Published on Aug 22, 2012 with 0 comment
The use of sunscreens has become a routine part of our daily lives due to our recognition of the dangers associated with prolonged sun exposure. These dangers include the cosmetic disfigurement associated with sun-damaged skin and the obvious risk of skin cancers.Years ago, sunscreens were used only when there was anticipated exposure to direct sunlight over long periods of time, such as going to the beach. Today, sunscreens are used daily by some and are often found in combination with cosmetics and other skin products.This exposure to the chemicals in sunscreens has led to an increasing frequency of allergic skin reactions. Most of these allergic reactions result in the skin inflammation of contact dermatitis.
Contact dermatitis is a red, itchy, and sometimes blistering skin rash typically caused by the direct contact to the skin by a sensitizing chemical present in the sunscreen preparation. There are two types of contact dermatitis, irritant and allergic. This difference is often difficult to tell apart, but it is irrelevant, as the treatment is often the same.
Contact dermatitis results in 5.7 million doctor visits each year in the United States, and all ages are affected. Females are slightly more commonly affected than males, and teenagers and middle-aged adults seems to be the most commonly affected age groups.Many of these physician visits are the result of the use of sunscreens.
Sunscreens work in one of two ways. Firstly, they act as chemical absorbers. Most sunscreens absorb ultraviolvet (UV) radiation (the energy from the rays of the sun) and turn this energy into a less dangerous form of radiation that causes less damage to the skin. There are sunscreens that absorb different types of UV radiation, such as UVA and UVB. Chemical absorbers include most of the available sunscreens that can be rubbed completely into the skin.
Secondly, sunscreens can act as physical blockers. These sunscreens reflect the sun’s radiation away from the skin, so that the radiation is not absorbed. Physical blockers include zinc oxide, the brightly colored sunscreens frequently used on the nose and lips of beach goers.
While contact dermatitis to sunscreens is not as common as skin allergy caused by cosmetics, it is not a rare condition. The reaction to sunscreens can occur anywhere the substance is applied on the body, although it tends to be more common on the areas of the body with the most exposure to the sun. This is called “photo-contact dermatitis”. Photo-contact dermatitis usually occurs in a sun-exposed pattern on the body. These areas would include the face (but not the eyelids), the “V” area of the upper chest and lower neck, and the backs of the hands and the forearms.
Those most at-risk for developing sunscreen allergy include the following groups: women, possibly as a result of higher use of cosmetics containing sunscreens; those with chronic sun-related skin conditions, such as sun-damaged skin; individuals with eczema or atopic dermatitis; people who have applied sunscreens to damaged skin; and those with outdoor occupations.
There are many active ingredients are present in sunscreens that cause contact dermatitis. Some of these chemicals cause more problems than the others. Many sunscreens have multiple active ingredients, so it may be difficult to determine the exact cause without testing for the individual chemicals. Common active ingredients in sunscreens reported to cause contact dermatitis include Para-Aminobenzoic Acid, Benzophenones, and Cinnamates, among others.
Para-Aminobenzoic Acid (PABA) was one of the earliest ingredients used in sunscreens. It is used less frequently now due to the many side effects of this chemical including contact dermatitis, and its tendency to stain clothing. A number of chemicals related to PABA still used today, including padimate A and O. Many sunscreens are falsely labeled “hypo-allergenic” since they do not contain PABA, but can still cause contact dermatitis from other active ingredients. Those with PABA allergy may be allergic to other similar chemicals, including para-phenylenediamine (found in hair dye) and sulfonamide (sulfa) medications.
Benzophenones have been used in sunscreens for 50 years and are one of the most common causes of sunscreen-induced contact dermatitis in the United States. Other names for benzophenones include oxybenzone, Eusolex 4360, methanone, Uvinal M40, diphenylketone and any other chemical name ending with “-benzophenone”.
Cinnamates are less commonly found in sunscreens but are a common ingredient used as flavorings and fragrances in everything from toothpaste to perfumes. These chemicals are related to Balsam of Peru, cinnamon oils and cinnamic acid and aldehyde, so people allergic to cinnamates may also be allergic to these other chemicals. Other names of cinnamate containing chemicals include Parsol MCX and any chemical ending with “–cinnamate.”
Patch testing is the best way of identifying the cause of contact dermatitis. This test is commonly performed by allergists and dermatologists.
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