Photoprotection of ultraviolet-B filters: Updated review of endocrine disrupting properties

The Ultraviolet (UV) radiation is emitted by the sun and is part of the electromagnetic spectrum. There are three types of UV rays (UV-A, UV-B and UV-C), however only UV-A and UV-B have biologic effects in humans, with UV-B radiation being primarily responsible for these effects. Among the measures of photoprotection advised by the health authorities, the topical application of sunscreens (containing UV-B filters) is the preferred worldwide. Currently, octylmethoxycinnamate (OMC) is the most commonly used UV-B filter in sunscreens. Their application has proven to be effective in preventing burns, but its efficiency against melanoma continues under intense controversy. Studies have shown that OMC behaves like an endocrine disruptor, altering the normal functioning of organisms. However, few studies have evaluated their multiple hormonal activities. Some studies suggest that the OMC exerts an estrogenic, anti-androgenic, anti-progestenic and anti-thyroid activity. But, through what mechanisms? In humans, few studies were performed, and some questions remain unclear. Thus, the purpose of this review is to present the multiple hormonal activities established for the OMC, making a critical analysis and relationship between the effects in cells, animals and humans.