If the gold-plated surface is not designed to be in direct and prolonged contact with the skin, there is no problem; however, any surface intended for contact with the skin will be a possible source of nickel ions.
Image Gallery (3 Images)
Scratching at the surface
By Bianca Mangion
The incidences of nickel allergy are increasing, with consumers sporting more jewellery and piercings. According to BRUCE MCKEAN, director of sustainability and stewardship, Nickel Institute, jewellers can help prevent it.
Nobody knows exactly how many Australians suffer from Allergic Contact Dermatitis or nickel allergy; however, it would be a rare jeweller who hadn't encountered customers that have mentioned an aversion to the metal. The inappropriate use of nickel is a worldwide problem, and responses such as, "Don't show me anything with nickel in it," or, "I can't wear this. I get all red and itchy," are now commonplace.
In simple terms, any nickel allergy arises when skin is exposed to nickel ions, particles that are created when nickel is dissolved (corroded) from nickel metal or alloys containing nickel. Though it sounds severe, corrosion can occur very easily; for example, the salt and acidity of human sweat can promote corrosion that may result in the release of nickel ions.
Like any allergy, thresholds differ from person to person but, overall, skin is somewhat permeable to nickel ions; when they do penetrate the skin, such ions are recognised as foreign, leading to the creation of memory cells that facilitate a reaction to nickel when subsequent exposures are high enough (greater than the elicitation threshold).
This means that one is not born with the allergy, but develops it through contact with nickel, and once a person has it, it is with them for life. There are many medical journal articles devoted to understanding what happens when someone experiences initial nickel sensitisation. This stage is called "induction", and it occurs after a relatively high exposure to nickel ions. Subsequent exposure to the metal leads to incidences of dermatitis, or "elicitation", and a broad range of skin symptoms can occur, including dryness, chapping, inflammation, eczema and blisters. In highly sensitive people, chronic eczema or severe dermatitis can be caused by contact with low concentrations of nickel, or even nickel in foods such as chocolate, oatmeal, peas, beans, lentils, tea and coffee.
Hand eczema is another consequence where there is frequent contact with nickel containing objects like coins and cutlery. According to a report entitled Don't Let Nickel Get under your Skin, by former Assay Office development director Roy Rushforth, about 40 per cent of sensitised people will develop hand eczema throughout their lifetime. (The Assay Office in Birmingham, England is the largest of its kind in Europe, and serves a chief function of testing and hallmarking precious metal items.)
Because direct and prolonged contact between skin and nickel is the quickest way to trigger an allergic reaction, the greatest single cause of nickel sensitisation is thought to be body piercing.
In fact, according to Rushforth's report, it is estimated that 20 per cent of all individuals with pierced ears who wear nickel-containing earrings will become nickel-sensitive. The report details a study conducted by Swedish dermatologist Alexander Fisher that determined 95 per cent of nickel-sensitised women had pierced ears. The study professes that the majority of the participants (111 sensitised people in Denmark, Sweden and Great Britain), became sensitised directly after ear piercing or within a year of it.
Resultantly, it's unsurprising to note that the generally accepted ranges of nickel allergy in Europe are 10-15 per cent of all women and 1-2 per cent of all men. This helps to show that the level of sensitisation is directly related to jewellery products - as women generally wear more jewellery than men - but jewellery is not the only factor and other factors such as hormone differences are also believed to play a role.
There's no reason to think that such numbers are significantly different for Australia. According to the Queensland Government Health website, it has been estimated that eight per cent of Australian women and one per cent of Australian men have an allergy to nickel.
Furthermore, the report attests that these figures display a worldwide increase in the number of people experiencing nickel allergy over the last two decades: a trend that correlates with that of the increased prevalence of body piercing. Such results are supported by rising levels of nickel allergy in men as piercing has become more common among them, the report alleges.
But not according to Peter Sheringham, co-owner of prominent Australian piercing studio The Piercing Urge. In the 16 years he's been piercing, Sheringham has actually noted a decline in the nickel allergy among his customers: "No, it's gone down because the quality of steels available has become better," Sheringham states.
"Full-blown allergies are rare. I get many people coming in saying they have an allergy to nickel, but they're sitting there wearing a stainless steel watch, a silver chain around their neck and silver earrings and they have no irritation."
While Sheringham believes nickel allergies have reduced, he warns that a recent glut of poor materials into body jewellery threatens to change all that in coming years. "Many jewellery companies are starting to make body jewellery and they're selling lots of 9-carart gold," Sheringham says. "9-carat gold is inappropriate for body piercing because it's only 37.5 per cent gold and the rest are all alloys and metals that will make you allergic. And that's where you'll get the problem."
