Seeing is not necessarily believing in Camelford in Cornwall.

Twenty tons of aluminium sulphate were accidentally tipped into the wrong tank in 1988, contaminating the water supply.

When people complained of green hair, joint pain, sickness and memory loss, their symptoms were dismissed as products of anxiety.

Aluminium is a light metal with no known useful function in the body but it can cause a deterioration in mental function and disrupt bone metabolism if present in excess.

Children may become hyperactive if overly exposed to the metal.

The degree of toxicity varies from person to person and is dependent on intake and ability to detoxify.

People less able to excrete aluminium, such as those with kidney disease, are more at risk.

Individual mineral status is also important, because toxic metals may displace minerals or use them up during detoxification.

Chronic deficiencies, such as a lack of calcium, iron or zinc can make the situation worse.

Aluminium sulphate is routinely used by water companies t o remove suspended matter during treatment.

At permitted levels, aluminium is not thought to cause health problems.

However, concentrations of the metal can be affected by acid rain, which releases aluminium from rocks and soil into the water supply.

Furthermore, there are concerns that water treated with fluoride increases the uptake of aluminium into the brain.

A report in The Lancet in 1989 suggested there was a higher incidence of Alzheimer's Disease in those parts of the UK in which tap water had higher levels of aluminium.

Still, cause and effect are not fully understood and remain contentious.

Other sources of aluminium include indigestion remedies such as Gaviscon tablets and some anti-diarrhoea preparations; cooking acidic foods such as rhubarb, chutneys, marmalade and tomatoes in aluminium pans (use cast iron, stainless steel, glass or enamel cookware instead);

foil and packaging; soft drink cans and fruit juices in aluminium-coated waxed containers;baking powder and the food additive E541 (used as a raising agent in biscuits and cakes ) ; table salt (aluminium is added to prevent grains from sticking); some dried milk products; sliced, processed cheese (eg. in cheeseburgers); stronglybrewed tea in excessive amounts; antiperspirants (you can buy an excellent, aluminium-free deodorant called Crystal Spring for £5.95, including p&p, from Stewart Distribution, 01273 558112; astringents, shampoo, for aluminium shampoo, toothpaste (read labels) and dental amalgams.

Excess levels of aluminium can be detected by hair mineral analysis.

Certain nutrients minimise the accumulation of toxic metals. If levels are high, however, a full nutritional programme is needed to assist with their excretion.

Silicon helps to prevent the absorbtion of aluminium.

Silicon-rich foods include kelp, alfalfa, cabbage, lettuce, onions, dark green vegetables and milk.

Recent Japanese research has also found that fresh coriander is a potent metal detoxifier another good reason to cook with herbs.