4. Encouraging the prevention or reduction of waste production and its harmfulness, in particular by—
(a)the development of clean technologies more sparing in their use of natural resources;
(b)the technical development and marketing of products designed so as to make no contribution or to make the smallest possible contribution, by the nature of their manufacture, use or final disposal, to increasing the amount or harmfulness of waste and pollution hazards; and
(c)the development of appropriate techniques for the final disposal of dangerous substances contained in waste destined for recovery.