Using sunscreens on infants and children

August 2001

About 80% of lifetime sun exposure occurs before the age of 18 years. The implications of sun exposure for damaging effects upon skin, including various malignancies, are reasons for pediatricians to be familiar with the various over-the-counter (OTC) sunscreen products. This month’s column will review an important summertime topic, the appropriate use of sunscreen products.

Damaging effects of UV light

Ultraviolet light (UV) is that part of sunlight radiation composed of relatively short wavelengths (200-400 nm), which are not visible. Visible light is composed of longer wavelength radiation (400-700 nm). UV radiation includes A (320-400 nm), B (290-320 nm), and C (200-290 nm). UVA is further divided into UVA I (340-400 nm) and UVA II (320-340 nm). The shorter the wavelength of light, the greater the energy level, and the potentially more damaging to skin. UVC is blocked by the earth’s atmosphere and does not reach the surface. Less than 0.5% of sunlight reaching the earth’s surface is UVB, but is believed to be responsible for most skin damage. Considerably more UVA sunlight reaches the earth’s surface, and although of higher wavelength (and thus, less energy), UVA can still result in significant skin damage. UVB and UVA II are considered main UV causes of sunburn.

Sunlight exposure can result in numerous effects upon the skin – erythema (sunburn), photoaging (wrinkling), pigment alterations and increased risk for malignancy. Sunlight can result in obvious adverse skin effects (sunburn) or effects that are not as easily apparent (photoaging). It has been shown that suberythemal doses of sunlight (about 10% of sunlight energy necessary for sunburn) can initiate the process of skin damage. Exposure to sunlight results in damaging effects to normal skin production and maintenance processes, causing very small scars, as skin is repaired and healed. Over years of sun exposure, these scars become visible, resulting in wrinkles and aged skin (sagging, thickening or thinning), referred to as photoaging. It is thought that much of this damage results from UVA. Tanning, a process that many associate with a “healthy look,” is in reality a protective measure against the harmful effects of sunlight. Tanning results from UV radiation stimulating melanocytes in the skin to generate more melanin, which protects the skin from further damage.

The relationship between sun exposure and the development of skin malignancies is probably the most concerning effect of sun exposure to the average person and the major reason for sunscreen use. Cumulative sun exposure is an important risk factor for the development of basal cell and squamous cell carcinomas, forms of nonmelanoma skin cancer. UVB is mainly responsible for their development. While nonmelanoma skin cancers are the most common malignant neoplasm affecting adults, fortunately they have a relatively low mortality rate. Melanoma, while less common than nonmelanoma skin cancer, has a higher mortality rate, especially if not detected and treated early. Exposures to sunlight sufficient enough to cause sunburn in childhood and adolescence significantly increase the risk of some forms of melanoma. While the effects of sunscreens on the incidence of skin cancers has not been definitively proven by controlled trials, many, including the American Cancer Society and the American Academy of Pediatrics, continue to recommend their use as part of a complete sun protection plan.

Sunlight exposure can also result in photosensitivity and phototoxicity reactions when combined with certain topically applied or systemic drugs. Numerous medications have been implicated in photosensitivity reactions. Some of these medications more commonly used in children include ibuprofen, sulfa antibiotics, tetracycline antibiotics, ciprofloxacin (Cipro, Bayer, not recommended in children), griseofulvin, antihistamines and estrogen products. UVA appears mainly responsible for these effects.

The various sunscreen products available OTC include at least one of 16 active ingredients. Most OTC products contain 2 to 4 active agents. Most of these chemicals function as sunscreens by absorbing UV radiation, although at different wavelengths. Two agents, titanium dioxide and zinc oxide, function as sun blockers, and offer the widest wavelength protection of sunlight. Unfortunately, they are often cosmetically unappealing (eg, sunblock commonly applied to a lifeguard’s nose and ears). Most of the remaining 14 active agents absorb UVB and some UVA. Avobenzone absorbs the entire UVA wavelength. Table 1 lists sunscreen active ingredients and their absorbency range.

Sun protection factor (SPF)

Sun protection factor (SPF) is the identifying parameter of sunscreen products that the average consumer is probably most familiar with. A product’s SPF rating is determined under artificial conditions using a predetermined amount of sunscreen. SPF is defined at the ratio of the time necessary to produce a minimal erythema on skin covered by sunscreen to the time necessary to produce the same degree of erythema on skin not covered by sunscreen. SPF values describe protection against UVB only, and not UVA, which, as described above, can also result in significant damaging effects upon skin. While the SPF can imply the degree of protection against UV light, it is not meant to imply that using a higher SPF product allows more prolonged, safe exposure to sunlight. The amount of protection against UVB does not increase greatly with higher SPF values: SPF 15 absorbs 93% UVB, SPF 30 absorbs 96.7% UVB, and SPF 40 absorbs 97.5% UVB. In reality, other factors affect the actual SPF of an applied product, including the amount applied, wind, heat, humidity and physical activity.

Product choice and application

Numerous OTC sunscreen products are available. Similar to many other OTC products lines, choosing a specific product best for an individual can be a confusing task.

