Studies of the prevalence of nickel sensitivity generally show that in the general population up to 15% of women and up to 2% of men are nickel sensitive.(4)
Public health advocates are using these figures to project that over 10% of the world's population, that is hundreds of millions of people, are at risk of being sensitized to nickel. This projection, however, fails to take into account the method of exposure that has likely caused the current prevalence. It is generally agreed among dermatologists that "the principal way in which sensitization can be induced in susceptible individuals appears to be by contact with a high concentration of sweat-soluble nickel from a localized area."(5)
Nickel-releasing ear-piercing studs, nickel-plated jewelry, and nickel-plated clothing clasps are viewed as the items primarily responsible for the current prevalence of nickel sensitivity. Body-piercing practices are increasing in North America and Europe. The significant differences in prevalence between females and males is sometimes correlated with the much higher prevalence of ear-piercing among women, particularly in European cultures, but other factors such as hormone differences and the tendency for young women to wear more and/or low quality jewelry than males may also play a role.(6)
An important question is: If the use of nickel-releasing materials in jewelry and ear-piercing studs were reduced, what would be the resulting long-term risk of nickel sensitization among the population? Regulatory controls (similar to the Nickel Directive and REACH) were adopted in certain Scandinavian countries towards the end of the last century and many reports have now demonstrated a significant reduction in the prevalence of individuals testing positive for nickel sensitization.(7-14) The Nickel Directive has now been in place in Europe as a regulatory control since 1998 and more widespread support of the earlier Scandinavian studies of decreased sensitization to nickel in European countries has developed.
4. Thyssen, J.P., Menné, T. 2010. Metal allergy—a review on exposures, penetration, genetics, prevalence, and clinical implications. Chem. Res. Toxicol. 23(2): 309-318.
5. Consensus Document from the NiPERA-Sponsored Nickel Dermatitis Workshop, March 17-18, 1997, Brussels, Belgium. NiPERA, Durham, NC, USA.
6. Kwangsukstith, C.; Maibach, H.I. 1995. Effect of age and sex on the induction and elicitation of allergic contact dermatitis. Contact Dermatitis 33: 289-298.
7. Johansen, J.D.; Menné, T.; Christophersen, J.; Kaaber, K.; Veien, N. 2000. Changes in the pattern of sensitization to common contact allergens in Denmark between 1985-1986 and 1997-1998, with a special view to the effect of preventive strategies. Br. J. Dermatol. 142: 490-495.
8. Mattila, L.; Kilpeläinen, M.; Terho, E.O.; Koskenvuo, M.; Helenius, H.; Kalimo, K. 2001. Prevalence of nickel allergy among Finnish university students in 1995. Contact Dermatitis 44: 218-223.
9. Ehrlich, A.; Kucenic, M.; Belsito, D.V. 2001. Role of body piercing in the induction
of metal allergies. Contact Dermatitis 12: 151-155.
10. Lu, L.K.; Warshaw, E.M.; Dunnick, C.A. 2009. Prevention of nickel allergy: the case for regulation? Dermatol Clin. 27(2): 155-161.
11. Thyssen, J.P.; Linneberg, A.; Menné, T.; Nielsen, N.H.; Johansen, J.D. 2009. Contact allergy to allergens of the TRUE-test (panels 1 and 2) has decreased modestly in the general population. Br. J. Dermatol. 161(5): 1124-1129.
12. Thyssen, J.P.; Johansen, J.D.; Menné, T.; Nielsen, N.H.; Linneberg, A. 2009. Nickel allergy in Danish women before and after nickel regulation. N. Engl. J. Med. 360: 2259-2260.
13. Carøe, C.; Andersen, K.E.; Mortz, C.G. 2011. Fluctuations in the prevalence of nickel and cobalt allergy in eczema patients patch tested after implementation of the nickel regulation in Denmark. Contact Dermatitis 64(3): 126-131.
14. Thyssen, J.P.; Hald, M.; Avnstorp, C.; Veien, N.K.; Lauer-berg, G.; Nielsen, N.H.; Kaaber, K.; Kristensen, B.; Kristensen, O.; Thormann, J.; Vissing, S.; Menné, T.; Johansen, J.D. 2009. Characteristics of nickel-allergic dermatitis patients seen in private dermatology clinics in Denmark: A Questionnaire Study. Acta Derm. Venereol. 89: 384-388.