Distribution of 40K and 137Cs in food and food additives from western Serbia and associated radiological ingestion risk.

Soil may contain certain concentrations of the natural radionuclide 40K as well as the artificial radionuclide 137Cs, which can accumulate in the edible parts of plants. This can lead to an exceedance of the ingestion dose. In this study, measurements of 40K and 137Cs were conducted for 144 food samples (including fruit, tea, cereals, beans, salt, and sugar) using gamma spectrometry. In addition to food samples, for the first time, the presence of these radionuclides was analyzed in 168 samples of food additives (15 types). The samples were collected in the western region of Serbia between 2010 and 2023. Measured 40K activity concentrations in food and food additives ranged from 5.8-641 Bq kg-1 and 1.7-5861 Bq kg-1, respectively, while 137Cs ranged from 0.2-5.2 Bq kg-1 and 0.1-21.0 Bq kg-1, respectively, wet weight. All 137Cs values were below recommended limits, indicating no contamination of food following the Fukushima accident in 2011. 40K contributes the most to the annual ingestion dose, while the contribution from 137Cs is negligible. The highest total annual ingestion dose was recorded in wheat flour samples (0.35 mSv y-1), exceeding Serbia's recommended limit of 0.2 mSv y-1, while for food additives it was 0.036 mSv y-1. Based on the calculated dose values, there is a possibility of exceeding this threshold through the combined consumption of multiple food types over the year, likely due to the use of mineral fertilizers with high 40K content. The measured values of both radionuclides are comparable to those found in previous studies on other food types, suggesting that the estimated health risk is similar to the values found in food in other countries. These findings indicate that there is no need, from the radiological point of view, to restrict the use of food additives in the food industry.