HEVL Exposure & Skin Cell Damage

Increasing consumer awareness regarding the dangers of excessive UVA and UVB exposure has worked in the industry’s favor by boosting demand for sun-protection products. Sun-protection products continue to be increasingly popular with consumers.

Globally, sun protection products represent the largest segment in the sun care products market. Rising concerns about exposure to ultraviolet radiation and the need to prevent skin damage are contributing to the increased demand for sun protection products with requisite SPF levels. The market for after-sun products is driven by the growing demand for products with skin care, anti-aging and relaxation properties.

The future looks bright for the Sunscreen Manufacturing industry. The industry’s performance over the next five years will be underpinned by growing per capita disposable income and heightened demand from drugstores.

Misconceptions About HEVL and Skin Damage

A persistent misconception is that visible light is safe for the skin. In reality, visible light can damage melanocytes through melanin photosensitization and singlet oxygen (O2) generation, thus decreasing cell viability, increasing membrane permeability, and causing both DNA photo-oxidation and necro-apoptotic cell death.

Although melanin can protect against cellular damage induced by UVB, exposure to visible light leads to pre-mutagenic DNA lesions (i.e., Fpg- and Endo III- sensitive modifications); these DNA lesions may be mutagenic and may cause photoaging, as well as other health problems, such as skin cancer.

When the cells were pigmented and treated with 36 or 72 J.cm2 of visible light, both cell lines exhibited substantial decreases in viability (50% for H36, 25% for M36 and 40% for M72), which clearly demonstrates that the presence of melanin increases visible light.

Irradiation of Skin with Visible Light Induces Reactive Oxygen Species and Matrix-Degrading Enzymes

  • Skin contains several chromophores for visible light and the cumulative effects of visible light could result in skin damage, which may contribute to premature skin aging.

  • Daily skin exposure to solar radiation causes cells to produce reactive oxygen species (ROS), which are a primary factor in skin damage. Although the contribution of the UV component to skin damage has been established, few studies have examined the effects of non-UV solar radiation on skin physiology.

  • Solar radiation comprises of approx. 40-45 % of visible light (400-700 nm). Irradiation of human skin equivalents with visible light induced production of ROS, proinflammatory cytokines, and matrix metalloproteinase (MMP)-1 expression. The findings suggest that other portions of the solar spectrum aside from UV, particularly visible light, may also contribute to signs of premature photoaging in skin.

How Much Sun Protection is Needed?

Are we on the way to full-spectrum protection?

  • Irradiation of skin cells with visible light, in doses comparable to 15–90 min of sunlight exposure, elicited a skin response similar to that induced by UV radiation, i.e., inflammation, ROS production, and the release of matrix-degrading enzymes.

  • Liebel et al. (2012) did not find any thymine dimer formation (DNA damage) following visible light irradiation. However, 8-oxo-guanosin formation was found by Kielbassa et al. (1997) after irradiation of Chinese hamster cells with visible light. Maximum DNA damage occurred between 400 and 450 nm. More research is needed to investigate the exact contribution of visible light to DNA damage as most of the earlier studies were carried out with mixtures of UV and visible radiation.

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