In modern Western body piercing, a wide variety of materials are used. Some cannot be autoclaved, and others may induce allergic reactions, or harbour bacteria. Certain countries, such as those belonging to the EU, have legal regulations specifying which materials can be used in new piercings. Minimum standards for jewelry for initial piercings The Association of Professional Piercers has developed safety standards for body jewelry based on research and historical experience. Products with an ISO or ASTM designation are so noted and a statement specifying the finish requirements particular to body jewelry has been added. In addition, several materials designated for applications other than implants have been proven through historical and practical application to be suitably biocompatible for initial piercing. Steel that is ASTM F-138 compliant or ISO 5832-1 compliant Steel that is ISO 10993-6, 10993-10, and/or 10993-11 compliant Titanium (Ti6Al4V ELI) that is ASTM F136 compliant or ISO 5832-3 compliant Titanium that is ASTM F-67 compliant Solid 14-carat or higher nickel-free white or yellow gold Solid nickel-free platinum alloy Niobium (Nb) Fused quartz glass, lead-free borosilicate or lead-free soda-lime glass Polymers (plastics) as follows: Tygon Medical Surgical Tubing S-50HL or S-54HL Polytetrafluoroethylene (PTFE) that is ASTM F754-00 compliant Any plastic material that is ISO 10993-6, 10993-10 and/or 10993-11 compliant and/or meets the United States Pharmacopeia (USP) Class VI material classification. Minimum Standard for Jewelry Threading for Initial Piercings All threaded or press-fit jewelry must have internal tapping (no screw threads on posts). Minimum Standard for Jewelry Surface Finish for Initial Piercings For body jewelry purposes, surfaces and ends must be smooth, free of nicks, scratches, burrs, polishing compounds and metals must have a consistent mirror finish. Metals Steel Surgical stainless steel is a grade of stainless steel that is used in biomedical applications. The most common "surgical steels" are austenitic 316 stainless and martensitic 440 and 420 stainless steels. There is no formal definition on what constitutes a "surgical stainless steel", so product manufacturers and distributors apply the term to refer to any grade of corrosion resistant steel. 316 stainless steel, also referred to as marine grade stainless steel, is a chromium, nickel, molybdenum alloy of steel that exhibits relatively good strength and corrosion resistance. Along with the titanium alloy Ti6Al4V, 316 stainless is a common choice of material for biomedical implants. Although Ti6Al4V provides greater strength per weight and corrosion resistance, 316 stainless components can be more economical