SPF tests are done by putting 2 milligrams per square centimetre of sunscreen on the backs of human volunteers. A special UV lamp is shone onto the backs, and how much UV the skin can take with and without the sunscreen is compared.
The FDA estimates a one-time cost of $2,200 per sunscreen product to test for UVA protection. In addition to testing, manufacturers must also comply with labeling requirements, as seen in FIGURE 1. The estimated costs for relabeling sunscreen products are $7,600 per product.
To know if sunscreen is effective, look for the SPF number on the bottle. SPF stands for sun protection factor. The higher the SPF number, the more protection the sunscreen provides.
The Best Sunscreen
Blue Lizard has reformulated its Sensitive Mineral Sunscreen SPF 50+, our top pick. It now contains an aloe extract and the SPF booster butyloctyl salicylate, among other inactive ingredients. The active ingredients, zinc oxide (10%) and titanium dioxide (8%), remain the same.
The location of the patches is identified by marking your back with ink. Occasionally the arms or the thighs are also used for patch testing. Itching of the test areas is normal, but you are advised not to scratch.
Work with a testing facility or beauty lab to conduct RIPT testing on your skin care products. Hire a dermatologist to review the RIPT results and give their stamp of approval. (Some beauty labs will complete this process for you. If you are a professional dermatologist you can sign off on this testing yourself)
Poor Packaging Quality: Spelling errors, blurry logos, or mismatched fonts are signs of counterfeits. Unfamiliar Sellers: Purchase from trusted retailers or the brand's official website. Lack of Seals: Authentic sunscreens usually have safety seals or tamper-proof packaging.
It's a measure of protection from the sun's UVB rays, which cause sunburn. The SPF rating is calculated by comparing the amount of time needed to produce sunburn on protected skin to the amount of time needed to cause sunburn on unprotected skin. The better the protection, the higher the SPF number.
“It is not necessary to purchase a more expensive sunscreen unless you have a particular preference for how a product feels or agrees with your skin,” Camp said.
OR, you can obtain some black construction paper and smear some samples of sunscreen on the paper. Use about the same amount you would use on your face/body. Multiple stripes/trials = good. Then set the paper out in the direct sun and check every hour or so and record your observations.
Patch Test
Allergens are applied to patches placed on the back for 48 hours, after which the skin is checked for reactions. Affiliated Dermatology offers this test with costs ranging from $150 to $250, based on the number of allergens tested.
A dermatologist or another doctor may offer patch testing in their office. However, people can perform a patch test at home to trial a cosmetic or skin care product before fully incorporating it into their routine.
While allergic contact dermatitis is common, you don't have to suffer in itchy silence. A patch test—which tests for allergic reactions that typically develop over several days— is often the most effective way to eliminate guesswork and relieve your symptoms of allergic contact dermatitis.
Do you wear sunscreen, but still get sunburned? You might be using it incorrectly. “The biggest thing I see with patients is that they are not applying enough sunscreen, and they aren't reapplying it,” says David Harvey, M.D., a dermatologist and Mohs surgeon at Piedmont Healthcare.
"Properly applied SPF 50 sunscreen blocks 98 percent of UVB rays, while an SPF 30 sunscreen blocks 97 percent of sunburn rays – the difference being one percentage point."
Dermatologists recommend physical sunscreens, also called mineral sunscreens, for people with sensitive skin. If your sunscreen doesn't contain titanium dioxide or zinc oxide, you have a chemical sunscreen.
Put another way, if your unprotected skin would take ten minutes to show signs of burning, then properly applying SPF 30 sunscreen would slow the rate of burning to the point where it would take 30 times longer, or 300 minutes in total. SPF 15 would take 150 minutes, while SPF 50, 500 minutes.