Can the ingredient in sunless tanners, dha go into the bloodstream? what about other beauty products? definitive answer please.

Yes: However, the amount you absorb through your skin is so miniscule as to pose no problems from use of the products as directed. You can feel completely safe using these products on intact, normal skin. If have any skin disorders, then talk to dermatologist about appropriate amounts and ingredients which may or may not be problematic with abnormal skin.