The same way for so many years there was "no evidence" that smoking tobacco caused cancer. In fact there was planty of evidence, it just wasn't compelling evidence, at least not to those who had good rerasion not be see it as compelling.

I don't think "innocent until proved guilty" is the right way to deal with these kind of issues. That's a relevant principle when it comes to   criminal charges, but not when it comes to avoiding danger. You don't drive along a raod at high speed in a fog just because you can't see anything ahead that you might hit, you slow down just in case.