Current Status of the Study on Assessment of I Specific Activity in Milk, Milk Products, and Leafy Vegetables Based on Total Beta- Activity Measurements Conducted in Belarus after the Chernobyl Accident

In 2002, a special study was initiated on the additional collection of total beta-activity measurements in milk, milk products, and leafy vegetables conducted in Belarus in April through June 1986 after the Chernobyl accident with subsequent analysis and assessment of the I specific activity. This study is conducted in the framework of a long-term epidemiological study of thyroid diseases among 12,000 Belarusian children exposed to I in fallout from the Chernobyl accident. Within two months following the accident, a small number of spectrometric (about 160) and radiochemical (about 100) measurements of milk and milk products were made in Belarus, but a very large number (about 40,000) of measurements of total beta-activity were carried out using DP-100-M radiometric devices with gaseous discharge end-window counters as detecting elements. Almost all of the total beta-activity measurements in milk and milk products were conducted by the laboratories of the State Sanitary and Epidemiological Inspection of the Ministry of Public Health and by the laboratories of the Main Agency of Veterinary of the Ministry of Agriculture of the USSR. The ongoing study encompasses all available total beta-activity measurements for Belarus, but this paper addresses only the measurements in Gomel Region, which was the most contaminated area of Belarus. The overall number of total beta-activity measurements (milk, milk products, and leafy vegetables) that were collected from the archives of sanitary and veterinary laboratories of 17 of the 21 districts of Gomel Region is estimated to be 22,834. However, about 40% of measurements in Gomel Region were below the minimum detectable level (3.7 kBq L) of the measuring DP-100-M device and cannot be used in the analysis. The methodology used to assess the I concentrations in milk, milk products, and leafy vegetables is described. The comparison of the estimates of I concentrations in milk derived from total beta-activity measurements and from spectrometric measurements shows a satisfactory agreement.