In its raw form, PABA is a white crystalline powder that at a distance resembles flour, but up close clearly consists of small crystals that are more like sugar or salt. Often, PABA is found in its processed liquid form, which has a golden color and a thick texture that is similar to that of cooking oil. Although it is unusual to find PABA called by other names in the skin care industry, the ingredient can also be referred to as para-aminobenzoic acid and 4-aminobenzoic acid.
PABA first appeared in beauty products following World War II. Studies conducted during the war found that the substance had the ability to absorb ultraviolet type B (UVB) rays, which are those with wavelengths between 290 and 320 nanometers in size. At that time, researchers had already concluded that this intense energy, which is absorbed by the outer layer of the skin (the epidermis) was responsible for causing sunburns.
When applied to the skin, PABA absorbs UVB rays before they have the ability to penetrate the epidermis. This prevents the energy from producing the inflammatory reaction that results in sunburns. PABA was one of the first substances ever to be used in sunscreens; however, the very first formulas that contained the ingredient were not widely available. It wasn't until the 1960s and 1970s that PABA sunscreens became more popular throughout the world; however, other sunscreens, like those that contained zinc oxide, were still far more common.
As early as 1964, criticisms about PABA surfaced. In meetings at the annual conference of the Dermatological Association of Australia, doctors and researchers reported that the use of PABA appeared to occasionally contribute to autoimmune responses in which users' immune systems began to attack their skin, mistaking it as a foreign threat. These responses ranged from everything to allergic reactions to sudden, severe reactions that mimicked debilitating diseases like dermatomyositis.
Despite these early criticisms, the U.S. Food and Drug Administration approved PABA for use as an active ingredient in sunscreens in concentrations of up to 15 percent. Following the approval, a large number of sunscreens that contained PABA emerged on the market, and during the 1980s and 1990s, these products largely dominated as the sunscreens of choice.
One reason for the popularity of PABA sunscreens is that unlike zinc oxide, these products do not leave noticeable white marks on the complexion. This made PABA preferable for those who wanted to head outdoors and still look their best. In addition, PABA's chemical structure allows it to adhere tightly to the skin cells of the epidermis. This makes it harder for the sunscreen to be wiped away or be washed away by sweating or swimming. As a result, PABA requires less frequent reapplying than other types of sunscreens.
Although PABA still retains its FDA approval and appears in some sunscreens, most skin care companies have switched to PABA-free formulas. Part of what has caused this shift is continued research into the effects of the sun. Where once scientists cautioned only against the ill effects of exposure to UVB rays, modern day physicians also recommend protecting the skin from ultraviolet type A (UVA) rays, those with wavelengths that are 320 to 400 nanometers in length.
UVA rays pass through the epidermis and reach the middle layer of skin tissue, called the dermis. There, these intense rays cause cellular damage that leads to the aging of the skin tissue. Like UVB rays, UVA raises one's risk of developing skin cancer. Now that the dangers of UVA are more widely known, PABA is viewed as an incomplete active ingredient, as it offers no protection against this type of energy. Most doctors and skin care experts instead recommend the use of a broad-spectrum sunscreen, which blocks both UVA and UVB.
Concerns about sensitivity to PABA have also led to its drop in popularity. As was discovered in the 1960s, the ingredient does have the potential to spark mild to severe allergic reactions. Those most commonly affected by PABA allergies are those who are also sensitive to anesthetics in the "-caine" family, such as Novocaine. Also, people who have never had an allergic reaction to these topical anesthetics are at an increased risk for developing one if they have repeatedly used PABA.