List I contains certain individual substances which belong to the following families and groups of substances, selected mainly on the basis of their toxicity, persistence and bioaccumulation, with the exception of those which are biologically harmless or which are rapidly converted into substances which are biologically harmless:

1. 1.

   organohalogen compounds and substances which may form such compounds in the aquatic environment;

2. 2.

   organophosphorus compounds;

3. 3.

   organotin compounds;

4. 4.

   substances which have been proved to possess carcinogenic properties in or via the aquatic environment8;

5. 5.

   mercury and its compounds;

6. 6.

   cadmium and its compounds;

7. 7.

   persistent mineral oils and hydrocarbons of petroleum origin;

and for the purposes of implementing Articles 3, 7, 8 and 12:

1. 8.

   persistent synthetic substances which may float, remain in suspension or sink and which may interfere with any use of the waters.