I don't think you should be downvoted, but realize that people might be responding negatively because the citation you provided is exactly the citation that defenders of the vans and backscatter scanners at airports provide to dismiss safety concerns. So, without context around your citation, it might seem that you're trying to provide an opinionated defense of the safety of the vans.

As others have mentioned, there are also issues regarding whether those numbers can really be interpreted to mean that they are relatively safe. The manufacturers of backscatter tech claim that's true, but others suggest that because of the concentration in the skin, it's not a good estimate of safety. To interpret your cited numbers, the discussion also needs that side of the story, which other commenters have provided, but your original post did not.