Ultraviolet Radiation From the Sun
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The Issue
The earth's ozone layer is not as thick as it used to be and more ultraviolet radiation from the sun is reaching the Earth. Overexposure to ultraviolet radiation, often referred to as “UV rays,” can cause skin cancer and other serious health effects.
Fortunately, there are simple guidelines you can follow to protect against damage from the sun's harmful rays.
Background
Ultraviolet radiation (UV) is a type of invisible light emitted by the sun and by certain kinds of lamps.
The earth's ozone layer protects people from the sun's harmful rays. However, over time, the release of certain chemicals into the environment has damaged the ozone layer.
Many countries around the world, including Canada, have recognized this problem and have taken steps to protect the ozone layer from further damage. Efforts have focused mainly on controlling the production and use of chemicals known to damage the ozone layer.
When grouped together, these chemicals are called ODCs, which stands for “ozone-depleting chemicals.” These types of chemicals are used mainly in refrigeration and air-conditioning.
Health Effects of UV Radiation
Overexposure to UV radiation is the main cause of skin cancer. UV rays can trigger the development of skin cancer by creating changes in the cells of the skin. In some cases, the UV rays cause direct damage to the cells. Tans and sunburns, for example, are both signs that UV rays have damaged the skin. In other cases, UV rays can cause skin cancer indirectly, by weakening the immune mechanisms in skin and the rest of the body.
Most often, skin cancer is the result of overexposure to UV rays from the sun. There are three types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. The last one can be fatal if not treated early. Many studies of skin cancer show links between malignant melanomas and an individual's intolerance to sun exposure. The studies indicate that people who have suffered severe and frequent sunburns during childhood are at greater risk of developing melanoma. The features most closely associated with intolerance to sun exposure include fair or freckled skin, blue eyes, and light-coloured or reddish hair.
The two other types of skin cancer tend to develop later in life on areas of skin that have been exposed repeatedly to the sun, such as the face, neck, or hands. Basal and squamous cell carcinomas progress slowly and rarely cause death because they usually do not spread to other parts of the body.
Overexposure to ultraviolet radiation has also been linked to a number of other health effects, including sunburns, cataracts, premature aging of the skin, and weakening of the immune system.
Minimizing Your Risk
There is no quick fix for the ozone layer. Once they get into the environment, ozone-depleting chemicals disintegrate very slowly, so they are likely to be with us for a long time. While governments around the world deal with the source of the problem, it is important to take steps to avoid overexposure to ultraviolet radiation.
These guidelines will help you protect your family from the sun's harmful rays:
- Seek shade if you are taking part in outdoor activities when the UV index is three or higher. (See the Need More Info? section at the end of the article for a link to more on the UV index.)
- Cover up. Wear long-sleeved shirts, long pants, gloves, and a broad-brimmed hat or visor. Avoid see-through clothing when possible.
- Avoid sunbathing for the purpose of tanning, especially between 11:00 a.m. and 4:00 p.m. in the summer when the sun's rays are strongest.
- Use sunscreen lotion and reapply it often, as directed on the label. Look for a “broad spectrum” sunscreen with a sun protection factor (SPF) of at least 15.
- Wear sunglasses that screen out ultraviolet radiation. Your eyes have no built-in defence against the sun, and damage to the eye from UV rays can lead to cataracts.
- Do not think you are safe just because the sky is cloudy. The sun's harmful rays can get through fog, haze, and light cloud cover.
Children Need Extra Protection
Children and teenagers have more sensitive skin than adults, so they need extra protection if they are going to be out in the sun for a long time. Sunburn may increase the risk of skin cancer later in life, so it is best to get children used to wearing protective clothing and sunscreen lotion from the start.
At the very least, young children should wear a sunhat, T-shirt, and shorts. When you put sunscreen on children, pay special attention to the parts that are most exposed, including their ears, face, neck, shoulders and back, knees, and the tops of their feet. Avoid using sunscreen on babies. Cover them and keep them in the shade instead.
It is important to protect against ultraviolet radiation all year round; not just in the summer. You can continue to enjoy outdoor activities, as long as you take steps to protect yourself when the UV index is three or higher to avoid sunburns and overexposure.
The Government of Canada's Role
In 1987, Canada was one of 24 nations to sign the Montreal Protocol on Substances that Deplete the Ozone Layer. This was the first international agreement to limit the use of ozone-depleting chemicals. Since that time, more than 70 countries have signed the Montreal Protocol.
On the domestic front, Canada has phased-out the production of all ozone-depleting chemicals, and has taken steps to control the use of ODCs through regulations that are part of the Canadian Environmental Protection Act (CEPA).
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 also promotes public awareness about sun safety and the harmful effects of UV radiation.
Need More Info?
Contact:
Consumer and Clinical Radiation Protection Bureau
Health Canada
775 Brookfield Road
Ottawa, ON K1A 1C1
Telephone: 613-954-6699
Email: ccrpb-pcrpcc@hc-sc.gc.ca
Or visit the following Web sites:
You can also call toll free at 1-866-225-0709 or TTY at 1-800-267-1245*
Updated: August 2006
Original: October 2001
©Her Majesty the Queen in Right of Canada,
represented by the Minister of Health, 2004
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