During the last thirty years people have continued to poison the planet with pesticides and other toxic chemicals, which has led to the destruction of ecosystems and the extinction of many species. More recently people have realized that they too are now threatened by human actions. The ultimate design challenge of the twenty-first century is to avoid or minimize the adverse impacts of all products on the environment. Material as the basis of the product can not be neglected. Like all challenges, this constitutes both a demand and an opportunity - to steer the debate on more sustainable patterns of production and consumption.