Tests are being carried out on the body of a man who drank water from a contaminated supply, it has emerged.
The drinking supply to 20,000 homes in Camelford became toxic when 20 tonnes of aluminium sulphate were accidentally added to the water supply in 1988.
The Cornwall Coroner confirmed an inquest into 60-year-old Richard Gibbon's death was opened and adjourned in June. Mr Gibbons died in May.
Another inquest is under way into the death of Carole Cross, 59.
She lived in Camelford at the time of the contamination incident at the Lowermoor treatment works.
Mr Gibbons, who lived at nearby Tintagel, claimed before he died that he was suffering from the effects of the contaminated water and asked his wife to make sure his brain was examined.
His body is the third to be investigated for links with the Camelford water contamination.
An inquest heard there were high levels of aluminium in the brain of 91-year-old Irene Neal, from Rock, who died in 2007.
The inquest into Mr Gibbons' death was adjourned for further tests to be carried out by a pathologist in Plymouth.
Phil Reed, Mr Gibbons' son in law, told BBC News: "We believe he was mentally affected by it.
"We are waiting for the pathologist's report."
An inquest is taking place in Taunton into the death of Mrs Cross who died in 2004. Tests on her brain showed high levels of aluminium.
The poisoning happened when a relief driver added aluminium sulphate to the wrong tank at the Lowermoor works, where no-one was on site to direct him.
It caused health problems, including cramps, rashes, diarrhoea and ulcers.
The original inquest into Mrs Cross's death was adjourned two years ago, when the coroner asked for more tests into aluminium and brain disease links.
The hearing continues.