This CDC Tobacco Products Laboratory study measured nine metals by ICP-OES and QQQ-ICP-MS in the filler material of 14 commercial U.S. hemp cigarette brands and compared them against tobacco cigarettes and published U.S. state cannabis testing action limits. Hemp cigarette filler is predominantly hemp inflorescence material in ground form. Authors are from the U.S. Centers for Disease Control and Prevention.
Key numbers
All concentrations are µg/g dry mass. Ranges below are across the 14 brand means (Table 2). LOD and lowest statistical threshold of detection (LSTD) in Table 2. [VERIFY table check]
| Metal | Range across 14 brands | LOD (µg/g) | LSTD (µg/g) |
|---|---|---|---|
| Be | 0.0175 to 0.0933 | 0.0027 | 0.0050 |
| chromium (Cr) (total) | 0.566 to 3.14 | 0.089 | 0.200 |
| Mn | 124 to 355 | 56 | 20.0 |
| Co | 0.165 to 0.726 | 0.013 | 0.100 |
| nickel (Ni) | 1.68 to 5.47 | 0.110 | 0.500 |
| total arsenic (tAs) | 0.0527 to 0.638 | 0.031 | 0.050 |
| cadmium (Cd) | all brands <LSTD (0.500) | n/a | 0.500 |
| lead (Pb) | <LSTD to 1.06 | 0.012 | 0.200 |
| uranium (U) | 0.0161 to 0.258 | 0.0022 | 0.010 |
CRM NIST RM 8210 (hemp plant): lead (Pb) at 0.240 ± 0.089 µg/g, outside accepted reference range; all other elements within range (Table 1).
U.S. state cannabis testing action limits cited (Table 5; µg/g): total arsenic 0.200, cadmium 0.016, lead 0.012. When brands had detectable arsenic, several exceeded 0.200 µg/g. Cadmium and lead exceeded state action limits in brands with detectable concentrations. No comparison to state limits was possible for cadmium because all brands were below the LSTD (0.500 µg/g), which itself exceeds the state action limit of 0.016 µg/g.
Methods (brief)
Modified tobacco cigarette filler preparation method; ICP-OES (Cr, Mn) and QQQ-ICP-MS (Be, Co, nickel (Ni), arsenic (As), cadmium (Cd), Pb, U); dry-mass basis; three brand replicates; LOD = three times standard deviation of reagent blank (n=10). CRM: NIST RM 8210 hemp plant; Pb fell outside accepted range.
Evidence fitness
This study provides directly comparable metal concentrations in U.S. hemp cigarette filler material (ground hemp inflorescence). It is the most detailed U.S. brand-level survey for hemp smokables currently available. The cadmium LSTD of 0.500 µg/g substantially exceeds state action limits of 0.016 µg/g, making cadmium screening in this study effectively uninformative for compliance purposes. The Pb CRM failure reduces confidence in absolute lead values. Arsenic is total arsenic, not speciated. The comparison to state action limits in Table 5 is to individual state limits (California, Colorado, Oregon, and others), not a uniform federal standard. NIST RM 8210 is ground hemp plant; the article does not specify whether the CRM preparation is inflorescence-only or whole-plant.
Limitations
CRM Pb recovery fell outside the accepted range, introducing uncertainty in absolute Pb concentrations. The cadmium LSTD (0.500 µg/g) is 31 times higher than the most stringent state action limit (0.016 µg/g), so reported cadmium non-detections cannot confirm regulatory compliance. Brand identities are concealed by numerical assignment. Sampling represents 2022-2023 U.S. retail.
Related evidence
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