Quantum-Mechanical Suppression of Accretion by Primordial Black Holes

The Schwarzschild radii of primordial black holes (PBHs) in the mass range of 6x10^{14}g to 4x10^{19}g match the sizes of nuclei to atoms. I discuss the resulting quantum-mechanical suppression in the accretion of matter by PBHs in dense astrophysical environments, such as planets or stars.