Natural radionuclide distribution in Brazilian foodstuffs and radiological dose assessment of coffee and fresh produce from Southeastern Brazil.

This study quantified the activity concentrations of226Ra,228Ra,40K, and the anthropogenic137Cs in coffee and fresh produce from Southeastern Brazil and assessed the associated ingestion dose to consumers. Seventeen coffee samples were collected in four municipalities representing distinct geological settings, Itatiaia and Rio de Janeiro (Rio de Janeiro state) and Poços de Caldas and Mariana (Minas Gerais state), while 27 fresh-produce items were collected in the three producing municipalities (Itatiaia, Poços de Caldas, and Mariana). Activity concentrations were determined by high-purity germanium (HPGe) gamma-ray spectrometry. Annual effective doses (E) and the excess lifetime cancer risk (ELCR) were calculated using consumption data from the Brazilian Household Budget Survey (IBGE) and dose coefficients from ICRP Publication 119. Coffee showed mean activity concentrations of 563 ± 26 Bq kg-1(40K), 3.7 ± 0.6 Bq kg-1(228Ra), and 1.4 ± 0.2 Bq kg-1(226Ra), with a mean annual effective dose of 3.2 × 10-02mSv yr-1. Fresh produce exhibited marked regional variability, most notably for228Ra: carrots from Itatiaia reached 27 ± 1.9 Bq kg-1, nearly an order of magnitude above those from Poços de Caldas (3.3 ± 0.5 Bq kg-1).137Cs was below the detection limit in all samples, indicating negligible anthropogenic contamination. All individual annual effective doses represented a negligible fraction of the 1 mSv yr-1public dose criterion recommended by the ICRP. The highest individual values were observed for cassava from Mariana (1 × 10-02mSv yr-1), followed by banana and papaya (Mariana) and orange (Itatiaia) at 9 × 10-03mSv yr-1each, and onion from Poços de Caldas (6 × 10-03mSv yr-1). Cumulative annual effective doses obtained by summing all analysed fresh-produce items were 5.9 × 10-02mSv yr-1(Itatiaia), 2.2 × 10-02mSv yr-1(Poços de Caldas), and 6.3 × 10-02mSv yr-1(Mariana); combined with the mean coffee dose (3.2 × 10-02mSv yr-1), the total remained below 1.0 × 10-01mSv yr-1(<10% of the criterion). ELCR values ranged from 4 × 10-07-4 × 10-05for individual fresh-produce items and from 7 × 10-05-2 × 10-04for coffee. For reference, the global average ingestion dose from natural radionuclides is approximately 0.29 mSv yr-1(UNSCEAR 2000).