Leukemia in Male Employees of Atomic Energy of Canada, Ltd.

A later study by M.A. Gribbin et al. examined leukemia mortality of 9,997 male employees of Atomic Energy of Canada, Ltd., with an average exposure of 4.9 cSv (4,900 mrem) compared to 5,504 unexposed co-workers. [Gribbin, M.A., Howe, G.R. and Weeks, J.L. A study of the mortality of AECL employees, V, The second analysis: Mortality during the period 1950 - 1985, Report No. AECL-10615, p48, Atomic Energy of Canada, 1992. Also quoted by Z. Jaworowski in "Stimulating effects of ionizing radiation: New issues for regulatory policy." Regulatory Toxicology and Pharmacology, 22:2, 1994.]

Figure 18 presents the data in the form of standard mortality ratios for the various types of leukemia.

Source for Figure 18 Leukemia Mortality of AECL Employees: Gribbin, M.A., Howe, G.R. and Weeks, J.L. A study of the mortality of AECL employees, V, The second analysis: Mortality during the period 1950 - 1985, Report No. AECL-10615, p48, Atomic Energy of Canada, 1992.

Commenting on this study, Dr. Jaworoski states: "As shown in Table 6 [from which the graph data was taken], the mortality due to all leukemias in the exposed group was only 32% of that in the general Canadian population. The observed mortality among employees of AECL from all cancers and from all non-cancer diseases was also less than expected." [Zbigniew Jaworowski, professor emeritus at the Central Laboratory for Radiological Protection (Poland) and a member of the U.N. Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).]

While this is a relatively small study, the consistently lower leukemia mortality rate - previously considered the established sign of excessive radiation exposure - seems to be a powerful argument for hormesis at work.