ABSTRACT
In some places the background is considerably higher than the average, in regions where the rocks and soil contain exceptionally large concentrations either of uranium or of thorium—the other naturally radioactive element. An example of a place where the general run of uranium in the rocks is higher than normal is the county of Cornwall, and in the United States there are many regions of Utah, Colorado, and Wyoming where this is so. Radioactive materials emit fast-moving particles, which in the early years of the present century were known as either a or ß particles. When the outcome of the investigation of Japanese survivors was published (S. Jablon and H. Kato, The Lancet, November 14,1970) the result was challenged, apparently in the hope that the condition of survivors would on reinvestigation turn out to be less favourable.
