In addition to the CDC, other government agencies including the National Institutes of Health (NIH) and the Environmental Protection Agency (EPA) have reiterated concern about the effect of UVA on the skin. The “MEDLINEplus Health Information” service of the U. S. National Library of Medicine and the National Institutes of Health states that
• . [s]unscreens help to prevent sunburn and reduce the harmful effects of the sun such as premature skin aging and skin cancer.
The EPA has related materials on its Web site to promote greater public awareness of the impact of UV exposure:
• Exposure to UV radiation from the sun can seriously harm human health. Mild exposure can lead to sunburn. More extended exposure to the sun may result in premature aging and discoloration of the skin and, ultimately, skin cancer. These
health effects have only been made more acute by the destruction of the ozone layer which protects the earth from the sun’s UV radiation. … The EPA and other agencies also promote awareness of the dangers of sun exposure and the safety precautions such as minimizing exposure and using sunscreen.
Given the potential health benefits of sunscreens, it is perhaps not surprising that they have been referred to as the “ultimate cosmetic” (66). It is clear that exposure to solar UV damages human skin. This can be in the form of acute over-exposure resulting in sunburn or more subtle subclinical damage. In either case, repeated exposure to solar UV manifests as photoaging and skin cancers after many years. The molecular mechanisms of skin cancers and photoaging have been studied using human and animal models. More important, use of sunscreens protects against short-term markers of UV-induced skin damage and the molecular events believed to be responsible for skin cancers and photoaging. That is, based on experimental investigations, sunscreens or UV filters reduced molecular, biochemical, and clinical events associated with skin cancer and photoaging.
An international meeting with experts from around the world concluded that sunscreens were probably of benefit in reducing squamous cell carcinoma but there was not enough evidence supportive of protection against basal cell or melanoma skin cancers (67,68). Prospective clinical studies in areas of high incidence such as Australia (69,70) and Texas (71) clearly show the benefits of regular application of sunscreens. Demonstration of such effects in these relatively short duration studies, i. e., less than five years, are if nothing else encouraging.
The formulation of sunscreen products should be focused on improving compliance rather than increasing the Protection Factor of products. It is easy for sunscreen manufacturers to get caught up in the SPF horsepower race since consumers may purchase product based on the SPF number and physicians may recommend/prescribe products thinking that sunscreens are not applied at the proper dose and, as such, a higher SPF will compensate for this underdosing. However, as with any preventive therapy, compliance is the key and making products which are applied at the proper dose and reapplied should be the goal of manufacturers.
Also, sunscreen products need to protect against the breadth of solar UV and not simply short wavelengths. Presently, consumers purchase products which infer protection against harmful rays of the sun, i. e., SPF. As discussed, this does not ensure any protection against long wavelength UVA-I. Arguably, sunscreen manufacturers should only market products which protect against the breadth of solar UV. In the U. S., the FDA could ensure all products sold meet or exceed a single criteria to achieve a “broad spectrum” label such as recommended by the AAD (40) thereby ensuring consumers are fully protected by the sunscreen products purchased.
The public health message endorsed by numerous governmental and academic groups is that of a “safe sun strategy,” which includes the daily use of a sunscreen at least SPF 15. It will be important to maintain this basic message and expand it to include sunscreen products that provide “broad spectrum” protection. This could be achieved by regulatory adoption of, and in vitro substrate spectrophotometric measure of UVA efficacy and a simple pass/fail label. As such, consumers could choose products which protect against the solar UV spectrum.
