Pitfalls in the in vitro determination of sunscreen protection factors using broad band ultraviolet radiation detectors and solar simulating radiation.

Synopsis Reliable in vitro techniques for assessing sunscreen protection factors have relied upon obtaining the forward scattering transmission spectrum of the test compound applied to a suitable substrate such as mouse or human epidermis. A theoretical analysis of alternative techniques using broad-band ultraviolet radiation detectors in conjunction with a source of simulated sunlight shows that the method is likely to yield unreliable values of sun protection factors and the reasons for this are discussed.