Activity Concentrations of Natural Radionuclides and Ingestion Radiological Risk in Common Medicinal Plants from Iraq

The increasing use of medicinal plants as natural alternatives to pharmaceutical drugs has raised concerns about contamination by naturally occurring radioactive materials and the potential health risks associated with their consumption. This study aimed to determine the activity concentrations of U-238, Th-232, and K-40 in commonly consumed medicinal plants and to assess the associated radiological risks resulting from their ingestion. Twenty medicinal plant samples were collected from four herbal shops in Al-Diwaniyah City, Iraq, and analyzed using gamma-ray spectrometry with a NaI(Tl) detector on a dry-weight basis. The mean activity concentrations were 3.90 ± 0.39 Bq.kg-1 for U-238, 13.03 ± 1.16 Bq.kg-1 for Th232, and 548.99 ± 12.65 Bq.kg-1 for K-40. The results showed that the activity concentrations of U-238 and Th-232 were below the global average values reported by UNSCEAR, whereas the activity concentration of K-40 exceeded these values in most samples because of natural uptake and agricultural practices. All calculated radiological hazard indices, including radium equivalent activity and excess lifetime cancer risk, were within the recommended safety limits. Overall, the findings confirm that the investigated medicinal plants are radiologically safe for consumption under normal conditions of use while emphasizing the need for regular monitoring to support long-term public health protection.