Overview
Nickel is everywhere in modern hardware, from corrosion-resistant plating to stainless steel and battery cathodes. Its drawback for consumer products is biological. Nickel is one of the most common causes of allergic contact dermatitis, so the rules focus less on how much is present and more on how much escapes onto skin.
Where it's restricted
REACH Annex XVII takes an unusual approach with nickel. Instead of capping the total content, it limits the rate at which nickel may be released from articles in prolonged contact with the skin. Jewellery, watch straps, fasteners and spectacle frames all fall under this release limit.
That release-based control reflects the hazard. The problem is repeated skin exposure to free nickel ions, not the nickel locked inside an alloy.
Typical uses
Nickel plating resists corrosion and gives a bright finish. Nickel is a key alloying element in stainless steel and in superalloys for high-temperature parts. In rechargeable batteries it sits in the cathode of nickel-metal-hydride and many lithium-ion chemistries. Across automotive supply chains it is tracked as a declarable substance through lists like the GADSL.
The nickel rule is about migration, not bulk content. A stainless part can hold plenty of nickel and still pass, as long as it does not release more than the allowed amount during prolonged skin contact.
Note: general educational information, not legal advice. Always check the official source before relying on it.