Excessive exposure to ultraviolet (UV) radiation is associated with sunburn, photoaging, and skin cancer. Sunscreens are widely used to reduce these risks, but questions remain about their effectiveness and safety. The FDA has issued a proposed rule that would require manufacturers to perform additional safety studies for some sunscreen active ingredients and would mandate better UVA protection in sunscreen products. Some sunscreen products containing FDA-approved active ingredients are listed in Table 2.

Patients who receive pretravel advice can reduce their risk for many travel-related conditions. Vaccines recommended for travelers are reviewed in a separate issue.

Use of insect repellents is strongly recommended by the Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency (EPA) to prevent infections transmitted by mosquitoes and ticks. Insect repellents applied to exposed skin should be used in conjunction with other preventive measures such as wearing pants and long-sleeved shirts, and avoiding outdoor activities during peak mosquito-biting times. Mosquitoes can transmit Zika, chikungunya, dengue, West Nile, eastern equine encephalitis, and yellow fever viruses, as well as malaria. Ticks can transmit Lyme disease, rickettsial diseases such as Rocky Mountain spotted fever, and viruses such as Powassan virus.

Excessive exposure to ultraviolet (UV) radiation is associated with sunburn, photoaging, and skin cancer. Sunscreens are widely used to reduce these risks, but some questions remain about their effectiveness and safety.

Use of insect repellents is strongly recommended by the CDC and the EPA to prevent Zika virus infection and other mosquito- and tickborne diseases. Mosquitoes can transmit chikungunya, dengue, West Nile, and yellow fever viruses, and malaria. Ticks can transmit Lyme disease and rickettsial diseases such as Rocky Mountain spotted fever.

Patients planning to travel to other countries often ask for information about prevention of diarrhea, malaria, and other travel-related conditions. Vaccines recommended for travelers based on their destination, length of stay, and planned activities were reviewed in a previous issue.

Sunscreens are widely used now, but some questions remain about their effectiveness and safety.

Sunscreens are an important component of photoprotection. A new definition of their effectiveness has been proposed, and some issues have arisen concerning their safety.

Ecamsule (terephthalylidene dicamphor sulfonic acid), the first new sunscreen agent to be approved by the FDA in 18 years, is now available in the US in a moisturizer called Anthelios SX. Ecamsule has been used in Canada and Europe for more than 10 years.

Solar ultraviolet (UV) light capable of injuring the skin is classified by wavelength into UVA I (340-400 nm), UVA II (320-340 nm) and UVB (290-320 nm). UVB is responsible for most of the erythema of sunburn. UVA has been implicated in the development of phototoxicity and photoaging. The FDA permits sunscreen manufacturers to claim broad-spectrum protection if their products block at least part of UVA II in addition to UVB.

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Several new treatments are now available for actinic keratoses (AKs), scaly pink papules commonly found on sun-exposed areas of the face, scalp, forearms and dorsal surface of the hands, particularly in the elderly. Some AKs regress spontaneously, but a few may progress to squamous cell carcinoma; the risk of progression has been estimated to be about 0.25% to 1% per year (EWB Jeffes III and EH Tang, Am J Clin Dermatol 2000; 1:167).

Exposure to the sun can cause acute and chronic injury to the skin. Sunburn is the visible acute injury, but immunosuppression also occurs.

In 1989, Photoplex (Allergan Herbert), a combination of the dibenzoyl methane avobenzone (Parsol 1789) and the aminobenzoic acid (PABA) ester padimate O, was the first 'broad spectrum' sunscreen to become available in the USA (Medical Letter, 31:59, 1989). Now, Shade UVAGuard (Schering-Plough), a similar product, has been approved by the US Food and Drug Administration; it also contains avobenzone, plus the benzophenone oxybenzone and octyl methoxycinnamate.

Photoplex (Herbert), a new sunscreen formulation containing 7% padimate O and 3% Parsol 1789, is being advertised as the first and only chemical sunscreen with proven absorption throughout the UVB and UVA spectrum.

Exposure to the sun can cause acute and chronic injury to the skin. The acute injury is sunburn; the chronic effects include degenerative changes such as wrinkling and pigment alterations, and DNA damage leading to premalignant actinic keratoses, basal and squamous cell carcinoma, and possibly malignant melanoma (J Scotto and TR Fears, Cancer Invest, 5:275, 1987). Sunscreens with various active ingredients to prevent the skin are available in the USA in may diffrent vehicles and a wide range of prices (Consumer Reports, 54:370, June 1988).