Acute toxicity of the UV filter oxybenzone to the coral Galaxea fascicularis.

Coral reefs are impacted by a variety of anthropogenic stressors including inputs of chemical contaminants. Although data is currently limited, sunscreens containing ultraviolet (UV) filters have recently been suggested as an emerging class of chemical contaminants. To provide further data on the toxicity of the UV filter oxybenzone (benzophenone-3 or BP-3) to corals, we conducted three independent acute toxicity tests exposing the colonial stony coral Galaxea fascicularis to BP-3 (0.31 to 10 mg/L nominal concentrations). Assessments included daily analytical verification of the exposure concentrations, calculation of the lethal concentration to result in 50% mortality (LC50) and numerous biological endpoints to further investigate the potential impact to both the coral and symbiont. LC50s for the three tests were similar and averaged 6.53 ± 0.47 mg/L nominal concentration BP-3 (4.45 mg/L measured dissolved BP-3). BP-3 did not initiate coral bleaching or show a significant loss of symbionts from the coral tissue in this species as reductions in measurements used for bleaching (i.e. visual color, color saturation and photosynthetic pigment concentrations) were only seen concurrently with tissue loss (i.e. at ≥2.5 mg/L nominal concentration BP-3). Polyp retraction, the most sensitive endpoint of this test, was seen to be a sub-lethal behavioral response to BP-3 exposure. Using the calculated LC50 with measured concentrations from a high-quality UV filter monitoring study in Hawaii, a preliminary, conservative risk quotient for BP-3 was calculated at 0.032. These results suggest that BP-3 likely does not pose an acute risk of mortality to G. fascicularis and additional testing is required to determine sublethal impacts of BP-3 under environmentally relevant concentrations and longer-term chronic exposures. This study highlights complications in conducting toxicity tests with organic UV filters including under-estimations of exposure concentrations and provides recommendations to improve these methods for better comparisons between studies.

A Critical Review of Organic Ultraviolet Filter Exposure, Hazard, and Risk to Corals.

There has been a rapid increase in public, political, and scientific interest regarding the impact of organic ultraviolet (UV) filters to coral reefs. Such filters are found in sunscreens and other consumer products and enter the aquatic environment via direct (i.e., recreational activities, effluents) or indirect (i.e., land runoff) pathways. This review summarizes the current state of the science regarding the concentration of organic UV filters in seawater and sediment near coral reef ecosystems and in coral tissues, toxicological data from early and adult life stages of coral species, and preliminary environmental risk characterizations. Up to 14 different organic UV filters in seawater near coral reefs have been reported across 12 studies, with the majority of concentrations in the nanograms per liter range. Nine papers report toxicological findings from no response to a variety of biological effects occurring in the micrograms per liter to milligrams per liter range, in part given the wide variations in experimental design and coral species and/or life stage used. This review presents key findings; scientific data gaps; flaws in assumptions, practice, and inference; and a number of recommendations for future studies to assess the environmental risk of organic UV filters to coral reef ecosystems. Environ Toxicol Chem 2021;40:967-988. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Occurrence and distribution of UV-filters and other anthropogenic contaminants in coastal surface water, sediment, and coral tissue from Hawaii.

The occurrence of UV-filters in the environment has raised concerns over potentially adverse impacts on corals. In this study, the concentrations of 13 UV-filters and 11 hormones were measured in surface seawater, sediment, and coral tissue from 19 sites in Oahu, Hawaii. At least eight UV-filters were detected in seawater, sediment, and coral tissue and total mass concentrations of all UV-filters were <750 ng L-1, <70 ng g-1 dry weight (dw), and <995 ng g-1 dw, respectively. Four UV-filters were detected in water, sediment, and coral tissue at detection frequencies of 63-100%, 56-91%, and 82-100%, respectively. These UV-filter concentrations generally varied as follows: water, homosalate (HMS) > octisalate (OS) > benzophenone-3 (BP-3, also known as oxybenzone) > octocrylene (OC); sediment, HMS > OS > OC > BP-3; coral, OS ≈ HMS > OC ≈ BP-3. BP-3 concentrations in surface seawater were <10 ng L-1 at 12 of 19 sites and highest at Waikiki beach (e.g., 10.9-136 ng L-1). While BP-3 levels were minimal in sediment (e.g., <1 ng g-1 dw at 18 of 19 sites), and ranged from 6.6 to 241 ng g-1 dw in coral tissue. No quantifiable levels of 2-ethylhexyl 4-methoxycinnamate (also known as octinoxate) were recorded in surface seawater or coral tissues, but 5-12.7 ng g-1 dw was measured for sediment at 5 of 19 sites. No hormones were detected in seawater or sediment, but 17α-ethinylestradiol was present in three corals from Kaneohe Bay. Surfactant degradation products were present in seawater, especially at Waikiki beach. These results demonstrate ubiquitous parts-per-trillion concentrations of UV-filters in surface seawater and is the first report of UV-filters in coral tissue from U.S.A. coastal waters. These data inform the range of environmentally-relevant concentrations for future risk assessments on the potential impacts of UV-filters on coral reefs in Oahu, Hawaii.