Sunscreens and Exposure to UV Radiation, Rays

by Health Canada

More Canadians are using sunscreens to protect themselves from the sun's harmful ultraviolet (UV) rays.

Exposure to UV radiation, primarily UVB, can cause sunburns and may eventually result in skin cancer. It is important to note that while sunscreens can help reduce sunburn, they are not as effective against the other harmful effects of UV rays, such as premature aging of the skin and depression of the immune system.

All sunscreens have a sun protection factor (SPF) on their labels. The SPF represents the length of time that sunscreen-protected skin can be exposed to UVB rays before a minimal redness (erythema) appears, compared to the length of time it takes on unprotected skin. In other words, it indicates how much longer you can be exposed to the sun before getting a sunburn.

The amount of time it takes for unprotected skin to burn depends on skin type. In general, fair skin burns more quickly than darker skin. If you have the type of skin that would burn after 20 minutes in the sun without protection, then the proper application of sunscreen with SPF 15 would allow you to spend up to 300 minutes (15 times longer) in the sun without getting a sunburn. However, this does not mean that your skin is protected from all UV effects. Damage to your skin, other than sunburning, may have already started.

The SPF varies depending on the nature of the sunblocking ingredients in the product. Since the SPF refers only to protection against UVB, it is important to choose a "broad spectrum" sunscreen that also protects you from UVA radiation.

How Sunscreens Protect Your Health

There are many different brands of sunscreen available. They are classified according to their active ingredients, as some products contain chemical filters, some contain physical filters, and some contain both.

Chemical filters absorb some of the UV radiation and convert it into heat. There are more chemical filters that absorb UVB rays than absorb UVA rays.

Physical filters are small particles (usually zinc oxide or titanium dioxide) that scatter and reflect both UVB and UVA rays.

Minimizing Your Risk

Protect your health by using a broad spectrum sunscreen with an SPF of at least 15. Look for claims on the label indicating that the product has staying power (e.g., water resistant, very water resistant, waterproof).

For best results, be sure to follow the instructions on the product label. Use the recommended amount of sunscreen and respect the waiting period between application and exposure to the sun. Reapply sunscreen 20 minutes after you go out, so that the product stabilizes on your skin and gives you maximum protection. If you are sweating heavily or swimming, reapply sunscreen frequently to get the best protection.

Here are other steps that Health Canada recommends you take to protect against UV exposure:

• If possible, avoid being in the sun between 11:00 a.m. and 4:00 p.m.
• Look for shade, stay under a tree, or use an umbrella.
• During outdoor activities, wear sunglasses to protect your eyes. When the UV index is three or higher, you should also wear protective clothing and a large-brimmed hat.
• Remember to apply sunscreen to all exposed areas of your skin.

Health Canada's Role

Health Canada regulates the safety, effectiveness, and quality of sunscreens in Canada. Sunscreen products are classified as drugs and must meet the requirements set out in Canada's Food and Drugs Act before they may be imported, advertised, or sold in this country.

Also, Health Canada and the Public Health Agency of Canada work in partnership to monitor cancer in Canada. This involves identifying trends and risk factors for cancer, developing programs to reduce cancer risks, and doing research to evaluate risks from the environment and human behaviours. As part of this work, Health Canada promotes public awareness about sun safety and the harmful effects of UV radiation.

About the Author

www.hc-sc.gc.ca
Health Canada is the Federal department responsible for helping Canadians maintain and improve their health, while respecting individual choices and circumstances.