(HealthDay News) – An application of water-resistant sunscreen with a sun protection factor (SPF) of >70 adequately protects people against skin cancer and photodamage even when applied irregularly.
Hao Ou-Yang, PhD, of the Neutrogena Corporation in Los Angeles, and colleagues measured the actual SPF values of six sunscreens labeled SPF 30–100 when applied by volunteers in amounts typically used by consumers (0.5, 1.0, 1.5, and 2.0mg/cm²) to determine if the products provided adequate protection from solar rays.
The researchers found that significant protection from ultraviolet radiation was provided by sunscreens with SPF values of >70 even when consumers used low application densities. Data showed that SPF 70 and SPF 100 sunscreens applied at 0.5mg/cm² by consumers resulted in actual SPF values of 19 and 27, respectively, and that a linear relationship existed between application density and the actual SPF.
“Sunscreens with SPF >70 add additional clinical benefits when applied by consumers at typically-used amounts, by delivering an actual SPF that meets the minimum SPF levels recommended for skin cancer and photodamage prevention,” the authors write. “In contrast, sunscreens with SPF 30 or 50 may not produce sufficient protection at actual consumer usage levels.”
Several authors are employees or consultants for consumer companies, including Neutrogena, which makes sunscreens and funded the study, and Johnson & Johnson.