engleski

Radioceasium activity concentrations in potatoes in Croatia after the Chernobyl accident

In the paper are summarized the results of systematic investigations of 137Cs and 134Cs activity concentrations in potatoes (Solanum tuberosum) for the post-Chernobyl period in the Republic of Croatia. Potatoes are very important foodstuff in Croatia, the average annual consumption being about 40 kg per person. Due to a comparatively high contribution of the ingestion doses to the total dose received by population after the exposure to nuclear fallout, a reliable prognosis of the expected ingestion doses is of utmost importance. The ingestion dose strongly depends on the consumption of various types of foodstuffs, and related activity concentrations of respective radionuclides in those foodstuffs, which themselves usually depend upon the transfer from fallout. In addition, a reliable prediction of the expected ingestion dose received by consumption of a particular foodstuff requires the detailed knowledge of decreasing behaviour of activity concentrations in the environment and respective foodstuffs. The correlation between 137Cs activity concentrations in fallout and potatoes, has been found to be very good, the correlation coefficient being r2=0.88 with P(t) < 0.001 for 17 degrees of freedom. As the radiocaesium levels in potatoes decreased exponentially, the mean residence time of 137Cs in potatoes was estimated by fitting the measured activity concentrations to the exponential curve. The mean residence time was found to be 6.3 &#177; 0.8 years, the standard deviation being estimated by the Monte Carlo simulations. The initial observed 134Cs:137Cs activity ratio in potatoes has been found to be quite variable, but slightly lesser than theoretically predicted value of 0.5, calculated by applying the known inventory of these radionuclides in the Chernobyl reactor to the equation for the differential radioactive decay. This can be explained by presence of the pre-Chernobyl 137Cs in soil that originated from nuclear fallout. As in other environmental samples, 134Cs relatively quickly disappeared from potatoes and its activity concentrations were in 1990 under the detection limit of the instrument. The annual effective doses received by 134Cs and 137Cs intake due to consumption of potatoes estimated for an adult member of Croatian population were found to be very small, as the per caput dose for the entire 1986 &#8211; 2004 period was calculated to be about 2.5 &#956; Sv, 134Cs accounting approximately for 1/3 of the entire dose. Consequently, it can be argued that after the Chernobyl accident consumption of potatoes was not the critical pathway for human intake of radiocaesium from the environment in Croatia.

potato; concentration factor; 137Cs; 134Cs; Chernobyl accident; dose

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