A Few Snippets

Allow me to give you just a few snippets on other subjects related to both medicine and radiation:

"Court-Brown and Doll (1958) using a standard cohort technique, analyuzed the mortality of radiologists belonging to the 2 major radiological societies in the United Kingdom through 1956. Radiologists joining radiological societies after 1920 have had 176 deaths if they had the same life expectancy as the general population, or 169 death if their life expectancy was the same as that of physicians in general. Only 145 deaths were recorded." [Henry, Hugh (Oak Ridge National Laboratory). Is all radiation harmful? Journal of the American Medical Association, 16, 671, 1961.]

A study of 100,000 female radiology technicians, with a mean follow-up time of twenty-nine years since certification, showed no association for breast cancer with vocational experience in radio-therapy, nuclear medicine or fluoroscopy. [Boice, J.D., et al. U.S. National Cancer Institute risk of breast cancer evaluation. Journal of the American Medical Association, Vol. 274, No. 5, 1995.]

"A critical review of the literature leads to the conclusion that at the radiation doses generally of concern in radiation protection [greater than 2 gray (or 200,000 mrad)], protracted exposures to low linear energy transfer (LET) radiation does not appear to cause lung cancer. There is, in fact, indication of reduction of the natural incidence. [Emphasis added.] [Rossi, H. and Zaider, M. Radiogenic lung cancer: the effects of low doses of low linear energy transfer (LET) radiation. Radiation Environmental Biophysics, 36, 1997.]

Finally, there is the connection between cancer and the application of radium to watch dials, which is fairly notorious in medical texts. The women (there were only about a dozen men in this vocation) touched their tongues to their brushes while painting, thereby receiving a large internal dose. Just as in the case of H-bomb test fallout victims, I thought all the painters died early deaths from radiation-induced cancer. Perhaps the literature left you with the same erroneous impression.

"The absence of leukemia and other potential radiogenic cancers in the population of highly exposed radium dial painters - from both internal and external radiation - contradicts the LNT; moreover, the increase longevity of these workers has been noted, but competent documentation does not exist at this time." [Note: Support for study of these workers has been cancelled.] [Kondo, Sohei. (Senior Researcher, Atomic Energy Research Institute, Osaka) Health Effects of Low-Level Radiation. Kinki University Press, Osaka, and Medical Physics Publishing, Madison, Wisc., 1993.]

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Before turning the page, consider for a moment what evidence it would take to make you a "hormesian." (Not to worry, I promise not to use that word again.)

Measuring Radiation Doses

In the USA system of radiological measurements, there are three somewhat confusing units for measuring the exposure to and doses of radiation:

• the roentgen (pronounced rent'-gen),
• the rad, and 
• the rem.

To understand these you might imagine yourself on a sunny beach. The roentgen is analogous to the intensity of the sunlight striking the beach. The rad (radiation absorbed dose) corresponds to the amount of sunlight absorbed by your skin, while the rem (roentgen equivalent man) is comparable to the biological effect of the sunlight exposure. In the case of the rem, however, the difference in its effect is not due to your sunscreen, skin pigment, or hours spent in the tanning salon - but in the type of radiation being absorbed.

You may recall that the different types of radiation were either particles (alpha and beta rays, protons, neutrons) or high-energy photons similar to light (X- and gamma rays). Except for beta rays - which are electrons having some 1/1836 the mass of protons or neutrons - the particles, because of their large masses, have a more catastrophic effect when colliding with a cell in the body. For this reason the quality factor - usually designated as Q - is used to adjust the absorbed dose to its biological counterpart, the rem.

Mathematically, rads x Q = rems.

Fortunately, most of the exposures we will be referring to in the study of hormesis are gamma and X-rays where Q is equal to one, allowing rads and rems to be used interchangeably. (Your radiologist, dental hygienist, and others working with X-rays will usually talk in terms of rads or millirads - but these are the same as rems and millirems, because it is the X-ray source that produces the radiation.) There is one other term with which you should have at least a vague familiarity - Linear Energy Transfer or LET. Beta, famma and X-rays are considered low LET radiation, which means they have a Q of one. High LET particles can have Qs up to 400. A typical alpha particle has a Q of four.

[Wilhelm Roentgen (1845-1923) discovered an unknown emission (X-rays) from cathode ray tubes. It still happens today - that's how X-rays are made today. Incidentally, your TV screen is a cathode ray tube, and it emits many times the radiation we get from nuclear power plants. Somehow this fact escapes notice of the TV doomsayers.]