Contact allergy to methylchloroisothiazolinone/methylisothiazolinone in north‐eastern Italy: a temporal trend from 1996 to 2016

Abstract

Background Methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI) (Kathon â CG) is a common preservative used in industrial products, owing to its strong biocide effect. Contact allergy to MCI/MI has been reported in different occupations, including mechanics, hairdressers and healthcare workers. Objective To retrospectively analyse the temporal trend of MCI/MI sensitization in north-eastern Italy and to evaluate the associations with occupations in our geographical area.Methods From 1996 to 2016, 27 381 patients with suspected allergic contact dermatitis were patch tested in eight departments of Dermatology or Occupational Medicine in north-eastern Italy. Individual characteristics were collected through a standardized questionnaire. ResultsThe overall prevalence of MCI/MI sensitization was 4.2%, with the highest prevalence found in women and in patients younger than 25 years. MCI/MI sensitization was significantly associated with atopic eczema (OR: 1.34, 95% CI: 1.10-1.70), hand/forearm dermatitis (OR: 1.20, 95% CI: 1.05-1.36) and face dermatitis (OR 1.30, 95% CI: 1.10-1.40). There was a significant association between MCI/MI sensitization and chemical processing workers (OR 1.74, 95% CI:1.03-2.94), while mechanics and healthcare workers resulted more sensitized to this hapten only in the last 3 years.Conclusion Sensitization to MCI/MI is rising in the last years in Triveneto region, the 'epidemic' of sensitization to MCI/ MI is mainly driven by extra-occupational dermatitis, and sensitization in some occupational groups is emerging only in the last years. A full labelling is compulsory for all products that contain isothiazolinones, to permit to identify the culprit agent.

Methylchloroisothiazolinone/methylisothiazolinone and methylisothiazolinone contact allergy: A 24‐year, single‐center, retrospective cohort study from Turkey

“…During the epidemic in Europe, the allowed concentrations of MCI/MI and MI in all cosmetics in Turkey were the same as in Europe. 62,63 Our study showed that the rate of sensitization to 12,13,36,44,64 Higher levels were reached in Spain (18.9%) in 2015. 35 The highest prevalence was observed in Australia (20.3%), 15 followed by other non-European countries such as Thailand (18.5%), 16 and Canada (15.3%) 14 27 This study was probably conducted shortly after the epidemic, in the "decreasing period" of the prevalence.…”

“…Presenting the largest dataset on patch test results with MCI/MI and MI from Turkey, this study highlights some similarities and differences from previous reports on this topic. First of all, many studies on MCI/ MI sensitization reported a clear female preponderance 10,12,16,26,[35][36][37] and a high percentage of patients aged over 40 years. 26,35,38 The present study, however, shows an almost equal sensitization share in male patients.…”

“…56 The low sensitiza- Concomitant patch test reactions were most frequently seen with nickel and other metals, rubber allergens, and formaldehyde/formaldehyde releasers in our study. Nickel, 35 fragrances, 35,36,44,60 and preservatives such as formaldehyde 36,38,44,60,61 were reported as the main co-allergens, the latter two often coexisting in the same product together with isothiazolinones. Interestingly, fragrance allergens were positive only in a minority of patients in our study.…”

Occupational contact dermatitis in Triveneto: Analysis of patch test data of the North Eastern Italian Database from 1996 to 2016

“…The North‐Eastern Italian Database has been already described in several publications 17‐22 . From 1996 to 2016, a total of 27 381 patients (age >15 years) with symptoms and/or signs of suspected ACD consulted one of the eight departments of dermatology or occupational medicine comprising the North‐East Italy Contact Dermatitis Group (NEICDG): Trieste, Padua (three clinics), Pordenone, Rovigo, Trento, and Bolzano.…”

Contact Allergy—Emerging Allergens and Public Health Impact

“…While existing contact allergy may not necessarily lead to ACD if the allergen(s) can be sufficiently avoided, such avoidance often proves difficult. Difficulties increase with the ubiquity of substances, lack or shortcomings of identifying the presence of a substance in the environment [328] (cosmetic ingredient labelling is one laudable exception), the extent of cross-reactions with related substances, and a low individual elicitation threshold. In the following sections, some relevant public health aspects are discussed.…”