Isothiazolinone derivatives and allergic contact dermatitis: a review and update

Abstract

Allergic contact dermatitis (ACD) from isothiazolinones has frequently been described in the literature. Following an epidemic of sensitization to methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) in the 1980s, and more recently to MI, the Scientific Committee on Consumer Safety of the European Commission banned their use in leave‐on products, while restricting that in rinse‐off cosmetics. Despite a decreasing prevalence of ACD from MCI/MI and MI, cases caused by occupational exposure and non‐cosmetic isothiazolinone sources are on the rise. Moreover, sensitization to newer and lesser known isothiazolinones has been reported. This paper reviews the epidemiology of contact allergy to different isothiazolinones, clinical presentation of isothiazolinone‐induced ACD, most relevant sensitization sources and potential cross‐reactions between isothiazolinone derivatives. It also provides an update on recent legislative measures.

The methylisothiazolinone epidemic goes along with changing patients' characteristics – After cosmetics, industrial applications are the focus

“…Before 2010, sensitization was clearly below 2% . In retrospective analyses, several publications identified the years 2010/11 as the years of the beginning of an epidemic . Most of the published studies covered the period 2010 to 2015 or parts of it, where sensitization rates were high (>7%) .…”

“…In retrospective analyses, several publications identified the years 2010/11 as the years of the beginning of an epidemic . Most of the published studies covered the period 2010 to 2015 or parts of it, where sensitization rates were high (>7%) . The peak of the epidemic was reached in 2013/14 and a decline noted for 2014/15 .…”

“…Shortly after the first publication pointing to the dawning epidemic already in 2012, with sensitization rates rising from <2% in 2009 to >4% in 2011, reports from all over Europe, North America, and other parts of the world disclosed the full‐blown epidemic showing sensitization frequencies of >7% in patch‐tested dermatitis patients. In the preceding years, MI sensitization rates had remained <2%, attributed mainly to the use of MI (and mixture of methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) acting via cross‐reactions) in occupational applications, for example, paints . In contrast, the sudden rise of MI allergy in 2010 and thereafter is thought to be caused mainly by sensitization through MI‐containing cosmetics, as was shown, for example, by risk factor analysis …”

“…The Scientific Committee on Consumer Safety of the European Commission (SCCS), as well as Cosmetics Europe (the association of the cosmetic industry) recommended that MI be banned from use in leave‐on cosmetics in 2013. The overall frequency of sensitization decreased thereafter but remained at a high level, for which continued occupational exposure, rinse‐off or household products, still too high use concentrations, and undisclosed occurrence in a variety of products were thought to be responsible …”

Allergic contact dermatitis and photosensitivity to methylisothiazolinone and methylchloroisothiazolinone/methylisothiazolinone: Portrait of an epidemic in Brazil

“…Methylisothiazolinone (MI) is a preservative associated with an epidemic of allergic contact dermatitis worldwide, mainly owing to its use in cosmetics, where it is found alone or combined with methylchloroisothiazolinone (MCI/MI, eg. Kathon CG) . There are very few studies on sensitization to MI in Brazil, although cases of an unusual pattern of photoeczema associated with MCI/MI allergy have been reported in the country .…”