People can partially be to blame for sunscreens not protecting as well as some would think. According to Consumer Reports, people don’t use enough, don’t rub it in properly or don’t reapply enough or at all.

Another issue that the sunscreen may not deliver the sun protection factor, or SPF, it promises on the label.

Consumer Reports tested and rated more than 60 lotions, sprays and sticks that claimed to have an SPF of 30 or higher - 30 being the minimum level recommended by the American Academy of Dermatology.

According to Consumer Reports, 28 of those tested failed to meet the SPF claim on the label.

Three of them fell far short, with  tests showing an SPF of less than 15. That could lead to sunburn, possible skin damage, wrinkles or skin cancer.

Consumer Reports said it observed a pattern in the testing it has done over the past four years. Of all the sunscreens tested, fully half came in below the SPF number printed on the label and a third registered an SPF below 30.

For more on the study, click here.