What are fragrances and how we are exposed to them?
Fragrances are organic compounds with distinctive, and usually, pleasant smells. The use of fragrances is prevalent in perfumes and other scented cosmetics. In addition, these substances are also used in food and drinks to add flavour and to drugs because of antiseptic properties.
Fragrances are volatile compounds and thus readily become airborne so that many people are exposed to them. Contact is achieved by direct application of the product to the skin or mucous membranes, contact with contaminated products (e.g. clothing, bedding washed with scented detergent / fabric softener) and by inhalation. In this way, both internal and external body surfaces become exposed.
Which undesirable effects can fragrances cause?
Exposure to fragrances can cause a variety of reactions including contact dermatitis, urticaria (hives), photoallergy and skin discolouration (dyschromia). In Europe, it is believed that about 1-3% of the population has allergic contact dermatitis or allergic contact urticaria caused by fragrances. Women seem to be more often allergic to fragrances than men, reflecting a more frequent use of scented products among women. Perfumes and deodorants most often cause skin allergy to fragrances in women. Related products for men include after-shave and deodorant.
In addition to skin contact, inhalation of fragrances can trigger or aggravate asthma and other respiratory problems. Fragrance ingredients can be detected by sensory cells in the eye and the upper and lower respiratory tract and cause an irritation response. People with asthma, allergies, sinus problems and rhinitis are more susceptible to irritants, and often at lower concentrations than which causes problems in the general population.
As fragrances smell, it may be difficult to determine if it is the fragrance or other characteristics of the product that have negative health effects. Fragrances are shown to cause undesirable health effects although the substances themselves are considered to be harmless (conditional responses).
Allergic contact dermatitis is the most common allergic response to skin allergens and typical clinical symptoms include itching, redness (erythema), swelling (oedema) and at worst blistering. The reaction normally appears where the cosmetic product was applied, but strong reactions can also trigger reactions outside the application area. Remains of the cosmetic product can also be transferred from your fingers and cause contact dermatitis in unexpected areas such as the genitals.
Allergic contact dermatitis from fragrances often occurs on the hands, in the armpits and on the face. It may be the primary cause of hand eczema, or occur as a complication of irritative or atopic dermatitis. Reactions in the armpit are often caused by the use of deodorants. If the reaction is extreme, it can spread down the arms and to other areas of the body. Eczema of the face is often caused by perfumed skin care products and after-shave products, but wet-shaving has also been proven to give an increased risk of fragrance allergy.
Irritative contact dermatitis from fragrances is believed to be a general problem but there is a lack of studies that quantify the proportion of the population with this form of contact dermatitis. The clinical symptoms of irritative and allergic contact dermatitis are very similar, and it may therefore be difficult to distinguish between these two conditions.
Symptoms of contact urticaria include itching and localised areas of swelling and redness (wheal-and-flare) where the cosmetic product was applied but also generalised urticaria (swelling anywhere on the body) and anaphylaxis. The symptoms may appear just minutes after exposure to the allergen, and usually abate relatively quickly (within a few hours). Fragrances such as cinnamal, cinnamic acid and Myroxylon pereirae have been shown to cause non-immunological contact urticaria. Other substances that have been reported to provide the same type of response include menthol, vanillin and benzaldehyde.
Photoallergy and phototoxicity
Clinical symptoms of photoallergy are mainly eczema. The symptoms appear and disappear within 2-48 hours after application of the product. Sun-exposed areas are most commonly affected but symptoms can also spread to other areas. In the 1970s many cases of allergy were observed that were caused by musk which was subsequently banned in cosmetic products. Other fragrances that may cause photoallergy include cinnamates.
Phototoxicity (non-allergic) reactions from fragrances can occur. This can cause symptoms such as redness of the skin followed by hyperpigmentation. Furanocoumarins are plant-derived fragrances that have been shown to cause such a reaction.
Can fragrances be avoided?
Unfortunately, it is difficult for consumers to avoid fragrances. The term "fragrance-free" is misleading because it only means that no substances are added to the product in order to provide a scent. Products labelled "perfume-free" may still contain fragrance substances added for other reasons (for example to mask a smell, added as a preservative). This means that allergic people must read the ingredient list to see if the product contains substances that they react to. In the case of substances that are added to scent a product, there are currently 26 fragrances that are classified and must be listed on an ingredient list. For the other fragrances it is enough to state "perfume" or "fragrance".
Prevention of fragrance allergy may be made with respect to primary and secondary prevention. Primary prevention means to prevent people from becoming allergic to fragrances. This can be achieved by introducing regulatory measures to prohibit and / or restrict fragrance use. Further measures include replacing allergenic fragrances with other fragrances that cause fewer or no allergies, avoiding the use of fragrances in products where they are not essential, and improved labelling of products so that consumers can choose to avoid exposure to certain fragrances. Secondary prevention means to prevent allergic people from exposure to fragrances. It is therefore important to have a reliable diagnosis to identify the fragrances a patient reacts to.