"Current science" is really key here because it wasn't so long ago that science was convinced that heroin could be given to babies, smoking was harmless, and leaded gasoline is safe.
Science as a whole never was, there was just a shitton of money going to anybody publishing studies saying so. There's not a cannon of grant money fired at any scientist who says "radiation is good actually".
The lead gas thing is as you described but heroin and tobacco especially were in wide use for many years without anyone really knowing the full extent of damage they caused. Sometimes it does actually just take science a while to gather the data and catch up.
Science as a whole never was, there was just a shitton of money going to anybody publishing studies saying so. There's not a cannon of grant money fired at any scientist who says "radiation is good actually".
The lead gas thing is as you described but heroin and tobacco especially were in wide use for many years without anyone really knowing the full extent of damage they caused. Sometimes it does actually just take science a while to gather the data and catch up.