Why are chemicals known to be able to cause contact allergy used in cosmetics?
The most potent potential allergens in cosmetics are some of the preservatives which are needed to protect the cosmetic from bacterial and fungal growth. The very good preservatives are usually good allergens. A cosmetic not properly preserved may be unsafe. UV -filters are important cosmetic ingredients in reducing sun damage to the skin. Although modern UV filters are uncommon causes of contact allergy, it does occur. Is it the fault of a cosmetic when an individual acquires and then develops an allergic contact reaction? Usually not although there have been some examples where ingredients previously considered to have a low sensitising potential have caused problems from their inclusion in particular formulations. These problems have been caused by increased skin penetration because of enhanced ‘delivery function’, because of a higher level of the substance than usual or because of cross reactions occurring with similar chemicals which may have a greater sensitising potential. There
