Most sunblocks are good at protecting users from harmful UV A and B rays, but they can also be absorbed by the skin and enter the body, possibly causing hormonal side effects and even potentially cause skin cancer.

Scientists now have a solution for this dilemma. A team of researchers were able to make a sunscreen that doesn't penetrate the skin.

Researchers from the Yale University reported that they were able to develop a sunscreen lotion made of nanoparticles which do not sink past the epidermis or the top layer of the skin, unlike regular sunscreens. Sunscreen penetration has been thought to cause potential health problems based on previous research.

This prompted Mark Saltzman, a professor at the Yale University, to find an alternative way to make sunscreen from bioadhesive nanoparticles.

The nanoparticles do not get absorbed into the dermis because the particles used were too large to seep past the skin's top layer. This makes the chemicals remain on the epidermis, thus preventing absorption into the bloodstream.

"The idea for creating an improved sunblock came pretty quickly after we had discovered that we could make nanoparticles that were strongly adhesive to skin," Saltzman said. "We found that when we apply the sunblock to the skin, it doesn't come off, and more importantly, it doesn't penetrate any further into the skin."

The nanoparticle-made sunblock was tested against ultraviolet rays on mice models. Results showed that even though the nanoparticle sunblock had much less active ingredients compared to the regular ones, the formula was still able to protect the skin just as effectively.

And because of the fewer active ingredients and its inability to penetrate the skin, the new sunblock formula does not carry the risks of causing skin cancer and cellular damage that commercial ones do.

"Commercial chemical sunblock is protective against the direct hazards of ultraviolet damage of DNA, but might not be against the indirect ones," explained co-author Dr. Michael Girardi from Yale Medical School.

Health and safety concerns on current sunblocks still remain, but Saltzman reminded that the advantages of using these lotions still outweigh whatever negative effects they may have, including skin absorption of the chemicals. Saltzman added that their research was meant to tilt the risk-benefits ratio through reformulating sunblocks to include bioadhesive nanoparticles.

Saltzman said that, with successful human clinical trials and further testing, the new formula may become available in a few years' time.

Photo: Shawn Campbell | Flickr

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