MethylchloroisothiazolinoneMethylisothiazolinone and Methylisothiazolinone Sensitivity in Hungary

Abstract EN

Background.

Due to allowing of methylisothiazolinone (MI) in cosmetics, cleaning products, and paints, an epidemic of MI-hypersensitivity emerged.

Patch testing Kathon CG® (3:1 mixture of methylchloroisothiazolinone and methylisothiazolinone, MCI/MI) does not correctly detect MI contact allergy, due to the low concentration of MI in the test material.

Methods.

A retrospective survey was performed to estimate the prevalence of MCI/MI hypersensitivity in 14693 patients tested consecutively between 1993 and 2014.

Moreover, currently 314 patients were prospectively tested with the allergens MCI/MI and with MI during one year.

Results.

MCI/MI hypersensitivity increased retrospectively from 0.5% to 6.0%.

By current prospective testing we detected 25 patients (8%) with MCI/MI and/or MI positive reactions.

Out of the 25 patients 10 were only MCI/MI positive, 9 were only MI positive, and 6 were MCI/MI and MI positive.

If MI had not been tested separately, MI contact allergy would have missed in 36% of all detected cases and in 2.8% of the total 314 patients.

Conclusions.

The frequency of MCI/MI hypersensitivity is increasing also in Hungary.

We confirm that, in order to detect MI contact allergy, it needs to be tested separately.

A further increase of MI hypersensitivity might be expected in the future as products containing MI are still widely available.