Activity of cesium 137Cs and potassium content in new potatoes imported to Poland.

Background: Potatoes are an important component of the human diet. In addition to components which determine the nutrition and dietary values, potato tubers also contain anti-nutritional substances, inter alia radioactive elements. Natural and artifical radionuclides are released to the environment as a result of antropogenic activity, in a controlled or uncontrolled manner, and they are transferred to the human body through the food chain.

Objective: The aim of the study was to determine the activity of radioactive cesium 137Cs isotope and potassium content, including the activity of 40K isotope, in new potatoes imported to Poland during the winter period from Mediterranean countries.

Material And Methods: The study material included new potatoes imported from Cyprus, Egypt and Israel, purchased in the city of Siedlce from the beginning of February to the end of March 2015. The activity of 137Cs and 40K isotopes in potato tubers was determined. Analyses were performed by γ-spectrometric method. Laboratory tests were performed on a total of 18 samples. Based on the activity of 40K isotope, the total potassium content of potato tubers was calculated, with the assumption that 31.00 Bq 40K is equivalent to 1 g potassium.

Results: The activity of 137Cs in most tested potato samples was below 0.2 Bq kg-1 (limit of quantification), and in other samles it was from 0.3 Bq kg-1 to 5.4 Bq kg-1. Potatoes of the same variety, originating from the same country, differed in terms of the activity of 137Cs. The highest activity of 137C, determined in potatoes imported from Cyprus, was seven times higher than the lowest value. The activity of 40K changed from 93.3 Bq kg-1 to 259.1 Bq kg-1. The average activity of 40K in potatoes imported from Cyprus, Egypt and Israel was at a similar level. The ratio of the activity of 137Cs determined in the tested potatoes to the activity of 40K changed from 0.00242 to 0.04163. The calculated potassium content in imported new potatoes was on average 4.376 g K kg-1 of the fresh weight of tubers and ranged from 3.010 g K kg-1 to 8.358 g K kg-1.

Conclusions: The activity of the 137Cs cesium isotope in imported new potatoes in most tested samples was at a very low level (below the limit of quantification) and in other samples it did not exceed 5.5 Bq kg-1 and posed no threat to human lives. Potatoes originating from the same country differed in terms of the activity of 137Cs. The average activity of 40K in potatoes imported from Cyprus, Egypt and Israel was at a similar level and did not differ from the activity of 40K in domestically produced potatoes. The potassium content in imported new potatoes was determined by the variety.