Permissible Dose: A History of Radiation Protection in the Twentieth Century (review)

Permissible Dose: A History of Radiation Protection in the Twentieth Century. By J. Samuel Walker. Berkeley: University of California Press, 2000. Pp. xii+168. $35.

As J. Samuel Walker makes clear, Permissible Dose is intended to be a, not the, history of radiation protection. Nevertheless, it can be considered the history of the scientific and political forces that shaped the current regulations limiting radiation exposures to workers and the public. That the focus is on the Nuclear Regulatory Commission (NRC) is understandable given the author's position as that agency's historian and the fact that this is the third volume in a series sponsored by the NRC. (The two previous volumes were Controlling the Atom: The Beginnings of Nuclear Regulation, 1946- 1962, coauthored by Walker and George T. Mazuzan, and Walker's Containing the Atom: Nuclear Regulation in a Changing Environment, 1963-1971, published in 1985 and 1992 respectively.)

Walker begins Permissible Dose with a brief description of the radiation-related injuries that occurred during the quarter century immediately following the discoveries of X rays and radioactivity. He then quickly turns to the heightened concerns about radiation that arose during and after World War II as a result of the unprecedented quantities of radioactive materials that began to be produced. By page thirty or so, Walker has taken us into the 1970s, the halcyon but nonetheless controversial days of nuclear power, and the decade wherein the bulk of the narrative unfolds. Examples of the events and topics covered include: Atomic Energy Commission (AEC) restrictions on effluent releases from nuclear powerplants; the claims of John Gofman and Arthur Tamplin that the risks associated with radiation exposures had been underestimated by the AEC; the origin and impact of the "As Low as Reasonably Achievable" (ALARA) philosophy; the "real cow" versus "fencepost cow" debate; turf battles between the AEC and the Environmental Protection Agency (EPA); struggles over the regulation of medical exposures; the incidence of cancer downwind from the Nevada Test Site; Three Mile Island; the "below regulatory concern" (BRC) fiasco; the NRC's and Sierra Club's reactions to EPA's proposed regulation of radioactive effluents under the Clean Air Act; the ambiguous results of the epidemiological studies of the effects of low-level radiation; and possible explanations for the public's--some say inordinate--fear of radiation.

One small disappointment is the occasional weak handling of technical matters. In particular, the explanations of the quantities and units related to radiation dose (e.g., rad and rem) are sometimes misleading or incorrect. Better, but still inadequate in my opinion, is the treatment of the effective-dose-equivalent concept. The latter is the method employed by the radiation-protection community that equates a given dose for an individual tissue or organ (such as the thyroid) to the smaller uniform whole-body dose that carries the same risk. Ironically, a misunderstanding of this method led to the widespread belief, described by Walker, that the NRC's adoption of the effective-dose equivalent represented a relaxation of the exposure limits.

My disappointment is minor, however. Walker is an excellent writer. His prose is clear, and the narrative develops a nice momentum that carries the reader along. Personal opinion is kept in the background while the author presents the various sides of each issue in a remarkably balanced manner. Just the right amount of detail is provided in each discussion to suggest further avenues of study for anyone inclined to pursue them. Depending on one's reading habits, this informative and enjoyable book could be consumed easily in one or two sittings. Indeed, I found the time I devoted to it sufficiently well spent that I am tracking down the first two volumes in the series to discover what I have been missing.