By Stephen Beck, MD - Board Certified Dermatologist
Four generations ago, our great-grandmothers knew that wearing a bonnet or covering up with long sleeve clothing was vitally important. They saw people in their communities whose noses, ears or cheeks were literally eaten away by skin cancer before the advent of good local anesthetics. It's hard to imagine that one severe sunburn before the age of 18 doubles ones lifetime risk of skin cancer but this is unfortunately true. The time from exposure to the consequences of that exposure can be 50 or 60 years
The number one cancer facing humankind is skin cancer. Caucasians and even dark skinned individuals are most at risk having shown an increasing incidence of skin cancer. There are three main reasons for this phenomenon. The first major cause of skin cancer can be traced to fair skinned Europeans colonizing areas of the world with higher ultraviolet exposure profile. Whether this is a move to areas that are closer to the equator, or areas that are higher in altitude, being fair skinned definitely predisposes one to a greater chance of skin cancer.
The second major cause of skin cancer is the increase in longevity. Modern medicine has extended the lives of our population and this coupled with many immune suppressive drugs used for arthritis and organ transplants, have led to an explosion of skin cancers. The third causes the change in habits where bronzed skin is prized and people willingly expose themselves to more ultraviolet radiation in the form of sunbathing or tanning bed exposure.
Recognition of the need to block the ultraviolet spectrum was made in the 1960's and 1970's. Late in the 1960's the first sunscreens appeared. They were crude and not very effective, however, improvements continued to be made. In the 1970's, the labeling of an SPF or sun protection factor was introduced in the United States. This was then and is still today basically only the parameter to block a very narrow band of ultraviolet radiation, which is ultraviolet-B radiation. This narrow band of ultraviolet radiation is 290 nanometers to 320 nanometers.
Unfortunately, it is not just ultraviolet-B that caused damage and the evolution of skin cancer. Early in the 1980's, using mouse studies, it was shown that ultraviolet-B range light is the initiator for most skin cancers. Less notice was taken that the same time it was discovered that ultraviolet-A or those rays between 320 nanometers and 360 nanometers are cancer promoters whereas these were initially studies performed on laboratory mice. This has been confirmed clinically by the increasing incidence of squamous cell cancer relative to basal cell cancer over the last 50 years. Numerous studies document the increased number of squamous cancers induced in patients receiving ultraviolet-A light for psoriasis (PUVA treatment).
In the 1990's Australia reported that there was a higher incidence of malignant melanoma in persons who use sunscreens when matched to persons who didn't use them. Unfortunately, this was interpreted by the popular press that sunscreens are not needed or might actually cause skin cancer.
Nothing could be farther from the truth. Many of these sunscreens contained weak ultraviolet-A blockers that are ineffective. Unfortunately there is no numbering system for UVA blockers. Evidence is mounting that the higher incidence of melanoma as well as squamous cell cancers is due to ultraviolet-A exposure.
The 1990's saw improved ultraviolet-A blocker with the introduction of a more effective blocker-Parsol. Physicians recommended Parsol to be used by their photosensitive patients, especially patients with diseases such as lupus. Unfortunately, this still was not a very good solution. It was not until the middle of the 1990's when ultramicronized zinc and titanium oxide was incorporated in many Sunscreens. Unfortunately, these products containing zinc oxide and titanium oxide are still not as cosmetically acceptable as the formulations that do not contain then. It is also more difficult and less cosmetically acceptable to produce sunscreen that is waterproof or sweat proof but this is highly desirable for people who engage in outdoor activities. This ability to withstand wash off or sweat off is known as substantively.
Australia is the melanoma and skin cancer capital of the world. This is due to the fact that it was predominately colonized by very fair Brits, Scots and Irish. Different countries have different parameters for defining sunscreen as being waterproof. The US has a rather lax standard, which is that the ultraviolet-B blocking effectiveness is tested after 30 minutes in standing water. The Australian standard is far more rigorous and sunscreens must demonstrate their ability to prevent wash off or sweat off after two hours of rapidly moving water. It is for this reason that American made sunscreens are not sold in Australia.
Our antiquated method of labeling sunscreen measured only by an SPF value is no longer in the best interest of persons who use sunscreen and lulls us into a false sense of security. The Food and Drug Administration in the United States has not yet revised this standard although the American Academy of Dermatology has urged them to do this for many years. This policy is probably not in the best interest of Americans as some more reasonable system needs to be adopted, which recognizes the detrimental effects of ultraviolet-A light as a cancer promoter.
Manufacturers of popular sunscreens without zinc or titanium dioxide are not likely to incorporate effective ultraviolet-A blockers until there is either a public outcry or a change in the standards by the Food and Drug Administration.
Chasing the highest number on your sunscreen can no longer be relied upon as a measure of safety. When possible, persons in the spring, summer and fall should avoid sun activities during the peak hours of sun exposure and those are 10am to 1pm standard time or 11am to 3pm daylight savings time. Waterproof sunscreens with an SPF of 15 or greater, containing either zinc oxide or titanium oxide should be applied liberally before the body is overheated or water exposure by at least 20 minutes so that they may bind to the skin. Persons should also wear a hat and cover as much of the body as is reasonable for the planned activity.
Skin Care Topics include age spot removal, acne remedies, skin cancer, and dry skin remedies.