Are all sunscreens the same?
What is the difference between sunscreens?
Sunscreens vary in their content (ingredients and concentration) and therefore in their ability to protect the skin from harmful radiation (UVA and UVB rays).
Sunscreens may contain physical (inorganic) or chemical (organic) protecting agents. Physical agents that protect the skin against the widest spectrum of UVA and UVB rays are titanium dioxide and zinc oxide.
Chemical agents such as Avobenzone and Cinoxate are often included to beef up the SPF rating, but these can be unstable and form breakdown products, which can cause inflammation creating free radicals and may damage the skin. More gentle chemicals may offer greater protection on skins hyper sensitive to the sun.
Is there a difference between a sunscreen and a sunblock?
Yes. The term sunblock implies that it completely prevents harmful UVA and UVB rays from reaching the skin. There is no product that can do this and you should not choose a product just because it is labelled sunblock over one labelled sunscreen. The term sunblock is now banned by the FDA in the US.
The product’s effectiveness in protecting you from the sun depends on its ingredients and whether or not it is used as recommended, e.g. reapplication within required timeframe, and doseage. Not weather it is termed a block or a screen.
What is the difference between UVA and UVB? Are both harmful to us?
UVA rays (aging) account for 95% of our sun exposure. They cause skin aging and contribute to skin cancer. UVA rays penetrate deeply into the skin layers, damaging collagen and cells, which lead to wrinkling, hyperpigmentation and loss of elasticity.
UVB rays (burning) mostly affect the outer layer of skin. They cause sunburns and tanning that increase the risk of skin cancer and other disorders. The risk for skin cancer doubles in people who have had more than 5 sun burns, according to the Skin Cancer Foundation.
Therefore proper use of an effective sunscreen, protecting against UVA and UVB (broad spectrum) will definitely reduce the risk of developing common skin cancers such as basal cell (locally invasive), squamous cell (locally invasive and rarely spreading to the lymph nodes) and malignant melanoma which if not treated in time can rapidly spread to the lymph nodes and via the blood stream to distant parts of the body causing death.
What is the difference between the spf numbers?
SPF stands for Sun Protection Factor. It applies to UVB rays only. It is a value determined in laboratory testing that measures the protection level of a sunscreen product in relation to sun burn (UVB radiation). It does not indicate protection from cancer causing rays (UVA). There is no standard for measuring UVA protection.
It measures how much protection you are given from burning, so if you normally burn in 1 minute, applying a SPF 30 should prevent your burning for 30 minutes. Or if you normally burn in 20 minutes a SPF 30 should prevent your burning for 30 times 20 minutes, which makes it effective for 600 minutes or 10 hours. But only if it is reapplied and the recommended amount is being used.
The SPF number can be deceiving as to the protection a product provides.
The SPF is calculated based on:
1. Time of day of exposure
2. Length of exposure
3. Skin type
4. Activity while exposed
For the SPF number specifically, the higher the number the better the protection. However generally speaking a SPF of 30 gives about 97% protection and there is little to gain from higher SPF ratings. For example an SPF of 45 gives about 98% protection. 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. New Zealand follows the Australian lead.
What is the most important thing to look for when buying a sunscreen?
A broad spectrum sun screen of at least SPF 30 (see above), ideally with 7% to 10% Zinc oxide and/or Titanium dioxide. Also one that meets the demands your lifestyle. To get the most suitable sunscreen for your skin you should consult your skin care specialist. Some sunscreens now include ingredients that treat skin conditions as well as protecting from sun damage. For example niacinamide for acne and rosacea.
Key issues that drive sunscreen use are skin type, lifestyle and 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.
What are the key ingredients we should be looking for in our sunscreen and why?
We encourage patients to use physical rather than chemical sunscreens, if possible. Physical sunscreens use Titanium dioxide and / or Zinc oxide to deflect the sun’s rays and are considered safe and effective.
Generally speaking we are looking for sunscreens without many or any chemical (also called organic) agents, such as Avobenzone, Cinoxate, Ecamsule, Menthyl anthranilate, Octyl methoxycinnamate, Octyl salicylate, Oxybensone and Sulisobenzone, which are often included to beef up the SPF rating, because they can irritate and inflame some skins.
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.
How often should we reapply sunscreen?
Reapplication is usually every two hours or after swimming or perspiring heavily. The amount applied is also important. We recommend EltaMD and Results Rx sunscreens. The recommended dose with EltaMD is two tablespoons of sunscreen to the entire body about 30 minutes before sun exposure.
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 sunscreen 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. Living in New Zealand means we are likely to get the required 30 minutes of sun exposure regardless of the amount of sunblock we use.
What is your favourite sunscreen for your face and body and why?
I use a SPF 30. For my face I use Results Rx Reflect sunscreen because it’s a spray I don’t need to rub it in and its quick so I’m never tempted to leave the house without it on.
When swimming, playing tennis or golf, I use EltaMD Sport SPF 50 on my face and body because it won’t wash off in water or with perspiration.
What is the best thing we can do to prevent our skin from ageing?
About 90% of aging is due to sun exposure, so the most effective thing we can do is to protect our skin from the sun between the hours of 10am and 4pm. Essentially this means wearing a SPF30 sunscreen that is suitable for your skin, every day, even when going to the office. When outside add a hat and protective clothing. Women can add mineral makeup as this too deflects the sun’s rays. Just remember that UVA which causes aging penetrates glass and cloud.