have you tried showing her statistics about the different hazards in their environment? I would think they shouldn't be hard to find.

But the issue itself is not as simple as everybody makes it sound.

It IS possible to be overprotective, but there is plenty of statistically valid literature about that, too.

My mother was paranoid about a lot of things and i learned at an early age to just go behind her back. But my brother wasn't so lucky. Mom was chronically OCD, and my brother developed severe asthma because of it. The results were permanent and devastating. https://en.wikipedia.org/wiki/Hygiene_hypothesis