Calcium Phosphates from Fishery Byproducts as a Booster of the Sun Protection Factor in Sunscreens

Calcium phosphates (CaPs) have been recently proposed as a bio- and eco-compatible alternative to UV filters in sunscreens, which are in the spotlight for being associated with health 0 risks for both people and the environment. Here, natural CaPs extracted from fish bones have been tested as a booster of the sun protection factor (SPF), that is, as material working in synergy with UV filters to increase sunscreen UV-shielding efficiency, in combination with three of the most used UV filters, namely, octocrylene (OCR), octinoxate, and padimate-O, at different concentrations (10.0 and 20.0 wt %). The material obtained by calcination at 800 degrees C (CaP-N) was also enriched with Zn (CaP-Zn) or Mn (CaP-Mn) in an attempt to increase its SPF-boosting abilities. CaP-N and CaP-Zn consisted of a biphasic mixture of hydroxyapatite and beta tricalcium phosphate, while CaP-Mn presented a small quantity of Mn oxides. CaP-N was the most effective at increasing the SPF of the final emulsions, doubling the SPF of the formulation containing 20.0 wt % of OCR from 40.6 to 80.8. The results show that these CaPs, produced according to a circular economy approach, can be used as effective SPF boosters to decrease the concentration of UV filters used in sunscreen, while retaining high SPF values.