The radiation absorbed by someone during an ordinary commercial airline flight is no more dangerous than that received during an ordinary dental X-ray. Since a dental X-ray does negligible harm to a person, we can conclude that the radiation absorbed by members of commercial airline flight crews will also do them negligible harm. A flaw in the argument is its failure to consider that ['there may be many forms of dangerous radiation other than X-rays and the kinds of radiation absorbed by members of commercial airline flight crews', 'receiving a dental X-ray may mitigate other health risks, whereas flying does not', 'flying at high altitude involves risks in addition to exposure to minor radiation', 'the longer and the more often one is exposed to radiation, the more radiation one absorbs and the more seriously one is harmed']