Well, maybe 95% of those 84 persistent chemicals are harmless - but if gastrointestinal cancer cases in young people consistently correlated with the other 5%,

Well, maybe 95% of those 84 persistent chemicals are harmless - but if gastrointestinal cancer cases in young people consistently correlated with the other 5%, then you know where the problem lies. It's a pretty straightforward approach, and while testing labs cost money, at scale it would be a relatively minor cost.