(1981, p. 26) reports: Anderson and
Spangler maintain that their several observations of statistically significant deviations from the (random) expectation strongly suggests that an unreliability factor must be incorporated into age-dating calculations.Such irregularities were
observed for carbon 14, cobalt 60, and cesium 137. The source for this information is Anderson, J.L. and Spangler, G.W., "Radiometric Dating: Is the `Decay Constant' Constant?", Pensee, p. 31.