VOL. 48, NO. 1 JANUARY/FEBRUARY 1992
OF THE ATOMIC SCIENTISTS
Radiation-Induced Cancer from Low-Dose Exposure
by John Gofman
Committee for Nuclear Responsibility, 1990
480 pages; $29.95
GREGG S. WILKINSON
Few topics divide scientists more than that of the human effects of low doses of ionizing radiation. Some hold that very small doses of ionizing radiation are beneficial, a phenomenon dubbed "hormesis." In contrast, other researchers argue that low doses are relatively more dangerous than higher doses (especially in relation to cancer). In Radiation-Induced Cancer from Low-Dose Exposure, John Gofman, an activist and scientist with the Committee for Nuclear Responsibility, argues that no level of radiation exposure is safe. His reasoning, and the criticisms he offers regarding the ongoing study of atomic bomb survivors, should provoke more discussion.
The first 25 chapters of Gofman's work contain his major points and supporting data. They are followed by 12 chapters of additional data and discussion. This text, amply illustrated with 113 tables and figures, explains not only his arguments, but their bases.
The debate on low-level radiation is not an academic exercise. Gofman warns: "Partly because radiation research has been so well funded, there are far more data about ionizing radiation as a potentially toxic agent than there are about many other agents to which entire populations are exposed. Thus the field can be regarded as the `canary' which can warn humanity about practices which mean `trouble ahead' if adopted in other fields of toxicology."
Gofman sets out to prove four basic points: First, researchers have retroactively altered bomb-survivor data in a manner that will destroy the scientific integrity of a valuable study. Second, his calculations of radiation-induced cancer risks correlate closely with those of major radiation studies at moderate and high doses, but he finds risks as much as 30 times higher than estimates from those same studies at lower doses and dose-rates. Third, contrary to recent speculation, low doses of radiation have no beneficial effects and there is no safe dose or dose rate. And finally, the outcome of the low-dose controversy has major practical implications: if low-dose exposures are deemed safe, medical, industrial, and environmental exposures will escalate--with corresponding increases in cancer rates.
Gofman raises several important issues. Researchers have redefined the cohorts of atomic bomb survivors and deleted the original structure of those cohorts after many of the study's results became known. This practice should be carefully examined by epidemiologists and others to determine if serious biases have been introduced and if the study's integrity has been compromised.
Gofman's criticisms of "dose rate effectiveness factors" (reducing risk estimates to bring them in line with the results of animal studies) and his suggestion that the risk of cancer may be relatively greater in the low-dose range than in moderate and high-dose ranges have sparked controversy in the past and will continue to do so in the future. For instance, Gofman predicts that approximately 400,000 Europeans and Soviets may die of cancer due to fallout from the Chernobyl disaster, a figure far higher than "official" estimates.
Although Gofman has simplified the many complexities of a topic at the crossroads of radiation physics, medicine, epidemiology, and statistics, some readers will find the technical details difficult to follow. The thoughtful organization and an expansive index and glossary will, however, make the more complex sections of this important resource understandable to the well informed lay reader.
Gregg S. Wilkinson is chief of the Division of Epidemiology and Biostatistics in the Department of Preventive Medicine and Community Health at the University of Texas Medical Branch, in Galveston.
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