Study of K-40, Ra-226, Ra-228 and Ra-224 activity concentrations in some seasoning and nuts obtained in Rio de Janeiro city, Brazil

Abstract This work presents an investigation of the activity concentration (AC) of naturally occurring radionuclides in 26 samples of seasoning and nuts utilized for Brazilian population. The samples were measured using gamma spectroscopy technique with a high-purity germanium detector. The analysis shows that K-40 AC was measured in all samples, and its AC ranges from 21.0 Bq/kg to 1288 Bq/kg. The highest K-40 AC was measured for cheiro verde, a Brazilian seasoning made of chives (Allium schoenoprasum) and parsley ( Petroselinum crispum), while annatto, made with the fruit of Bixa orelhana , presented the lowest AC. Brazil nut (Bertholletia excelsa ) presented the highest AC for Ra-226 and Ra-228 with 24 Bq/kg and 25.7 Bq/kg, respectively, and black pepper (Piper nigrum) presented the highest Ra-224 AC, with 33.9 Bq/kg. Behavior of radionuclides present in the seasoning samples and dose percentage due to ingestion was evaluated. The highest effective dose for members of the public due to idealized intake of 1 kg of seasoning was 23.5 µSv/y due to Brazil nut and the lowest effective dose was found for annatto: 0.13 µSv/y. The Syrian seasoning was the only sample that presented a measurable amount of Cs-137, (6.1 ± 1.1) Bq/kg for AC and 0.08µSv/y for effective dose.