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BACKGROUND: Preservatives are used widely in cosmetic, household, and industrial products to prevent microbial growth and spoiling of the products. There has been a recent epidemic of contact allergy to methylisothiazolinone (MI). OBJECTIVES: To establish emerging trends in preservative contact allergy as MI is replaced. METHODS: We performed a retrospective study on consecutively patch-tested patients at our center from January 2011 to December 2019. RESULTS: A total of 7846 consecutively patch-tested patients were included who were patch tested between January 2011 and December 2019. The prevalence of allergy to MI fell from a peak of 9.39% in 2013 to 1.98% in 2019. MI/methylchloroisothiazolinone (MCI) followed a similar trend, with a peak prevalence of 7.85% in 2014 and falling to 1.39% in 2018. The prevalence of contact allergy to benzisothiazolinone (BIT) has increased steadily increased in 2014 from 0.26% (confidence interval CI 0.03-0.93) to 3.42% (CI 2.43-4.66) in 2019. CONCLUSIONS: Our data show a significant increase in the prevalence of contact allergy to BIT over the last 6 years, probably as a consequence of increased use in household products. It is essential to continue to look for emerging trends in contact allergy to enable prompt preventative measures to be taken.
King et al. (Sun,) studied this question.