New research should be carried out into the effects on unborn babies and young children of Britain's worst mass poisoning, a long-awaited report recommended yesterday.
However, the Government-appointed committee said that it was "unlikely" that the pollution, which hit the water supply serving the North Cornwall area around Camelford in 1988, had "caused delayed or persistent harm to health among local people".
Those conclusions frustrated both campaigners, who said it was "insulting and speculative", and politicians who described the report as a "bitter disappointment".
Peter Smith, who resigned from the Lowermoor Sub Group of the Committee on Toxicity in October last year, said the report was seriously flawed. "To use the term 'unlikely' is both insulting and speculative, given that the committee would not consider the medical records of those that were exposed," the Truro-based homeopath said.
"I find that completely unacceptable.
"At the very least, the Government should be carrying out the recommendations without delay, while there are a range of other tests that can be done now which would either put people's minds at rest or help them receive appropriate further treatment."
The incident happened when 20 tons of aluminium sulphate were dumped into the wrong tank at the Lowermoor water treatment works on Bodmin Moor in July 1988.
It turned the tap water serving 20,000 people in North Cornwall highly acidic, with the supply containing massive levels of aluminium and other metals which were stripped from pipes.
Many believe that the Government's handling of the accident, and its aftermath, was influenced by the impending privatisation of the water industry and that a public inquiry, even 25 years on, is the only means of establishing the truth.
After a long-campaign, Environment Minister Michael Meacher announced an inquiry in 2001. A disputed draft report was published in 2005.
Yesterday's final version was delayed by the inquest into the death of Carole Cross – the wife of Lowermoor campaigner Doug Cross, who also resigned from the committee in October – who died in 2004 aged 59 from a rare neurological disease usually associated with Alzheimer's.
The concluded that there was a "very real possibility" that the ingestion of aluminium by Mrs Cross had contributed to her death.
The committee's report said it recognised that "many local people are concerned and distressed about the possible health consequences of the incident".
While it said "no conclusive link was found between the incident and the chronic symptoms and diseases reported" it said further research was necessary.
Those included the effects on neurological health, the development of unborn babies at the time of the incident and those under a year old. Further analysis was also needed of cancer and mortality rates.
Professor Frank Woods, chairman of the subgroup, said: "Our research indicates that it is unlikely that the relatively short-term exposure to chemicals from this incident would have caused long-term health effects among local people.
"However, work on potential long term neurological effects is needed because of problems with the design of previous studies and to follow up an unusual case of dementia in an individual who lived in the Lowermoor water supply area at the time of the incident.
"Further work is also needed to track the health of the most vulnerable groups exposed to the chemicals. These are children born to women who were pregnant at the time of the incident, and youngsters aged under one at the time."
A campaign by former North Cornwall MP Paul Tyler, now Lord Tyler, helped to force the subgroup's inquiry. But, he said yesterday: "After nearly 25 years, this is a bitter disappointment.
"Many local people will justifiably find it difficult to see how this group can conclude that exposure to the aluminium has caused no delayed or persistent harm, when the coroner's conclusions in the recent case of Mrs Cross were so different.
"Meanwhile, the subgroup has failed to live up to the hopes of those of us who campaigned to set it up. We have no further information on the role of Ministers in the then Conservative government, whom we all know were complicit in a cover-up for many hours and days after the contamination took place.
"Residents in the Lowermoor area will neither forget who was responsible at the time, nor thank the subgroup for glossing over this part of the story in their report."