Sun Screen

Jun 21, 2018

By: Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy

Sheldon doesn't fetch. Well not often anyway. If it is the right piece of raw hide and it skitters on the floor the right way, he might chase it three or four times. Otherwise, Sheldon is not interested. Find a toy, a sock, a chewy-squeeky thing or whatever. Wave it in front of Sheldon to get his attention. Throw it. Say, "Sheldon Fetch!" Nothing. All I get is a blank stare and maybe a head tilt. If Sheldon could talk, I'm sure he'd say, "Why did you do that?" It turns out maybe it's me, not Sheldon. I recently met the Loucks' dog, Hazel. She was very friendly. She sniffed my butt and everything. Nolan threw one of Hazel's toys and Hazel brought it back. I threw the same toy, nothing. Just a blank stare, a head tilt and a, "Why did you do that?" look.

By this point of the year, you've seen someone who spent too much time in the sun and turned bright red. They said they didn't put on sunscreen, and you asked, "Why did you do that?" Skin damage from the sun is something you want to avoid in the summer. Too much sun can damage your skin. And that damage can add up. Sun exposure can lead to serious problems like skin cancer.

The sun emits radiation across the entire electromagnetic spectrum, from radio waves to X-rays. The part of the spectrum we are interested in for skin damage are the Ultra-violet wavelengths. There are 2 types of UV radiation we talk about with skin damage, UVA and UVB. Sun burn is most often caused by UVB. UVA & UVB can both cause premature skin aging, and skin cancer.

Sun exposure is a factor in the development of three types of skin cancer. Basal cell carcinoma is caused by the exposure to UV radiation and is the most common type of skin cancer. Basal cell carcinoma often affects fair-skinned people with blond or red hair who sun burn easily. Basal cell carcinoma is usually very easy to treat. Squamous cell carcinoma, the second most common form of skin cancer, is caused by repeated exposure to the sun over a long period of time. It can be very successfully treated if it is identified early. Malignant melanoma is a less common skin cancer. We believe sun exposure is one of its causes. If malignant melanoma is found early, it has a high cure rate. However, if it is not caught early, it can spread to the blood stream and in the worst cases, it can cause death. If sunscreen is used properly, it has been shown to reduce the number of cases of squamous cell carcinoma, and it may help reduce the risk of malignant melanoma. There is debate about how well sun screens protect against basal cell carcinoma.

Sunscreens should be applied liberally 15 minutes before sun exposure. That gives the sunscreen ingredients time to bond to the skin. Sunscreen should be reapplied at least every 2 hours while you are in the sun. Very broadly, there are 2 types of sunscreens. There are physical sunscreens which reflect off the light. They have ingredients like Zinc Oxide and Titanium Dioxide. The physical sunscreens are less likely to cause skin sensitivities. But they are thicker, less cosmetically appealing, and tend to melt off when you exert yourself. The chemical sunscreens usually have more than one ingredient in them to increase the amount of UV light they block. The chemical sunscreens bind to your skin and disappear completely from view. They are much harder to wash off, but they are more likely to cause skin sensitivities.

The Food and Drug Administration in the US started to require changes in the labeling of sunscreens in 2012. Health Canada followed suit in July 2013. Sunscreens can no longer be labeled "Sunblock", and they can't claim immediate protection upon application. The FDA thinks "sunblock" implies too much protection. If the sunscreen protects against both UVA and UVB and has an SPF of 15 or greater, it can be labelled as "Broad Spectrum". The FDA also won't allow a sunscreen to claim an SPF of greater than 50 as they feel there is no evidence that numbers above 50 have any real meaning. Sunscreens aren't to be labelled "water proof" or "sweat proof". They are only able to say they are water resistant. The label must state how long they are water resistant for. The two labeling options are water resistant for 40 minutes or water resistant for 80 minutes.

Sunscreen shouldn't be your only defense used to prevent skin cancer. Here are some practical suggestions.

  • Avoid the sun when it is most intense. This is generally between the hours of 11 am and 4 pm.
  • Seek the shade when you are outside for a long period of time
  • Wear a hat with a wide brim and long-sleeved shirt.

A few weeks ago, I was in Ste. Rose watching soccer. Eric was playing, and Emily was reffing. It was a hot, sunny day. I had a hat on to protect my bald head. But my white knees were exposed while I sat. So, my knees burnt. And it wasn't like I didn't know better. My wife and several of the other parents warned me I should put on more sunscreen. At that point I'm sure I looked like Sheldon with my head tilted to the side asking, "Why would I do that?"

As always if you have any questions or concerns about these or other products, ask your pharmacist.

The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

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Canadian Dermatology Association- Sun Screen FAQ -


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