Hangnails are not nails at all, but little triangular pieces of skin at the edge of a fingernail that occassionally bleed and, are often, quite irritating.

Formaldehyde is a natural substance. Every living organism produces it, including the human body. It is present in every breath we exhale. Formaldehyde is also present in fruits, vegetables, meat, fish, and many beverages including alcoholic beverages and coffee.