They can cause cancer, kidney problems, nervous-system diseases, but it all depends on how much is in the ash, and that depends to start with, with the coal itself.

NPR: Coal Ash May Pose Health Hazard

Mr Phillips told the BBC Wales current affairs programme Week In Week Out that there could be long term financial benefits to the opt-out system, such as savings on dialysis treatment for kidney patients.

BBC: Wales organ law puts 'too much pressure' on hospitals

Other reported problems include skin ailments, kidney damage, hypertension, central-nervous-system disorders, insomnia and nausea.

CNN: NUCLEAR FALLOUT

Roy Thomas, of Kidney Wales, which is campaigning for an opt-out system, said better communication was needed with the public.

BBC: Wales politics