Revision 1
March 19, 1998
by Radiation, Science, and Health, Inc.,
Edited by J. Muckerheide

1.2.2
Occupational

1.2.2.2
Nuclear Shipyard and Power
Plant Workers

"Information about the workers in nuclear energy, weapons and ship plants is given in Table 1. The data were taken from available studies which had significant numbers of exposed nuclear workers. Different reports of the same plant were used when they involved different cohorts."

"Several studies were perverted because the control was not well defined. Workers who received no radiation (many were unmonitored office personnel) and workers who received < 1 cSv (< 1 rem) are listed as unexposed workers. This practice is not justified on the basis that ‘the median of the group is zero’ (Muirhead 1992). The investigators assumed that the results from workers exposed with < 1 cSv (< 1 rem) are equivalent to those from workers having no exposure. This assumption is invalid. The results suggest that the control group would show increased cancer mortality rates if lightly exposed workers were not included in the same cohort with the unexposed workers. When this assumption was corrected for the Japanese bomb victims, those exposed to the lowest dose were found to exhibit radiation hormesis for both leukemia and total cancer mortality rates (Shimizu et al. 1992). Since some of these studies are ongoing, the directors should correct this flagrant error in radiobiology."

"In order to decrease variability between different studies, the data were normalized to give death rates as percent of control values (Figure 2). In order to differentiate between reports using unexposed workers from those using workers exposed to < 1 cSv (< 1 rem) as controls, exposures for the control groups were arbitrarily set at 0.3 cSv (0.3 rem). Total cancer mortality rates were plotted for different lifetime exposures for over 300,000 nuclear workers."

"A summary study of 95,673 nuclear workers in three countries showed that those who received 2-5 cSv (2-5 rem) had a relative cancer mortality rate which was 94% that of the control group (Cardis et al. 1995)."

"High LET radiation protects workers as well as low LET radiation. Mortality from cancer in those with a measured neutron exposure was significantly (p<0.05) lower than among other workers with a radiation record, but the deficit became smaller and non-significant after a lag of five or 10 years was assumed. (Beral et al. 1988).

"The dose-responses curves for leukemia death rates mimic those of total cancer mortality rates (Luckey 1994a,b, 1995a, 1996). No leukemia deaths were found in over 30 years observation of 4,742 workers who were exposed to plutonium, uranium, polonium, actinium or tritium (Beral et al. 1988)."

Table 1. Information on Nuclear Workers