contact allergy

A new study validates the Spring 2016 Scientific Community of Consumer Safety decision to restrict the use of methylisothiazolinone (MI) in cosmetic, household, and occupational products due to a recent surge in contact allergy dermatitis occurrences in Europe.


How often do you use rinse-off cosmetic products or toiletries? Imagine each of those products contained a preservative known to cause higher rates of contact allergy reactions on your hands and face. Now, what if the use of that preservative is unregulated and brands can legally avoid posting information about its content levels in their products? Prior to a March 2016 decision to officially classify the chemical in question as a skin sensitizer, the EU found itself in a similar situation with widespread use of the preservative methylisothiazolinone (MI) in rinse-off and leave-on cosmetics, household chemicals, and occupational/industrial products causing allergic reactions on contact.

Researchers emphasize particular concern over use of MI in rinse-off cosmetics due to both greater frequency of use and more lax regulation (as concentrated maximums of 100 ppm MI – enough to register a contact allergy reaction – were permitted in the EU until the Scientific Community of Consumer Safety ruled in favor of restricting that level to 15 ppm MI). Given relevant data showing how cosmetics cause contact allergy with MI usage, the EU agreed to ban MI in leave-on cosmetic products effective January 1, 2017.

A recent Contact Dermatitis (2016) study collected data from 3434 patients (mean age: 47 years) who tested positive with patch test reactions to MI in 11 dermatology departments across 8 European countries during the time period from May to October 2015. Clinicians applied patch tests to patients’ upper back and left the area sealed for 2 days before reading results. Any patients who tested positive for the contact allergy to MI or methylchloroisothiazolinone (MCI/MI) were asked to bring in the cosmetics, toiletries, household cleaning products, and occupational products they used for further testing. Researchers recorded the type and use of each product containing the preservative MI or MCI/MI, and the specific name and manufacturer information was recorded for any substance found to contribute to present contact dermatitis (allergic skin inflammation or irritation).

Results show that of the tested population, 205 patients (6%) registered positive patch test reactions in relation to MI, with females identified as the predominant group with MI contact allergy reactions and current or previous dermatitis noted, mainly located on the hands and face. One in ten participants had “widespread dermatitis” (skin irritations on more than three sites on their body). Occupational contact dermatitis was seen most often in workers within healthcare, cleaning, and office settings.

72.7% of patients with relevant MI contact allergy were found to be related to current cosmetic use, with a majority having noticed the onset of dermatitis occurring between 2013 and 2015. More than half of the 149 patients with relevant MI contact allergy had exposure to multiple products containing MI or MCI/MI. Some popular brands were cataloged with greater frequency than others in patients who had MI contact allergies, including Clarins, Pantene, TRESemmé, Nivea, Head & Shoulders, Dove, Revlon, etc. Notably, the study’s conclusion in October 2015 likely resulted in a significant underestimation in the reported data for that year. This study also does not include any data related to the potential cross-reactivity between isothiazolinones.

In conclusion, researchers found that the collected data supports the planned restriction on MI-use in Europe as a public health and safety measure. Furthermore, researchers suggest additional restrictions be placed on the use of MI in water-based paint, as evaporation from freshly-painted surfaces risks causing airborne allergic contact dermatitis. Due to broad exposure to rinse-off and leave-on cosmetics containing MI, contact allergy is still a widespread issue in European countries. Increasing awareness about the dangers of certain preservatives in commonly used products is vital to ensuring public health and safety. Educated consumers can now be more vigilant when choosing which products to buy at home and abroad.

Written By: Jennifer Newton

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