Effect of 10 UV Filters on the Brine Shrimp Artemia Salina and the Marine Microalgae Tetraselmis Sp

bioRxiv preprint doi: https://doi.org/10.1101/2020.01.30.926451; this version posted January 31, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Effect of 10 UV filters on the brine shrimp Artemia salina and the marine microalgae Tetraselmis sp. Evane Thorel, Fanny Clergeaud, Lucie Jaugeon, Alice M. S. Rodrigues, Julie Lucas, Didier Stien, Philippe Lebaron* Sorbonne Université, CNRS USR3579, Laboratoire de Biodiversité et Biotechnologie Microbienne, LBBM, Observatoire Océanologique, 66650, Banyuls-sur-mer, France. *corresponding author : E-mail address : [email protected] Abstract The presence of pharmaceutical and personal care products’ (PPCPs) residues in the aquatic environment is an emerging issue due to their uncontrolled release, through grey water, and accumulation in the environment that may affect living organisms, ecosystems and public health. The aim of this study is to assess the toxicity of benzophenone-3 (BP-3), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), butyl methoxydibenzoylmethane (BM), methylene bis- benzotriazolyl tetramethylbutylphenol (MBBT), 2-Ethylhexyl salicylate (ES), diethylaminohydroxybenzoyl hexyl benzoate (DHHB), diethylhexyl butamido triazone (DBT), ethylhexyl triazone (ET), homosalate (HS), and octocrylene (OC) to marine organisms from two major trophic levels including autotrophs (Tetraselmis sp.) and heterotrophs (Artemia salina). In general, EC50 results show that both HS and OC are the most toxic for our tested species, followed by a significant effect of BM on Artemia salina but only at high concentrations (1 mg/L) and then an effect of ES, BP3 and DHHB on the metabolic activity of the microalgae at 100 µg/L. BEMT, DBT, ET, MBBT had no effect on the tested organisms, even at high concentrations (2mg/L). OC toxicity represent a risk for those species since it is observed at concentrations only 15 to 90 times 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.01.30.926451; this version posted January 31, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. higher than the highest concentrations reported in the natural environment and HS toxicity is for the first time reported on microalgae and was very important on Tetraselmis sp. at concentrations close to the natural environment concentrations. Keywords UV-filters Toxicity tests Marine microalgae Artemia salina Marine environment 2 bioRxiv preprint doi: https://doi.org/10.1101/2020.01.30.926451; this version posted January 31, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 Introduction 2 3 In recent decades, the sunscreen production and skin application have continuously 4 increased to protect against sunlight exposure damages and to prevent skin cancer risk (Azoury and 5 Lange, 2014; Waldman and Grant-Kels, 2019). Sunscreen products contain many chemical 6 ingredients including UltraViolet (UV) filters, the aim of which is to absorb or reflect UVA and/or 7 UVB radiations ranging from 280 to 400 nm (Sánchez-Quiles and Tovar-Sánchez, 2015). 8 More than 50 different UV filters are currently on the market (Shaath, 2010). Despite the 9 fact that the use of these compounds is subject to different regulations around the world, UV filters 10 are regularly detected in various aquatic environmental compartments including lakes, rivers, 11 surface marine waters and sediments. These chemicals can enter in the marine environment in two 12 ways, either indirectly from wastewater treatment plants effluent or directly from swimming or 13 recreational activities (Giokas et al., 2007). Furthermore, their lipophilic nature results in low 14 solubility in water, high stability and tendency to bioaccumulate (Gago-Ferrero et al., 2015; Vidal- 15 Liñán et al., 2018). 16 In recent years, many ecotoxicological studies have focused on the impact of organic UV 17 filters on various trophic levels, from microalgae to fish, passing by corals. Several studies have 18 demonstrated that some of these compounds can disrupt survival (Chen et al., 2018; He et al., 2019; 19 Paredes et al., 2014), behavior (Araújo et al., 2018; Barone et al., 2019), growth (Mao et al., 2017; 20 Paredes et al., 2014; Sieratowicz et al., 2011), development (Giraldo et al., 2017; Torres et al., 21 2016), metabolism (Esperanza et al., 2019; Seoane et al., 2017; Stien et al., 2019), gene expression 22 (Gao et al., 2013; Zucchi et al., 2011) and reproduction (Araújo et al., 2018; Coronado et al., 2008; 23 Kaiser et al., 2012) in various species. It should be noted that the majority of toxicological studies 24 on organic UV filters were conducted on BP3, EMC and 4-MBC. 25 The adoption and implementation of the European legislation on the registration, evaluation, 26 authorization and restriction of chemicals (REACH) required several additional ecotoxicity data 3 bioRxiv preprint doi: https://doi.org/10.1101/2020.01.30.926451; this version posted January 31, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 27 promoting the use of invertebrates as models for toxicity assays (European Commission, 2007). 