Hamburg: Pure gold can produce allergy symptoms in some people, according to a researcher in Germany whose findings fly in the face of conventional dermatological wisdom that says pure gold is a non-allergic substance. 

For more than two decades, dermatologists have known that a small proportion of people display allergic skin responses to gold jewellery or dental fillings. But it has always been assumed that those allergies were caused by nickel or chrome in gold alloys.

Not so, says Thomas Fuchs of Goettingen University Hospital in Germany. He and Johannes Geier, also of Goettingen, conducted surveys of 30 dermatological clinics and hospitals throughout Germany and came to the conclusion that some people are indeed allergic to pure, unalloyed gold.

"These are indeed isolated cases," Fuchs says.

"But they are enough to prove conclusively that there is such a thing as an allergy to gold," he said

The degree of allergy varies. Some people develop dermatitis, also called eczema, from even brief contact with gold items, while others break out only after many years of skin contact with gold.

Some people develop intermittent or persistent eczema on their hands and feet. It is usually a blistering type of eczema, known as pompholyx.

"Until now, the medical community has assumed that this allergic response is due entirely to gold alloys including nickel, but often there is no obvious reason for it," Fuchs says.

"It has even been suggested that in some, dyshidrotic hand dermatitis is due to nickel in the diet. Unfortunately, it is not possible to avoid ingesting nickel as it is present in most foodstuffs," he adds.

"No one ever thought to test pure gold itself because it has always been assumed that gold is the purest of all metals and that it cannot possibly produce an allergic response," Fuchs says.

The problem with testing for allergic reactions to gold jewellery is complicated by the fact that gold jewellery is never made of 100 percent solid gold.

Unless your name happens to be Tutankhamun, it is inconceivable that you own any jewellery that is fashioned from solid gold.

What is commonly called 'hypo-allergenic' or solid gold (12 carat or more) is in fact an alloy comprised of gold and some other metal, usually nickel or chrome to add strength to malleable gold.

The lower the carat number, the higher the content of base metals in gold jewellery.

Nine-carat gold, which is popular in such items as high school class rings, contains nickel. So does white gold, which takes its name from the fact that it has lots of gleaming nickel mixed in with the gold. What is often marketed as red gold is an alloy that combines copper with gold, producing a pinkish or ruddy colour.

 Allergy to jewellery is a phenomenon that has assumed growing importance in recent years, largely because of the introduction of cheap fancy jewellery in which the underlying metal layers consist of nickel and other base metals.

So when patients have complained of "gold allergy," dermatologists have been quick to assume that the patients had allergies to nickel. That is because 10 to 12 percent of the female population and 6 percent of the male population is estimated to be allergic to nickel.

In fact the allergy is not caused by nickel itself but by the nickel salts which are formed under the effect of perspiration in contact with the piece of jewellery piece or watch. This phenomenon is always accompanied by corrosion of the object.

While Fuchs does not refute the existence of nickel allergy, he says a small number of patients are in fact sensitive to pure gold.

Contact allergic dermatitis to gold may develop at any age. Once this gold allergy has occurred, it persists for many years, often it will remain for the rest of your life. Body piercing can cause an increasing susceptibility to gold allergy.

If you suffer from this type of allergy you should avoid contact with gold. If you have dental gold crowns, you may want to have them replaced with a palladium-silver alloy or you may prefer to get porcelain dental work.