Tuesday, March 1, 2016

American Weapons Plant Workers

In the first of several planned efforts to combine data on workers at all Department of Energy facilities, this 1989 study was supervised by Dr. Ethel Gilbert of the Pacific Northwest Laboratory. [Gilbert, E.S., et al. Analysis of Combined Mortality Data on Workers at the Hanford Site, Oak Ridge National Laboratory, and Rocky Flats Nuclear Weapons Plant. Radiation Research, 120, 19, 1989.]

Table III of the report gives a breakdown of Causes of Deaths for 3,368 workers out of a total exposed population of 35,933; these data are summarized in Figure 19.


Source for Figure 19 Combined Mortality Data: Gilbert, E.S., Fry, S.A., Wiggs, L.D., Voelz, G., Cragle, D., and Gilbert, G.R. Analysis of Combined Mortality Data on Workers at the Hanford Site, Oak Ridge National Laboratory, and Rocky Flats Nuclear Weapons Plant. Radiation Research, 120, 19, 1989. Also American Journal of Epidemiology, 131, 917, 1990.

The report summary has some interesting observations:

"These combined analyses provide no evidence of a correlation between radiation exposure and mortality from all cancer or from leukemia. Of eleven other specific types of cancer analyzed, multliple myeloma was the only cancer found to exhibit a statistically significant correlation with radiation exposure. Estimates of the excess risk of all cancer and of leukemia, based on the combined data, were negative." [Emphasis added.]

Sounds terrific for LNT opponents! Could it ever be made more clear than by saying "the analyses provide no evidence of a correlation between radiation exposure and mortality from all cancer or from leukemia"? No doubt the report conclusions will cast aspersions on the LNT and set the stage for hormesis resarch, right? Well, not exactly. It continues:

"SMRs for all cancers were significantly less than one in all three populations, probably because of selection bias and other factors related to the healthy worker effect." [Emphasis added.]

You would think that in a study that expects to "provide a direct assessment of health risk" from exposure to low-level radiation, a provision would be made to eliminate the healthy worker effect. Certainly there were enough non-exposed personnel at these facilities to provide a control cohort. The question is, "Why wasn't this done?"

Ruling out conspiracy and stupidity, one is left with only one possibility I can think of: It was expected that the data would show a cancer mortality rate higher than predicted by the standardized rate - which would be the case if the LNT and collective dose were true. No provision was made for the "unexpected result," thus leaving the study with the extremely weak conclusion that the data showed a negative correlation probably because of well, eh, ah... you know. Almost without doubt the researchers were honest, intelligent, dedicated people. But one thing was simply overlooked in analysis of the data: All results that showed evidence of hormesis were simply ignored.