by theglamscientist | | chemical sunscreen, physical sunscreen, sunscreen, UV radiation, UVA, UVB |
Now that we’ve discussed what SPF is and how it’s determined, we can get into a few of the ingredients that actually deliver the sun protection.
Octyl Methoxycinnamate (octinoxate) is the most common chemical sun blocking agent. It absorbs UVB rays and also has waterproofing qualities which makes it ideal for summertime fun. When exposed to the sun, Octyl Methoxycinnamate loses some of its effectiveness so it is rarely the single sun blocking ingredient found in a sunscreen formula.
Octyl Salicylate is a less effective UVB absorber. It is often used in conjunction with other blocking agents as its effectiveness decreases upon sun exposure. Although uncommon, this ingredient has been known to produce mild skin irritation. There is also concern that this ingredient is a penetration enhancer which means it may make the skin more susceptible to invasion by other topical treatments that ordinarily couldn’t pass through the skin’s natural barriers.
Oxybenzone and its close cousin Sulisobenzone are both photo stable (not affected by sunlight) chemical UVB absorbers. They are typically used to stabilize other UVB absorbers that degrade with sun exposure. These chemicals can possibly be absorbed by the skin and raise concern of free radical invasion.
Titanium Dioxide is a physical sun blocking agent that is effective in the UVB and UVA range of the light spectrum. It covers the full UVB range however it doesn’t reach the peak region of UVA. Titanium Dioxide is a common sun blocker in natural formulations. It is very efficient in preventing sunburn; however since it does not cover the entire UVA spectrum, skin cancer is still a relative concern. Most over the counter sunscreens that contain this ingredient incorporate other chemical and physical UV blockers.
Although Titanium Dioxide is stable, it has been known to cause reactions with other chemicals which again raises the possibility of free radical formation. This ingredient is unsightly as it goes on white and stays white. Titanium Dioxide nanoparticles (super small) are a more esthetically pleasing option because they leave a less noticeable white residue, but the verdict is still out on the safety of such. On a positive note, Titanium Dioxide is not known to cause skin irritation and is even safe to use on sensitive skin.
Zinc Oxide is another common physical sun blocker that is actually more effective and less reactive than Titanium Dioxide. In fact it covers the full range of UVB and UVA wavelengths which makes it the most effective single ingredient sunscreen available. Even so, it is usually used in conjunction with other chemical protectors. Zinc Oxide is not a known skin irritant and it can be used on sensitive skin. Similar to Titanium Dioxide, Zinc Oxide leaves a white residue on the skin. In nanoparticle form there is the threat of formation of free radicals, however, scientists have been successful in coating the nanoparticles to prevent such occurrences.
What’s in your favorite sunscreen?
by theglamscientist | | spf, sun care, sun protection factor, sunscreen, UV radiation, UVA, UVB |
Late last week, someone tweeted that they were about to put on their SPF 100 lotion. My immediate reaction was “Wow! Marketing at its finest!” We all know by now that sunscreen is of the utmost importance in protecting our skin from harmful sun rays. Sun damage rears its ugly head in the form of dry rough skin, wrinkles and even skin cancer. None of which any of us want. But is one SPF any better than another? Let’s explore sun protection.
What are we afraid of?
There are actually 3 forms of UV (ultraviolet) rays: UVC, UVB and UVA. UVC has the shortest wavelength of the 3 and is also the most dangerous. We don’t often hear about UVC because the ozone layer protects us from those rays. UVB appears next in the light spectrum with a longer wavelength. It is the culprit behind sunburn. Finally, UVA rays have the longest wavelength of all ultra violet light. The longer wavelength results in less damage in a given time period. In fact, the difference in rate of damage caused by UVB and UVA rays is astronomical. UVA rays are thought to cause more long term damage that may affect deeper layers of the skin. In short, we should focus on protecting our skin from both UVB and UVA rays.
I like to use metaphors to simplify science so let’s try this explanation of UV rays. Consider a day at the beach. The day could be pleasant—warm, sun shining, very relaxing… there’s a gentle breeze so any noticeable waves are few and far between. Or the day could be slightly overcast with a stronger breeze… waves are coming with significantly more frequency, but it’s not exactly a tropical storm. Then you have stormy weather, not only is it cold and wet, but the waves are beating the shore more often than not. The frequency and tenacity of the waves at the beach represent the various UV rays. The best day at the beach correlates to UVA and the worst day to UVC. Get the picture? Good!
Sunscreen agents are classified as physical protectors (UV reflecting) or chemical protectors (UV absorbing). The physical protectors work to reflect both UVB and UVA rays. Chemical protectors generally absorb UVB rays although there is some overlap in function between the two. Some UV protectors are compromised by the sun; thus, they must be used in conjunction with other ingredients to stabilize them.
So what is SPF and how is it determined?
Sun Protection Factor (SPF) refers to the level of UVB protection a product offers. Note I said UVB protection. Currently there is no test for level of UVA protection in a product. While many companies have released high SPF products ranging from 45+ to 100, this is more of a marketing strategy than a real difference in protection. It would be easy to assume that SPF 30 was twice as effective as SPF 15 and so on, however, that is not the case. In reality, SPF 15 will block around 94% of UVB rays, SPF 30 blocks 97% and SPF 45 blocks 98%. The increase in sun protection becomes more and more negligible as the SPF increases. In essence, an SPF of 100 is not as amazing as it sounds.
In order for a product to make an SPF claim, it must undergo clinical testing. In this testing, 10-20 healthy, fair skinned individuals are exposed to UVB radiation from an artificial source similar in intensity to that of the noon sun. The test measures the time it takes each participant’s skin to burn while wearing sunscreen in comparison to the time it takes the skin to burn without sunscreen. Of course, everyone’s skin is different, thus the average of this ratio is taken to determine the SPF of a given product. Keeping in mind that testing is very controlled, there are a number of factors that will determine how well a given product will protect you. Those factors include the actual intensity of natural UVB rays, your unique skin type, the amount of sun care product you apply and how often you apply it.
To sum it all up:
Everyone needs sun protection.
Don’t believe the hype, SPF 30 is Glam approved.
Use sunscreen liberally and apply it often, especially when you’re outdoors.
Here’s to the Glam Life!
