Yep, and the ones claiming these things to be safe always make such statements as, "You receive more of a dose on a transcontinental flight," etc. That's all fine and dandy when we're talking a once-a-year chest X-ray, but when that exposure takes place twice a day (or more) every day on an ongoing basis as a part of one's everyday commute, well, exposure to ionizing radiation and the damage it causes is largely cumulative.