Several factors should be considered when evaluating products. While SPF is important, the degree of its importance is relative. Products with a SPF of 15-30 is generally all that is needed. Products with SPF of below 15 should not be used. New guidelines proposed by the FDA recommended that products be labeled at a maximum SPF of 30+ (ie, SPF 40 labeled as 30+). The FDA recommended this change because testing procedures to determine higher SPF rankings are not adequate. The change should prevent the implied message that one can be exposed safely to sunlight for prolonged periods when using a high SPF product.

Those with sun-sensitive dermatological conditions, receiving potentially photosensitive drugs and at higher risk for sunburn (eg, lighter skin, blonde or red hair, history of at least one serious sunburn) should use higher SPF products ( SPF 30). Those not meeting these conditions can safely use SPF 15 products. Products advertising an SPF rating of greater than 30 probably have little added benefit to most users. Wavelengths of light absorbed by the active ingredients of a product can be equally important as the SPF. Most OTC products contain at least 2 active ingredients, and these agents should absorb a wide range of UV light (ie, UVB and UVA). Products containing agents that absorb UVA should be used in those receiving potentially photosensitive drugs and those with sun-induced skin disorders.

Perhaps most important to consider when using a sunscreen is the amount of sunscreen applied, and the frequency with which it is applied. Studies have revealed that many do not apply adequate amounts, thereby decreasing effectiveness and SPF. The average adult should apply approximately 4-5 teaspoonfuls of sunscreen lotion for one application. This should be repeated at least every 1-2 hours, depending upon activity (ie, more frequent application if swimming). One study showed that the applied product’s actual SPF was reduced 50% (eg, to 7-8 with SPF 15 product) when the patient applied what was thought to be a sufficient amount. Using this amount as a guide, it is reasonable to conclude that a typical bottle of sunscreen (4-8 ounces) will be used in 5-10 applications, or perhaps 1-3 weeks.

Appropriate application also includes using the product 15-30 minutes prior to sun exposure, to allow the sunscreen sufficient time to adhere to the skin. Additional application tips to consider include use of sunscreen even on cloudy days, for 70-80% of UV radiation penetrates through clouds. All body areas exposed to the sun should be covered with sunscreen, including the feet, ears, neck and nose.

Several OTC products are marketed for children. These products, along with colorful packaging, may contain lotions that are brightly colored. While this can be conducive for allowing a child to permit application, certainly the active ingredients and SPF are most important. The use of sunscreen products in infants younger than 6 months of age is controversial. OTC sunscreen products often state they are not for use on young infants. Concerns include potential alterations in metabolism of the active ingredients that may be systemically absorbed, the relative lack of melanin in young infants and the lack of mobility of young infants (and thus, inability to move from uncomfortable heat exposures).

The American Academy of Pediatrics and the American Academy of Dermatology both recommend limiting direct sun exposure to young infants. However, they also state that small amounts of sunscreen (eg, to face and hands) can be applied when sun exposure occurs.

The numerous OTC sunscreen products are available in several different dosage forms, including lotion, gel, cream, liquid, stick, spray (lotion) and spray mist. Several products are also available as lip balms, specific for application to lips. Which dosage form to use depends upon the individual’s preference.

Most products are available as lotions or creams, as these are probably the easiest to use and apply. Some products contain alcohol, which can function as a preservative or cooling agent (ie, gives a cooling sensation when applied). Alcohol can be potentially irritating when applied, especially to minor cuts or abrasions, which children seem to frequently have. Products with alcohol should have it listed as an ingredient.

Spray mists may offer a convenient method for applying sunscreen, although the potential exists for applying an inadequate amount. One must be careful with applying spray mists near the eyes and mouth as well.

Some products are labeled as “waterproof,” or as offering “all day protection.” In proposed new regulations of sunscreen products, the FDA encourages manufacturers not to use these terms, as “waterproof” implies that reapplications of sunscreen are not necessary after swimming. The FDA has suggested that “water resistant” be used instead. The FDA has also suggested that use of the term “all day protection” be dropped, as this may imply that one application is sufficient for prolonged sun exposure.

Specific products that contain active ingredients absorbing UVB and UVA include Coppertone Kids Colorblock Purple Disappearing Sunblock Lotion (SPF 30), Coppertone Water Babies UVA/UVB Sunblock Lotion (SPF 30), Banana Boat Cool Colorz Berry Blue (SPF 30) or Water Babies Little Licks lip balm (SPF 30). These products contain ingredients absorbing UVB and partial UVA. Products containing ingredients providing the most complete UVA protection include PreSun 30 Ultra Gel (SPF 30), Neutrogena UVA/UVB Sunblock (SPF 30), and Shade UVA Guard Sunblock Lotion (SPF 30).

For more information:

• Committee on Environmental Health, American Academy of Pediatrics. Ultraviolet light: a hazard to children. Pediatrics 1999;104:328-33.
• DeSimone EM. Prevention of sun-induced skin disorders. Handbook of Nonprescription Drugs, 12th ed. American Pharmaceutical Association, Washington DC, 2000.
• Thompson L. Trying to look sunsational? FDA Consumer. 2000;34:15-21.