28 Brine shrimps Artemia spp. (here A. salina) are readily available worldwide and easy to breed. They 29 have therefore been frequently used as test organism in ecotoxicity assays, and A. salina was chosen 30 to investigate the toxicity of UV filters in this study (Caldwell et al., 2003; Libralato, 2014; Nunes 31 et al., 2006). 32 The green algae Dunaliella tertiolecta is commonly used for chronic algal toxicity testing. 33 The Haptophyta Isochrysis galbana is interesting too as it is widely cultured as food for the bivalve 34 industry. Green algae such as Chlorella and Tetraselmis sp., belonging to the phyllum Chlorophyta, 35 have also been frequently exploited in toxicity assays. Tetraselmis have been used before to study 36 the toxic effect of several antibiotics and PCPs, but also the UV filter BP-3 (Seoane et al., 2017, 37 2014). This is why this algae was used in this study. 38 Previous studies about the toxic effects of different pollutants on microalgae physiology 39 demonstrate that flow cytometry (FCM) can be an alternative to standard algal population-based 40 endpoints, since it allows a rapid, quantitative and simultaneous measurement of multiple responses 41 to stress in individual cells (Esperanza et al., 2019; Hadjoudja et al., 2009; Prado et al., 2015; 42 Seoane et al., 2017). Seoane et al., (2017) showed that the most sensitive parameters are the 43 metabolic activity and cytoplasmic membrane potential. Therefore, we decided to use FCM to 44 analyze the toxicity of UV filters on Tetraselmis cells. 45 46 2. Materials and methods 47 48 2.1 Test substances and experimental solutions 49 The UV filters benzophenone-3 (BP-3), bis-ethylhexyloxyphenol methoxyphenyl triazine 50 (BEMT), butyl methoxydibenzoylmethane (BM), and methylene bis-benzotriazolyl 51 tetramethylbutylphenol (MBBT) were purchased from Sigma-Aldrich (Saint-Quentin Fallavier, 52 France). 2-Ethylhexyl salicylate (ES), diethylaminohydroxybenzoyl hexyl benzoate (DHHB), 4 bioRxiv preprint doi: https://doi.org/10.1101/2020.01.30.926451; this version posted January 31, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 53 diethylhexyl butamido triazone (DBT), ethylhexyl triazone (ET), homosalate (HS), and octocrylene 54 (OC) were provided by Pierre Fabre Laboratories. 55 Before each toxicity test, and due to the low water solubility of the compounds, stock 56 solutions at 1 mg/ml were prepared by dissolving each UV filters in dimethyl sulfoxide (DMSO, 57 Sigma-Aldrich, purity >99%). These solutions were diluted in order to add the same amount of 58 DMSO to all samples and to obtain exposure concentrations ranging from 20 ng/L to 2 mg/L for A. 59 salina, and 10 µg/L to 1 mg/L for Tetraselmis sp.. The lower concentrations tested were roughly 60 those reported in natural ecosystems. DMSO concentration in the experiments was always 2.5 % 61 (v/v). A DMSO control (2.5 % v/v) and a blank control were also included. The blank control was 62 artificial seawater for A. salina and growth medium for Tetraselmis sp.. 63 64 2.2 Artemia salina mortality test 65 66 A. salina cysts were purchased from AquarHéak Aquaculture (Ars-en-Ré, France) and 67 stored at 4 °C. Dried cysts were hatched in a constantly aerated transparent «V» hatching incubator 68 filled with 500 mL of artificial seawater (ASW) at a salinity of 37 g/L, prepared with Instant Ocean 69 salt (Aquarium Systems, Sarrebourg, France). Incubation was carried out for 48 h, at 25 °C under 70 continuous light the first 24 hours. A 12:12 h light regime was then applied until the nauplii reached 71 the instar II-III stage. Ten nauplii were transferred into 5 ml glass tubes filled with ASW (2 mL) 72 contingently supplemented with DMSO and UV filters. The tubes were incubated at 25 °C under a 73 12:12 h light regime. The experiments were performed in sextuplicate. During the exposure period, 74 there was no aeration and the nauplii were not fed. The mortality rate was estimated after 48 h by 75 counting the dead nauplii under binocular. Organisms with no swimming activity or movement of 76 appendices for 10 s even after mechanical stimulation with a Pasteur pipette were counted as dead. 77 The tests were considered valid if the control’s average mortality rate was < 20%. 78 5 bioRxiv preprint doi: https://doi.org/10.1101/2020.01.30.926451; this version posted January 31, 2020.

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