Sustainability and street-art is it possible?

In a class presentation I've examined the possibilities of street art and sustainability. Can Street-art occur   without harming the health of the artist and the environment?
Alternatives presented in the form of water / milk stamping "reverse graffiti" and unique method of using a hydrophobic material. Moss seem to be the best solution in the "Sustainability" domain.
http://greengraffiti.com


OrenR