"Low Level
Radiation Health Effects: Compiling  the Data"

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

1.2.2
Ocupational

1.2.2.1
Nuclear Shipyard & Power Plant Workers

"A ten-year study by the Johns Hopkins Department of Epidemiology, School of Public Health and Hygiene of nuclear shipyard workers was concluded recently. The Technical Advisory Panel (TAP), chaired by Arthur C. Upton, advised on the research and reviewed results.

"The results contradict the conclusions of the BEIR V report that small amounts of radiation have risk — the linear risk hypothesis. The database of almost 700,000 shipyard workers included almost 108,000 nuclear workers with exposures beginning in the 1960s until the end of 1981. Three study groups were selected: 33,352 non-nuclear workers (NNW), 10,462 nuclear workers with a working lifetime dose equivalent (DE) of less than 5 mSv (NW<5), and 28,542 nuclear workers with a DE greater than or equal to 5 mSv (NW>5) where 5 mSv (0.5rem) is approximately equal to the sea-level background radiation (340 mr/yr) one would receive in 1 1/2 years." [ The data are summarized in Cameron 1994 and Table 1, above. ]

"The nuclear worker groups had a lower death rate from all causes, leukemia, and LHC than the non-nuclear workers. These apparently beneficial effects of low dose irradiation are consistent with the increased longevity and 15% lower mortality and cancer death rates seen in the seven western states with high natural background radiation averaging about 1 mGy per year above that of the other states.

"The non-nuclear workers’ death rates exactly matched those of the external non-shipyard matched control population. This demonstrates absence of the external healthy worker effect ascribed to adequate income, better health care, and the presence of health sufficient to allow maintenance of a reliable work schedule. There remains the question of an internal healthy worker effect resulting from the possible selection of more active individuals to be nuclear workers. The NW>5 group with the greater exposure had a death rate from all causes of 0.76 the standardized mortality rate (SMR), 16 standard deviations below that of the non-nuclear worker group (NNW). The NW<5 with lesser exposure had 0.81 SMR, about 8 SD below the NNW. While a possible internal healthy worker effect could contribute to the lowered SMR of nuclear workers, comparison of the NW>5 group with the NW<5 group demonstrates that the group with the greater dose had the lower SMR with even greater statistical power. This provides very strong evidence that low levels of ionizing radiation are without health hazard."