8 I would say is a bit early, there is some pretty gory scenes, and adult themes like "working girls" you might not want to be explaining in detail. I would say 10-12, mine is in the middle.

Although I had to laugh at https://en.wikipedia.org/wiki/Firewalker_(The_X-Files) which is about a contagious alien(?) virus which I remember being super scary. The whole idea of viruses, pandemics and quarantine didn't really phase the kids at all. How times have changed.