Abstract
The aim of this study was to assess the effect of storage duration on the accumulation of long-lived beta-emitting radionuclides of the radon decay chain, namely 210 Pb and 210 Bi, in consumer products from Kazakhstan, including buckwheat grain, tea, and tobacco products. Samples with storage periods ranging from 3 months to 6 years were analyzed using beta spectrometry. It has been established that the activity concentration of 210 Pb in food products increases over time: from 1.16 ± 0.24 to 14.2 ± 2.9 Bq/kg in buckwheat over 4.5 years, and from 3.12 ± 0.64 to 8.74 ± 1.81 Bq/kg in tea over 4 years. In contrast, tobacco shows a pronounced decrease in 210 Pb activity (by 76% over 6 years) against the background of high 210 Bi activity, indicating a disruption of radioactive equilibrium. The measured activity concentrations in food products were several orders of magnitude below national hygienic standards. Based on consumption data, the annual effective dose was estimated: for long-stored buckwheat, it may reach up to 21% of the average global dose from natural radionuclides in food, whereas for tobacco products, the additional inhalation dose ranged from 1.83 to 7.61 μSv/year. The results highlight the importance of considering storage duration in the radiological risk assessment of dry food products and demonstrate the need for separate dosimetric approaches for tobacco products due to their fundamentally different radionuclide behavior.