What does "safe" mean?

As I start this post, let me re-iterate that the primary argument against TSA scanners is that it infringes on our basic human rights, which were specifically protected in the US Constitution.

A new study is out that concludes that the radiation from TSA scanners is "trivial." What exactly does this mean?

“Trivial’’ means only six additional cancers over the lifetimes of 100 million people who represent 750 million boardings a year in the U.S.

So, very few people in the general population will get cancer from the scanners. But that's not zero. Trust me: if you are one of the people who get the "additional" cancer, this is not trivial. This argument is not new. We've seen many people say that - yes, the risk is low, but it's not zero. So using this as primary screening is irresponsible.

Furthermore, there are many caveats to this conclusion that we can also predict from statements from other scientists. A biggie:

In addition, the study’s authors note they had to rely on TSA’s claims about radiation dosage from the machines. “Alas, the TSA has not made the machines available for researchers to make direct measurements,’’ Dr. Smith-Bindman said in an email.

So, we're still just taking the TSA's word on how these machine's work. Feel safer, yet?

Another one, pointed out in the original UCSF letter of concern last spring:

But other researchers have questioned the long-term safety of the machines, suggesting that radiation doses may be more harmful than previously reported because the X-ray machines concentrate radiation on the skin rather than penetrating the whole body.

The new study likely won’t put all the questions to rest, largely because models don’t exist to calculate incidence of most cancers based on skin-concentrated doses rather than whole-body organ penetration.

 I don't mean to criticize this study. We need scientists to help bring this issue to light. They're doing the best they can with the means available.