In our last article, we discussed the different types of UV radiation, and talked about their effects on your skin. With that knowledge in hand, it is now time to discuss protection from the sun's harmful rays. In may seem like a simple thing, but when you begin to look closer, choosing the right sun protection can be quite difficult.

Protecting yourself from all of the sun's damaging effects is important, but it isn't just sunburn from UVB rays, or long-term damage from UVA, that you have to worry about. In almost every product there is at least one ingredient that is unstable, ineffective, or downright dangerous.  There used to be some concern that the use of certain UV filers led to an increase in melanoma. This is still a somewhat controversial issue, but it appears to have been debunked.

However, there is plenty of evidence that numerous chemical UV filters have the potential to increase cancer-causing free radicals.  Others may have possible estrogenic and other adverse effects, and another is actually systemically absorbed and excreted in urine at a much higher rate than any other sunscreen filter.

The topic of sun protection could (and actually has been) covered in an entire book. We will do our best to cover everything here.

First let's cover the wrong way to do it. Although there is some controversy surrounding the issue, studies have shown that some chemical products actually promote free radical production, thus causing more damage than they prevent! In brief "photo-unstable sunscreens may damage your skin."

The Wrong Way to Protect Against UV
The topic of how not to protect against UV damage could actually be quite a lengthy one. For the purpose of this article we will just discuss some of the more damaging effects of sunscreens. In particular the chemical sunscreens that we buy in the stores can have adverse effects to the skin.

Simply applying a sunscreen with ingredients like avobenzone, bemotrizinol, or benzophenone-3 (Oxybenzone) isn't enough. In fact, when used by themselves, some studies show that they do as much harm as good. There are a number of problems with using a commercials sunscreen alone. These include:

Not all ingredients are created equal: It is important to be aware that not all ingredients are created equal. Some UV blockers work better than others, some are more stable and last longer, and each protects against only a certain range of UV wavelengths.
Some ingredients cause harm: There are ingredients that are easily absorbed by the skin, and can cause damage. Oxybenzone for example, which is a very common ingredient in commercial sunscreens, has been shown to promote the production of free radicals.
Some stabilizers cause damage: With ingredients that degrade, stabilizers are often used to make them last longer. This can lead to other problems. For example, in a sunscreen that uses avobenzone as a UV blocker, it may have octocrylene as a stabilizer. This increases the risk of irritation and adds to the low-level toxicity of the product.
Constant chemical use on the skin has shown negative effects: Some studies have shown that the repeated use of chemical UV blockers can have negative effects; especially in those that promote free radical production.
Micronized Ingredients are being found to cause problems. With physical UV blocks (the ones that look white on your skin) some companies have created micronized version of these products to make them more cosmetically elegant. Studies are showing that the micronized particles of zinc or titanium can actually be absorbed by the skin, and cause further problems.
With that in mind, it begins to become apparent that simply lathering up with chemical sunscreens each time you go out in the sun isn't enough. To protect yourself, the right way, requires some special considerations.

The Right Way: Protection Against UVA, UVB, and Antioxidant Protection
To ensure that you have the best protection actually requires choosing the right product for the job. How much time will you be spending in the sun? Is it a cloudy day, or will you be out in the dead-heat of the midday sun? When you begin to look at the answers to these questions you can begin to choose the right product(s) to protect yourself. You also need to consider photo-stability of ingredients, the cosmetic elegance of the product, and whether to choose physical or chemical blockers. You also need to ensure that along with UV filters, you always have an antioxidant to reduce the production of free radicals.

Photo-stability of UV filters
The first thing to consider is the photo-stability of the ingredients. A sunscreen filter is photo-stable if it does not degrade in sunlight. Photo-unstable filters may lose their protective effect. The rate of degradation can be reduced by stabilizers. However, photo-stabilizers may increase the risk of irritation.

