NICKEL RELEASE FROM STAINLESS-STEELS

In 1994, a study of nickel release and allergic contact dermatitis fro m nickel-plated metals and stainless steels was published in this jour nal. It was shown that low-sulfur stainless steel grades like AISI 304 , 316L or 430 (S less than or equal to 0.007%) release less than 0.03 mu g/m(2)/week of nickel in acid artificial sweat and elicit no reacti ons in patients already sensitized to nickel. In contrast, nickel-plat ed samples release around 100 mu g/cm(2)/week of Ni and high-sulfur st ainless steel (AISI 303 - S approximate to 0.3%) releases about 1.5 mu g/cm(2)/week in this acid artificial sweat. Applied on patients sensi tized to nickel, these metals elicit positive reactions in 96% and 14% , respectively, of the patients. The main conclusion was that low-sulf ur stainless steels like AISI 304, 316L or 430: even when containing N i, should not elicit nickel contact dermatitis, while metals having a mean corrosion resistance like a high-sulfur stainless steel (AISI 303 ) or nickel-plated steel should be avoided. The determining characteri stic was in fact the corrosion resistance in chloride media, which, fo r stainless steels, is connected, among other factors, to the sulfur c ontent. Thus, a question remained concerning the grades with an interm ediate sulfur content, around 0.03%, which were not studied. They are the object of the study presented in this paper. 3 tests were performe d: leaching experiments, dimethylglyoxime and HNO3 spot tests, and cli nical patch tests; however, only stainless steels were tested: a low-s ulfur AISI 304 and AISI 303 as references and 3 grades with a sulfur c ontent around 0.03%: AISI 304L, AISI 304L added with Ca? AISI 304L+Cu. Leaching experiments showed that the 4 non-resulfurised grades releas ed less than 0.5 mu g/cm(2)/week in acid sweat while the reulfurized A ISI 303 released around or more than 0.5 mu g/cm(2)/week. This is expl ained by the poorer corrosion resistance of the resulfurized grade. Ye t (et all these grades had the same reaction to the DMG test (negative result), which shows again its lack of sensitivity. In contrast, the HNO3 spot test distinguished AISI 303 from the non-resulfurized grades . Clinical patch tests again showed that some patients (4%) were intol erant to AISI 303, while none were intolerant to the other grades. Thu s, this study confirms that non-resulfurized stainless steels (S less than or equal to 0.03%) like Ni-containing 304 and 304L should not eli cit Ni contact dermatitis, while the resulfurized grades (S> 0.1%) sho uld be avoided.