Flash storage: Limited read cycles?
Activating the read lines in a Flash module can result in lowering the number of electrons stored in a cell.
But the answer is much more complex.
The stored charge will leak away with time/temperature, so a cell with few electrons (perhaps only 100 or so) will eventually lose electrons and be sensed as a zero when it should be a one. To alleviate this different controllers will alter the read voltage threshold and/or read/error correct - erase and refresh the data.
Flash memory may be single or MLC, and in the case of MLC the leakage problem and read disturb is accentuated.

This paper is a good explanation of the complexity involved.