A driver who dumped aluminium sulphate in the wrong tank at a water treatment plant, causing the UK’s worst mass poisoning, has spoken at an inquest.
Carole Cross, 59, lived in Camelford, north Cornwall, at the time of the poisoning in 1988. Her inquest is being heard in Taunton, Somerset.
Large amounts of aluminium were found in her brain after her death in 2004.
Relief driver John Stephens said the Lowermoor works had been unattended when he arrived on 6 July 1988.
The original inquest was adjourned two years ago, when the coroner asked for more tests to be carried out.
Mrs Cross and her husband Doug moved to Dulverton in Somerset two years after the poisoning.
Mr Stephens told the inquest he had let himself into the works with a key given to him by the regular driver Barry Davey.
Unknown to Mr Stephens, the former South West Water Authority, which ran the works, used the same key at all its plants.
Mr Stephens said he had believed the key would let him into the site and open one tank.
In 2005, West Somerset Coroner Michael Rose said Mrs Cross had had a neurological disease “usually associated with Alzheimer’s”, but complex DNA tests had ruled out any genetic origin for the disease.
He said the “abnormally high level of aluminium” in her brain could have caused the disease and adjourned the inquest for further medical research.
After the water poisoning those who drank or bathed in it reported a range of health problems, including stomach cramps, skin rashes, diarrhoea, mouth ulcers and aching joints.
In 1991 the South West Water Authority was fined £10,000 with £25,000 costs for supplying water likely to endanger public health.
But an independent inquiry report, published in January 2005, said it was unlikely the chemicals would have caused any persistent or delayed health effects.
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