Rocky ”demonstrates” that the TSA’s backscatter x-ray screening may be “deadlier” than the terrorists — unless the terrorists succeed in blowing up an airplane every few years.
From this generally accepted statistic:
A typical dental X-ray exposes the patient to about 2 millirems of radiation. According to one widely cited estimate, exposing each of 10,000 people to one rem (that is, 1,000 millirems) of radiation will likely lead to 8 excess cancer deaths. Using our assumption of linearity, that means that exposure to the 2 millirems of a typical dental X-ray would lead an individual to have an increased risk of dying from cancer of 16 hundred-thousandths of one percent. Given that very small risk, it is easy to see why most rational people would choose to undergo dental X-rays every few years to protect their teeth.More importantly for our purposes, assuming that the radiation in a backscatter X-ray is about a hundredth the dose of a dental X-ray, we find that a backscatter X-ray increases the odds of dying from cancer by about 16 ten millionths of one percent. That suggests that for every billion passengers screened with backscatter radiation, about 16 will die from cancer as a result.
Rocky notes that the phrasing of this statement is horribly misleading!
He observes that there are 600 million airline passengers per year. Source: http://www.transtats.bts.gov/
That means an incremental 10 people will die each year from cancer due to backscatter screening. Since 9/11 (and before the backscatter technology was implemented) there were no successful terrorist attacks on US planes. If one extrapolates this trend, the statement that the TSA is more deadly than the terrorists is both bizarre and true!
However, if the terrorists successfully blow up an airplane, it simultaneously makes the backscatter look comparatively safer and the TSA look comparatively worse.
[Disclosure: This is a great illustration of how statistics can be manipulated to prove one's point -- even if the point is silly.]