Tinggi et al. 2025 — Heavy metals in commercial spices and herbs, Queensland Australia
This study analyzed eight heavy metals (Al, As, Cd, Cr, Pb, Hg, Ni, Sr) in 69 dried commercial spice and herb samples purchased from Queensland, Australia markets, representing seven commodity types (basil, chilli, cinnamon, paprika, black pepper, sesame seeds, turmeric) imported from multiple countries. A separate analysis compared 13 conventional and 7 organic turmeric products. All metals were measured by ICP-MS following microwave-assisted acid digestion, with results validated against certified reference materials. The study found wide variation in heavy metal content across commodities and origins, with lead in cinnamon from Vietnam (7.0 mg/kg) and India (2.5 mg/kg) representing the most concerning findings; estimated dietary exposures from typical Australian spice consumption (1.9 g/day) were below health-based guidance values for all metals. Organic turmeric showed significantly higher Cr and Ni than conventional turmeric, contrary to consumer expectations of superior safety.
Key numbers
Lead (Pb), all samples (n = 69): mean 0.36 ± 0.92 mg/kg, range < 0.005–7.0 mg/kg
- Cinnamon (n = 10): mean 1.60 ± 2.07 mg/kg, range 0.15–7.0 mg/kg (highest: Vietnam 7.0 mg/kg, India 2.5 mg/kg)
- Paprika (n = 11): mean 0.22 ± 0.11 mg/kg, range 0.09–0.46 mg/kg
- Chilli (n = 14): mean 0.11 ± 0.046 mg/kg, range 0.04–0.19 mg/kg
- Black pepper (n = 13): mean 0.13 ± 0.09 mg/kg, range 0.016–0.37 mg/kg
- Turmeric (n = 10): mean 0.24 ± 0.27 mg/kg, range 0.033–0.90 mg/kg
- Sesame seeds (n = 9): mean 0.018 ± 0.016 mg/kg, range 0.005–0.05 mg/kg
Cadmium (Cd), all samples (n = 69): mean 0.13 ± 0.45 mg/kg, range 0.008–3.7 mg/kg
- Cinnamon (n = 10): mean 0.59 ± 1.10 mg/kg, range 0.046–3.7 mg/kg (outlier: 3.7 mg/kg)
- Chilli (n = 14): mean 0.080 ± 0.071 mg/kg, range 0.027–0.31 mg/kg
Arsenic (tAs), all samples (n = 69): mean 0.11 ± 0.21 mg/kg, range 0.007–1.7 mg/kg
- Black pepper (n = 13): mean 0.18 ± 0.46 mg/kg, range 0.007–1.7 mg/kg (highest: 1.7 mg/kg single sample)
Mercury (tHg), all samples: ~75% below LOR of 0.005 mg/kg; maximum 0.059 mg/kg
Aluminium (Al), all samples (n = 69): mean 178.8 ± 178.6 mg/kg, range 0.1–920 mg/kg
- Cinnamon (n = 10): mean 308.1 ± 289.1 mg/kg, range 11–920 mg/kg
Nickel (Ni), all samples (n = 69): mean 1.11 ± 0.76 mg/kg, range 0.28–4.8 mg/kg
- Black pepper (n = 13): mean 2.08 ± 1.07 mg/kg, range 0.85–4.8 mg/kg
Chromium (Cr), all samples (n = 69): mean 0.61 ± 0.70 mg/kg, range 0.01–4.0 mg/kg
- Cinnamon Vietnam: 4.0 mg/kg (highest; same sample with Pb 7.0 mg/kg and Al 920 mg/kg)
Turmeric comparison (n = 20):
- Conventional turmeric (n = 13): Pb mean 0.10 ± 0.085 mg/kg, range 0.034–0.33 mg/kg
- Organic turmeric (n = 7): Pb mean 0.19 ± 0.14 mg/kg, range 0.031–0.45 mg/kg
- Organic significantly higher for Cr (P < 0.05) and Ni (P < 0.01); no significant difference for Pb, As, Al, Sr
Dietary exposure estimates (1.9 g/day spice intake, 70 kg adult):
- Pb: 0.65% of EFSA BMDL01 (1.5 µg/kg bw/day)
- Cd: 1.0% of EFSA TWI (2.5 µg/kg bw/week)
- tAs (using iAs BMDL01): 0.038–1.0% of EFSA BMDL01
- Al: 3.4% of EFSA TWI (1,000 µg/kg bw/week)
- Ni: 0.23% of EFSA TDI
Methods (brief)
ICP-MS (Agilent 8800 Triple Quad) following microwave-assisted acid digestion (CEM MARS 6) in sealed Teflon vessels with HNO3 (69%). LOD: Pb 0.002 mg/kg, Cd 0.001 mg/kg, As 0.001 mg/kg, Hg 0.001 mg/kg, Ni 0.003 mg/kg, Al 0.04 mg/kg, Cr 0.006 mg/kg. LOR: Pb 0.005 mg/kg, Cd 0.005 mg/kg, As 0.005 mg/kg, Hg 0.005 mg/kg. Validated against ERM CE-278K (mussel tissue) and NIST SRM 1547 (peach leaves); recoveries 89–106% except Al (68.5% due to matrix effect). Study reports total arsenic and total mercury (no speciation). Concentrations below LOR substituted with LOR values in statistical analysis.
Implications
Certification: Cinnamon from Vietnam and India shows lead concentrations (2.5–7.0 mg/kg) that exceed EU limits for dried bark spices (2.0 mg/kg) and substantially exceed Australian FSANZ limits (0.1 mg/kg). The co-occurrence of very high Al (920 mg/kg), Pb (7.0 mg/kg), Cr (4.0 mg/kg), and Ni (2.0 mg/kg) in a single Vietnamese cinnamon sample suggests multi-metal contamination possibly from processing equipment or adulteration. HMT&C sourcing specifications for cinnamon should include Pb and Al screening, with Vietnam and India as elevated-risk origins.
Courses: Illustrates that organic label does not guarantee lower heavy metal content in spices: organic turmeric had significantly higher Cr and Ni than conventional turmeric. Useful case study for supply-chain and QA courses. Also demonstrates that dietary exposure from typical Western spice consumption levels remains below guidance values even when individual samples are elevated, because consumption is low.
App: Provides Australian market data for cinnamon (Pb up to 7.0 mg/kg, Cd up to 3.7 mg/kg), black pepper (tAs up to 1.7 mg/kg, Ni up to 4.8 mg/kg), and turmeric (Pb up to 0.90 mg/kg conventional, 0.45 mg/kg organic) as contamination_profile inputs for spice ingredients. High Al in cinnamon (up to 920 mg/kg) is notable for any Al tracking.