Sunscreen may not deliver the sun protection factor it promises on the label, according to Consumer Reports.
In a news release Tuesday, the organization said it tested and rated more than 60 lotions, sprays and sticks that claimed to have a SPF of 30 or higher.
However, the study found that 28 of the 60 lotions failed to meet the SPF claim on the label.
This could leave people vulnerable to sunburn and possible long-term skin damage like wrinkles or skin cancer.
There are two types of ultraviolet rays, UVA and UVB. The chief cause of sunburns are from UVB rays which only penetrate the top layer of skin. Sunscreens are designed to protect against UVB rays.
UVA rays penetrate deeper into the skin. They can contribute to wrinkles and damage your DNA deep within cells. Conventional sunscreens do not protect you from UVA rays, but broad-spectrum ones are.
Both UVA and UVB rays can increase the risk of developing skin cancer.
In the UVB tests, technicians applied sunscreen to volunteers' backs and had them soak in a tub for 40 or 80 minutes, with the length of time depending on a specific product's water-resistance claim.
The area protected by the sunscreen was then exposed to UVB light.
Technicians waited 24 hours to check the test area to see if sunscreen worked or if redness developed on the skin, a sign the sunscreen failed. More than 40 percent of the sunscreens tested did not offer the SPF they promised.
Technicians repeated the test to check for UVA protection.
Consumer Reports found some broad-spectrum sunscreens had problems. Mineral-only sunscreens also failed to meet their claimed SPF number more often than sunscreens which use either a chemical formulation or a combination of both chemicals and minerals.
What are the most effective sunscreens?
There is good news for people who want to enjoy the sun and avoid both UVA and UVB rays. Consumer Reports found some sunscreens aced their tests and are a good value.
The best lotions were:
Pure Sun Defense SPF 50 ($6)
Equate Ultra Protection SPF 50 ($8)
No-Ad Sport SPF 50 ($10)
Consumer Reports also tested spray-on sunscreens.
The best spray-ons were:
Trader Joe's Spray SPF 50 ($6)
Walmart's Equate Sport Continuous Spray SPF 30 ($5)
Dollar General's DG Body Sport SPF 30 ($5)
If you are worried your favorite sunscreen does not offer you the protection you need, Consumer Reports recommends you should choose a product with a SPF 40 or higher.
They say that gives you a better chance of getting at least an SPF 30, the level most dermatologists recommend you use.
Consumer Reports said they are submitting their four-year results to the FDA and asking that it review its sunscreen requirements and investigate further.