The role of cobalt, nickel and chromium sensitization in occupational contact dermatitis

Background: Exposure to nickel, chromate, and cobalt is a common cause of metal sensitization. The sensitization and the contact dermatitis caused by these haptens are frequent in the general population but also in some occupational groups that can come in frequent contact with these metals.  

Objectives: to evaluate the prevalence of nickel, cobalt and chromate allergy in a population of consecutive patients with contact dermatitis that underwent patch test and to investigate the possible association with individual and occupational risk factors. Patients/methods: 14464 patients (67.6% women and 32.4% men) living in North-Est of Italy. The associations between patch test results and occupations were studied by multivariate logistic regression analysis considering patients with hand and forearm contact dermatitis (2625 women; 1486 men). White collars were used as reference category.

Results: 24.6% of the patients reacted positively to nickel, 10.2% to cobalt and 8.7% to chromate. Considering people with hand and forearm dermatitis, we found significant association with occupation. In men, the prevalence of positive reactions to nickel was positively associated to wet work (OR 2.96; 95% CI 1.34-6.53), drivers (OR 3.40; 95% CI 1.49-7.76), carpenters (OR 3.33; 95% CI 1.36-8.15), farmers (OR 3.37; 95% CI 1.24-9.17). No significant association with occupation was found in female workers. Chromate sensitization was higher in building trade workers (OR 4.63; 95% CI 2.60-8.22), in drivers (OR 3.48; 95%CI 1.57-5.71) and in cleaners (OR 3.99; 95% CI 1.93-8.23) in men and in cleaners (OR 3.99; 95% CI 1.93-5.06) in women. Cobalt sensitization was associated with cleaning work in men (OR 2.28; 95% CI 1.02-5.1) and with drivers in women (OR 2.9; 95% CI 1-8.59).  Conclusions: Our study showed interesting association between some occupations and nickel, chromate and cobalt allergy.