Complying with the law on nickel transfer rates

Most people are familiar with food and breathing allergies – from nuts to asthma, from hay fever to gluten. But there is another class of allergies that also affects many people: contact allergies. And the worst of these is an allergy to nickel.

The trouble is that nickel is to be found all around us. Many other metals are alloyed with small quantities of nickel to strengthen and harden them or to improve their appearance. Gold, for example, can be made less soft and more shiny by the presence of nickel. Add enough nickel to it and you get white gold, which rivals platinum in appearance if not price. Add nickel to silver and it stops it tarnishing – or at least substantially reduces the risk and slows down the process.

Nickel can also be applied to the surface of jewellery, again to make it shiny, but also to make it smoother. This process, known as levelling, is based on the fact that nickel has one of the smoothest surfaces of all metals. The only metal that can match it is palladium.  But palladium is a precious metal, and while it can be used in high-end jewellery, it is not suitable for the more modestly priced magnetic bracelets and copper bracelets that millions of people wear all over the world for their therapeutic effects.

So nickel can’t really be taken off the market, despite the fact that it brings out as small number of people in a rash. But what can be done – and what the government has done – is set standards by law on how much nickel can be transferred in a specific amount of time. As currently drafted, the law sets a maximum “migration limit” of 0.5µg × cm^-2 per week for articles intended to come into direct and prolonged contact with human skin and a limit of 0.2µg × cm^-2 per week  for all post piercing assemblies inserted into pierced ears and other pierced parts of the human body.

Suppliers of jewellery containing nickel are required by law to act with “due diligence” and to test a reasonable sample of their products to make sure that they are complying with the law. Obviously, they cannot test all their products, not only because the tests are expensive, but also because the test destroys the product.

There are a number of labs that do these tests and a number of ethical suppliers, like magnetic therapy bracelets who go to great lengths to make sure that their products comply with the law.

And their products are very pleasing to look at too – don’t you think?