by Susan MacVittie
Studies are showing that some of the ingredients in sun screens may have adverse affects on our health and the environment. As summer heats up it’s time to learn about the pros and cons of lathering on suntan lotion.
Ultra-Violet Rays
Exposure to solar energy, ultra-violet radiation (UV), can cause premature aging and at worst, skin cancer. Two forms of UV radiation that reach us via the sun, sun lamps, and tanning booths are UVA and UVB.
UVA, though not as powerful as UVB, penetrates deeper into the skin and is responsible for photodamage. There’s a high level of concern that UVA increases the risk of malignant melanoma, the most dangerous form of skin cancer.
UVB primarily affects the skin’s outer layers, causing your skin to darken and burn. Exposure to UVB increases the risk of basal cell carcinoma and squamous cell carcinoma, two forms of non-melanoma skin cancer.
Both UVA and UVB from sunlight accounts for 90% of the symptoms of premature skin aging, including wrinkles.
SPF
The US Food and Drug Administration (FDA) regulates a sunscreen’s ability to block out the sun’s ultra violet rays by designating a sunburn protection factor (SPF) number. SPF is a measure of how much solar energy (UV radiation) is required to produce sunburn on protected skin (i.e., in the presence of sunscreen) relative to the amount of solar energy required to produce sunburn on unprotected skin. As the SPF value increases, sunburn protection increases.
There is a popular misconception that SPF relates to time of solar exposure. This is not true because the SPF is not related to time of solar exposure but to amount of solar exposure. Although solar energy amount is related to solar exposure time, there are other factors that impact the amount of solar energy such as the intensity of the sun, skin type, amount of sunscreen applied and reapplication frequency. So using a sunscreen with a SPF 30 does not guarantee you can lie in the sun 30 times longer without burning.
Keep in mind that the SPF is for UVB rays only. There is no widely accepted comparable SPF rating for UVA sunscreens.
Vitamin D
You may have heard that exposure to the sun is the best way to get your daily dose of vitamin D. Questions about sun protection and vitamin D deficiency led the Canadian Dermatology Association to state that most Canadians get enough vitamin D in the spring, summer and fall from their exposure to the sun in their normal daily routines.
Proper Sunscreen
The only way to determine if a sunscreen protects against UVA and UVB radiation is to look at the ingredients.
There are currently 17 active ingredients approved by the US FDA for use in sunscreens. These filters fall into two broad categories: organic/chemical and inorganic/physical. Most UV filters are organic: They form a thin, protective film on the surface of the skin and absorb the UV radiation before it penetrates the skin. The inorganic sunscreens are insoluble particles that reflect UV away from the skin, such as zinc oxide or titanium oxide. Most sunscreens contain a mixture of organic and inorganic active ingredients.
Look for a sunscreen with an SPF of 15 or higher, plus some combination of the following UVA-screening ingredients: stabilized avobenzone, titanium dioxide, and zinc oxide. You may see the phrases multi spectrum, broad spectrum or UVA/UVB protection on sunscreen labels, and these all indicate that some UVA protection is provided.
Hazard or Protector?
The very ingredients in sunscreens that offer sun protection, may also have adverse side effects. Some of the chemicals used in sunscreens are feared because they are said to enter our bloodstream through ongoing topical use and may have hazardous effects once they accumulate, either in our bodies or the environment. In a disturbing investigation of 952 name-brand sunscreens, the Environmental Working Group found that 4 out of 5 sunscreen products offer inadequate protection from the sun, or contain ingredients with significant safety concerns. In a recent Australian study adverse reactions from sunscreen ingredients occurred in as many as 19% of individuals. There is also a growing awareness that sunscreen ingredients like the parabens and Benzophenone may function like human estrogens and actually disrupt the normal hormonal functioning of the body.
Others ingredients like zinc oxide and titanium dioxide, popular UVB and UVA sun blocks known for giving the skin a whitish glow, are being decreased to nanoparticles to reduce visibility on the skin. Although they have been cleared by the US FDA and US National Toxicology Program, these miniscule particles are making scientists worry, says a recent survey done at the University of Wisconsin-Madison published in Nature Nanotechnology, (November 2007). Their concern is about the tiny particle’s ability to penetrate the skin, inducing free radical formation. They agree there haven’t been enough studies to be sure of the safety of using nanotechnology in personal care products.
In Canada, although labelling is required, the nano-ingredients are not listed as such, and companies can even not list ingredients if they are “confidential business information.” Sandra Madray of Chemical Sentisitivey Manitoba says this is a less than satisfactory situation.
To assist consumers in their decision making, the Environmental Working Group has created a database of sunscreen and sunblock products. Each product is scored according to its effectiveness at blocking UVA and UVB rays, as well as the amount of ingredients that have been linked to health concerns like cancers, developmental and reproductive toxicity, allergens, persistence, and bioaccumulation. Each product ingredient is given a score between one and 10 (one being the best, 10 being the worst) in each category, as well as overall.
Sunny Side
Regardless, of the research available it is important to remember that sunscreen use should not be seen as a replacement for sun avoidance measures, but only as a tool that sometimes helps when used in conjunction with sun avoidance measures.
So cover up, go indoors during the midday, and enjoy the heat of summer in a smart way!
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Sources:
Environmental Working Group, http://breakingnews.ewg.org/2011sunscreen/
US Food and Drug Administration, www.fda.gov/cder/offices/OTC/understanding_spf_sunscreen.htm
[From Watershed Sentinel, Summer 2010] Updated January 16, 2012
