Measuring the radioactivity concentration of 40K and 137Cs and calculating the annual internal doses from ingesting liquid and powdered milk

Abstract

Thirty-three samples of powdered milk and thirteen samples of liquid milk (mostly imported from several countries) were collected from the local market in Saudi Arabia to measure the activity concentrations of artificial and natural radionuclides and evaluate the safety of milk for humans. Spectrometric analysis using the HPGe detector was performed. The results show that the activity concentration of ⁴⁰K in powdered milk ranged between 130 ± 7 and 595 ± 32 Bq kg^–1 (average 285 ± 29 Bq kg^–1), and that of ¹³⁷Cs ranged between 0.05 ± 0.02 and 1.3 ± 0.2 Bq kg^–1 in powder milk. In liquid milk, the activity concentration of ⁴⁰K ranged between ⁴⁰ ± 2 and 98 ± 5 Bq L^–1 (average 66 ± 4 Bq L^–1), and that of ¹³⁷Cs was 0.12 ± 0.03 Bq L^–1. The annual internal dose for ⁴⁰K and ¹³⁷Cs was calculated, and it is lower than the regulated dose.