Though you are obviously correct that science is never settled DDT has been so extensively studied that I am comfortable that it and its effects are well understood. Should new information come along that turns that understanding on its head then by all means, bring it on. But in the meanwhile "settled science" is not incorrect IMO. The real point, however, is that people like to trot it out to use as a shining example of "where science done us wrong". They like to claim that DDT is bad for humans despite that to the best of our knowledge it is not. And they completely disregard the true danger of DDT, namely how bad it is for the environment. I mean it's like fucking napalm to certain species but there's never any mention of that. There are many many good examples of where science did get it wrong, why not use one of those? It's because DDT is *easy* because everybody 'knows' it's bad for you, regardless of whether or not that's correct. And easy is not the same as correct.