Selection and use of stainless steels for skin contact and body piercing jewellery applications
Concerns about the potential for the nickel content of stainless steels to result in health risks have been extensively investigated and reported. The Euroinox publication ‘Stainless Steel-The Safe Choice‘ summarises the issues and findings.
EC Directives concerning nickel
There are various pieces of legislation concerning nickel. The European Directives 76/769/EEC and 94/27/ECC, (12th amendment to 76/769/EEC, dated 30th June 1994), have some relevance to the use of stainless steels in skin contact and body piercing jewellery applications. These are sometimes referred to as the ‘nickel or jewellery’ directives.
The requirements of directive 94/27/EEC cover two quite separate issues, Body Piercing and Skin Contact
A maximum nickel content of 0.05%, (by mass), only is allowed for any metallic object inserted into a fresh flesh wound during or immediately after piercing. (This stage is termed the ‘epithelization’ of the wound). British Standard BS EN 1810:1998 has been implemented to determine nickel level of such items.
A maximum ‘nickel release’ of 0.5micrograms / sq.cm. / week is set for any product, such as earrings, necklaces, bracelets, rings, watch cases and straps, button, zips etc that is direct and prolonged contact with the skin.
British Standard BS EN 1811 specifies a test method using a synthetic sweat solution to check such items.
Selection of stainless steels to meet the directives
Most stainless steels contain deliberate additions of nickel.
These steels cannot be considered for ‘post assemblies’ to meet the 0.05% maximum nickel level. Some attempts have been made to make ferritic or manganese / nitrogen based austenitic stainless steels with very low nickel levels. Such steels are not widely available in the UK and so the use of stainless steels in body piercing posts is unlikely to result in compliance with the legislation.
The Euroinox publication ‘Stainless Steel-The Safe Choice’ shows results of nickel release tests from some of the most widely used stainless steel grades in synthetic sweat, along with results of allergic reaction patch tests. These show that grades
AISI 430 / 1.4016, (ferritic)
AISI 304 / 1.4301 304L/ 1.4307/1.4306, (austenitic)
AISI 316/ 1.4401 316L / 1.4404, (austenitic)
can be expected to meet the 0.5 micrograms / sq.cm. / week nickel release rates. (Actual release rates are shown as being less than 0.05 micrograms / sq.cm. / week.) Grade AISI 303 / 1.4305 however gave a release rate close to the 0.5micrograms / sq.cm. / week limit. Clinical patch tests reinforced the nickel release sweat test results showing no allergic reaction in grades 1.4016, (430), 1.4301, (304), 1.4307, (304L0), or 1.4401, (316), 1.4404, (316L). The 1.4305, (303), grade was found to result in a small number of allergic reactions in some people and so should be considered unsuitable for any items to be worn in close and prolonged contact with the skin.
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