Experimental nickel elicitation thresholds – a review focusing on occluded nickel exposure

Abstract

Nickel (Ni) is the most frequent cause of contact allergy among the female population. This makes it interesting to examine thresholds for elicitation under different conditions. Even though Ni exposure may be open, occluded, penetrating or oral, most dose-response studies in the literature concern single occluded application. The aims of this study were to assess thresholds of response by making a statistical analysis of available dose-response studies with single occluded exposure and comparing the results to thresholds from other modes of exposure. 8 occluded Ni dose-response studies were selected based on statistical considerations. The statistical analysis showed that 5% of a sensitized population react to 0.44 mg Ni/cm 2 and 10% react to 1.04 mg Ni/cm 2 . In another study with a single open application, 7.8% of sensitized persons responded to a dose Â6 higher than the dose to which 10% reacted in occluded exposure. When combining the exposure to Ni with an irritant, divagating results were found, although the literature shows evidence of an augmented response when combining exposure to an allergen and an irritant. The thresholds of penetrating exposure were found to be lower than the thresholds of single occluded exposure. Comparisons of different kind of exposures across studies are difficult, because of differences in the studies, although a comparison could be made by a study that compares the different exposures within the same individuals at the same time.

Face and Neck Dermatitis from a Stainless Steel Orthodontic Appliance

“…Possible explanations could be the considerably smaller total amount of metal in the test compared with that in the real appliance, the relatively short exposure time, and the absence of mechanical irritation from smooth bands. [9][10][11] Regular smoking recently has been suggested to play a role in contact allergic reactions as well, although the mechanisms are not known. 12 When two metals come in contact, corrosion of the less precious metal is increased.…”

“…Moreover, the immunology of the oral mucosa may differ from that of the skin, because the oral mucosa is potentially less reactive than the skin to contact allergens such as nickel. 10 According to current evidence, orthodontic treatment does not increase the risk of nickel allergy; neither has nickel allergy been shown to be an obstacle to treatment with fixed appliances made of stainless steel. 14,15 Yet, although most nickel-allergic patients can be treated without discomfort, individual variation exists, and orthodontic treatment occasionally may even aggravate the existing allergy, as may have happened in our patient.…”

“…2,4,8 Evidence shows that the elicitation threshold of a nickel-allergic reaction varies among individuals and individually over time. [9][10][11] Elicitation of this reaction depends on the conditions under which nickel exposure occurs and is affected by such factors as hapten concentration on the contact area, open or occluded exposure, the presence of an irritant, and individual degree of contact allergy.…”

Nickel release from earrings purchased in the United States: The San Francisco earring study

“…12 A recent metaanalysis demonstrated that this limit is most likely reasonable. 35 Furthermore, the EU directive prohibits nickel in coated products, unless the coating is sufficient to ensure that the nickel release will not exceed 0.5 g/cm 2 /wk after 2 years of normal use. 12 Finally, it restricts the level of permitted nickel release in post assemblies (also called ''studs'' or simply ''posts'') at 0.2 g/cm 2 /wk.…”

Evaluation of Beryllium, Total Chromium and Nickel in the Surface Contaminant Layer Available for Dermal Exposure After Abrasive Blasting in a Shipyard

“…Nickel itch or nickel allergy is a reaction that develops after repeated and prolonged exposure to nickel or nickel-containing items (12). For this reason, the European Union has set nickel release from items with prolonged skin contact at 0.2 µg per cm 2 (20).…”