Discrepancy between soil safety and herbal risk: high cadmium enrichment in roots and leaves of Plantago asiatica and associated health implications

Plantago asiatica (P. asiatica) plays an important role in traditional Chinese medicine treatments and ecological environment assessments. This study focused on the heavy metals discrepancy between soil safety and health risk from different parts of P. asiatica. The contents of 10 heavy metals in the roots, stems, leaves, seeds and corresponding soils were determined using ICP-MS. A health risk assessment method for heavy metal elements was established and simulated by Monte Carlo. The assessment integrated the Bioconcentration Factor (BCF), Hazard Index (HI) and Total Carcinogenic Risk (TCR) models. Results revealed significant variations in heavy metal concentrations and exceedance rates among different plant parts. Roots and leaves exhibited the highest exceedance rates (100% and 57.69%, respectively), while the growth soils remained below the risk screening values for agricultural land. This was primarily attributed to their strong Cd enrichment capacity (BCF: 10.18 in roots, 6.73 in leaves). However, low translocation factors (TF < 1) were found in stems, leaves and seeds, suggesting P. asiatica as a potential candidate for phytostabilization research. Furthermore, risk assessment from the proposed medicinal material safety threshold indicated that heavy metal levels in all four parts posed potential non-carcinogenic health risks for both adults and children under the conservative assumption that all measured As was inorganic As. This contrasted with the food safety framework, under which only roots exceeded the threshold. Moreover, a potential carcinogenic effect was identified in roots for adults under the conservative assumption that all measured As was inorganic As. Therefore, significant discrepancy existed in heavy metal contamination and associated health risks across different parts of P. asiatica. In particular, As in roots and leaves were identified as the primary drivers of potential non-carcinogenic health risks, warranting prioritized attention in quality control and risk management. It was recommended to avoid or reduce using high-risk parts (especially roots) in medicinal applications.