Basically: How does one pursue the truth when direct engagement with evidence is infeasible?
I came to this question while discussing GMO labeling. In this case I am obviously not in a position to experiment for myself, but furthermore: I do not have the time to build up the bank of background understanding to engage vigorously with the study results themselves. I can look at them with a decent secondary education's understanding of experimental method, genetics, and biology, but that is the extent of it.
In this situation I usually find myself reduced to weighing the proclamations of authorities:
- I review aggregations of authority from one side and then the other--because finding a truly unbiased source for contentious issues is always a challenge, and usually says more about the biases of whoever is anointing the source "unbiased."
- Once I have reviewed the authorities, I do at least some due diligence on each authority so that I can modulate my confidence if a particular authority is often considered partisan on an issue. This too can present a bias spiral checking for bias in the source pillorying the authority as partisan ad infinitum.
- Once I have some known degree of confidence in the authorities of both sides, I can form some level of confidence in a statement like: "I am ~x% confident that the scientific consensus is on Y's side" or "I am ~Z% confident that there is not scientific consensus on Y"
I think I disagree on these examples. I don't know that these were all proven safe. And not for very long. Even when they were proven "safe" temporarily, there were some science or medical events that caused concern.
Your idea of "proven-safe" is that they were used for two decades without proof of problems. Those examples fit that standard.