Contact Dermatitis • Original Article COD Contact Dermatitis Nickel, chromium and cobalt sensitization in a patch test population in north-eastern Italy (1996 – 2010) Francesca Rui 1 , Massimo Bovenzi 1 , Andrea Prodi 1 , Anna Belloni Fortina 2 , Ilaria Romano 2 , Maria Teresa Corradin 3 and Francesca Larese Filon 1 1 Clinical Unit of Occupational Medicine, University of Trieste, Trieste 34129, Italy, 2 Dermatology Unit, Department of Pediatrics, University of Padua, Padua 35128, Italy, and 3 Dermatology Unit, S. Maria degli Angeli Hospital, Pordenone 33170, Italy doi:10.1111/j.1600-0536.2012.02133.x Summary Background. Sensitization to nickel, cobalt and chromium is frequent in patch test populations. The prevalence is affected by geographical and socio-cultural factors. Objectives. To investigate the temporal trend of nickel, cobalt and chromium contact sensitization between 1996 and 2010 in north-eastern Italy. Patients/methods. Nineteen thousand and eighty-eight patients (67.2% women and 32.8% men) with suspected allergic dermatitis underwent patch testing with the European baseline series. The associations between nickel, cobalt and chromium sensitization and patient age (in quintiles) and year of patch testing were investigated by means of multivariate logistic regression analysis. Results. The prevalence of nickel sensitization decreased signiﬁcantly among younger women (≤26 years), from 38.3% (1996–1998) to 31.9% (2002–2004), 28.3% (2005–2007) and 29.0% (2008–2010), whereas an increase was observed in the 36–45-year and 46–58-year age groups. The overall prevalence of chromium sensitization dropped from 10.2% (1996 – 1998) to 4.6% (2008 – 2010) among women, and from 11.3% (1996–1998) to 5.9% (2008–2010) among men. The prevalence of cobalt sensitization increased among younger men (≤26 years), from 2.7% (1996 – 1998) to 7.3% (1999 – 2001), 9.6% (2002 – 2004), and 6.6% (2005 – 2007). Conclusions. Our study showed a decreasing trend of nickel sensitization (only among younger women) and of chromium sensitization in both sexes. Key words: chromium; cobalt; dermatitis; nickel; patch test; prevalence. Introduction Nickel, chromium and cobalt are three of the most common allergens in patch tests (1 – 3). The prevalence of Correspondence: Dr Francesca Rui, Unit ` a Clinica Operativa di Medicina del Lavoro, Dipartimento di Scienze di Medicina Pubblica, Universit ` a degli Studi di Trieste, Centro Tumori, Via della Piet ` a 19, I-34129 Trieste, Italy. Tel: +39 040 3992409; Fax: +39 040 368199. E-mail: frui@units.it Conﬂicts of interest: The authors have declared no conﬂicts. All centres are members of the North-Eastern Italy Contact Dermatitis Group (NEICDG). Accepted for publication 17 May 2012 sensitization is different from one country to another, and is inﬂuenced by socio-cultural factors (4 – 8) and probably by different patch test referral patterns. There is evidence that regulatory interventions on nickel exposure (e.g. Directives 1994/27/EC and 2004/96/EC) (9, 10) and on chromium exposure (Direc- tive 2003/53/EC) (11) have inﬂuenced sensitization trends in some European countries (12–14), although some authors recently described a tendency for an increas- ing prevalence of chromium allergy in Denmark after a signiﬁcantly decreasing trend (15, 16). The present study investigated the prevalence of nickel, cobalt and chromium contact allergy in a patch test population in north-eastern Italy, between 1996 and  2012 John Wiley & Sons A/S Contact Dermatitis, 68, 23–31 23