Nassim Nicholas Taleb, the author of The Black Swan and Fooled by Randomness, has a book chapter coming out that addresses this danger. Prof. Teleb's draft chapter on Medicine, Convexity, and Opacity from his upcoming book, Antifragile: Things That Gain from Disorder, can be found at:
http://www.fooledbyrandomness.com/medicine.pdf
While the entire chapter is worth a read, at page 389 he observes:
The “do you have evidence” fallacy, mistaking evidence of no harm for no evidence of harm, is similar to the one of misinterpreting NED (no evidence of disease) for evidence of no disease. This is the same error as mistaking absence of evidence for evidence of absence, the one that tends to affect smart and educated people, as if education made people more confirmatory in their responses and more liable to fall into simple logical errors.
That may have been the case here. That is, for years no evidence of harm was mistaken for evidence of no harm.
More generally, Prof. Taleb argues at page 376:
Simple, quite simple decision rules and heuristics emerge from this chapter. Via negativa, of course (by removal of the unnatural): resort to medical techniques when the health payoff is very large (say, saving a life) and visibly exceeds its potential harm, such as incontrovertibly needed surgery or lifesaving medicine (penicillin). It is the same as with government intervention. This is squarely Thalesian, not Aristotelian (that is, decision making based on payoffs, not knowledge). For in these cases medicine has positive asymmetries —convexity effects— and the outcome will be less likely to produce fragility. Otherwise, in situations in which the benefits of a particular medicine, procedure, or nutritional or lifestyle modification appear small—say, those aiming for comfort—we have a large potential sucker problem (hence putting us on the wrong side of convexity effects).
