Before You Spend $4,000 to Shorten Your Life

The observed lung cancer rates of females in high residential radon areas in the former uranium mining areas in Southern Saxony are substantially lower than the population average of East Germany. - Professor Klaus Becker, German Standards Institute

Bernard Cohen, doctor of science and professor emeritus at Pittsburgh University, is a liberal Democrat. [He mentions this in his terrific book, The Nuclear Energy Option, Plenum Press, New York, 1990, p. 269.] I probably would disagree with everything he believes in politically. But Dr. Cohen is also a scientist. He is convinced that the way mankind can continue to raise itself up from our back-breaking labor and mud huts is through increasing our knowledge about the world we live in. And most important, he is convinced this knowledge is objective. We can find truth. It is verifiable. It can stand on its own.

In by far the largest "ecological" study of low-level radiation ever made, Professor Cohen was attempting to refine the Linear No-Threshold theory. But, in his words, "It came as a great shock to me that my data ran contrary to the LNT, and I didn't fully believe it until about 1993 - when I shut off the $1,200 radon reduction system in my home to save electricity." But he was using the scientific method, which is very clear about hypotheses that have been shown to be false: they are stuffed immediately into the trash can.

Under the LNT theory, cancer rate increases with increasing doses of radiation - even at very low exposures. If you are to plot response (cancer) versus dose, you should have a straight line with a positive slope according to this theory that has been sanctified by the regulators and rule writers. Using data from the American Academy of Sciences' Biological Effects of Ionizing Radiation committee (BEIR), the slope of this line should be an increased cancer risk of 4% per gray for chronic radiation and 8% per gray for acute exposure. By knowing the "whole body" dose given by various radon concentrations, this slope can also be expressed in terms of lung cancer mortality (since that is the only place in the body where significant radon progeny reside) per picocurie per liter of air.The value of this prediction for men, without any consideration of smoking, is 4.5 deaths per 10,000 men per year for each pCi/l increase in airborne radon. Remember this figure.

Cohen's initial study took five years, cost millions of dollars, and accumulated data from homes in 1,729 counties, comprising about 90% of the U.S. population. [Because so many retirees move to California, Florida and Arizona, these data were deleted, reducing the number of counties to 1,601. This deletion, incidentally, had an insignificant effect on the results.] It considered radon data from the EPA, state agencies, and 272,000 measurements made by the University of Pittsburgh. Census data on smoking, rural-urban balance, occupations, education, housing, medical care - a total of fifty-four socioeconomic "confounding" factors (alone and in combinations with each other) were analyzed to determine if and how they affected the lung cancer rate.

The study found - as you may now suspect - a discrepancy between the LNT's prediction of lung cancer and the actual data. This has since been known as "our discrepancy," and Cohen has invited his colleagues to try to find a confounder that would explain it. He notes that unless someone can come up with a reason to put aside "our discrepancy," the LNT must be considered a false and unacceptable theory and discarded as a source for use in regulatory authority. With more than 500 of the suspected confounders and combinations thereof already eliminated, it does not look good for the LNT advocates - most of whom do not address "our discrepancy" but prefer to snub Dr. Cohen as a mere physicist, and not an epidemiologist. (Critics overlook that G.A. Colditz is a world-class epidemiologist and was co-author with Cohen on "Tests of the linear-no-threshold theory for lung cancer induced by exposure to radon" in Environmental Research, 64, 1994.)

Note and source for Figure 33: Effect of Residential Radon Levels on Lung Cancer - Each data point represents an average of eighty-nine U.S. counties. Source: Cohen, B.L. Test of the linear-no-threshold theory of radiation carcinogenesis for inhaled radon decay products. Health Physics, 68, 157, 1995.

Figure 33 is typical of the curves plotted from the University of Pittsburgh data and is one of four similar figures in the report - this one is for males without smoking's begin taken into account. The others are for males with smoking taken into consideration, and similar data on females both considering and not considering smoking. [These are available from his paper, Test of the Linear-No-Threshold Theory of Radiation Carcinogenesis for Inhaled Radon Decay Products," Health Physics, February 1995. All curves give a similar negative correlation between radon and cancer through 6 pCi/l.]

I have deleted the error bars and the "first and third quartile" curves because I don't think they'd mean much to the average reader. Cohen also had indicators of the numbers of counties for each data point on his curves ranging from 4 to 216 with an average of 88.9. These are counties, bear in mind, not individuals.

Remember the increase by 4.5 deaths per pCi/l predicted by the LNT? That is shown graphically by the dashed line on Figure 33. The solid line with a negative slope is the best fit of the collected data. It shows a minus 4.7 deaths per pCi/l. If some hypothetical man (recall our graph is of male data) had a choice between being exposed to, say, 6 pCi of radon in his house, or being exposed to none, what is the significance of this choice? By sealing his house and spending some $3,000 to $4,000 for the government-recommended heat exchangers, he could increase his risk of lung cancer by 7.5%.

