Divergent contact allergy trends linked to regulatory approaches
The downward trend of isothiazolinone allergy in Europe after its peak in 2013 and 2014 may have been due in part, the authors explain, to a memo released in 2013 by Cosmetics Europe after it and the European Society of Contact Dermatitis reviewed reports of increased contact allergy to MI. The memo urged companies to remove MI from leave-on products.
Later that year, the European Union’s Scientific Committee on Consumer Safety advised omitting MI from leave-on consumer personal care products and moved to restrict the ingredient in rinse-off products to less than 15 ppm. The recommendation took effect in 2015.
That year, Canada banned the use of MCI/MI in leave-on products but allowed MI alone in leave-on products until 2018. The total concentration of MI and MCI in wash-off products was limited to less than 15 ppm.
The authors add that, to their knowledge, the U.S. government does not restrict the use of MCI/MI or MI.
Policy implications for contact allergy
MI is still widely used in “countless products,” including shampoos, skin cleansers, dishwashing and laundry detergents, paints, and adhesives, Daniel W. Shaw, MD, associate professor of dermatology at the University of California, San Diego, told this news organization by email.
Dr. Daniel W. Shaw
“Exact figures between the U.S. and Europe are difficult to compare due to differing patch test concentrations, but the overall trends strongly suggest that stricter and earlier regulation in Europe resulted in lower MI allergy prevalence there than in the U.S.,” added Dr. Shaw, who was not involved in the study.
Steven R. Feldman, MD, PhD, professor of dermatology at Wake Forest University in Winston-Salem, N.C., said by email that accurate information on allergic reaction prevalence is difficult to find.
“The NACDG, ESSCA, and IVDK databases may contain the best data available, but the data depend on people who get patch tested and are not directly informative of the allergy rates in the general population,” added Dr. Feldman, who was not involved in the study.
Dr. Steven R. Feldman
“The great majority of people in the population may not be allergic,” he said. “For those with itchy rashes, getting patch tested or avoiding products with preservatives may be prudent. Broad regulations, however, should consider the overall risks and benefits in the population, and this particular study does not fully capture those issues.”
“This study shows that government regulations are important to limit consumer exposure to common allergens, especially to the concentrations used in personal care products,” Kelly Tyler, MD, associate professor of dermatology at the Ohio State University Wexner Medical Center in Columbus, noted by email. She was not involved in the study.
She advised clinicians to ask their patients who may have allergic contact dermatitis whether they have been exposed to products containing these compounds.
Dr. Kelly H. Tyler
“All personal care products in the store contain preservatives, and their maximum concentrations should be limited,” she advised. “The Expert Panel for Cosmetic Ingredient Safety should establish stricter guidelines for MI use in personal care products, especially given the findings of this study.”