Inner Workings of Sunscreen

In a nutshell, sunscreens absorb, reflect, or scatter the sun's rays on the skin. The higher the SPF (sun protection factor), the more they can protect from sunburn- mostly caused by the UVB rays. Sunscreens come in creams, sprays, gels, lotions, sticks, and ointments. Although a higher SPF number provides better protection, it does not necessarily increase the length of time you can be exposed to the sun. If you have sensitive skin, it’s best to go with a broad-spectrum sunscreen which will protect you from both UVA and UVB radiation as well as help protect your skin from sun rashes and burn.

It’s important to use sunscreen as part of your skin protection program. However, if you want to use it most effectively, you should be sure that the sunscreen you choose is both effective and a good match to your skin type and lifestyle. To that end, this article will go deeper into the workings of sunscreens so that you can understand how they work, what impacts their effectiveness, and what the potential risks are.

Chemical and physical sunscreens/sunblocks.

Physical sunblocks act by reflecting or scattering UV radiation; Chemical sunscreens absorb UV rays. Although the two words are used interchangeably, sunblock tends to be insoluble and leave skin with a white matte look. Additionally, sunblock rubs off easily and needs to be frequently reapplied. The main ingredients in sunblock are zinc oxide and titanium dioxide.

Chemical sunscreen works by absorbing UV rays. Again this may also be referred to as sunblock, but the difference is that chemical sunscreens generally contain chemicals that are absorbed into the skin so that you don’t necessarily get the white matte look that physical sunblocks leave.

Some sunblocks act both physically and chemically. One example is bisoctrizole (Tinosorb M). Its main ingredient, titanium dioxide, is by definition considered a physical sunblock. However, because of its ability to absorb UV rays, it can also be considered a hybrid sunblock.

Physical sunblocks, in general, offer a wider range of UV protection and are overall safer than the chemical alternatives as they aren’t absorbed into the skin. The flip side of that is that they sit on top of the skin and, as mentioned, tend to leave the skin with a white matte look.

It’s best when choosing a sunblock to look very carefully at the ingredients and to read the labels thoroughly. Remember UVB rays are the ones that cause sunburn, but UVA rays are dangerous as well. It’s best to find a sunblock/sunscreen that works to counteract the effects of both types of UV rays. Here are some things to think about while choosing your sunscreen:

To What Degree will you be Protected?

Regardless of the choice you make- physical sunblock, chemical sunblock, cream, stick, etc. - what you really want is a sunblock that protects you from the harmful UV rays. While each chemical and active ingredient in a sunscreen may have its advantages, the one indicator given on every product that will let you know its effectiveness is the SPF- sun protection factor. The higher the SPF, the better the UV protection.

Is it Soluble or insoluble?

In other words, is the sunscreen absorbed into the skin (soluble) or does it remain topical (insoluble)? Soluble sunblocks by definition penetrate the skin which, as a positive side effect, tends to extend UV ray protection time. The bad news is that, depending on the sensitivity of the skin, other problems could occur like a reaction or increased acne. If the sunscreen is water soluble, however, it might be better for acne sufferers as such sunscreens tend to be low-oil. If sunscreens are insoluble, then you can think of them as physical sunscreens (see above).

Is it Toxic?

Acute toxicity of sun blocking agents isn’t a problem in the sunscreens being used nowadays. Only amino benzoic acid (PABA) has been known to cause skin irritation, and its use in skin care has been declining for years. But you can’t discount safety concerns altogether. First, there is a lack of data on the possibility of low-level skin damage over time with frequent use of sun blocking ingredients; lack of long term data is also prevalent in other skin care ingredients. One concern is with a UVB sunbock called octyl methoxycinnamate. In animal studies it has been shown to produce hormonal (estrogenic) effects. While there is no evidence that such effects occur with human usage, it’s certain that more safety research of this and other sunblocks is absolutely needed.

Does it protect from both UVA and UVB Rays?

Read labels carefully as you choose your sunscreen. Most offer a sufficiently high degree of reliable, comprehensive and safe sun protection. However, some sunscreen products protect against UVB but not UVA and vice versa. Even for those that protect against both UVA and UVB rays, they still may rub off easily or not be long lasting. Again, the best thing you can do is read labels carefully. If you are still unsure, check with your dermatologist.

In most commercial sunscreens you can find a combination of two or more sun blocking agents. In fact, some sunscreens attempt to improve the performance of their products by including special active ingredients that enhance their UV-blocking capacity. This helps to inhibit the sunscreen’s degradation and neutralizes harmful free radicals. Octocrylene, for example, is a fairly weak UV blocker. However, used in conjunction with other UV absorbers it has been shown to improve their performance.

And Finally...

Now that you understand sunscreens a bit better, it’s time to choose the best sunscreen for yourself. It can be a little difficult at first to find the best sunscreen. The next section explores that concept deeper to better equip you in your search.

It’s common knowledge that sun damage is the number one factor in skin cancer and in the aging of the skin. In fact, in the three decades from 1973 to 2003, the incidence of melanoma, the deadliest skin cancer, rose by 81 percent.
Ultraviolet rays are divided into three separate categories and have different effects upon our bodies. Those three are: UVA, UVB and UVC rays- often written as UVA, UVB, and UVC. There are varying theories about UV radiation, but most experts agree that only type UVA and UVB rays can reach the Earth and are, therefore, harmful to our skin. UVC rays, while also dangerous, cannot get through the ozone layer to the Earth.
During peak sun hours use window blinds or shades to block out direct exposure. If you can, try to arrange your workspace and sitting areas not to be too close to the windows. These areas will best serve you away from direct sunlight. As you get further away from a window, UVA rays decrease significantly. Therefore, it makes the most sense to avoid spending too much time close to the windows- especially if you have large windows.
The first step in finding and choosing the best sunscreen for you is to choose a product that blocks both UVA and UVB rays. That is, the better the sunblock, the stronger its ability to provide you with a high degree of protection against sunburn, skin aging, and skin cancer.
In the previous sections, the dangers of UV radiation exposure have been clearly explained and expounded upon. However, total avoidance of the sun can also lead to negative consequences. That is, there are health benefits to be had from exposure to sunlight.