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Environmental assessment and comparative analysis of toxic metal(loids) contamination: application to herbal plants from Jordan

Year: 2026

Type: article

Abstract: This study evaluated 13 metal(loid)s (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb, Pd, Sb, Sr) in 28 medicinal and edible plants from Jordan’s Southern Badia using ICP-MS and ICP-OES with certified reference material validation (excluding Pd and Sb). The study revealed that As, Co, Hg, Pb, Pd, and Sb were below their maximum contaminant limits (MCLs), indicating low uptake and minimal anthropogenic influence. Cd, Cr, and Cu were generally below MCLs, with only five species near or slightly exceeding limits. In contrast, Ni exceeded the MCL (0.30 mg·kg−1) in all plants, ranging from 0.320 ± 0.001 mg·kg−1 (Ziziphus spina-christi) to 6.32 ± 0.34 mg·kg−1 (Nigella sativa). Al was consistently high, surpassing the MCL (5.00 mg·kg−1) across all samples, from 22.42 ± 2.42 mg·kg−1 (Coriandrum sativum) to 1322.31 ± 72.26 mg·kg−1 (Origanum majorana), with several species exceeding 500 mg·kg−1. Ten species surpassed the Fe MCL (300 mg·kg−1), with O. majorana reaching ~4.4× MCL, while Artemisia Judaica, Teucrium polium, Mentha sp. and Ocimum basilicum had 2~3× MCL. Sr varied widely, with 12 species above the MCL (50 mg·kg−1); the highest concentrations occurred in O. majorana (365.14 ± 27.91 mg·kg−1) and Z. spina-christi (358.92 ± 21.44 mg·kg−1). PCA and HCA showed that Al, Fe, and Sr were the dominant contributors to plant clustering. The generally low levels of the remaining metal(loid)s reflect the region’s calcareous sandy – loamy soils, alkaline pH, low urbanisation, semi-arid climate, and plant exclusion mechanisms, all of which limit metal bioavailability and uptake. These findings provide a crucial baseline for assessing metal contamination in Jordanian herbal plants and offer implications for product safety, environmental policy, public awareness, and the use of native plants as bio-indicators in arid regions.

Source: International Journal of Environmental & Analytical Chemistry

DOI: 10.1080/03067319.2025.2612573