Skin allergy trigger in shampoo and soap

Wednesday April 1st, 2009

The rate of allergy to a common ingredient of shampoos, conditioners and soap is much higher than previously thought, a researcher has reported.

An expert from Sweden looked at the rate of allergy to the fragrance ingredient linalool. It is present in lavender, mint, and other plants, but can cause allergy once it is exposed to air (oxidised).

Johanna Brared Christensson tested more than 3,000 people with eczema, using patch testing. She found that between five and seven per cent were allergic.

"I would suspect that about two per cent of the complete population of Sweden are allergic to air oxidised linalool," she said. "That may not sound very much, but it is serious since linalool is so widely used as a fragrance ingredient."

Linalool is found in 60 to 80 per cent of perfumed hygiene products, washing up liquids and household cleaning agents that can be bought in any supermarket. It will be listed on the label, but it can be difficult for people who are allergic to avoid these products.

Ms Christensson added: "Linalool is present in many products around us, and this is probably the reason that contact allergy to this material is so common. Some people can shower with shower cream that contains linalool but never develop contact allergy, but we know that the risk increases as the exposure to the substance increases.

"One way of trying to minimise exposure to oxidised linalool is to avoid buying large packs of soap and shower cream, and always to replace the top after using a bottle."

Ms Christensson is based at the University of Gothenburg, Sweden. This work forms her academic thesis.

Christensson, J. B. Clinical and Experimental Studies on Oxidized Fragrance Terpenes as Contact Allergens. Thesis presented for the degree of Doctor of Philosophy (Medicine) at the University of Gothenburg, Sweden.

Tags: Europe | Allergies & Asthma | Dermatology

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