Radiation exposure and cancer: a simpler view of Three Mile Island.

The article by Wing et al. (1) introduced the idea of calculating the relative intensity of radioactive fallout between sectors of a circle drawn around the accident at Three Mile Island. The partition derived from wind and weather data allowed a comparison of ratios of radiation exposure between sectors with cancer incidence ratios and bypassed much of the uncertainty involved in calculating actual doses. The results indicated that higher fallout was correlated with higher cancer incidence. Considering that the average levels of radioactivity in each sector were low, this could be interpreted as evidence for a proportional carcinogenic response to low doses of ionizing radiation. There is, however, a simpler way to interpret the same set of data. Wing et al. (1) reported that some of the people exposed to the fallout from the accident showed signs of acute radiation damage. They also reported that ground measurements of radioactivity were not adequate to show the details of distribution of the fallout or the resulting doses to individuals. We are free to infer that the fallout was patchy, that some of the residents were exposed to high doses of ionizing radiation , and that the data of Wing et al. (1) show a correlation of the frequency of high exposure "hits" on people in each sector with the sector's share of the region's radioactive burden. In this view, increases in cancer incidence were simply correlated with the number of people hit by high doses of ionizing radiation. This interpretation is consistent with the conclusions drawn by Raabe et al. (2) from data on radium dial painters, the data set that offers the most precise readings of both individual radiation doses and carcinogenic effects in humans. It is also consistent with the patchy distribution of radioactive fallout from explosions often observed at the Nevada Proving Grounds.