Dr. Jacqueline Gerhart: Sunburn is Dangerous
Madison, Wisconsin - UW Health Family Medicine physician Jacqueline Gerhart writes a column that appears weekly on madison.com and in the Wisconsin State Journal. Columns are re-published here with permission.
Dear Dr. Gerhart: I get sunburned multiple times each summer and everyone says I'm at risk for skin cancer. Is the occasional sunburn really that dangerous?
Dear Reader: While it is fun to enjoy outdoor activities and get a tan, frequent mild sunburns can increase your risk for skin cancer.
Sunburn is caused by exposure to ultraviolet (UV) light. We cannot see UV light, but it is a strong form of radiation that can penetrate deep into all skin types and cause harm. Mild sunburns often cause redness and pain, but may not cause skin peeling. However, just because your skin doesn't peel off or blister doesn’t mean that the sunburn is benign.
DNA in our skin cells can become permanently damaged from exposure to UV radiation. When the sun is out, intense UV light can directly cause chemical and structural changes to our DNA. While most DNA damage (more than 99.9 percent) is fixed by our body's natural response to UV exposure, the occasional change goes unnoticed.
An unrepaired DNA defect, called a mutation, is permanent and dangerous. If the mutation occurs in a gene that is important for a cell's life cycle, the mutation might make the cell grow abnormally – and lead to cancer.
So, the more frequently you get sunburned, the more likely you are to permanently damage DNA in your skin and develop cancer. In fact, you're twice as likely to get melanoma (a serious form of skin cancer) if you have had five or more sunburns in your life. Also, getting one bad sunburn during childhood or adolescence doubles your risk of developing melanoma. Once the sunburn has occurred, there isn’t much you can do to "remove" the cellular damage that was created during the sun exposure.
So how do you avoid the harmful effects of UV light?
- Shade your body, especially between 10am and 4pm when sunlight is strongest.
- Try planning outdoor activities in the early morning or evening.
- Avoid other sources of UV light like tanning beds.
- Use these principles on cloudy days - as much as 90 percent of UV light can pass through clouds, so it is still possible to get burned!
If you must spend time outdoors during the day, use sunblock or sunscreen. These lotions reflect light away from your skin and absorb UV radiation before it reaches your cells. Choose a "broad-spectrum" sunscreen that protects against both UVA and UVB light. Thirty minutes before you go outside, generously apply sunscreen to your entire body, and reapply sunscreen every two hours. If you are swimming or perspiring, reapply more frequently. Remember, being in the sun is not all bad. We actually recommend moderate amounts of sunlight – about 20 minutes per day – for absorption of vitamin D. Just be sure that you take the proper precautions to prevent yourself from burning.
Thank you to Bob Freidel from UW-Madison for his assistance with this column.
Enjoy the final days of summer!
This column provides general health information and is not specific advice intended for any particular individual(s). It is not a professional medical opinion or a diagnosis. Always consult your personal health care provider about your concerns. No ongoing relationship of any sort (including but not limited to any form of professional relationship) is implied or offered by Dr. Gerhart to people submitting questions.
Date Published: 09/04/2013