Toxicity of UV filters on marine bacteria: Combined effects with damaging solar radiation

Clément Lozano,Sabine Matallana-Surget,Justina Givens,Salomé Nouet,Louise Arbuckle,Zacharie Lambert,Philippe Lebaron

doi:10.1016/j.scitotenv.2020.137803

Abstract

Organic UV filters are of emerging concern due to their occurrence and persistence in coastal ecosystems. Because marine bacteria are crucial in the major biogeochemical cycles, there is an urgent need to understand to what extent these microorganisms are affected by those chemicals. This study deciphers the impact of five common sunscreen UV filters on twenty-seven marine bacteria, combining both photobiology and toxicity analysis on environmentally relevant species. Seven bacteria were sensitive to different organic UV filters at 1000 μg L−1, including octinoxate and oxybenzone. This is the first report demonstrating inhibition of bacterial growth from 100 μg L−1. None of the UV filters showed any toxicity at 1000 μg L−1 on stationary phase cells, demonstrating that physiological state was found to be a key parameter in the bacterial response to UV-filters. Indeed, non-growing bacteria were resistant to UV filters whereas growing cells exhibited UV filter dependent sensitivity. Octinoxate was the most toxic chemical at 1000 μg L−1 on growing cells. Interestingly, photobiology experiments revealed that the toxicity of octinoxate and homosalate decreased after light exposure while the other compounds were not affected. In terms of environmental risk characterization, our results revealed that the increasing use of sun blockers could have detrimental impacts on bacterioplanktonic communities in coastal areas. Our findings contribute to a better understanding of the impact of the most common UV filters on bacterial species and corroborate the importance to consider environmental parameters such as solar radiation in ecotoxicology studies.

Highlights

Organic UV filters are chemicals that absorb UVB (280–315 nm) and/ or UVA (315–400 nm) (Shaath, 2010)
Our study addressed for the first time, the combined impact of five common UV filters with solar radiation on diverse marine bacteria
It is interesting to note that BP3 only affected gram negative species (Bacteroidetes and Proteobacteria), while Ethylhexyl methoxy cinnamate (EHMC) and HS showed toxicity against both gram negative and gram positive bacteria (Actinobacteria and Firmicutes), suggesting that UV filters could target different membrane structures according to their physicochemical properties

Summary

Introduction

Organic UV filters are chemicals that absorb UVB (280–315 nm) and/ or UVA (315–400 nm) (Shaath, 2010). Due to their absorbing properties, UV filters are the main components of sunscreen, and are found in industrial products such as paints and plastics as stabilizing agents. UV filters are of emerging concern due to their large production volumes, the increasing coastal tourism, their persistence related to their chemical properties, and their toxicity (Raineri et al, 2017). While benzophenone-3 (BP3), octocrylene (OC) and 4methylbenzilidene camphor (4-MBC) were described as photostable (Rodil et al, 2009; Herzog et al, 2009; Liu et al, 2011), cinnamate and triazone derivatives were found to produce photoproducts (Jentzsch et al, 2016; MacManus-Spencer et al, 2011; Damiani et al, 2010) and their toxicity is yet to be explored

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