Richard Gibbons, from Tintagel in North Cornwall, died in 2010 after years of suffering from a catalogue of debilitating conditions which he steadfastly believed were caused by the 1988 acid water incident.
Details of the investigation first emerged during an inquest into the death of 59-year-old Carole Cross, who died in 2004 from a rare neurological disease usually associated with Alzheimer's.
She was living in the Camelford area when the public water supply was polluted with tons of aluminium sulphate. Two leading scientists told the hearing it was "highly likely" that the aluminium found in her brain was a factor in her death.
At Mrs Cross' inquest in November 2010 experts said samples taken from Mr Gibbons showed "no unusual amounts of aluminium" while there was "no significant pathology in the brain either". However, his family have confirmed that further tests have now revealed "high levels" of aluminium in his brain.
Phil Reed, Mr Gibbons' son-in-law, told the Western Morning News: "After Richard's death in May 2010 we asked for tests to be performed to establish if there was any evidence of aluminium accumulation in his brain tissue. Initial tests were performed, which proved to be inconclusive for aluminium. Unfortunately these tests were performed on small samples of tissue rather than the whole brain. We requested that the test be re-run but using the whole brain to establish if there was any accumulation.
"After the second test it turns out that Richard's brain did indeed have high levels of aluminium particularly in the hippocampus, the area of the brain responsible for short term memory. The two people tested for brain aluminium levels, Carole Cross and now Richard Gibbons, have shown high levels of aluminium in their brain tissue.
"This evidence shows the need for further study amongst the population exposed in July 1988."
Mr Gibbons had complained of terrible short-term memory loss, osteoporosis, osteoarthritis, kidney damage, decaying finger and toe nails, skin problems and recurring gum and ear infections, which he believed were linked to the tainted water.
In an interview in 2002, he described returning home in July 1988 from shooting rabbits. He had a cup of coffee and, halfway through drinking it, his chest felt as if it was burning. He said: "We did not realise we were drinking poison and carried on drinking it and news reports said it was OK to drink."
The incident was sparked on July 6, 1988, when a relief delivery driver inadvertently dumped 20 tons of aluminium sulphate directly into the public supply at the unmanned Lowermoor water treatment works on Bodmin Moor. It polluted the supply serving 20,000 people living in North Cornwall, from Boscastle down to Port Isaac.
The inquest into Mrs Cross' death heard water officials initially misdiagnosed the problem but suspected the true cause two days later when stocks of aluminium sulphate were found to be low. Details of the mistake were kept from the public – and key health and environmental officials – until the water authority published a notice in the Western Morning News on July 22. A full report explaining exactly what had happened was not published until August 15.
West Somerset coroner Michael Rose, who is also investigating Mr Gibbons' death, was told the then chairman of South West Water Authority, Keith Court, refused to issue a press release on July 12 because he did not want to cause panic.
In his summary of the evidence, Mr Rose said the former South West Water Authority had been "gambling with as many as 20,000 lives" when it failed to disclose the truth about the incident.
He said there had been a "deliberate policy to not advise the public" about the nature of the accident at the Lowermoor works.
Mr Rose concluded that there was a "very real possibility" that the ingestion of aluminium by Mrs Cross had contributed to her death.
No date has so far been set for the inquest into the death of Mr Gibbons which, Mr Rose said, could be held in Plymouth.
