Human Bio-matter as an Artistic Medium- How do artists get away with it?

Urine, feaces, tears, blood, hair, skin– the human body has been used not merely as the subject of art works, but also as the substance. The way this has occurred has been diverse in terms of appearance and art-making practices, encompassing casting and sculptural processes, drawing, painting and photography. As diverse as they are, the artworks we’ll explore today have one thing in common: they are all considered to be examples of what we term “biomaterial” artworks. 
Human bodily materials are invested with highly symbolic cultural association and complex emotional entanglements, so the use of human biomatter as an art medium opens up an intriguing opportunity to reflect upon the relationships between materiality, aesthetics and most interestingly, ethics. How do artists get away with it?