Last Updated May 19, 2010 11:19 AM EDT
"Many people will approach this as, 'Oh, it must be safe, the government has thought about this and I'll just submit to it,'" says David Agard, a biochemist and biophysicist at the University of California, San Francisco. "But there really is no threshold of low dose being OK. Any dose of X-rays produces some potential risk."While the actual risk is minimal, but when paired with frequent fliers or those making routine business flights across the country, the risk rises past negligible. According to researchers, radiation is measured in microsieverts, such as:
Agard and several of his UCSF colleagues recently wrote a letter to John Holdren, the president's science adviser, asking for a more thorough look at the risks of exposing all those airline passengers to X-rays.... "Ionizing radiation such as the X-rays used in these scanners have the potential to induce chromosome damage, and that can lead to cancer," Agard says.
As you can see from the above chart, only five flights across country give a person the equivalent of a chest X-ray. And while each airport scanner emits a low dose of radiation, a fraction of a percent of a mammogram, scientists said they signed off on the scanners thinking they wouldn't be used on such a huge population. Generally, a few scans a year wouldn't be a problem, but about 5% of the population are considered especially sensitive to radiation -- they can't repair X-ray damage to their DNA and could be more susceptible to mutations associated with cancer, including skin cancer. (The FDA has already approved the scanners.)
Screening at an airport X-ray scanner .02 microsieverts Negligible risk 10 microsieverts/year Transcontinental flight 20 microsieverts Average yearly radiation exposure from the environment 3000 microsieverts Chest X-ray radiation exposure 100 microsieverts Mammogram 700 microsieverts Abdominal CT scan 10,000 microsieverts Enough to cause radiation sickness 1,000,000 microsieverts Enough to cause death 6,000,000 to 8,000,000 microsieverts
The scientists are concerned about X-ray back-scatter scanners, about half of those in use at airports. So far about 150 of body scanners have been ordered for use this year. The body scanners, which have the ability to see beneath someone's clothes, are supposedly still optional for passengers who don't want their naked bodies seen by a lone TSA worker in a cubicle. (In Europe, however, the scans are becoming mandatory.) But the TSA is still pushing for more scanners without research or studies showing the safety of the machines.
The TSA downplayed the risk and suggestions that it should avoid causing basal cell carcinoma by not scanning the head and neck. Officials said that security lines would be too long if they had to adjust the machine's height.
While the risk is small, the safety concerns merely show the danger that knee-jerk security decisions and planning can unknowingly create. (Research has shown that security measures don't prevent terrorist attacks, they are simply a reaction to them.) In 10 years, will we see an increased risk of cancer in frequent fliers and lawsuits against the federal government or airlines because the TSA didn't bother to research or implement the alternatives?
Perhaps the decisions being made aren't the best because after more than a year, the agency still doesn't have a chief. The TSA chief can modify current security rules and standards that have been in place since January 2009, including changing the rollout of the body scanners to millimeter-wave technology, machines considered to be less dangerous.
The TSA certainly shouldn't be allowed to decide what's healthy for us, yet every day hundreds of frequent fliers and airline employees are giving that power to the agency and letting it irradiate their bodies. Maybe they, like the TSA, should start thinking about the consequences.
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