Skin care products, cosmetics and sun protection lotions are well-known to be associated with contact allergy. Photo: Mitchell Shapiro/Flickr cc

Contact allergy is one of the major skin health problems in the Western world. In his thesis, Ahmed Ramzi at the Department of Environmental Science and Analytical Chemistry (ACES), shows the importance of developing analytical methods for the identification, measurement and detection of important molecules in contact allergy. He also hopes to increase the common awareness of the strong allergenic potencies of skin-sensitizing chemicals in commercial items.

The human skin is continuously exposed to numerous chemicals in our surroundings, such as substances originating from clothes, skin care products, cosmetics and air pollution.

“Skin proteins may react with compounds able to penetrate the skin barrier, resulting in antigen formation that can give rise to one of the major skin health problems in the Western world: contact allergy. This is a lifelong condition, which so far has no cure and causes much suffering and problems among those affected”, says Ahmed Ramzi.

In his thesis, presented in spring 2018, he describes analytical methodologies for the determination of important skin-sensitizing chemicals in two types of commercial items: chloroprene rubber, often found in products such as wet suits and gloves, and fragrance products, found in make-up and sun protection lotions. Both are well-known to be associated with contact allergy.

“Exposure to chloroprene rubber materials has resulted in numerous cases of allergic contact dermatitis”, he says.

Products made from chloroprene rubber contain compounds such as thioureas and isothiocyanates. The most widespread fragrances in cosmetics and perfumes on the market are monoterpenes, such as linalool and limonene. These easily oxidize  when exposed to air forming hydroperoxides, which have been shown to be strongly skin sensitizing compounds.

“Fragrances constitute one of the main causes of contact allergy, next to nickel and preservatives”, he says.

Why is it important to identify these chemicals?

“In clinics, patients are seen who react with skin inflammation caused by a seemingly non-allergenic material or a product having only harmless compounds listed on the label. In some cases, a skin-reactive compound may have formed unintentionally by exposure of the product to for example heat or air. Chemical analysis is then the only option to reveal the actual hapten or molecule. The identity is, of course, crucial knowledge for an affected individual to be able to avoid further exposure”, says Ahmed Ramzi.

In his thesis, he has developed a toolbox of different analytical methodologies to determine hydroperoxides in different matrices such as essential oils and fragranced commercial products.

“Hydroperoxides are now possible to detect in fragranced products thanks to our new methods and we have, therefore, for the first time, been able to correlate a case of fragrance skin allergy to hydroperoxides in a specific product”, says Ahmed Ramzi. He gives an example of a seven-year-old girl who had suffered from contact dermatitis symptoms for six months and no topical treatment helped her to recover.

“After patch testing and chemical analysis, it was realized that a specific shampoo containing linalool hydroperoxides was most likely the culprit, and her eczema disappeared as soon as she stopped using the shampoo. The thesis shows the importance of developing analytical methods for the identification, measurement and detection of important molecules in contact allergy.”

Ahmed Ramzi points out that organic thioureas still are not a part of the European base line series of patch tests for diagnosis of contact allergy.

“But I hope they soon will be included. Also, there are no regulations for hydroperoxide content in products due to lack of chemical analysis methods. Now the methods are available, so fragrance hydroperoxides will hopefully soon be included in the EU regulatory framework. This is important for prevention and also a way to increase the common awareness of the strong allergenic potencies of these compounds”, he says.

Ahmed Ramzi’s thesis, “Analytical methodologies for common skin allergens. Organic thioureas, isothiocyanates and fragrance hydroperoxides in everyday life products”, can be read here.