Is it possible to dye human blood safely?!

Okay, so I was looking through different body modifications and I thought of dyeing human blood. But I would like to know if it would be possible to do this safely with like some kind of non-toxic permanent dye. Maybe something similar to tattoo ink. Or would the spleen just clean it it all out? I know it's a crazy idea, but I am very curious. Also I do realize that no one would see it even if it were a different color, but it's more of a self thing than it is for other people.