If logic and data were enough to win the war, environmental extremists would be waving a white flag after the 12th annual meeting of DDP, held in Tucson August 27-28. Moreover, if the ideas presented in Tucson are correct, certain efforts intended to protect human health are actually harmful.

The keystone of environmentalist risk assessment is the Non-Threshold Linear Hypothesis. Bernard Cohen, Professor of Physics at the University of Pittsburgh, demolished this hypothesis with a study of lung cancer incidence versus average home radon levels in counties containing 90% of the US population. Radon levels were measured in 272,000 homes.

If lung cancer rate corrected for smoking is plotted against radon exposure, the Non-Threshold Linear Hypothesis predicts a positive slope (+7%/pCiL^-1). The data give a negative slope (-8%/pCiL^-1). Dr. Cohen refers to the difference as ``our discrepancy.''

Cohen's ``discrepancy'' lies 20 standard deviations from the expected value predicted by the Non-Threshold Linear Hypothesis. The probability P of such a deviation occurring by chance alone, if the Hypothesis is true, is less than 10^-80. Hypotheses are customarily rejected if P is less than 0.05 (two standard deviations). However, the consequences of rejecting the Non-Threshold Linear Hypothesis are enormous. Dr. Cohen examined many potential sources of error in the study.

The data could be in error. But three independent data sets all give the same result. Collecting more data increased the discrepancy. Eliminating outliers increased the discrepancy. Stratifying data by each of 54 potentially confounding variables (such as socioeconomic status) decreased the discrepancy only slightly. All of the slopes remained negative.

Dr. Cohen wrote a letter to each author of a paper on the pitfalls of ecological studies: ``I offer you a consulting fee of $300 to provide me with what you consider to be a plausible cause for the discrepancy discussed in [our] paper....I consider this offer to be legally and morally binding upon me with no right of refusal or retraction.'' There was no response to the letter or a follow-up telephone call, even when the offer was increased to $500. ``You suggest a fee,'' also elicited no response.

Dr. Cohen's conclusion: ``By far the most credible explanation for our discrepancy is failure of the linear-no threshold theory in the low dose, low dose-rate region, where it has never been tested.''

If Dr. Cohen is correct, the following problems disappear:

Ø Diagnostic x-ray precautions, limits

Ø Carryover to chemical carcinogens

And the following problems appear: unemployment among health physicists, bureaucrats, and lawyers, and serious discrediting of the government-sponsored scientific establishment that has inflicted enormous costs on Americans, based on a theory for which there is no experimental basis whatsoever.

Dr. Cohen outlined the theoretical basis for the hypothesis: a cancer is initiated by a single particle of radiation hitting a single cell nucleus, causing genetic damage. The risk is therefore proportional to the number of such hits, which is proportional to the dose.

The problem is that the theory disregards biological defense mechanisms, without which thousands of cancers would be initiated in every person every day.

Dr. Cohen presented data to show that low-dose pre-exposure to radiation reduces the gene mutation frequency from later high-dose exposure, probably because of stimulation of biological defense mechanisms. Nevertheless, he was reluctant to draw the conclusion that low-dose radiation is actually beneficial.

T. Don Luckey, however, is quite convinced that the optimum dose of ionizing radiation is higher than the usual ambient dose-perhaps ten to fifty times higher.

Dr. Luckey published an article on radiation hormesis in Health Physics in 1982. Japanese researchers noted that ``if Luckey's claim were to be true, radiation management in Japan [and elsewhere] has been extremely erroneous.'' Japanese studies suggest that atomic bomb survivors exposed to 8 cGy of radiation were actually protected from leukemia. Furthermore, atomic bomb survivors appear to have a lower death rate 55 years later.

At Tohoku University, Professor Sakomoto is using low-dose radiation hormesis to cure and to suppress the reappearance of cancer. The addition of low-dose whole body irradiation to the high-dose local irradiation treatment regimen for non-Hodgkin's lymphoma appears to have increased five-year survival from 36% to 90% (BELLE Newsletter, July, 1994, Northeast Regional Environmental Public Health Center, University of Massachusetts, Amherst, MA 01003).

Behavioral effects (suppression of aggressive behavior) and anti-aging effects are also under study in Japan.

In the US, radiation experts fear even to mention the word ``hormesis'' (which refers to the beneficial-possibly essential-biologic effects of low-dose ionizing radiation). A draft report on ionizing radiation submitted this month to the Arizona Comparative Environmental Risk Project states only that : ``Some observers [Luckey 1991] have called into question the use of the non-threshold linear model for this extrapolation [of high-dose risks in Japanese bomb survivors to low-dose exposures].'' Yet Luckey, Radiation Hormesis, CRC Press, 1991, is a 336-page compendium of actual observations showing beneficial effects of radiation in many species, with more than 1000 references.

Low doses of ionizing radiation are associated with increased mean life span, fecundity, immune competence, growth and development, and neurologic function, and with decreased morbidity, neonatal death, cancer mortality, sterility, and infections, according to Luckey (``A Rosetta Stone for Ionizing Radiation,'' Radiation Protection Management, Jan-Feb 1994).

Overall, the DDP meeting considered two types of hazards: the continuing serious risks associated with war, now largely being ignored or downplayed, and the nonexistent or vastly exaggerated ``environmental'' risks, to which society's response might best be compared with anaphylaxis (an often fatal overreaction of the body's immune system to a tiny dose of an allergen).

Banquet speaker Frederick Seitz, President Emeritus of Rockefeller University, told of the debacle that occurred when a bag of ``waste asbestos'' fell off a truck in San Francisco. The Bay Bridge was closed for 18 hours, causing a horrendous traffic problem. The problem was solved only when a very brave person found a revolutionary solution: he kicked the bag of waste into the bay. The resulting ecological problem: none. The bay was already so ``contaminated'' with asbestos due to natural serpentine rock that the added fibers could have made no difference.

An order form for meeting tapes is enclosed. We have been overwhelmed by unprecedented demand, but will be able to start shipping orders this week.