In practice, the most photo-unstable filter is avobenzone. Octyl methoxycinnamate is also photo-unstable but it does not degrade quite as quickly. However, the combination of avobenzone and octinoxate degrades faster than either alone (1).  Oxybenzone (benzophenone-3) is also photo-unstable.

List of Common UV filters and blockers

Chemical name: zinc oxide
UV spectrum: UVA-1 , UVA-2, UVB
type :physical
stability: stable
irritation : none
Pros: broad range protection, safe, anti-irritant
cons: white residue


Chemical name: titanium dioxide
UV spectrum: UVA-1, UVB
type: physical
stability: unstable
irritation: none
Pros: none
cons: insufficient protection against UVA-2, may generate free radicals, white residue


Chemical name: phenylbenzimidazole sulfonic acid 
UV spectrum: UVB
type: chemical
stability: stable
irritation: low
Pros: may stabilize other chemicals, water soluble in salt form
cons: No UVA protection


Chemical name: homosalate
UV spectrum: UVB
type: chemical
stability: unstable
irritation: low
Pros: none
cons: No UVA protection, Poor range of UVB protection


Chemical name: octyl methoxycinnamate (octinoxate)
UV spectrum: UVB
type: chemical
stability: unstable (partially stabilized by bemotrizinol/ Tinosorb M)
irritation: potential high risk
Pros: none
cons: risk of possible estrogenic and other adverse effects


Chemical name: octyl salicylate (octisalate)
UV spectrum: UVB
type: chemical
stability: unstable
irritation: low
Pros: none
cons: Poor range of  UVB  protection


Chemical name: octocrylene
UV spectrum: UVB, UVA-2
type: chemical
stability: very stable,sStabilizes other UV filters
irritation: low
Pros: very stable, stabilizes other UV filters
cons: weak, cannot be used alone


Chemical name: Benzophenone-3 (Oxybenzone)
UV spectrum: UVB, UVA-2
type: chemical
stability: unstable
irritation: high risk
Pros: none
cons: weak, cannot be used alone, promotes generation of free radicals, systemically absorbed and excreted in urine at a much higher rate than other sunscreen filters.

Chemical name: Avobenzone ( butyl methoxydibenzoylmethane, Parsol 1789, Eusolex 9020, Escalol 51)
UV spectrum: UVA-1, UVA-2
type: chemical
stability: unstable (Octocrylene, increases stability. Zinc oxide and titanium dioxide reduce stability)
irritation: low
Pros: Full UVA protection
cons: loses effectiveness over time,             may produce low-level toxicity with long-term use

Chemical name: 4-Methylbenzylidene camphor , 4-MBC, 3-(4-Methylbenzylidene) bornan-2-one , 3-(4-Methylbenzylidene)-dl-camphor
UV spectrum: UVB
type: chemical
stability: unstable
irritation: potential high risk
Pros: Stabilizes Avobenzone
cons:risk of possible estrogenic and other adverse effects, not approved in the USA


Chemical name: Ecamsule/terephthalylidene dicamphor sulfonic acid  (Mexoryl SX and XL)
UV spectrum: UVA-1, UVA-2
type: chemical
stability: stable
irritation: low
Pros: Ecamsule is acidic, the alkaline base used for neutralizing may cause irritation for some people.
cons: Full UVA protection, photo-stable, expensive -patented by L'Oreal


Chemical name: Bisoctrizole/methylene bis-benzotriazolyl tetramethylbutylphenol  (Tinosorb M, S)
UV spectrum: UVA-1, UVA-2, UVB
type: Chemical and Physical
stability: stable
irritation: low
Pros: Full UVA protection, photo-stable,pPartially stabilizes octinoxate
cons: Not approved in the USA

Anti-Oxidant Protection to Prevent Free Radical Production
Whenever you go plan to expose yourself to the sun (and even when you aren't using a sunscreen) you should be using an antioxidant. The process is known as layering, and the antioxidant always goes on first. This works to counter the free radical production that comes both from sun exposure, and from the use of chemical UV blockers.