UV-filters, which are the active ingredients in sunscreen and other personal care products, have been detected in the aquatic environment. For example, we previously reported almost 100% detection frequencies for homosalate, octisalate, octocrylene, and oxybenzone in water, sediment, and oysters collected throughout the Chesapeake Bay. We hypothesized that organic UV-filters pose a threat to photosynthetic organisms, such as algae and submerged aquatic vegetation, because these chemicals partition into lipids and absorb sunlight. Thalassiosira pseudonana are marine centric diatoms that comprise an essential role in the diet of Eastern oysters and, therefore, Chesapeake Bay ecosystem services. The objective of this work was to establish the baseline toxicity of five UV-filters covering the natural sunlight spectrum to T. pseudonana. In this regard, T. pseudonana were cultured at a constant temperature of 26 °C and exposed to artificial estuarine water containing 0.1-1000 µg/L of avobenzone, homosalate, octisalate, octocrylene, or oxybenzone and salinity relevant to mid-Bay conditions. Mixtures of these UV-filters were also assayed against T. pseudonana to elucidate potential synergism or antagonism. After a 72-h exposure period, the optical density and relative chlorophyll fluorescence were measured to determine growth and chlorophyll inhibition, respectively. The toxicity of each UV-filter was calculated as the half maximal effective concentration (EC50), which is the UV-filter concentration required to inhibit the growth or chlorophyll fluorescence of T. pseudonana by 50%. The EC50 of each UV-filter was compared to previously reported UV-filter concentrations in raw wastewater, wastewater effluent, and the Chesapeake Bay to contextualize the relative risk to T. pseudonana.

Toxicity of sunscreen active ingredients to Thalassiosira pseudonana

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.