22 BIOLOGICAL EFFECTS OF LOW LEVEL EXPOSURES
Figure 1.9. Gompertz plots for control and 7-radiation treated male and female (pooled)
LAF1 mice. Exposure to 7-radiation (0.11-8.8 rad/day administered over 8 hr)
was begun at approximately 70 days of age and subsequently continued
throughout life. Time on the abscissa refers to the period following initiation of
exposure. The theoretical lines were obtained by simultaneous fitting of
Equations 3 and 12 (denoting both longevity hormesis and irreversible
toxicity), employing weighted least-squares regression analysis. In the
mathematical model, maximum longevity hormesis appeared to have been
reached at the lowest dose (0.11 rad/day). The toxicity parameter, 7, was
characterized by a logarithmic-logistic function. Note that the influence of
longevity hormesis only dominates (meagerly) with the 0.11-rad/day group,
whereas the impact of irreversible toxicity is principally observed at the other
dose levels. The original data came from Lorenz et al.84 Reprinted from
Neafsey et al.,25 p. 138, by permission of Marcel Dekker, Inc.the high degree to which anomalous information is ignored if it disconfirms
basic assumptions of established paradigms.88 Once a group agrees that a
particular kind of reality is desirable, they develop a style that permits them
to deal with observations solely on their own terms —and woe to the individ
ual with different ideas.89 For most individuals, escape from these
intellectual-scientific fetters is difficult, for the obduracy of established
perspective locks practitioners together in a rigid framework of beliefs that
is not readily overcome.88*90
Further support that 7 -radiation produces longevity hormesis is supplied
in Figures 1.10 and 1.11. However, in this case, the data deal with chip
munks living in the wild. The animals were live-trapped, irradiated with
either a single dose of 200 or 400 R 7 -radiation (except for controls), and
then returned to the wild. The original publication 47 equated Roentgens
with rads, although more specifically 1 R is approximately 0.95 rad with
respect to muscle tissue.91 Figure 1.10 illustrates representative survival
curves. It is readily apparent that 7 -radiation exposure, within the dose
range utilized, enhanced longevity. Figure 1.11 illustrates differences in
Napierian logarithms of age-specific mortality rates between treated and
control animal populations; an arbitrary value of 5 was added to ensure
positive numbers throughout. Values below 5 indicate net longevity horme-