Face Sunscreen
A face sunscreen or sun block is a cosmetic that protects delicate facial
skin from the sun's ultraviolet rays. Face sunscreens come in many
forms including lotions, sprays, creams, sticks, and gels. Sunscreens
reduce sunburn and other skin damage with the ultimate goal of lowering
the risk of skin cancer[1].
Some cosmetic lines carry specific face sunscreens.
Others create moisturizers with sunscreen to be used as part of your daily skin care regime. While the active ingredients in both facial sunscreen and sunscreens for the body are the same, some companies develop oil free formulas for oily facial skin and extra hydrating formulas for dry facial skin.
Broad spectrum sunscreens protect the skin from ultraviolet rays. UVA rays are long wave solar rays that penetrate the skin deeply. They are known to cause long term skin damage and premature or photo aging by causing DNA damage to skin cells. UVB are short wave solar rays that cause painful sun burn[2]. They are considered the leading source of basal and squamous cell carcinomas. UVB rays also significantly contribute to melanomas. It is thought that UVA rays exacerbate the carcinogenic effects of UVB rays[3].
Types of sunscreen
– There are two types of active ingredients in face sunscreens. Physical or mineral sun blocks are made from opaque materials that reflect the sun's rays. Chemical sun blocks absorb high-energy ultraviolet rays and release the energy as lower energy rays. This prevents the skin damaging rays from reaching the skin[4].
Application - Most recently, the National Institute of Health suggests applying sunscreen 10 to 15 minutes after going into the sun twice a week to allow the skin to properly synthesize Vitamin D[5]. Sunscreen application is advised after 10 to 15 minutes of sun exposure without sunscreen.
Further reapplication is necessary after swimming, sweating, rubbing, etc. No matter the activity, to remain effective, sunscreen must be reapplied within two hours. Not reapplying can cause even more damage due to extra free radicals absorbed into the skin from the sunscreen chemicals[6].
Sun protection factor (SPF)
– SPF is the laboratory test of the effectiveness of a sunscreen against UVB rays, the ultraviolet radiation that cause sunburn. The higher the SPF rating, the better the protection against UVB rays.
SPF basically compares the time a person can be exposed to sun with out burning while wearing sunscreen to the time it takes that person to burn without sunscreen. For example, if a normal person burns within 12 minutes of sun exposure without wearing a sunscreen, if they apply a sunscreen with a SPF of 10, they would only expect to burn after 2 hours (120 minutes) of sun exposure[7].
In reality, however, other factors also determine the level of protection achieved through use of an SPF rated sunscreen, including the:
- Skin type of the user
- Amount applied and frequency of reapplication
- Activities engaged in while wearing sunscreen (i. e. swimming, exercise, sweating, etc. )
- Amount of sunscreen the skin has absorbed during exposure[8].
SPF is an imperfect measure of sun protection as it only measures UVB protection and not UVA protection[9]. Current laws in the US do not require manufacturers to label sunscreens for UVA protection. Products labeled as broad spectrum UVA and UVB protection do not always provide good UVA protection at all. While not many UVA blocking ingredients are approved for use in the U. S. , zinc oxide, avobenzone and mexoryl are considered the best protection. Titanium dioxide may provide good UVA protection but it has not been proven to completely protect again the entire UVA spectrum[10]. UVA do not cause immediate damage like sunburn, however, are responsible for premature skin aging and penetrate the skin more deeply than UVB.
Worldwide, there are several systems to measure UVA protection including
Persistent Pigment Darkening (PPD), Immediate Pigment Darkening (IPD),
Boots Star System, and the Japanese PA system[11].
In 1999 the FDA passed legislation against SPF 30+ sunscreens. Because SPF over 30 does not provide significantly more protection than a product with SPF 30, this labeling discourages companies from making unrealistic claims such asall day protection[12],[13]. "Similar legislation is also in effect in Australia.
Adverse Risks of Sunscreens
– A study published in April 1992 reported the greatest increase in melanomas has occurred in regions where sunscreen is actually used most[14]. More recently, it has been shown in animal studies that while the use of sunscreen prevents sunburn, it does not protect the skin against other UV radiation effects, such as enhanced melanoma growth[15].
Other research shows that many face sunscreens are not as effective as consumers have been led to believe.
And here's why:
When UVA and UVB rays hit the skin, the skin produces free radicals known as reactive oxygen species (ROS). ROS can cause skin cancer and premature aging.
The active ingredients in chemical sunscreens are small enough to be absorbed through the skin's pores. Because these sunscreen ingredients absorb into the skin instead of staying on the surface of the skin, the skin is left vulnerable to the sun's damaging rays.
Worse, once absorbed into the skin, the sunscreen molecules become excited by UV energy due to the skin's exposure to the sun. These sunscreen molecules become reactive, generating ROS. ROS have the potential to attach to cell DNA and cause cellular mutations.
Unfortunately, the skin is more capable of repairing itself from sun damage than from these excited sunscreen molecules that generate free radicals. This is why the safety and efficacy of sunscreens have been called into question by many scientists. It appears that sunscreens can be more damaging to skin in the long term than sun exposure itself[16].
Because chemical sunscreens are absorbed into the skin and have the ability to cause potentially more damage than not using sunscreen, chemical sunscreens must be applied often.
Frequent application replenishes the sunscreen filters on top of the skin and reduces the amount of UV penetration to lower layers of the skin. Scientists suggest using face sunscreens that do not absorb into the skin and pairing them with antioxidants that have the ability to neutralize damaging ROS[17]. Sun blocks that contain opaque mineral ingredients such as titanium dioxide and zinc oxide do not penetrate the skin like their chemical sunscreen counterparts.
Chemical sunscreens have also been shown to disrupt hormones and affect the development of brain (specifically the hypothalamus, pituitary, and genital systems) and reproductive organs in lab rats.
Studies have shown that certain chemical sunscreens, including benzophenone, homosalate, and octyl methoxycinnamate are possible xenoestrogens[18].
Zinc oxide and titanium dioxide, both mineral sun blocks, appear to be the best choices for face sunscreen ingredients because they do not absorb into the skin.
While overexposure to the sun has undesirable health effects, sun is a necessary part of hormonal and metabolic functions. A lack of vitamin D has recently been linked to overuse of sunscreen. The body produces Vitamin D in the skin when 7-dehydrocholesterol reacts with UVB light. Under normal conditions, there is sufficient 7-dehydrocholesterol in the skin to meet the body's Vitamin D requirements[19].
Sunscreen can reduce the amount of UVB penetrating the skin and potentially inhibits the synthesis of Vitamin D. A product containing SPF 8 inhibits 95% of Vitamin D synthesis in the skin[20]. By getting 15 minutes per day of direct sun exposure without sunscreen, a person can optimally produce Vitamin D[21], which is needed for bone health, reduced risk of breast and ovarian cancers, colon[22], and prostate cancers[23].
