Just heard Radio 4's Today programme which had a 5 minute item about this.
bbc.co.uk/programmes/b083j4...
Date 26/22/16, about 1.45 into the programme - so nearly at the end
Includes Joanne Lomax of the campaign group 'Hull for Pure Water' saying that fluoride is potentially toxic to the body and can cause underactive thyroid.
More about this on the ThyroidUK website's News page