Perhaps that doesn't sound like much to you (especially if we're not talking about your lungs), but it is a huge increase in risk compared even with the LNTer's worst chortlings. You may recall the BEIR statistic for chronic radiation exposure predicts an increase in risk of cancer mortality of 8% for exposure to 2 gray, which is 200 cGy or 200,000 mrem. This is far above the risk experienced by all but a small fraction of A-bomb survivors! So if you missed Hiroshima and Nagasaki, just hang in there with the EPA recommendation on radon. They'll help you reach that goal of a significant increase in cancer risk!

I like the way Jay Lehr summed up Cohen's results in an article, "Good News About Radon: The Linear Nonthreshold Model is Wrong":

"Thus, in spite of extensive efforts to find a flaw in the obvious results indicated by the observed data, no potential explanation for the discrepancy between theory and reality could be found. It therefore appears that the linear no-threshold theory for carcinogenesis from inhaled radon decay products is invalid. This is indeed good news."

It would have been even better news if more people knew about it.

[Dr. Lehr is a senior scientist with Environmental Education Enterprises, a provider of high-technology short courses for environmental professionals.]

Hormesis U.: A Review

Before leaving dear old Hormesis U., here is a short review to see if you've got a handle on the curriculum. You should know...

• Elements are identified by the number of protons in the nucleus (atomic number).
• Isotopes of elements have different numbers of neutrons (n + p = atomic weight).
• Atoms of some isotopes are stable, while others are radioactive and, over time, will disintegrate (decay) into other elements of a lower atomic number.
• Alpha and beta particles have a short range (a few inches and a few feet respectively).
• Gamma rays and X-rays can penetrate several inches of steel or feet of concrete.
• The half-life of a radioactive isotope is the time it takes half of the original amount to decay; after thirty half-lives the original amount is considered to be gone.
• The longer the half-life, the lower the activity of an isotope.
• A curie is 37 billion becquerels.
• A pCi is a picocurie and is equal to one-trillionth (10^-12) of a curie.
• Absorbed doses of radiation are measured in rads or grays; 100 rads equal 1 gray.
• Biological doses are measured in rems or sieverts; 100 rems equal 1 sievert.
• The absorbed dose and the biological dose are the same for gamma and X-rays. 
• A fatal acute dose is about 4 sieverts or 400 rems (50% fatalities in thirty days) when received in a relatively short time (a few days or less).
• Radiation sickness occurs at about 1 sievert or 100 rems (50% of those exposed over a short time). 
• Doses below 1 sievert or 100 rems (100,000 millirems) have no immediate biologic effects but are generally thought to increase the risk of cancer in the future.

Thanks for your attendance at Hormesis U. No doubt you'll find the rest of the information on radiation hormesis much more understandable now than when you were a mere freshman. Oh, and be sure to send in your contribution to the Alumni Fund.

Specific Activities

When interested in relatively low-level radioactive material, the picocurie, or pCi (one-trillionth of a curie, remember?), is used. In Table 6, the activity is in pCi per liter and in Bq per liter. [You will also run across Bq per cubic meter (Bq/m3) in some radon studies. Multiply Bq/l by 1,000.]

Table 6 – Specific Activities of Common Substances
Material	Picocuries/liter	Becquerels/liter
Normal air	2	0.074
Typical radon level in homes	3	0.111
EPA limit: Ra-226 in drinking water	5	0.185
Nuclear power plant leak	15	0.555
“Contaminated” milk at TMI*	22	0.814
Rainwater **	360	13.3
Whiskey	1,200	44.4
Salad oil	4,900	181.5
Spa waters of Bad Gastein	16,200	599
Drinking water in Maine***	53,700	1,987
*The increase in radioactive iodine in Harrisburg after the Three Mile Island “disaster” was 1/20 that caused by Chinese A-bomb tests in 1976. You remember how Jane Fonda and Ralph Nader protested those, don’t you?
**Measured at Santa Fe, 5/11/1986. (Probably atmospheric carbon 14 and wind-blown potassium 40 salts.)
***Based on an average of 226 samples. Radiation Controversy, Ralph Lapp, Reddy Communications, 1979.

Since most Americans have no idea what danger might lurk in a glass of water having 200 picocuries per liter, we are at the mercy of those who might use this lack of knowledge to their political advantage. Professor Petr Beckmann pointed out that activity in a well-publicized reactor leak at Indian Point power plant outside New York City was equivalent to that in a pint bottle of salad oil. Without this knowledge, an interested citizen would be led to believe (a) nuclear power was unreliable, and (b) such technology was a danger to life and limb - exactly what anti-techologists Nader, Commoner, Ehrlich and their fellow primitivists would have us believe. Exactly the opposite of the truth.

You might want to bookmark this page, for easy reference to Table 6 as you read on.

In answer to the question posed in the chapter title, 100 picocuries is the approximate activity in a handful of average soil produced by the disintegration of potassium 40. (I always knew there was something dangerous about working out in the yard.)

Next we'll take a look at how the effect of ionizing radiation on the human body is measured.

