One of the most interesting sunscreen metrics is mentioned completely unceremoniously on the last page of the Final Order Monograph 2020. It is sad that we don

One of the most interesting sunscreen metrics is mentioned completely unceremoniously on the last page of the Final Order Monograph 2020. It is sad that we don't have access to the critical wavelength value calculations described on the last page of Monograph M020. The critical wavelength is identified as the wavelength at which the integral of the spectral absorbance curve reaches 90 percent of the integral over the UV spectrum from 290 to 400 nm. A mean critical wavelength of 370 nm or greater is classified as broad spectrum protection. Sunscreen users could benefit from understanding the UV blocking performance of each sunscreen on the market. Reference: U.S. Food and Drug Administration Final Administrative Order (OTC000006) Over-the-Counter Monograph M020: Sunscreen Drug Products for Over-the-Counter Human Use (Posted September 24, 2021) https://www.fda.gov/drugs/understanding-over-counter-medicines/sunscreen-how-help-protect-your-skin-sun https://www.fda.gov/drugs/understanding-over-counter-medicin...