Wise et al. 2025 — Elevated metal levels in U.S. honeys
Twenty metal levels were measured in 28 U.S. honey samples from 15 states using benchtop X-ray fluorescence (XRF), representing the most geographically broad survey of metal contaminants in U.S. honeys to date. The majority of samples exceeded EU maximum residue levels for lead (0.10 µg/g) and mercury (0.01 µg/g), with the highest Pb observed in Tennessee (0.918 µg/g), Massachusetts (0.820 µg/g), and New Mexico (0.367 µg/g), and the highest Hg in Massachusetts (8.94 µg/g), Tennessee (7.04 µg/g), and New Mexico (6.92 µg/g). Estimated weekly intake calculations at 300 mg honey/kg body mass/day showed that all four toxic metals (As, Pb, Cd, Hg) exceeded JECFA provisional tolerable weekly intake (PTWI) values, with Hg intake estimated at 2.504 mg/kg per week against a PTWI of 0.005 mg/kg (500× excess).
Key numbers
U.S. honey mean concentrations (n = 28, µg/g = mg/kg wet weight):
Sodium: 406.8 ± 1.8; Calcium: 234.8 ± 2.1; Zinc: 75.91 ± 12.2; Iron: 31.33 ± 7.23; Bromine: 4.82 ± 0.45; Copper: 3.61 ± 0.01; Manganese: 2.33 ± 0.37; Selenium: 0.51 ± 0.03; Arsenic: 0.06 ± 0.0; Silicon: 0.19 ± 0.02; Gallium: 0.14 ± 0.01; Titanium: 0.056 ± 0.01; Vanadium: 0.021 ± 0.0; Germanium: 0.035 ± 0.01.
Toxic metals mean (µg/g): As 0.060; Pb 0.178; Cd 0.132; Hg 3.710; Al 64.36.
Note: The text reports Hg mean as 3.710 µg/g but Table 2 lists US Honey Mean Weekly Metal Consumption for Hg as 2.504 mg metal/kg body mass (using 300 mg/kg body mass daily consumption and 70 kg adult). The 3.710 µg/g figure appears in Table 2 as the honey concentration column.
Highest values by state (µg/g):
- Pb: Tennessee 0.918, Massachusetts 0.820, New Mexico 0.367 (EU MRL = 0.10)
- Cd: Tennessee 0.918, Massachusetts 0.820, Vermont 0.350
- Hg: Massachusetts 8.94, Tennessee 7.04, New Mexico 6.92 (EU MRL = 0.01)
- As: Oregon 0.067, Indiana 0.065, Arkansas 0.065
Estimated weekly intake vs PTWI (assuming 300 mg/kg/day, 70 kg adult):
| Metal | EWI (mg/kg body mass) | JECFA PTWI (mg/kg body mass) | Ratio |
|---|---|---|---|
| As | 0.128 | 0.002 | 64× |
| Pb | 0.401 | 0.025 | 16× |
| Cd | 0.027 | 0.007 | 3.9× |
| Hg | 2.504 | 0.005 | 501× |
| Al | 77.233 | 2.000 | 39× |
| Cu | 1.084 | 3.500 | 0.31× (below PTWI) |
| Mn | 0.699 | 2.500 | 0.28× (below PTWI) |
| Zn | 22.77 | 7.000 | 3.3× |
| Se | 0.015 | 0.066 | 0.23× (below PTWI) |
States sampled: Arkansas (n=2), Florida (2), Indiana (2), Kentucky (4), Maine (1), Maryland (1), Massachusetts (2), New Mexico (4), North Carolina (1), Oklahoma (1), Oregon (2), Tennessee (3), Texas (1), Vermont (1), West Virginia (1). Note: paper abstract says 15 states and Table 1 lists 15 states, though the body text at one point says “14 different states.”
Thirteen metals detected in all 28 honeys: Si, Ti, V, As, Se, Ga, Mn, Cu, Br, Fe, Zn, Ca, Na.
Methods (brief)
Benchtop XRF (Epsilon 4, Malvern Panalytical), 15 W x-ray tube, 50 kV max, 300 µA, 7.5-min collection per sample. Samples placed in 30 mm XRF cup with 4 µm polypropylene film; no digestion required. Calibration with phantom samples doped with known metal concentrations; normalization via Compton scattering peak to correct for mass and thickness variation. Reported in µg/g. Key limitation: XRF does not speciate arsenic (values are total As, not iAs); mercury values should be interpreted with caution as XRF is less sensitive for Hg than ICP-MS and the very high Hg values (up to 8.94 µg/g) are unusual and may warrant independent ICP-MS verification. The paper does not discuss method-specific LODs for each metal.
Implications
Certification: U.S. honey has no federal maximum contaminant levels for metals; the EU MRL for Pb (0.10 µg/g) and Hg (0.01 µg/g) are exceeded by the majority of samples in this study. This is directly relevant to HMT&C if honey or honey-containing products are within the program’s scope: the literature demonstrates that commercial U.S. honey frequently fails EU standards for Pb and Hg. The arsenic values here are total As (tAs), not iAs; a speciation study would be needed to determine the fraction relevant to the HMT&C iAs threshold.
Courses: The XRF methodology note is instructive: this is a non-destructive, no-digestion approach that enables broad screening but cannot differentiate metal species. The contrast between the high estimated weekly intakes and typical honey consumption patterns (most adults do not consume 15 mL/day as a therapeutic dose) illustrates why exposure scenario assumptions dominate health risk calculations.
App: The state-level geographic variation data provide a basis for flagging honey from Tennessee, Massachusetts, and New Mexico as higher-risk origins for Pb and Hg. The absence of regulatory limits in the U.S. means the app cannot cite domestic regulatory exceedances, only EU benchmarks. Total As at mean 0.060 µg/g is at the low end of the food-matrix arsenic range; iAs fraction unknown.