Radiological Risk Assessment of Wild Medicinal Plants in the Sinai Peninsula: Chronic Dose Exceedance from NORM Accumulation

This study investigated the natural radioactivity and associated radiological risks of 17 key medicinal plant species utilized in the Sinai Peninsula, Egypt. Activity concentrations of the primordial radionuclides 40K, 232Th and 226Ra were determined using high-resolution HPGe γ-spectrometry, while 222Rn exhalation rates were measured using the CR-39 Can technique. The results showed the average Radium Equivalent Activity (Raeq) across all samples was 110.92 Bq/kg, which is below the internationally established public limit of 370 Bq/kg. However, specific species demonstrated significant radionuclide accumulation. Cleome droserifolia exhibited the highest concentrations of 226Ra (73.01Bq/kg) and 232Th (98.76Bq/kg) and the maximum radon exhalation rate. The radiological risk assessment focused on internal and external exposure, calculating the Annual Effective Dose Equivalent (EDEtotal). The maximum EDEtotal was found in the consumption of Shīḥ (Bu’aytharān), reaching an alarming 11.13 mSv/y. This value exceeds the ICRP public dose limit of 1mSv/y by more than a factor of eleven for chronic exposure in high-consumption scenarios. Furthermore, a strong correlation (r = 0.96) was observed between the 226Raconcentration in the plants and the indoor radon concentration in nearby living areas. This study concludes that while most species pose a low risk, the consumption of high-accumulating medicinal plants in the Sinai presents a non-negligible radiological hazard to regular users. Public health intervention and the establishment of safe consumption limits are strongly recommended to mitigate this specific environmental health risk.