Is there a difference between a sunscreen and a sunblock?
Yes. The US FDA defines the difference as substantial. The term “sunblock” implies stopping completely harmful UVA and UVB rays. A shirt or hat would classify as a sunblock. Zinc and Titanium (physical UV protection ingredients) used to be considered “blocks”, but the FDA did away with that allowed designation. Now it is not an allowed term for topical products as they perceived to only “screen” out levels of UVA/UVB radiation. Therefore, only the term “sunscreen” is permitted as a describer of how these products work.
Only by including the word “block” in the brand name of the product could it ever be used on a sun protection product in the US. In some countries (Canada for example) the word block cannot be used in conjunction with any topical sun protection products in any way.
What is the difference between the spf numbers?
SPF stands for Sun Protection Factor. It is a value determined in laboratory testing that indicates the protection level of a sun screen product regarding sun burn (UVB radiation). It does not indicate protection from cancer causing rays (UVA), and the SPF number can be deceiving as to the protection a product provides. There are several factors that contribute to causing a sun burn while being exposed to the sun to include:
- Time of day of exposure
- Length of exposure
- Skin type
- Activity while exposed
For the SPF number specifically, the higher the number the better the protection. But some people have gotten carried away with labeling super-high SPF’s for marketing purposes only. For example an SPF of 45 blocks about 97% of exposed UVB rays. An SPF of 100 would only raise this protection level to about 99%. Europe only allows an SPF of 50+ published on products sold there, and Australia only allows an SPF of 30+. The US is proposing a maximum SPF of 50 for products sold here.
What is the most important thing to look for when buying a sunscreen?
Good question. The answer will differ for many people for many reasons. We make our sun screens to address three core issues that drive sun screen use:
- Skin type
- Life style
- Geography
These three help describe the environment in which people encounter sun exposure, so sun screens built around these three provide the best protection. For example, people who enjoy outdoor sports would want to use a water proof sun screen. That same product might be thick to wear under makeup in an office environment. Also, some people have more oily skin, so having a sun screen that is oil-free is a best selection for them. Or perhaps someone lives in a very humid climate, in which case an oil-free sun screen would also make sense, assuming that their skin type is not excessively dry.
These are all indicators of how a sun screen should be selected, but the direct answer to your question is that people should purchase a sun screen that will afford them the best possible protection and that they will use. A study by P&G indicated that while 58% of women surveyed reported using a sun screen, daily usage dropped off rapidly when the sun screen being used was defined as “heavy” or “not cosmetically elegant”. Products that don’t appeal to or serve the user won’t be used at all.
How much sunscreen should we be using?
The dose recommended and used in sunscreen testing by the FDA is 0.6 mg/cm² of exposed skin; provided one assumes an “average” adult build of height 5 ft 4 in (163 cm) and weight 150 lb (68 kg) with a 32 in (82 cm) waist, that adult wearing a bathing suit covering the groin area should apply 29 g (approximately 1 oz) evenly to the uncovered body area. Considering only the face, this translates to about 1/4 to 1/3 of a teaspoon for the average adult face. Larger individuals should scale these quantities accordingly.
Coverage becomes the big issue here. Making sure of complete coverage, especially if a person in going to be out in the sun all day, or has very fair skin is far more important than measuring out 1/3 of a teaspoon of product.
Is there a danger of not getting enough vitamin D if we cover ourselves completely in sunscreen?
There was some concern about this, but recent studies that followed sun screen users for years determined that the affects of sun screen on Vitamin D product are minimal. This is largely because people don’t use enough sun screen when they apply it. Dr Lim at Henry Ford Hospital in Detroit has done some work on this as he is a spokesman for the American Academy of Dermatology. Although it only takes about 30 minutes per week of daylight exposure for the production of Vitamin D needed by the body, Dr Lim recommended eating more foods rich in Vitamin D rather than using less sun screen.
Prescription Skicnare recommends EltaMD sunscreens for their easy to wear formulas. EltaMD offers a variety of products for different lifestyles, preferences and needs, for people of all skin conditions, tones and types. Some products double as a lightweight moisturiser while others have tints to suit those who want their sunscreen to double as a foundation. There are those with added antioxidants for greater skin resilience. The common demoninator is that they are all fragrance free, paraben-free, noncomedogenic and dermatologically tested with zinc oxide.
Go to www.prescriptionskincare.co.nz/shop or pop into the clinic to find a sunscreen best suited to your skin and lifestyle.
Email info@prescriptionskincare.co.nz for more information.
