Nickel a sensitive issue. 

Do cheap earrings hurt your ears? Does the back of your watch make your wrist itch? Do bracelets
bring you out in a rash? If so, you may be allergic to nickel.
Nickel may be present in many items which come into contact with the skin, such as jewellery, zips,
buttons, spectacle frames and watches.
About 20% of the female population in Europe have been sensitised to nickel, mainly from wearing
cheap jewellery. Sensitisation means that when something containing nickel is in contact with your
skin over a period of time, you have an allergic reaction which makes the skin itchy and sore.
Sensitisation is caused by the nickel penetrating the skin and combining it with a body protein. The body
then reacts with the nickel-protein complex.

Controlling the problem

There is a lot of concern in Europe about sensitisation caused by the release of nickel from jewellery
and other items. The European Union has therefore introduced laws banning the sale of items worn
close to the skin that releases enough nickel to cause sensitisation. The limit for nickel release from such
items is 0.5 μg per cm2 per week. The laws came into force in July 2001.
Is it nickel?
The new laws will only help control the problem of nickel sensitisation if they can be enforced. Tests
are therefore required to identify items containing nickel, and to measure the amount of nickel
released. Chemists have developed a quick ‘spot-test which can be used to identify items containing
nickel. Items identified as containing nickel are then put through a more rigorous test to measure
accurately the amount of nickel released into artificial sweat. The results of this test are used to decide
whether the item releases enough nickel to cause sensitisation. Products that release more than the
legal limit are not allowed on the market.

How does the spot test work?

A drop of 10% ammonia solution is placed on a cotton
wool bud, followed by a drop of dimethylglyoxime (DMG)
solution (1%). The surface of the item is then rubbed with
the cotton wool bud for 15 seconds. If a pink or red
colour appears on the cotton wool, then the item
contains nickel in a releasable form. The colour is due to a
complex formed by the reaction of the ammonia and
DMG with the nickel. The spot test is quick to perform
and doesn’t even need to be carried out in a laboratory.
Trading Standards Officers can use the test to check items
at the point of sale. Using the spot test saves time and
money by reducing the number of items that need to be
put through the nickel release test. Iron and chromium
may interfere with the spot test. Adding a drop of 20%
citric acid before the DMG solves the problem.