Abstract: Edible salt, as a necessary mineral carrier with consistent daily intake in humans, may introduce trace natural radionuclides (238U, 226Ra, 232Th, and 40K) due to its diverse sources (sea salt, lake salt, and rock salt) and processing types (iodized and low-sodium), posing potential risks to food safety. This study systematically assessed dietary exposure to natural radionuclides from commercial edible salts in China from the perspectives of food safety and nutritional risks, analyzed the effect of processing techniques and geological sources on 40K levels in low-sodium salts (20%–35% potassium chloride substitution), and evaluated their safety based on human potassium metabolism regulation. Twelve mainstream edible salts from the Chinese market were selected and measured for activity concentrations of 238U, 226Ra, 232Th, and 40K using high-purity germanium (HPGe) γ-spectrometry. Dose-response models were applied to calculate radium equivalent activity, internal hazard index, and annual effective dose for carcinogenic risk assessment. The results showed that the 40K activity in low-sodium salts was markedly elevated (average 4 523 Bq/kg, approximately 100-fold higher than 45.3 Bq/kg for non-low-sodium salts), whereas other nuclide activities remained below the global averages reported by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), indicating they are within a safe range. This elevation stemmed from increased potassium content due to KCl substitution; however, given renal homeostatic regulation, the annual effective dose increment was less than 0.1 mSv, so that the risks were controllable; low-sodium rock salt exhibited lower radioactivity than did low-sodium lake and sea salts, which can be attributed to 40K migration induced by crustal compression during rock salt formation. Mainstream edible salts currently on the market pose minimal radioactive health risks and are safe for long-term consumption.

Key words: radioactive nuclides; edible salts; cancer risks; food safety