  Modern electron scattering experiments have determined the proton electric
form factor, G_{Ep}(Q^2), to high precision. We utilize this data, represented
by the different form factor parametrizations, to compute the third Zemach
moment of the proton charge distribution. We find that existing data rule out a
value of the third Zemach moment large enough to explain the current puzzle
with the proton charge radius determined from the Lamb shift in muonic
hydrogen. This is in contrast with the recent claim of De Rujula
[arXiv:1008.3861].
