The dumping of waste at sea is controlled under the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter of 1972 and its 1996 Protocol. If these are effectively and consistently implemented, that particular source of inputs of harmful substances will be satisfactorily controlled. However, there are serious gaps in knowledge about their implementation: over 50 per cent of the contracting parties to those instruments are not reporting, and it is consequently not known how effective the instruments are (chap.