Between 2010-2013, contact allergy to methylisothiazolinone (MI), a preservative used in cosmetics and household products, spiked dramatically in Europe—reaching 6-7% of dermatology patients tested. The majority of cases were middle-aged women with facial and hand rashes, though young children were also affected. This happened even though MI was deemed 'safe' at concentrations up to 100ppm, suggesting the approved limit wasn't actually safe for widespread use.

Researchers at dermatology centers in Belgium and France tested over 16,000 patients combined for MI allergy using standard patch testing. They tracked sensitization rates over several years and identified which products (cosmetics, detergents, paints) were causing reactions.

Funding not disclosed in abstract