Methylchloroisothiazolinone and methylisothiazolinone contact allergy: an occupational perspective.

BACKGROUND: Sensitivity to either methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI) or MI has increased, with a reported frequency of up to 11.1% among dermatitis patients, the main context being allergic contact dermatitis caused by MCI or MCI/MI in personal care products. Case reports have described occupational allergic contact dermatitis caused by MI in paints and within the beauty industry. PATIENTS/MATERIALS/METHODS: This study identified incident cases of occupational allergic contact dermatitis caused by MCI/MI and or MI reported from 1996 to 2012 to a UK-wide surveillance scheme (EPIDERM), with the aim of identifying changes in incidence over the study period. RESULTS: The data show an increase in occupational allergic contact dermatitis caused by MCI/MI and or MI from 1996 to 2012 of 4.1% [95% confidence interval (CI) 1.6-6.9] per annum. Analysis by industry showed a 3.8% (95% CI: -0.3 to 8.0) per annum increase in those exposed to personal care products in the workplace as a primary exposure [healthcare workers, 8.1% (95% CI: 2.1-14.4) per annum; beauty workers, 6.6% (95% CI: -2.2 to 16.2) per annum; hairdressers, 1.5% (95% CI: -4.7 to 8.1) per annum]. There was a 6.3% (95% CI: 1.8-10.9) per annum increase for manufacturing workers. A statistically significant rise in the frequency of occupational allergic contact dermatitis was shown to be attributable to MCI/MI and or MI between 1996 and 2012. CONCLUSION: The findings support recommendations for a review of the regulations relating to MCI/MI and/or MI in cosmetic and personal care products and in industrial settings.