Protection factor 6, 15, 30, protection against UVB rays or broad-spectrum protection against UVA/UVB; biologically, what does this mean?
Starting by addressing the importance of using sunscreen would not be new given the extensive discussion we've had about all types of radiation and their consequences that affect our skin daily. But after all, what harms are we protecting ourselves from?
Among the radiations we are exposed to, UVB is partially absorbed by the atmosphere but causes damage and burns to the outermost layer of the skin. UVA, on the other hand, is more constant throughout the year but can reach the deeper layers of the skin, causing damage to the dermis and even inducing melanomas. Thus, different wavelengths of UV rays can cause various damages to DNA, including mutations that contribute to the development of skin cancer. Therefore, the use of sunscreen is currently the main defense against the harmful effects of UV radiation. But how is the efficiency of this protection measured?
Specific parameters, such as SPF and PPD, are used by scientists to measure the level of protection against UVA and UVB rays. The sun protection factor (SPF) indicates how many times the time of sun exposure can be increased without the risk of developing erythema (reddening of the skin caused by vasodilation and inflammation resulting from sunburn after applying 2mg/cm2 of product). Persistent skin darkening (PPD) is the reason for the UVA dose required to produce changes in the structure of melanocytes as well as in the oxidation of the melanin pigment.
But all these parameters with biological relevance reflect profound changes that can occur in the DNA of cells after being hit by UV radiation.
So why not add a molecular parameter that quantifies changes at the DNA level and complements the existing methodologies, thus bringing greater reliability regarding the effectiveness of protection?
And this was exactly the proposal made in June of this year by Schuch and collaborators in a paper published in the journal PlosOne, stemming from a scientific cooperation project between Natura and USP. The researchers demonstrated that the proposed system called DNA dosimeter is efficient both in quantifying specific DNA molecules and in providing more comprehensive molecular-level information regarding the photoprotection provided by sunscreens. Furthermore, this methodology complements the existing ones for measuring the effectiveness of a sunscreen, as until now the measurements consist of parameters related to skin responses, but not to the quantification of possible molecules related to cancer development.
But what does this innovative methodology entail?
The DNA dosimeter evaluates the biological effects of UV radiation based on the induction of lesions in the DNA molecule. The protection factor for DNA (DNA-SPF) was calculated using specific DNA repair enzymes, and the induction of oxidative damage and the generation of photoproducts in DNA were also measured.
The results suggest that the tested sunscreens are more efficient in protecting against the generation of DNA photoproducts than against oxidative damage, although this still accounts for a significant portion of the total damage caused by solar radiation. Thus, the DNA dosimeter is capable of providing information about gene damage induced by solar radiation, which can assist in the development of more efficient photoprotective products.
These new discoveries make us think that technology allows us to expand our knowledge and improve the development of products that contribute to a healthier life. It also shows us that we can no longer detach ourselves from molecular biology and deny its potential to add new information to the complex and endless network of knowledge.
Bibliographic Reference
Schuch AP, Lago JC, Yagura T, Menck CF. DNA dosimetry assessment for sunscreen genotoxic photoprotection. PLoS One. 2012;7(6):e40344. Epub 2012 Jun 29.
Teaser: New technology to directly detect the damage caused to the DNA of our cells can assist in the development of more efficient sunscreens.
