Yes, wash in/wash out dye washes out over about a few weeks some dyes last about 6 weeks. The wash in/wash out dyes are mostly made of vegetable oil so it's safer and certainly wash out :)
Doomsday Will Not Happen In About 5 or 6 billion years. Unless, of course, Global Warming gets worse, And the ozone layer melts allowing the sun to burn through it, burning earth. That's not likely...