This Italian survey measured 14 elements by ICP-MS and direct mercury analysis (DMA-80) in 72 light cannabis (hemp, THC below 0.6%) inflorescence samples representing 6 varieties from 4 Italian regions. Light cannabis (also called CBD flower) is the regulated hemp smokable sold legally in Italy and other EU member states. The study assessed compliance with WHO and USP inhalation limits and found that most samples are below limits for lead, cadmium, total arsenic, and total mercury, but chromium, nickel, cobalt, and copper exceeded USP inhalation limits in a minority of samples, with strong geographic variation.
Key numbers
All concentrations are mg/kg = µg/g dry weight. Means and medians are across all 72 samples. [VERIFY table check]
Toxic elements (from text, pages 9-10):
| Element | Mean (µg/g) | Median (µg/g) |
|---|---|---|
| lead (Pb) | 0.14 | 0.03 |
| cadmium (Cd) | 0.009 | <LOD |
| total arsenic (tAs) | 0.004 | <LOD |
| total mercury (tHg) | 0.005 | <LOD |
| aluminum (Al) | 25.99 | 5.91 |
| chromium (Cr) (total) | 0.11 | 0.03 |
| nickel (Ni) | 0.45 | 0.11 |
| Cu | 6.21 | 2.28 |
| Co | 0.13 | 0.01 |
| Se | 0.32 | 0.12 |
| Mo | 0.20 | 0.11 |
| Mn | 21.19 | 17.50 |
| Fe | 16.60 | 8.37 |
| Zn | 61.16 | 57.54 |
Geographic outliers (from text):
- Lombardy: lead up to 38.33 µg/g (markedly elevated; highest lead (Pb) in any sample); chromium 18.55 to 22.80 µg/g
- Apulia: aluminum 23.86 to 134.07 µg/g; lead 0.31 to 0.79 µg/g
- Sicily: iron 32.73 to 49.08 µg/g; zinc 90.54 to 150.43 µg/g (highest)
Samples exceeding USP inhalation limits (Table 3):
- Copper: 8 of 72 (USP inhaled limit 3 µg/g)
- Total chromium: 6 of 72 (USP inhaled limit 0.3 µg/g)
- Cobalt: 6 of 72 (USP inhaled limit 0.3 µg/g)
- Nickel: 6 of 72 (USP inhaled limit 0.5 µg/g/day at 10 g/day)
- Lead: 2 of 72 (USP inhaled limit 0.5 µg/g)
- Cadmium, total arsenic, total mercury: 0 of 72
CRM recovery (Table 2; CRM BCR-402 white clover):
All recoveries within 95.85-102.50% for the analytes reported. DMA-80 for mercury: 98% ± 1%.
Methods (brief)
ICP-MS (iCAP-Q, Thermo Scientific); DMA-80 for mercury; acid microwave digestion; CRM BCR-402 white clover, 6 replicates; LOD = 3 times standard deviation of blanks; LOQ = 10 times standard deviation. Full LOD/LOQ table in Table 2. Cannabinoid analysis by HPLC-UV to confirm THC below 0.6%.
Evidence fitness
This study provides variety- and region-stratified data for Italian light cannabis (legally sold hemp flower), making it relevant for EU market occurrence profiling. The mean and median values for lead, cadmium, arsenic, and mercury are consistent with low contamination in most Italian-grown material. The Lombardy lead outlier (up to 38.33 µg/g) is 275 times the overall mean and indicates severe localized soil contamination at the Lombardy sampling site; pooling with other sites inflates the mean substantially. Arsenic is total arsenic only. The CRM is white clover (not cannabis), which introduces species-specific matrix matching uncertainty. Geographic outliers should not be treated as typical of Italian or European cannabis.
Limitations
Variety-by-region interaction means the 72 samples are not independent; each variety appears at each site in triplicate. The Lombardy lead outlier dominates the mean and should be reported separately from the other three regions for unbiased occurrence estimation. CRM is not cannabis-matrix. Arsenic not speciated; total arsenic only.
Related evidence
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