Airport body scanners pose ‘trivial’ cancer risk
MedWire News: US researchers estimate that the risk for cancer associated with airport body scanners is extremely small, even among frequent fliers.
"In the past year, the Transportation Security Administration has deployed full-body scanners in airports across the US in response to heightened security needs, explain Pratik Mehta (University of California, Berkeley) and Rebecca Smith-Bindman (University of California, San Francisco) in the Archives of Internal Medicine.
They add that the most commonly used scanner employs "backscatter" technology, which detects ionizing radiation reflecting off the person imaged. This contrasts with medical imaging where variation in the transmission of X-rays through the body is used to generate an image.
Following reported fears about the radiation emitted by the scanners, the researchers investigated radiation levels and estimated cancer cases associated with the machines.
They found that the scanners expose individuals to 0.03 to 0.10 microsievert (µSv) of radiation per scan or the equivalent to 3 to 9 minutes of radiation received from sources naturally occurring as part of daily living (estimated at 0.01 µSv/minute).
Since flying itself increases exposure to ionizing radiation, the researchers calculated that the scan contributes less than 1% of the dose a flyer will receive from exposure to cosmic rays at elevated altitudes (estimated at 14.3 µSv on a 6-hour flight).
Mehta and Smith-Bindman remark that "estimating the risk associated with these extremely low dose exposures is more difficult than quantifying the exposure."
Assuming that approximately 0.08 cancers occur per Sv of exposure, the researchers predicted that there would be six cancers as a result of the backscatter scans among the 750 million flights taken by 100 million passengers per year.
However, "these six cancers need to be considered in the context of the 40 million cancers that would develop in these individuals over the course of their lifetimes due to the high underlying cancer incidence," the duo points out.
They conclude: "Based on what is known about the scanners, passengers should not fear going through the scans for health reasons, as the risks are truly trivial."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Laura Dean