A number of frangrances are recognized to be both allergens and sensitizers (26 main ones). I am very sensitive to hexyl cinnamal and cannot use a shampoo with that fragrance additive in it. One can react to a fragrance additive and think that they are reacting to something else in a cosmetic formulation. My symptoms were an itchy, "burning", painful scalp. By comparing ingredient labels I was able to identify exactly what caused my symptoms. Any shampoo with that fragrance in it caused the same reaction.
"Risk management by labelling 26 fragrances? Evaluation of Article 10 (1) of the seventh Amendment (Guideline 2003/15/EC) of the Cosmetic Directive"
"... It was found that more than 50% of these cosmetic and washing and cleansing products contain at least one of the 26 substances above the thresholds for labelling ... Regulations are not effective if they load the major responsibility for risk management on consumers, instead of on authorities and manufacturers. ... "
Here is the list of the 26 fragrances. Hexyl cinnamaldehyde, a synonym for hexyl cinnamal is on it.
The article below is most disturbing because children suffered for far too long before the correct diagnosis was made. This underlines 2 things I have touched on before, pH being important in hair and skin products and reading labels and hopefully identifying an offending ingredient. Quaternary ammonium compounds are in all conditioners, some shampoos and many other products and many quats are known irritants. It is how one reacts to them and the concentration used that can be problematic. While one cannot change what products are used in schools, public restrooms or hospitals, one can be selective about what products one uses at home.
"Scrubbing Away Germs Can Backfire on Backsides"
" ... toilet-seat contact dermatitis ... incidence of this condition is rising in North America because of a resurgent popularity of exotic-wood toilet seats and frequent use of detergents that contain highly irritant/sensitizing compounds such as quaternary ammonium compounds ... detergents used in public restrooms and in hospitals are potentially more irritating to the skin than those used at home ..."
I reacted to an improperly formulated hair conditioner years ago (that was subsequently reformulated because of the number of bad reactions to it) and I cannot to this day use a product formulated with the quat behentrimonium chloride, no matter how far down an ingredient list it is on the label. I became that sensitized to it. I could not find information on it at the time and used other conditioners with it in them before I was sure it was the problem. Each time I was exposed to it my sensitivity became worse. From the MSDS on behentrimonium chloride, "Skin Contact: can cause skin irritation upon prolonged or repeated exposure."
The full version of the report above is available.