Andy Burnham,who was last week handed the Cabinet post of health secretary, resigned his role as vice-president of the British Fluoridation Society (BFS) on Friday.
He insisted he was leaving the position to avoid any “perceived conflict of interest”.
But activists fighting plans to introduce fluoridation in and around Southampton are disgusted that someone with such a partisan stance on an issue so contentious can now be in charge of the body that made the initial decision
They also allege that Mr Burnham had failed to declare his role on the register of MPs’ interests, so his position on fluoridation was not known until he was promoted to the head of the Department of Health (DoH).
Earlier last week, Hampshire Against Fluoridation (HAF) hand-delivered a letter to the department’s Whitehall offices, calling on Mr Burnham to personally step in to the row over the Southampton scheme.
But chairman John Spottiswoode said he now believes there is no way Mr Burnham can act objectively over the issue.
“We can hardly expect to get a fair hearing from someone who was vice-chairman of the BFS and does not declare this to other MPs until after he is made Health Minister,” he said.
“It is a clear conflict of interest to be vice-chairman of a pressure group when he is being required to judge fairly over questions of health policy and the right of local people to have a say in whether they are fluoridated or not.”
HAF had urged Mr Burnham to call on South Central Strategic Health Authority to rethink its decision to approve fluoridation “because there is no local mandate”.
With 72 per cent of responses to the public consultation from those in the affected area opposing fluoridation, and 38 per cent against it in a separate phone poll (compared to 32 per cent in favour), they argue it is clear the public don’t want it.
But SHA chiefs unanimously approved the scheme, citing evidence showing it should reduce tooth decay.
Announcing Mr Burnham’s resignation from the BSF, a DoH spokesman said there was “no question” of fluoridation being imposed by Government.
“Decisions should be taken locally following consultations conducted in accordance with procedures approved by Parliament,” she said.