This paper reports on the values of gamma-ray buildup factors and attenuation coefficients that rise steeply as the source energy decreases near the K edge in heavy materials and discontinuously fall at the K edge. However, the exposure rate attenuation factor, A(E,r) = D(E)B(E,{mu}r), given as a function of the penetration depth in centimeters, is relatively constant in the vicinity of the K edge. The development of a model that employs 4 K-shell X rays for the source shows that such behavior results from the large contribution of fluorescence radiation to the buildup factor for source photons of energies just above the K edge. In addition, an uncertainty in the extrapolation formula of the K parameter of the geometric progression buildup factor fitting function was removed for the energy range near the K edge.