Skin allergy affects up to 20 per cent of the population globally and can lead to severe and debilitating symptoms such as swelling, itching and rashes. The most common metal allergens can be found in jewellery, watches, keys and belt buckles, and include nickel, cobalt and chromium.
The first in this series of three studies by Dr Aoife Clancy, Dr Aaron Moore, Sophie Knox, and the O’Boyle research group, found that each of these metals had a different reaction when they came in contact with the skin. Nickel, for example, which causes allergies in up to 20 per cent of the general population, was found trapped in the outer layers of the skin, whereas cobalt and chromium penetrated deeper. The metals also changed the composition of lipids (essential natural fats).
Similarly, the second study found that a preservative called methylisothiazolinone (MI), detectable in everyday products like washing detergents, paints and cosmetics, was also trapped in the outer layers of the skin. This chemical also decreased the levels of some lipid or fatty compounds in these upper layers.
The final study focused on fragrance chemicals, such as citrus and lavender scents. These were also shown to stay in the upper layers of the skin, with small amounts of the chemical moving deeper below the surface. The chemicals also increased the amounts of certain lipid compounds. “Limonene and linalool are important causes of allergy in cosmetics and skin cleansers," says Dr John Bourke, Consultant Dermatologist at South Infirmary Victoria University Hospital, in Cork. "A lot of people develop dermatitis from these fragrances and become intolerant of products that contain them. The reason for this is unclear, but understanding the mechanism involved in dermatitis caused by these fragrances will help us to protect people from developing allergies.”
The interesting findings from these studies suggest that allergic reactions to these chemicals can be triggered deep in the skin, even though the chemicals themselves are mainly stuck in the outer layers. How these allergic reactions happen will be the focus of future studies, which will investigate why very small amounts of these chemicals produce such a strong allergic reaction for some people, and why the fatty compounds appear to be altered in the presence of the chemicals. The findings could contribute to the development of future prevention and treatment strategies for skin allergy.
More can be found on these topics at the links below:
https://onlinelibrary.wiley.com/doi/10.1111/cod.14711
