Technical Q&A Hypodermic needles and nickel allergy

ASK AN EXPERT FAQ FROM THE NICKEL INSTITUTE TECHNICAL ADVICE LINE

Geir Moe P.Eng. is the Technical Inquiry Service Coordinator at the Nickel Institute. Along with other material specialists situated around the world, Geir helps end-users and specifiers of nickelcontaining materials seeking technical support. The team is on hand to provide technical advice free of charge on a wide range of applications such as stainless steel, nickel alloys and nickel plating to enable nickel to be used with confidence.

https://inquiries.nickelinstitute.org/

QQ: I have a nickel allergy and am wondering about the availability of a hypodermic needle that is nickel free?

AA: Nickel in stainless steels, such as Type 304 (S30400), is an essential ingredient, that provides the high ductility, formability and weldability that enables the production of hypodermic needles.

For example, hypodermic needles might start as a flat strip 18 mm wide by 0.5 mm thick wrapped on a large spool. The strip is forced through a set of rolls to be formed into a tube, about 6 mm in diameter, seam welding the two edges. As the welded tube moves down the line it passes through a series of progressively smaller holes known as dies. As the diameter is reduced the strength of the tube increases and must be periodically softened by heating. What started out as 6 mm diameter would be reduced to 0.35 mm diameter, a 95% reduction.

As the outside diameter decreases, the wall thickness also decreases. After the final drawing step, the cold worked material is left in a strong and hard condition.

Most allergic reactions to nickel are from inexpensive nickel-plated jewelry that are in prolonged contact with the skin. Nickel plating can release nickel from contact with

sweat while Type 304 is very corrosion resistant to sweat and releases very little nickel and a hypodermic needle is only in contact with skin for a few seconds.

The following link discusses nickel allergy in more detail: nickelinstitute.org/science/humanhealth-fact-sheets/fact-sheet-1-nickelallergic-contact-dermatitis/

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