SPF has always confused me so I decided to do some research and help us figure out what it all means. SPF is Sun Protection Factor (SPF). This is how long you can stay in the sun without getting sunburned.
There is now credible information that even when sunburn is prevented, chronic sun exposure has other more subtle, long-term effects, including premature aging of the skin, which can cause a wrinkled, leathery, spotty appearance, and certain types of skin cancer.
Consequently, there is now a general consensus among scientists, physicians, and regulators, that SPF is at best an incomplete indicator of sunscreen effectiveness, and at worst, a misleading one.
SPF mostly indicates protection against UVB rays. In the 1980s, avobenzone was added to help protect against UVA rays. UVA radiation is the type that ages skin and is even implicated in some skin cancers. An easy way to remember it is: UVA is aging and UVB causes basal cell carcinomas (skin cancers).
Exposing yourself to sunlight between the hours of 10am and 2pm is when the energy from the sun is at its strongest. Anything that tends to scatter the sunlight will reduce its energy levels, but does not completely eliminate the dangers of UV light. A cloudy day, therefore, will offer you some protection, but not enough to allow you to stay out safely all day. Many of us who love the outdoors and sports have learned this too late.
UV filters absorb and dissipate photon energy from UV radiation. An SPF 30 sunscreen, if properly applied, absorbs about 97% of the UVB photons before they get to the skin. Typically, with most sunscreens, you must reapply every 2 hours.
However, not all sunscreens are photostable, and also, as the amount of radiation increases, the sunscreen’s absorbance ability decreases. When avobenzone (a UVA inhibitor affecting deeper layers of the skin) is mixed with octinxate (the most widely used UVB absorber, affecting the surface layer of the skin) and both are exposed to UV radiation, they, and their ability to protect your skin, are destroyed.
To prevent the sunscreen from losing its absorbance ability, it needs to be photostable. The new buzz product in photostabilising is SolaStay. It works fast to help absorb and dissipate photon energy. This means you dont need as much of the active ingredients to achieve higher levels of protection. Like all medicines, you want to take the minimum effective dose.
No product will give you 100% protection from UV light from the sun. There are 2 ways to reduce the sun’s UV light using commercial products. The first method is to employ physical blocks, such as afforded by zinc oxide or titanium dioxide. These inorganic compounds are now ground down to nanometer size, which makes them invisible on the skin, eliminating the ugly, white colouring of the products. The nano particles, however, do absorb the UV light, but they can also chemically produce free radicals. There are studies which indicate that these free radicals are capable of reacting with DNA in the skin. Initial studies show that nano particles of zinc and titanium dioxide do not penetrate beyond the very surface of the skin. For all intents and purposes, we can say these products appear to be safe, but the final word is not yet in.
The many chemical sunscreens in use do absorb the energy of the UV light as mentioned above, yet they can also undergo chemical changes that produce potentially dangerous adducts (a molecule that changes shape and becomes a new chemical). For this reason, it is important to find a sunscreen with a stabiliser.
SolaStay (ethylhexyl methoxycrylene, Hallstar), the recently developed product mentioned earlier, was designed for use in skin care and sun care products, so when it is added to a sunscreen formula, SolaStay is capable of stabilising the sunscreen to prevent the production of harmful adducts. The addition of this product makes the use of chemical sunscreens considerably safer.
When UV light passes through the skin, it is very important to understand what is happening. Keep in mind that the high energy of different frequencies contained in the waves of all UV light will interact with many of the complex proteins in the skin. Proteins, made up of amino acids, will change with UVA radiation, and one of those affected is elastin, important in the appearance and condition of skin.
Adding antioxidants to sunscreens prevents these changes, such as the sagging, thin-skin appearance we get with age. Vitamin E and C are critical to the protection of our skin. The skin receives very little of the Vitamin C that we ingest orally, so it is helpful if Vitamin C intake is increased when we venture out into the sun. The addition of lutein and lycopene as supplements, along with green tea, should also prove helpful in avoiding sun damage. Keep in mind that ultimately the effect of the UV light is to damage the DNA in the skin. The body has developed repair mechanisms in response to this damage, which is why you can get pigment patches such as brown spots, to protect the skin from the sun, or in worst-case scenarios, skin cancers.
So, after all that, what are we looking for in our sunscreens?
Physical Sunscreens: Titanium Dioxide and Zinc Oxide – to potentially reflect light rather than absorb energy.
Chemical Sunscreens: (UV filter or UV absorber) to intercept and absorb energy before it gets to the DNA. They may give off heat, or re-configure molecular structures to try to contain the energy. They need a good photostabiliser to ensure they are effective, eg SolaStay.
Look for these products as absorbers:
Octinoxate (Ethylhexyl Methoxycinnamate) – a UVB and UVA absorber
Octocrylene – a UVB absorber
Avobenzone (Butyl Methoxydibenzoylmethane) – a UVA absorber
SolaStay – a Photostabiliser
Make sure sunscreens with these products have antioxidants in them or make sure you are using an antioxidant product like the following ones alongside them:
PhytoCellTech Solar Vitis (grape stem cell extract) – protects against UV damage and oxidation
Lipochroman 6 (Dimethylmethoxy chromanol) – protects cells from damage and premature aging
Preventhilia (Diaminopropionoyl Tripeptide-33) – a tetrapeptide that prevents UV radiation damage to DNA and proteins, preventing photo-aging (peptides are revolutionising skin care now)
NOW, as a small add-on, let’s also look at Vitamin D and the sun.
Dr Gregory Taylor is very concerned about using Vitamin D as an excuse not to protect yourself against the sun as he is a melanoma specialist. So read the information below and keep it in mind. Especially in the New Zealand sun, it is better to be protected than to take the risk of melanomas in our severe sunlight.
Vitamin D: people often ask about exposure to the sun and Vitamin D. In the summer, UVB rays form a reaction in skin cells that produces vitamin D. A fair-skinned person, exposed to midday sun for 10 minutes, with enough exposed skin (say in a swimsuit), will get enough UV radiation to produce about 10,000 international units of the vitamin. If you have a darker-skin type, this 10 minutes will not be quite enough to supply your needs for Vitamin D. In general, the recommendation of 2000 international units per day in the wintertime would be an effective dose. However, UVB rays cannot fully penetrate the atmosphere in the winter, due to the low angle of the winter sun.
Vitamin D is known to protect individuals against breast cancer, prostate and colon cancer, osteoporosis and depression. There is also evidence that adequate doses of vitamin D may be protective against heart disease. NOTE: 10 Minutes of sun! Personally, I would be very careful about sun exposure for vitamin D – I prefer to take supplements. Also to note, this information is taken from an American article, which is not taking into account the severe New Zealand ozone problem.
I hope this helps to answer some of the questions you may have about sunscreens. I wrote this article because I was becoming confused by all the information I have been seeing about sunscreens, and I wanted to understand these products and how they work better. As I learn and begin to understand more I will write adjuncts to this blog post. If you have any questions, just let me know and I will research and write more on the topic to help our understanding.
NOTE: There are new FDA regulations for sunscreens and a lot of current sunscreens are not up to scratch at this time. So, looking into the products contained in the sunscreens you buy is even more important now.