A Comparison of the Concentration of Naturally Occurring Radionuclides in Organic and Conventional Staple Food

Fertilizers based on NPK are reported to have large concentrations of naturally occurring radionuclides. Hence, fertilizers usage can elevate the concentration of natural radioisotopes in soil and groundwater leading to a higher concentration of ⁴⁰K, ²³⁸U and ²³²Th in crops grown in these fields. In the last few years, a surge is witnessed in organic farming methods due to consumer demand. In this study, the concentrations of ⁴⁰K, ²³²Th and ²²⁶Ra are compared between organic and conventionally grown food crops. In total, 25 samples of organic and conventionally grown pulses and cereals were collected. The NaI(Tl) gamma-ray spectrometer was used for measuring naturally occurring radioisotopes in samples. The activity concentrations of ⁴⁰K, ²²⁶Ra, and ²³²Th are almost same for both categories. The values of activity concentration of ²²⁶Ra and ²³²Th are well within the recommended limits but ⁴⁰K activity concentration is higher than 400 Bq/kg in all the samples. The radium equivalent for all organic and conventional samples is below the reference value of 370 Bq/kg. The annual effective dose of children for ²²⁶Ra is higher than other age groups for wheat and rice samples but lower than the reference value of 2.4 mSv/year. The internal hazard index for all samples is less than 1 for both categories. All samples of both categories are safe for consumption as far as radionuclide concentrations are concerned. An elaborate investigation is advised for different food and drinking items to broaden the horizons.