Advances in photoprotection

Dermatology Nursing, August, 2008 by Elma D. Baron, Eugene B. Kirkland, Diana Santo Domingo

Objectives

This continuing nursing educational (CNE) activity is designed for nurses and other health care providers who care for and educate patients and their families regarding photoprotection. For those wishing to obtain CNE credit, an evaluation follows. After studying the information presented in this article, the nurse will be able to:

1. Describe the photoprotective recommendations of sun avoidance, indoor protection, and protective clothing.

2. List the photoprotective characteristics of sunscreens.

3. Discuss the chemopreventive properties of various skin care products.

In an era of increased cancer awareness and a focus on disease prevention, photoprotection has taken on new significance. Studies have linked ultraviolet radiation (UVR) to photoaging, skin cancer, immunosuppression, and exacerbation of certain photosensitive disorders. UVB (290320 nm) has almost always been at the center of attention because of its well-established role in carcinogenesis and ability to produce erythema (Verschooten, Claerhout, Van Laethem, Agostinis, & Garmyn, 2006). On unprotected skin, sunburns from UVB typically occur 4 hours post-exposure and peak within 24 hours. However, most incident sunlight is composed of UVA (320-400 nm), which is much less erythemagenic. In fact, 1,000 times more UVA is required to cause sunburn when compared with UVB (Kullavanijaya & Lim, 2005). Tanning is the more common result of UVA exposure, explaining its prominent role in the tanning industry. This lack of visible erythema can be deceptive because many of UVB's deleterious effects are shared by UVA.

Much still remains to be explored regarding the specific spectra responsible for each of UVR's damaging effects (Lim et al., 2001). Therefore, the need for broad protection against UVR deserves emphasis. Fortunately, major advancements in the realm of photoprotection have occurred over the last decade providing potential means to reduce the prevalence of UVR-related skin problems. In this review, the current methods of UV protection, along with recent progress in the field, are described.

Detection

The most feared long-term consequence of UV exposure is skin cancer formation, particularly the development of melanoma. According to the World Health Organization, the incidence of melanoma is increasing more rapidly than any other form of cancer (Provost, Landells, & Maddin, 2006). It's estimated that more than 62,000 cases of melanoma were diagnosed in 2006 with approximately 7,900 deaths (Goldberg et al., 2007). Fortunately, new technologies for early melanoma detection are now available to complement the standard clinical exam, which relies on the "ABCDE" technique (see Table 1).

Broad skin screening has a cost effectiveness similar to other cancer screenings only when done in populations with a higher than average prevalence of melanoma. The American Academy of Dermatology (AAD) identified this high-risk cohort in a recent study using the mnemonic "HARMM" (see Table 2) (Goldberg et al., 2007). Focusing screening efforts on high-risk populations may enhance the detection rates of malignant melanoma, especially when combined with new noninvasive technologies such as digital photography, dermoscopy, computerized image analysis systems, and confocal scanning laser microscopy. However, barriers to the widespread adoption of these technologies exist including a lack of knowledge and failure to effectively communicate information regarding these technologies with patients (Oliveria, Sachs, Belasco, & Halpem, 2003). Even with the availability of these novel technologies, preventive strategies remain critical in keeping melanoma incidence at a minimum.

Sun Avoidance and Indoor Protection

Avoiding UVR is an onerous task considering the high levels of indirect and unintended sun exposure. Almost 50% of UVA exposure occurs in the shade (Schaefer, Moyal, & Fourtanier, 1998). This is amplified in the presence of reflective surfaces such as snow, sand, and water (which reflect 30%-80%, 15%-30%, and <,5% of UVR respectively) (Rai & Srinivas, 2007). Since peak hours for UVR are from 10 a.m. to 4 p.m., exposure can be minimized by planning outdoor activities for the early morning or late evening (Rosen, 1999). The National Weather Service also issues a daily UV index that estimates UVR on a scale of 1 to 15. Indoor activities are encouraged for UV indices greater than 10 (Young & Sands, 1998).

Americans spend an average of 80% of their day indoors. Because clear glass transmits 72% of UVR (most of which is UVA), exposure can occur while indoors or even while driving. The use of reflective, tinted, or laminated panes helps reduce UVR transmission. More recently, glass with a very thin and almost invisible surface layer was developed, which blocks approximately 98% of UVR (Tuchinda, Srivannaboon, & Lim, 2006).

Protective Clothing

Clothing is an easy and effective way of keeping safe in the sun. The protective value of clothing is measured in vitro by the UV protection factor (UPF), which conveys a fabric's ability to prevent the transmission of UV light. Unlike the sun-protection factor (SPF) afforded by sunscreens, which mainly represents protection against UVB, the UPF supposedly represents protection against both UVA and UVB (Edlich et al., 2004). UPF is influenced by qualifies such as fabric type, color, thickness/tightness of the weave, and method in which the material is worn (Rai & Srinivas, 2007; Rosen, 1999). Denim, for example, has a UPF of 1,700 compared to cotton which has a UPF of 5 to 9. Typically, the UPF is higher for materials that are darker in color and those that have undergone fabric shrinkage after having been laundered (Kullavanijaya & Lim, 2005). However, color alone is not an accurate way of judging protection because UPF relies on factors such as dye type and concentration (Hatch &