Gamma radiation protects against cancer, in low doses?

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Cancer mortality reduction by 97% - huge!  Is it true?  Hormesis?

Paper:
  "Effects of Cobalt-60 Exposure on Health of Taiwan Residents Suggest New Approach Needed in Radiation Protection",   W.L. Chen et al.,   Dose Response. 2007; 5(1): 63–75, 

Quote:

... serendipitous contamination of 1700 apartments in Taiwan with cobalt-60 (T_1/2 = 5.3 y). This experience indicates that chronic exposure of the whole body to low-dose-rate radiation, even accumulated to a high annual dose, may be beneficial to human health. Approximately 10,000 people occupied these buildings and received an average radiation dose of 0.4 Sv, unknowingly, during a 9-20 year period. They did not suffer a higher incidence of cancer mortality, as the LNT theory would predict. On the contrary, the incidence of cancer deaths in this population was greatly reduced-to about 3 per cent of the incidence of spontaneous cancer death in the general Taiwan public. In addition, the incidence of congenital malformations was also reduced - to about 7 per cent of the incidence in the general public. These observations appear to be compatible with the radiation hormesis model.

   Figure 1 from the same paper.  Click to magnify and hires.

More readings:

1. by D.W.Miller, MD:  Afraid of Radiation

2.  Keeping the Lights On

3. by William R. Ware, Ph.D.:  Low-Dose Radiation Exposure and Risk of Cancer

4. Caroline Hadley: "What doesn’t kill you makes you stronger", Nature, EMBO reports   VOL 4 | NO 10 | 2003

5. Bernard L. Cohen: "Test of linear no threshold theory of radiation carcinogenesis for inhaled radon decay products", University of Pittsburgh 1994

Fig 1a from Cohen's paper 

To annoy anti-nuclear environuts:    Letter... 

More refs added (02-Mar-2011):

6.  Rheumatology 2000;39:894–902;
"Long-term efficacy of radon spa therapy in rheumatoid arthritis—a randomized, sham-controlled study and follow-up"

7. Int.J.Low Radiation,Vol.1,No.4,2005; "Nuclear shipyard worker study (1980–1988): a large cohort exposed to low-dose-rate gamma radiation"

see also John Cameron's (one of the study author) write-up here

Quote:

In 1980, the US Department of Energy (DOE) gave a contract to the School of Public Health at Johns Hopkins University to study radiation risks to nuclear shipyard workers. This study, which extended for more than a decade, cost the taxpayers $10 million. This was the World's best epidemiological study of nuclear workers. The study has yet to be published more than 12 years after its completion in early 1988.
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The reader may think that the nuclear shipyard study is contradicted by other human studies. I know of no contradictory studies. One other radiation worker study--the British radiologists study. (Smith and Doll 1981)-- also looked at the death rate from all causes. It gives results consistent with NSWS. (Table 2.)

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