How Do Chemical and Physical Sunscreens Work to Protect the Skin from UV?

Photoprotection is used to reduce skin damage and skin cancer caused by ultraviolet (UV) radiation. Photoprotection can be done by using sunscreen, clothing, hats, makeup, and sunglasses. The effects of UV radiation on the skin cause skin aging (photoaging) and carcinogenesis (photocarcinogenesis). Photoaging can appear as sagging skin and wrinkles, while photocarcinogenesis is caused by damage to cells and DNA.

• Types of UV Radiation and Their Effects
• Protective Factors in Photoprotection
• Advantages of Physical and Chemical Sunscreen

Types of UV Radiation and Their Effects

UV radiation has an immunosuppressive effect on antigen-presenting cells in the epidermis, which increases the likelihood of skin cancer. There are three types of UV radiation: UVC, UVB, and UVA.

• UVA is associated with aging and pigmentation. This radiation penetrates deep into the skin layers and produces free radical oxygen species that damage DNA indirectly. UVA also increases the number of inflammatory cells in the dermis.
• UVB causes sunburn and DNA strand damage, including pyrimidine dimer mutations associated with non-melanoma skin cancer.
• UVC is a type of ultraviolet radiation with the shortest wavelength (between 100–280 nm) and has the highest energy compared to UVA and UVB. However, UVC does not reach the earth's surface because it is completely absorbed by the ozone layer and the upper atmosphere.

Protective Factors in Photoprotection

Photoprotection involves two types of protective factors:

• The primary factor is sunscreen, which includes physical barriers that reflect and scatter light and chemical barriers that absorb light.
• Secondary factors include antioxidants, osmolites, and DNA repair enzymes that help limit skin damage by disrupting the photochemical cascade that occurs due to UV exposure.

The FDA regulates sunscreen as an over-the-counter drug. Currently, there are 16 registered UV filters, namely 14 organic filters and 2 inorganic filters, including zinc oxide and titanium dioxide. Chemical sunscreens are known as organic sunscreens. Their mechanism of action is based on a chemical structure involving aromatic compounds conjugated with carbonyl groups. This structure allows high-energy UV rays to be absorbed, causing the molecules to reach an excited state. When the molecules return to their ground state, energy is released in the form of heat.

Advantages of Physical and Chemical Sunscreen

Physical sunscreen works by forming a protective layer over the epidermis that is not absorbed into the skin. This is an advantage of physical sunscreen because it will not cause irritation or trigger acne on oily skin. UV rays will be reflected so that they do not enter the deeper layers of the skin.

The effectiveness of this sunscreen is faster than chemical sunscreen because it provides protection immediately when applied to the skin. Both types of sunscreen protect the skin from the sun's UV rays, the difference is how they work, either absorbed into the skin or forming a new layer. However, lately many have created a combination of the two which is called a hybrid sunscreen.

Read more:
How Sunscreen Works to Protect the Skin from Ultraviolet Rays

The way it works is the same, namely creating a UV-blocking layer while releasing UV rays that are absorbed into the skin. The results will be more optimal with minimal risk of irritation. Any type of sunscreen still has good and bad factors for the skin, back to each person's skin condition and needs.

To ensure that your cosmetic products provide effective protection against UV radiation, be sure to do a comprehensive lab test. A trusted laboratory test will help you understand how your product interacts with the skin and provides maximum protection. Don't hesitate to consult an expert to get accurate and reliable results. Protect your consumers' skin with well-tested products.

Author: Delfia
Editor: Sabilla Reza

References:

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Rai R, Srinivas CR. Photoprotection. Indian J Dermatol Venereol Leprol. 2007 Mar-Apr;73(2):73-9.

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