Here are some old examples:

Lead in gasoline. Lead washes out of the air and out of the body. There is no problem with lead in gasoline. Now, there is lead in solder, that is in an electronic device, that may be thrown in the dump! Eeeeekkk!!!

Cigarettes are healthy. Cigarettes don't cause lung cancer. And, actually that might be true, but the formaldehyde and other curing agents really do a number on people. Now every pack is labelled with horror warning.

Diseases caused by little things that you can't see? Of course there is demons. Its obvious. Everyone knows about the devil...

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Every one of these was hotly debated. And the big money people provided all the propaganda they could. And provided false oppositions, and controlled narratives.

We are embarking on paths that will lead to even larger upheavals.
Such as no-till farming. It actually works. Actually, it works really, really, really well. But, try to get a farmer to stop driving his tractor all over his farm as he has always done.