Sun exposure protection
Sun exposure, skin cancer, and sunscreen. What are the best ways to protect yourself from the sun?
Though some sun is good, protection from the sun is very important. The easiest form of protection is to cover your skin with the right clothing. Tight woven materials such as polyester will block the sun. Colored clothing may also absorb the radiation before it reaches the skin. Some clothing is designed to protect from the sun, but be sure to take a look at what chemicals are used to accomplish this goal. More often than not, they are optical brighteners (also, in some laundry detergents) which include stilbenes or umbelliferone. These chemicals absorb the UV rays, but the EPA indicates that these chemicals are potentially toxic and may lead to developmental or reproductive issues.
The next most popular form of protection is sunscreen. Sunscreen works by filtering out some of the rays so they can’t penetrate the skin. Sunscreens have SPF ratings which indicate how well they block UVB rays that cause sun burn. SPF 30 blocks 97% of the UVB rays and SPF 45 blocks 98%. The problem is that they don’t necessarily block the UVA rays which are also dangerous. The other problem is that the chemicals used to absorb these rays may be just as harmful as the rays themselves. Studies show that many of these chemicals, when absorbed into the skin, can disrupt hormone production and function, stimulate estrogen dependent tumors cells, and cause possible behavioral and developmental issues.
In an experiment by Hanson, et al., published in 2006, the amount of harmful reactive oxygen species (ROS which in high amounts leads to tissue destruction), was measured in untreated and in sunscreen-treated skin. In the first 20 minutes, the film of sunscreen had a protective effect, and the amount of ROS was smaller. However, after 60 minutes the amount of absorbed sunscreen was so elevated that the amount of ROS was higher in the sunscreen treated skin than in the untreated skin.
Sun block is another option. Most sun blocks contain the minerals zinc oxide or titanium dioxide and will deflect the bad rays (UVB and UVA) away from the skin. The biggest negative with most sun blocks is that they are thick and often leave a white film on the skin. Some sun blocks grind the minerals smaller into what are called nano-particles. However, nano-particles can be absorbed by the skin and into the blood stream creating some health concerns. Some companies such as Badger, Burts Bees, and Coola have sun blocks that are non nano-particles and have less whitening, which appears to be a safe option.
In the end, it appears that moderate amounts of sun are beneficial and actually healthy and avoiding sun burn is most important. The best protection is proper clothing or non nano-particle sun block. If using a sunscreen or sun block is your protection of choice, it should be applied 15-20 minutes before sun exposure and should be reapplied every 2 hours.