The author himself doesn't believe them. Here's what he (Peter Rez) says in the paper this is based on:
>The major public health effect of concern at low doses of ionizing radiation is cancer. There is clear evidence of cancer induction at effective dose above about 200 mSv. Below an effective dose of about 100 mSv radiogenic cancer mortality risk estimates for all cancers is highly uncertain. 16 It is not possible to determine reliably whether a radiogenic risk is present in an X-ray screening population because of the high spontaneous incidence of cancer and multifactorial nature of disease causation 17.
>Use of collective dose to estimate public health impacts when large populations are exposed to trivial doses is inappropriate and not reasonable. The assumptions implicit in the collective dose calculation conceal large biological and statistical uncertainties.16 If an individual passenger is not harmed by X-ray screening then the population isn’t either.
https://docs.google.com/viewer?url=http://www.public.asu.edu... (page 15)
linked from
also like the point raised in the comments that the main thing that killed off the IRA as a major terrorist movement in Europe, was when their American supporters finally remembered what terrorism was in 2001.