Japan

Spring waters have often been found to have significant amounts of dissolved radon. This seems particularly true at springs that are considered "health spas," such as Bad Gastein in Austria, where the activity from radon and its progeny reaches 16,200 pCi/l - a mere 73,600% higher than the "contaminated milk" of such great concern to the media at Three Mile Island. A case in point are the radon springs at Misasa, Japan, where Mifune et al. [Mifune, M., et al. Cancer mortality survey in a spa area (Misasa, Japan) with a high radon background. Japan Journal of Cancer Research, 83, 1, 1992], investigated the prevalence of cancer mortality in Misasa versus that in the nearby town of Beppu Spring, a village with minimal waterborne radon. Also, used as a control, were the Standard Mortality Ratios for all Japan. Data were collected during the period 1952-88.

Caption for Figure 24: Japanese Mortality vs. Radon Prevalence: Mifune, M., Sobue, T., Arimoto, H., Komoto, Y., Kondo, S. and Tanooka, H. Cancer mortality survey in a spa area (Misasa, Japan) with a high radon background. Japan Journal of Cancer Research, 83, 5, 1992.

Stomach cancer mortality is singled out and plotted in Figure 24, since it might be expected from ingesting radon in the water. Obviously there is a significant negative correlation between radon exposure and cancer - in conflict with the LNT and in good agreement with hormesis expectations.

One unusual feature of the data concerns female responses. Often the observed beneficial effect of radiation is less in females than in males. The Misasa data, however, indicate SMRs for colon/rectum and lung cancer that are signficantly lower for women.

Dr. Mifune, regarding a study much like that of Misasa, comments, "Similarly, in one region of Japan with an average indoor level of 35 Bq/m^3, the lung cancer incidence was 51% of that in a low-level radon region (11 Bq/m^3), and the mortality caused by all types of cancers was 37% lower." By the way, to convert Bq/m^3 to pCi/l, you divide by thirty-seven - which means both of the above cited areas have relatively low indoor radon. (Just wait until you see what Bernard Cohen says about all this in chapter 20.)

Table 12
Standard Mortality Ratios for Residents of Misasa, Japan
	Male	Female
Total Cancer	.538	.463
Stomach	.400	.452
Colon/rectum	.296	.142
Lung	.475	.187
Leukemia	.445	.534
Source: Mifune, M. et al. Cancer mortality survey in a spa area (Misasa, Japan) with a high radon background. Japan Journal of Cancer Research, 83, 1, 1992.