Nickel is a metal used for products such as tools and jewellery. Nickel can cause contact allergy. There are rules governing how much nickel different products may give off. This applies to products such as piercing ornaments, earrings, necklaces, chains, anklets, rings, watch-cases, clasps, rivets, zips, keys and metal studs on clothing. There are, however, no rules governing nickel in power tools.
A well-stocked chemist will offer a nickel test which will show if a product is giving off nickel.