Heavy metals in spices and herbs from worldwide markets: A systematic review and health risk assessment
Najla Alawadhi, Khaled Abass, Raghad Khaled, Tareq M. Osaili, Lucy Semerjian
Abstract
Culinary spices and herbs, renowned for their flavor, aroma, and medicinal properties, contain essential nutrients but also may pose health concerns due to heavy metal contamination. This systematic review, in accordance with PRISMA guidelines, investigates the global concentrations of heavy metals in culinary spices and herbs, and evaluates associated health risks. Fifty peer-reviewed studies from Scopus, PubMed, and Web of Science were examined and findings revealed variations in heavy metal content based on country of origin and spice type. In the MENA region, caraway and green cardamom from Bahrain had high levels of Pb (2.2 μg/g) and Cd (0.9 μg/g). Indian spices like cloves and Ajwain seeds exhibited high levels of iron (17.87 ± 8 mg/kg) and calcium (1353 ± 10 mg/kg). African and European spices showed regional disparities, with some exceeding permissible Pb and Cd limits. Non-carcinogenic human health risk assessments via oral exposure pathway conducted on reported Cd, Ni, and Cu concentrations throughout the reviewed global studies revealed no risks across all regions and for all spices and herbs under study except in Turkey for Cd levels found in chamomile with hazard quotients ranging between 1.26 and 1.47. On the other hand, carcinogenic risks varied based on reported Pb concentrations, ranging from 8.5 × 10 −8 to a maximum of 4.96 × 10 −3 . These findings underscore the need for global vigilance in food safety practices and future research in countries with less stringent policies. Recommendations include improved agricultural practices, enhanced soil management, and stringent post-harvest procedures to mitigate contamination. • Spices and herbs show diverse metal content, requiring safety monitoring. • Most spices and herbs are non-carcinogenic, few exhibited carcinogenic risks. • Studies recommend stringent controls to mitigate heavy metal contamination. • Review significant in future research directions and measures for spice safety.