March 24, 2012

Can Low Grade Radiation Protect Against Cancer?

Surprising Research Finds Beneficial Effects of Low Level Radiation Exposure

Author: Tom Heston, MD

Cancer is a heterogeneous disease characterized by uncontrolled cellular growth and multiplication. There are several risk factors associated with cancer, including smoking, inactivity, and a poor diet. However, the role of radiation exposure as a risk factor is unclear. We do know that sudden high doses of radiation, such as that experienced by people exposed to the atomic bomb blasts in Hiroshima and Nagasaki, increases cancer risk. But does all radiation increase the risk of cancer? Surprising evidence suggests that the opposite occurs, that low levels of radiation may actually protect against cancer by a process called radiation hormesis .

The best evidence for a beneficial effect of low level radiation comes from Asia. In Taiwan, approximately 25 years ago, recycled steel was accidentally contaminated with radioactive cobalt-60. This steel was used to build more than 180 buildings, and approximately 10,000 people occupied this buildings for about 10 to 20 years. The mean dose to the residents was approximately 13 mSv per year and the maximum dose was 160 mSv per year. For comparison purposes, the occupational limit for radiation workers in the U.S. is 50 mSv per year. The International Atomic Energy Agency sets the occupational limit at 20 mSv per year.

This unique research, made possible due to the accidental contamination of steel used to make apartment buildings, found that estimates of radiation risk from the International Commission on Radiological Protection were completely wrong. Compared to residents of nearby apartment buildings, that did not contain the radioactive cobalt-50 contamination, the people exposed to low level radiation had greatly reduced cancer deaths and congenital malformations. The cancer death rate among those exposed to low level radiation was only 3% of the rate of the general public. Put another way, the general public was more than 30 times more likely to die of cancer than the people living in the apartment buildings that exposed them to low level radiation over many years. Furthermore, the congenital malformation rate of the radiation exposed residents was 6.5% of the rate of the general public. The general public was more than 15 times more likely to have a child with congenital malformations compared to the radiation exposed residents.

This is strong evidence that a low level of radiation exposure has a beneficial health effect in terms of cancer and congenital malformations. Furthermore, this research is from real world data, not conjecture or theoretical mathematical models.

Based upon this promising research, and similar findings from other epidemiologic studies, some scientists have proposed that further human experiments be carried out, perhaps in nursing homes. Of course, such research would require full consent, Institutional Review Board oversight, and full disclosure to all individuals involved. But if death from cancer can be reduced by a factor of 30, certainly more research into this possibility is needed.

Current radiation hysteria and the linear no-threshold hypothesis do not appear to be based upon valid, scientific evidence. It is time to move out of the dark ages when it comes to radiation, and insist that policy decisions be based upon real world evidence.

REFERENCE: Chen WL et al. Is chronic radiation an effective prophylaxis against cancer? J Amer Phys Surg 2004;9(1):6-10.