A study on microplastic contamination in medicinal plants

The microplastic (MP) contamination of food plants is increasingly being recognised as an environmental and public health concern, yet raw medicinal botanicals remain understudied. We surveyed 70 wild‐harvested samples (5 g dry weight each) of herbs, flowers, leaves, seeds, roots, and fruits collected in May 2024 from remote meadows and orchards in Herzegovina, Bosnia and Herzegovina. All sample handling—including drying, oxidative digestion (30 % H₂O₂, 60 °C, 24 h), and vacuum filtration (0.45 µm)—was performed under clean‐air conditions with procedural blanks (n = 3), which showed no background particles. Retained particles were first inspected by stereomicroscopy (25–100×) and then identified via FTIR spectroscopy. To validate detection capability down to micrometre scales, two positive controls were used, (1) certified traceable polystyrene spheres and (2) in‐house ground polystyrene 678E resin, yielding size fractions of ~50 µm, 80 µm and 1.5 mm (MSDS provided). Polymer identity in both controls was confirmed by ATR‐FTIR, demonstrating that our qualitative workflow reliably detects and identifies particles ≥ 50 µm. No MPs were detected in any of the 70 plant samples, indicating that, when harvested from relatively pristine sites and processed under stringent contamination‐control measures, medicinal plants can remain free of detectable microplastic contamination. This qualitative survey provides a validated protocol for direct MP screening in botanicals. Future work should extend to additional regions, commercially processed products, and varied packaging practices to fully assess microplastic exposure across the herbal supply chain.

Acknowledgement: This work was carried out within the project "Food Safety and Quality Center" (KK.01.1.1.02.0004). The project is co-financed by the European Union from the European Regional Development Fund.