Heavy metal analysis in commercial spices and herbs by inductively coupled plasma mass spectrometry (ICP-MS) and estimated dietary exposure

Spices and herbs are widely used food ingredients with both cultural and dietary importance, but there is a concern that these products contain heavy metal contaminants. In this study, the levels of heavy metals (aluminium, arsenic, cadmium, chromium, lead, mercury, nickel, strontium) were investigated in dried spice and herb samples (n = 69) (basil, chilli, cinnamon, paprika, black pepper, sesame seeds, turmeric). These imported spice and herb products from different countries were purchased from markets in Queensland, Australia. For comparison, dried organic turmeric (n = 7) and conventional turmeric (n = 13) were also analyzed. This study aimed to assess the distribution of heavy metal levels in spices and herbs, evaluate whether their concentrations may cause dietary exposure concern, and compare levels among different countries of origin. The concentrations of heavy metals were analyzed by inductively coupled plasma mass spectrometry after microwave digestion, and appropriate standard reference materials were used for quality control and method validation. The results revealed a wide variation in heavy metal content across samples. Elevated aluminium concentrations were detected in cinnamon (< 0.1-920 mg/kg), while high strontium levels (260-290 mg/kg) were found in basil. Mercury levels were low (< 0.005-0.059 mg/kg) as were those of arsenic (0.007-1.7 mg/kg), cadmium (0.008-3.7 mg/kg), chromium (< 0.01-4.0 mg/kg), nickel (0.28-4.8 mg/kg), and lead (< 0.005-7.0 mg/kg). Organic and non-organic (conventional) turmeric samples also showed wide variation in metal content, with statistically significant differences observed for nickel (P < 0.01) and chromium (P < 0.05). Overall, estimated dietary exposure to heavy metals from the consumption of these spices and herbs was below levels of public health concern.