Conversion of oxybenzone sunscreen to phototoxic glucoside conjugates by sea anemones and corals

Abstract

The reported toxicity of oxybenzone-based sunscreens to corals has raised concerns about the impacts of ecotourist-shed sunscreens on corals already weakened by global stressors. However, oxybenzone’s toxicity mechanism(s) are not understood, hampering development of safer sunscreens. We found that oxybenzone caused high mortality of a sea anemone under simulated sunlight including ultraviolet (UV) radiation (290 to 370 nanometers). Although oxybenzone itself protected against UV-induced photo-oxidation, both the anemone and a mushroom coral formed oxybenzone–glucoside conjugates that were strong photo-oxidants. Algal symbionts sequestered these conjugates, and mortality correlated with conjugate concentrations in animal cytoplasm. Higher mortality in anemones that lacked symbionts suggests an enhanced risk from oxybenzone to corals bleached by rising temperatures. Because many commercial sunscreens contain structurally related chemicals, understanding metabolite phototoxicity should facilitate the development of coral-safe products.

Widening the Lens on UV Filters: Newfound Ubiquity of Triazine UV Filters in Breast Milk from South China and Implications for Augmented “Cocktail” Exposure in Infants

“…In the recent ten years, a large body of research has documented that most BTR- and BP-UVFs have persistence, bioaccumulation, and multiple toxicities, including strong endocrine activity, genotoxicity, cytotoxicity, neurotoxicity, mutagenicity, and reproductive and developmental toxicities, − as well as ecotoxicity, further raising significant concerns regarding their health and ecological risks. A compelling example is oxybenzone (BP-3), which can be converted to phototoxins, posing a mortal threat to vulnerable coral reefs . In view of their hazardous nature, worldwide regulatory agencies are beginning to act, and a series of BTR- and BP-UVFs are currently within the scope of international regulations.…”

“…A compelling example is oxybenzone (BP-3), which can be converted to phototoxins, posing a mortal threat to vulnerable coral reefs. 18 In view of their hazardous nature, worldwide regulatory agencies are beginning to act, and a series of BTRand BP-UVFs are currently within the scope of international regulations. For example, several BTR-UVFs, including 2- (benzotriazol-2-yl)-4,6-di-tert-tertbutylphenol (UV-320), 2,4di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol (UV-327), and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV-328), are listed as "substances of very high concern" under the European Union REACH (Registration, Evaluation, and Authorization of Chemicals) regulation.…”

Examining the substituent effect on mycosporine-inspired ultraviolet filters

“…5,6 A number of organic UV filters have come under scrutiny in recent years due to concerns about their safety to humans as well as aquatic environments and organisms. [7][8][9][10][11] With this in mind, research into understanding the fundamental photochemistry and photophysics of current organic UV filters as well as for novel alternatives is crucial to the development of sunscreens with improved safety profiles. 12 Toxicological studies and the monitoring of biological endpoints are also essential to assess the true safety of a candidate organic UV filter.…”

Unraveling the metabolic effects of benzophenone-3 on the endosymbiotic dinoflagellate Cladocopium goreaui

“…Recent researches implicated the metabolic products of BP-3, phototoxic oxybenzone-glucoside conjugates, can be considered as a culprit of the increasing bleaching rate of corals (Hansel, 2022;Vuckovic et al, 2022). On the contrary, it also has been revealed that Symbiodiniaceae could protect the coral host from the toxic effects of BP-3 metabolites by sequestering the phototoxins (Vuckovic et al, 2022). However, the protection mechanism by which Symbiodiniaceae protects the host remains unclear.…”