The observation and analysis of cancer deaths among classified radiation workers

The extent to which occupational radiation exposure contributes to cancer mortality is an influence on future world energy policy. It is also a factor in deciding the level of expenditure to reduce radiation levels experienced by workers. Here we discuss some of the difficulties in analysing the situation and present the results of some calculations which estimate the expected age-specific radiation mortalities from all inducible cancers and also from leukaemia separately. Using a high value for the average occupational exposure and a conservative estimate of the associated risk, we find that a survey of mortality among radiation workers must run over many years before sufficient data would be accumulated to resolve the effects of radiation-induced neoplasms from those arising from other causes. We show the advisability of determining the cause of death both of persons who remain employed in the industry and all for only a short time. Our estimates are based on maintenance of an occupationally exposed dose of one rad per person per year during the period of the survey which may extend over several decades. However, scaling of the estimates to any other exposure rates is easily performed. We also give estimates of the lowest risk coefficients detectable in a given observation time. Since for a work force of 3000 these lowest detectable values are an order of magnitude larger than those expected, it is clear that only a national or international survey can produce data adequate for even modest objectives.