Self-regulation will suffice for controlling any outbreaks; however, once people have reached the induction stage, it's already a case of too little too late. Nickel allergy is common, but it is also unnecessary. Retail jewellers have a responsibility to help reduce the chances of people becoming sensitised by moving away from items that contain the metal.
According to Fisher's study, earrings were the biggest culprits of the items causing dermatitis in nickel-sensitised patients, affecting 84 out of 111 sensitised participants. Running a close second was the wrist watch, with 74 affected, and finally necklaces irritating 47 of the 111 cases. Fisher also claimed that nickel caused more dermatitis problems than all other metals in total.
The importance of being vigilant with one's inventory cannot be overlooked. To help, what follows is a brief explanation of jewellery-related products where nickel is present, and a note about why it has been chosen.
Plated products
Nickel adheres extremely well to base metals, much like other metals such as silver and gold adhere extremely well to nickel. Thus you will often find nickel as a base layer under gold-plated items. Even expensive items may have gold-plated parts, such as clasps. Gold is soft and subject to wear and the underlying nickel will eventually show through if the gold layer is not thick enough. Combining this thinness with gold's porous nature increases the chance of nickel allergy.
If the gold-plated surface is not designed to be in direct and prolonged contact with the skin, there is no problem; however, any surface intended for contact with the skin will be a possible source of nickel ions.
Gold alloys
The presence of nickel in various alloys can be helpful to jewellers. It can improve casting properties, malleability, strength and hardness.
Nickel is also a very effective bleaching agent, as it appears in its pure state as a hard, silvery-white metal. Thus, it is used to develop shades of white gold that the market finds attractive.
White gold usually contains between 2-7 per cent nickel as nickel alloying additions form hard and strong white gold up to 18 carat.
While most commercial alloys are based on gold-nickel-silver-zinc alloys, it's widely interpreted that the presence of nickel in gold alloys is not a concern as long as the percentage of noble metals (gold, silver and platinum) does not fall below 70 per cent. This should be regarded as an estimate as every alloy has its own corrosion thresholds.
Watches
It is rare, but not impossible, for some models of high-end watches to cause allergic reactions for their wearers. The probable explanation is that the manufacturer has used a particular grade of stainless steel with low corrosion resistance - a so-called "free-machining", high-sulphur grade - in order to allow the intricate machining of the watchcase that justifies the prices and margins that such watches can command.
The vast majority of stainless steel watch elements use stainless steel grades with good corrosion resistance and cause no problems.
What is being done
While nickel is widely recognised as a major culprit in skin-irritation, little is being done around the world to control its use in jewellery and other items designed to come in contact with human skin. The USA is taking a somewhat relaxed approach, requiring jewellery to be labelled as nickel-containing, and much jewellery in the West is now advertised as "non-allergenic" or "nickel-free".
Only one jurisdiction has yet taken regulatory action. The European Union Nickel Directive (directive EC/94/27), which limits nickel release from jewellery, has been in place since January 20, 2000. Member states were required to pass national legislation necessary to comply with Directive 94/27/EEC. This entailed that nickel may not be used in products intended to come into direct and prolonged contact with the skin such as: earrings, necklaces, bracelets, chains, anklets, rings, wrist-watch cases, watch straps and tighteners, rivet buttons, tighteners, rivets, zippers and metal marks, when these are used in garments if the rate of nickel release from the parts of these products coming into direct and prolonged contact with the skin is greater than 0.5g/cm_/week in a standard sweat test.
Since then, surveys are beginning to show a decline in reports of nickel sensitivity in the current generation of teenagers; however, Sheringham is one who believes the legislation has had the reverse effect upon Australian consumers. "There was a flood in the Australian market directly following the passing of the law, with all these European companies trying to get rid of their rubbish jewellery," he says. "We saw an increase in the nickel allergy then."
No other jurisdiction including Australia has actively regulated the marketplace, citing lack of resources and competing priorities. While some might argue that governmental resources in this country are stretched too far to handle additional concerns, there is little that can be said to alleviate the industry of self-regulation.
Could manufacturing or purchasing specifications be drawn up for products that take the health and safety of the customers into account? Surely some discussion, however small, could be initiated on the topic of how to protect and enhance the reputation of the jewellery industry. After all, when it comes to nickel allergy, prevention is better than the cure.
Posted August 01, 2007