Method for evaluating the number of radon-caused lung cancer cases in Belarus
The role of radon in the development of lung cancer was suggested by scientists first noted the high rate of lung cancer incidence among miners worked at mines with high radon concentration. The results of epidemiological studies of lung cancer incidence among residents of homes with increased level of indoor radon confirmed the cause-and-effect relationship. Though research into the role that radon plays in the development of lung cancer and prevention of exposure to radon is of great importance, material and time expenditures for the research are very high. We present less expensive tool for evaluating the number of lung cancer cases associated with inhaled indoor radon. We detected relationship between oblasts-average standardized lung cancer incidence rates in 1975, 1980, 1985, 1990 and average volume radioactivity of residential radon in the same years. These relationships were presented as line graphs. The lines were approximated with line function and high correlation coefficient values related to years under study 1975 - r=0.68; 1980 - r=0.90; 1985 - r=0.89; 1990 - r=0.74. Difference in angles slope of approximated linear relationships dated to the years under the study is not large. This "parallelism" can be caused by the permanent existence of a factor associated with the lung cancer incidence induced by radon. Mean value with standard deviation is 380±40, i.e. 10% of 3910, the highest number of lung cancer cases registered in Belarus in 1990, the year under study. Estimated number of radon-associated lung cancer cases in each year under study were compared with published data on radon-related lung cancer prevalence in Sweden and the Czech Republic - the population size in these countries was similar to that in Belarus. However, Sweden developed radon mitigation strategy and used it in practice, in contrast to the Nordic country Belarus and the Czech did not carry out necessary preventive measures in that time. As the result, out of 3000 lung cancer cases detected in Sweden in 1975 500 cancers were caused by radon, in the Czech Republic the proportion of "radon" cancer cases was higher - 1000 of 4000. The difference in standardized incidence rates of radon-associated lung cancer prevalence in Sweden and the Czech Republic remains: in Sweden the rate reduced by about 1.5 times, in Czech the rate of increase is doubled. The presented method for evaluation of developed radon-caused lung cancer cases can be used in Belarus for making decision on the necessity of measures to prevent the development of lung cancer caused by elevated concentration of radon in homes and working places. In this paper, we did not evaluate the role of the main cause of lung cancer - tobacco smoking, so the results discussed in the study can be interpreted as a combined effect of 2 factors-radon and tobacco.