Evaluation of radioactive exposure from 137Cs in contaminated areas of Northern Ukraine.

The paper gives averages of 137 Cs deposition densities in soils from three areas in Northern Ukraine measured 12 to 15 y following the Chernobyl accident: in an area near Narodici (75 km west of the Chernobyl nuclear power plant in the so-called zone II) heavily contaminated by the Chernobyl fall-out and in areas around Korosten and Zhitomir showing contamination levels to be much lower. The three areas exhibited very different 137 Cs deposition densities of 2.2 MBq m -2 , 400 kBq m -2 , and 5 kBq m -2 , respectively. During a 1-y observation, measurements of the 137 Cs transfer in the food chain to humans and 137 Cs whole body contents dependent on the 137 Cs daily intake were carried out under realistic conditions of the rural inhabitants who lived in settlements within zone II. Detailed investigations of components of the daily diet showed that the high 137 Cs contamination levels found in soils of zone II do not affect in any way low 137 Cs concentrations of all important agricultural products harvested and consumed by villagers. With regard to consumption habits of the population of zone II, mushrooms and wild berries were found to contribute more than 95% of the 137 Cs daily intake to the 137 Cs whole body content of about 12 kBq (with maximum values up to 760 kBq) measured in a group of inhabitants of zone II during a period from July 1998 to July 1999. The median of the annual dose of these inhabitants from external and internal exposures was 1.2 mSv y -1 with a geometric standard deviation of 2.6. Excluding extreme habits, the geometric mean of the total exposure was 1.0 mSv y -1 with a geometric standard deviation of 1.3.