Evaluation of equivalent body burden in the thyroid for the people of Poland on results of 131I absorption after the disaster in Czernobyl. Determination of thyroid blockade with potassium iodide]

An assessment of effectiveness of the administering of single dose of stable iodine in Poland on the reduction of 131I doses in thyroid has been performed. 5-compartment model of metabolism of iodine developed by Johnson has been used to evaluate predicted levels of stable iodine and 131I content in thyroid and commitment dose equivalent H50 for different doses of stable iodine and various age and sex group population. The measured values of 131I concentration in air and in milk and standard values for milk and food consumption and inhalation rate as well as metabolic parameters were used. Theoretical calculations showed that administering of stable iodine on 1986-04-28, 1986-04-29, 1986-04-30 and 1986-05-01 could have reduced committed dose equivalent H50 form ingestion with inhalation pathway by about 44%, 40%, 26%, 12% respectively. On the basis of measured 131I activity in the thyroid for inhabitants from different districts in Poland (1400 measurement) committed dose equivalents were determined and analysis of radiation hazard from 131I were performed. In the most contaminated regions of Poland average H50 doses for children 1-5 and 5-10 years old are close to 50 mSv (permissible level for population) and maximal doses exceed this limit four times. These maximal doses occurred for about from 5% inhabitants from these area. In the moderate and low contaminated regions of Poland the average doses are fivefold and tenfold less respectively.