JANUARY/FEBRUARY 1992
THE BULLETIN
OF THE ATOMIC SCIENTISTS
REVIEWS
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.
January/February 1992 43