It's safe if you know who the exit node is. Problem is that you don't always know and have to trust that it's a safe source. Plus didn't hackers expose that shyt recently? The Navy created TOR, so I assume there's some back doors that we don't know about either.
Really you're only safe if you use Tails on a laptop bought with cash from a big box store while using an open/public network with a vpn and proxy or two (and change your mac address constantly).