Skin cosmetics (Sunscreens)

Skin cosmetic is defined as materials that are applied to the skin to enhance integrity or to beautify it according to beauty standards. Many products have been developed over the years, aiming to alter the skin in ways that can help a person better fit beauty standards. The most common form of skin-related “alterations” is skin whitening, as paler skin has been thought of as more attractive than other skin tones.

The most common form of skin whitening cosmetics is sunscreens, which aim to reduce the damage UV rays bring. There are two main types of UV rays, namely UVA and UVB. UVB rays are known as the form of UV rays that cause skin cancer and sunburns. It does not penetrate the skin as much as UVA but has more energy and can cause more damage to the skin.

Skin cancer is caused by too much sun, long-term exposure, and bad sunburns. It usually occurs on parts of the body exposed to the sun, most common on the face, neck, ears, forearms and hands. There are three main types of skin cancer: Basal cell, squamous cell, and melanoma.

Sunscreen filters are the active ingredients providing protection and they can be classified into two major classes: Organic and inorganic.

Organic sunscreens absorb UV radiation like melanin and transform it into heat. They must be frequently reapplied to maintain protection from the sun. These are further divided into UVA and UVB absorbers. UVA absorbers absorb mainly in the 320-360nm range and may include benzophones, avobenzone, and anthranilates as active ingredients. UVB absorbers absorb mainly in the 290-320nm range and commonly include PABA derivatives, salicylates, and cinnamates.

Inorganic sunscreens reflect or scatter UV radiation, absorbing little energy. They act longer and need fewer applications. A common ingredient used in these sunscreens is titanium dioxide, which is also a common coloring agent in many skin products, including cleansers and sunscreens. Recently, zinc oxide is also used in the manufacturing of inorganic sunscreens. However, the zinc is in nanoparticle form that can penetrate into the skin. While it is antibacterial, it can also be toxic to plankton, and long-term effects on humans have not been proven.

The efficacy of sunscreens on humans depends largely on individual responsiveness to UV radiation, which can vary quickly. There is a standardized measure widely used, to test how quickly the skin reddens when exposed to UV ray exposure. This standardized measure is known as the minimal erythema dose, which refers to the minimum UV radiation dose that produces clear redness in the exposed site. In fact, the SPF (sun protection factor) printed on the packaging of most sunscreens is calculated by dividing the time needed to produce redness on protected skin by the time needed to produce redness on unprotected skin. The higher the SPF, the more effective the product is at preventing sunburn. It is calculated using the final product. If it takes 60 minutes to produce redness, a sunscreen with an SPF of 6 will allow the person to stay in the sun 6 times longer before getting the same sunburn.

The thickness of the sunscreen also makes a difference! FDA recommends sunscreen application of 2mg/cm2 of skin. If you only apply half the dose, you will have protection equivalent to only the square root of the SPF, which will be insufficient if you have picked a product with a specific SPF because you want the product to achieve a certain effect.

If you have a skin type that causes you to burn more easily than you tan, you will require a product with higher SPF.

Water-resistant sunscreens are recommended if you are using sunscreen for sports or when doing activities where you are likely to sweat or come into contact with water.

It is always good to put on a layer of sunscreen when you are going out, to prevent the formation of aging/dark spots brought about by damaging UV rays.

On top of sunscreen products, after-sun products are also widely used to further prevent burns and to cool the skin down, which will be explored in the next blog post!