My four-year-old daughter is fair-skinned with several moles whose growth is being monitored by a dermatologist. She plays outside a lot and goes swimming in an outdoor pool at least once a week. I have lately received conflicting advice concerning the necessary SPF of sunscreens she should be using: While I have always understood that, at least for the pool, she should be using a high factor (SPF-45), I now heard that the factor itself is not important and I could use SPF-15. I understand that the higher factor might be harmful as it has more chemicals (my daughter suffers from occasional eczema). What is the current thought on the subject? The lower SPF sunscreens are considerably cheaper than the outrageously priced higher factored protective creams, but are they as effective? M.Y., Jerusalem Veteran Jerusalem dermatologist Dr. Julian Schamroth replies: Sunlight is comprised of a wide spectrum of light waves, ranging from infrared light to visible light to ultraviolet (UV) light. The dangerous light waves are the UV rays, and these are divided into UV-A, UV-B and UV-C. UV-C is the strongest. Since it doesn't really penetrate the atmosphere, it is of concern only to astronauts and those climbing very high mountains. UV-B is the next strongest and causes sunburn; it is also believed to predispose to the development of skin cancer. UV-A is the mildest and causes sun tanning, although it probably also predisposes to skin cancer. The Dead Sea has a much thicker layer of atmosphere and thus filters out more UV-B and lets in more UV-A. The SPF (sun-protection factor) is simply a measure of how long you can stay exposed to the sun without burning. For example, if you have sensitive skin and begin to get red after 10 minutes in the sun, then using a cream with an SPF of 15 will allow you to go in the sun for 150 minutes (10 x 15) before you begin to get red. And an SPF of 20 will allow you 200 minutes (10 x 20) in the sun before you begin to get red. When considering what sun-blocking cream to use, one should not be guided by SPF alone. Some creams have a high SPF and will block out the "burning" rays (i.e. UV-B), but still let in the "tanning" rays (UV-A), which may be harmful. So if you want adequate protection for your daughter, make sure the product has a high SPF and also a "broad spectrum" of protection (that it blocks both UV-A and UV-B). Unfortunately, these creams tend to be expensive. A cheaper option is to use creams containing zinc oxide or titanium dioxide, which act as a physical barrier, forming an "umbrella" over the skin. But because they appear white on the skin, they are not cosmetically acceptable for daily use. The use of sun protection creams is a very controversial issue among researchers and dermatologists. Some researchers claim that although these creams prevent sunburn, they don't necessarily prevent sun-induced skin cancer. Furthermore, it is possible that people who use sun-blocking creams have a false sense of security, tend to spend more time in the sun and thus get more exposure than those who do not. In summary, try to keep your daughter out of the sun. If she happens to be outdoors a lot, then use a broad-spectrum sunblock, give her a hat and dress her in adequate clothing (one can easily burn through a light cotton shirt). Last, remember that there is no such thing as a "healthy tan." A tan is a sign of skin damage! A child with very fair skin should use a higher SPF than one with darker skin. Most of the commercially available creams are hypo-allergenic and shouldn't cause any reaction, irrespective of the SPF number. Assume that a kindergarten child is going to get two hours of sun exposure in a single morning. Then, if she applies an SPF-15 sunscreen, it would protect a child who starts getting red after 120/15 (eight minutes). This degree of protection is adequate for this amount of exposure for average skin. I am an 86-year-old retired cardiologist and I suffer from presbycusis, classified as "moderate," with hearing aids for both ears. For more than 30 years, I've used for TV a Sennheiser headphone for up to two or three hours a day. Should I avoid non-essential TV noise, such as commercials, program announcements and the like to try to prevent extra noise-induced hearing loss from deteriorating into "severe" hearing loss? I consulted a hearing specialist who said such "noise pollution" should not accelerate my presbycusis, but I am not convinced. H.E., Haifa Haya Levi, head of the Speech and Hearing Center at Hadassah University Medical Center in Jerusalem's Ein Kerem, replies: The hearing specialist was right when he said that such "noise pollution" should not accelerate the presbycusis. In general, however, the TV, a Walkman and so on should be played at normal levels and not maximum ones. Rx For Readers welcomes queries from readers about medical problems. Experts will answer those we find most interesting. Write Rx For Readers, the Jerusalem Post, POB 81, Jerusalem 91000, fax your question to Judy Siegel-Itzkovich at (02) 538-9527, or e-mail it to firstname.lastname@example.org, giving your initials, age and residence.