100 Picocuries - That's a Lot! (Or is it?)

Since most Americans have no idea what danger might lurk in a glass of water with 200 picocuries per liter, we are at the mercy of those who might use this lack of knowledge to their political advantage.

Imagine sitting in a chair three feet away from a gram of an unknown radioactive metal, about the size of a penny, on the floor in front of you. Should you be concerned? I know I would be - at least until I knew more about what it was. Obviously we would be interested in what type of radiation was being emitted. It if were alpha or beta particles, there would be no problem as the 3 feet of air would stop any significant amount. But what if it were gamma rays? Then we would want to know just how "active" the source was - with the activity of a radioactive source being measured in the number of atoms that disintegrate every second.

Let's suppose our one gram of material is radium, specifically 226Ra. Would you care to guess the number of disintegrations per second? A mere 37,000,000,000 (37 billion)! This, by the way, is the number of disintegrations defined as 1 curie, or 1 Ci, since the curie is defined as the activity of one gram of radium. You needn't run away, but you might not want to hang around. If it were one gram of cesium 134, a quick exit would be advisable. [Cesium 134 is a gamma and beta emitter that has about fifteen times the activity of the Goian cesium 137, which is only a beta emitter.]

The curie, a United States (USA) unit, is still in common use but is gradually being replaced by the International Standard (SI) becquerel or Bq, which is defined as one disintegration per second. Obviously, then, 1 curie is equal to 37 billion Bq - not exactly the easiest conversion constant to work with, especially when you have to go the other way: 1 Bq = 2.7 x 10^-11 Ci = 27 pCi.

A few elements of interest and their specific activities - that is, their activity per gram - are given in Table 5.

Table 5 – Specific Activities of Selected Elements
Element	Curies	Becquerels	Half-Life
Thorium 232	0.000000166	4,316	14.05 billion years
Uranium 238	0.000000333	12,300	4.47 billion years
Potassium 40	0.00000722	267,200	1.27 billion years
Radium 226	1	37 billion	1,620 years
Strontium 90	139	5,143 billion	28.8 years
Cesium 134	1,290	47,900 billion	2.06 years
Iodine 131	124,000	4,588 trillion	8.04 days
Tellurium 133	113,000,000	4,200,000 trillion	12.4 minutes

Note that the half-life of the low activity 238U is very long - 4.5 billion years, while one-half the very active 131I isotope is gone in 8.04 days. We would expect this, since there are a finite number of atoms in a gram of any substance, and if the rate of decay (i.e., the activity) is high, it will take less time for the substance to lose its radioactivity. This is verified by the very low relative activity of the primordial radionuclides such as thorium, uranium and potassium, which have extremely long half-lives since these were presumably created at the same time as the Earth - estimated by most cosmologists as some 4.6 billion years ago. The shorter half-life isotopes - say a mere few million years or so - are long gone, although some are being replaced by decay products of the low activity elements.

Units of Measurement

There's just no way to avoid the next subject, because, unless you get at least semi-comfortable with certain units of measurement, most of the book is not going to make much sense. We'll start by looking at a little shorthand "trick" used by lazy scientists and engineers.

One curie of radioactivity is a sizable amount. Many times a much smaller unit is needed especially when referring to amounts contained in milk, water supplies and other common products. We could write this unit as 0.000000000001 curie, or 1 x 10^-12 curie or spell it out as one-trillionth of a cure. But that's time consuming and a heck of a lot of trouble when you're writing it fifty times a day. The shorthand version for a trillionth of a curie is generally written as 1 pCi - or even 1 pC - with the "p" standing for pico and pCi referred to as a picocurie.

Similarly, 1 becquerel is a very tiny amount of activity amounting to one radioactive disintegration per second, while we often are interested in millions or billions of decays for a single gram of a radioactive isotope. So instead of a million Bq or 10^6Bq, it is written as MBq, with the M standing for mega.

Table 4 shows prefixes and their corresponding powers of ten. Since I find that use of so many prefixes makes comparisons difficult, I'll be limiting them to as few as possible. However, others will occur in quotations and in literature you might run across.

Table 4 - International Standard (SI) Prefixes
Quintillion = 10^18 = exa = E
Quadrillion = 10^15 = peta = P
Trillion = 10^12 = tera = T
Billion = 10^9 = giga = G
Million = 10^6 = mega = M
Thousand = 10^3 = kilo = k
Hundred = 10^2 = hecto = h
Ten = 10^1 = deka = da
Tenth = 10^-1 = deci = d
Hundredth = 10^-2 = centi = c
Thousandth = 10^-3 = milli = m
Millionth = 10^-6 = micro = Greek letter mu
Billionth = 10^-9 = nano = n
Trillionth = 10^-12 = pico = p
Quadrillionth = 10^-15 = femto = f
Quintillionth = 10^-18 = atto = a

Well, we now know that radiation is caused by an atom suddenly going to pieces, but so far there is no clue as to why these particles are dangerous - if indeed they really are. So let's move on to some quantitative information about the effect of these atomic disintegrations.