I believe it happens on a regular basis worldwide - no one has died yet and as long as you don't make a habit of it it's probably no worse than a dental xray
for direct scanning in the machine:-
Airport x-ray machines and similar x-ray machines used by federal and state agencies to screen briefcases and packages give much lower doses than x-ray machines in hospitals and medical clinics—almost immeasurable. They are designed this way because they do not have to see as much detail, are not designed for looking into very large objects, and are usually looking for things that really "stand out" on images (like metal).
for full body scanning at say US airports
The amount of radiation exposure from one backscatter x-ray security scan is very small: less than a tenth of a microsievert, which is less radiation exposure than you get from eating a banana. The radiation you get from a regular chest x-ray is 20 microsieverts. A mammogram is 400 microsieverts. A chest CT is 7000 microsieverts. The reality is that all of us are exposed to background radiation from the atmosphere. High altitudes from air travel increase radiation exposure due to cosmic rays. You get 700 times more radiation exposure from a transatlantic flight, 70 microsieverts, than you do from 1 backscatter scan.