 ppm — one exceedance at 0.431 ppm
- Pb: 0.095–1.752 ppm (avg 0.433); WHO limit 10 ppm — all below
- As: 0.031–0.742 ppm (avg 0.159); WHO limit 5 ppm — all below
- Cr: 0.337–7.886 ppm (avg 1.686); WHO limit 2 ppm — approximately 25% of samples exceeded
- Additional trace elements quantified: Al, Ni, Sn, Sb, U, and 20 others.
- THQ and carcinogenic risk (CR) values were below thresholds indicating no non-carcinogenic or carcinogenic risk at current exposure assumptions (3 g/day consumption rate).
- Positive correlation between element concentrations and geographical origin and cultivar variety; leaves/flowers were more contaminated than seeds.
- Toxic heavy metals and metalloids collectively constituted less than 1% of total detected element concentrations.
Methods (brief)
ICP-MS (Thermo iCAP-RQ) with collision cell mode (KED) for polyatomic interference removal; 29 elements; microwave acid digestion (HNO3/HCl/H2O2/H2O at 180°C); internal standards (6Li, Sc, Ge, Y, In, Tb, Ir); CRMs BCR-191 brown bread and BCR-679 white cabbage; Au added for Hg stabilization. LOD = 3×SD of 10 reagent blanks; LOQ = 10×SD. Recovery 80–120% for all CRM and QC samples. Kruskal-Wallis test for between-variety and between-region comparisons.
Implications
Certification: Hemp-derived ingredients and CBD/hemp oil supplements should be screened for Cr in addition to the conventional four (Pb, Cd, As, Hg); approximately one quarter of Greek hemp samples exceeded WHO Cr limits. The Cd maximum (0.431 ppm) represents a moderate exceedance and warrants supplier specification for hemp sourced from regions with Cd-enriched soils.
Courses: Illustrates that hemp is a phytoaccumulator with geographic and varietal variation in heavy metal loading; Cr contamination in herbal materials is underappreciated relative to Pb, Cd, As, and Hg.
App: Hemp and cannabis-derived supplements should be flagged for Cr and Cd screening, particularly for European-origin material where soil composition varies significantly by region.
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Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Change | Description |
|---|---|---|---|
| e317189 | 2026-08-11 | correction | 6 sections added; narrative text revised |