Single and joint ecotoxicity data estimation of organic UV filters and nanomaterials toward selected aquatic organisms. Urban groundwater risk assessment

Highlights

• EC₅₀ values of UV-Fs in aquatic organisms are in the mg l⁻¹ range.

• Binary mixtures of UV-Fs show generally decreased toxicity.

• Binary mixtures of organic nanomaterials and UV-Fs do not show toxic effects.

• Binary mixtures of nano-silver and UV-Fs did show reduced co-toxicity.

• HQs for UV-Fs in urban groundwater from Barcelona are below 1.

Abstract

The hazardous potential of organic UV filters (UV-Fs) is becoming an issue of great concern due to the widespread application of these compounds in most daily-use goods, such as hygiene and beauty products. Nanomaterials (NMs) have also been used in personal care products (PCPs) for many years. Nowadays, both classes of chemicals are considered environmental emerging contaminants. Despite some studies performed in vitro and in vivo reported adverse effects of many UV-Fs on the normal development of organisms, there is scarce data regarding acute and chronic toxicity. The aim of the present study was to determine the EC₅₀ values of selected UV-Fs using standardised toxicity assays on three aquatic species i.e. Daphnia magna, Raphidocelis subcapitata and Vibrio fischeri. EC₅₀ values obtained were in the mg l⁻¹ range for all the species. The estimated toxicity data allowed us to assess the environmental risk posed by selected UV-Fs in urban groundwater from Barcelona (Spain). The calculated ecological risk indicated a negligible impact on the aquifer. Giving the increasing importance of studying mixtures of pollutants and due to the widespread presence of nanomaterials (NMs) in the aquatic environment, other objective of this work was to explore the response on D. magna after exposure to both binary combinations of UV-Fs among them and UV-F with NMs. In all cases but the nano-silver mixtures, joint toxicity was mitigated or even eradicated.

Introduction

Organic UV Filters (UV-Fs) constitute a diverse group of chemical compounds used as protection agents against the harmful effects of the UV solar radiation. The popularity of sunscreens largely increased the last decade since UV irradiation was known to be involved in the pathogenesis of skin cancer and skin aging. UV-Fs are present in a wide range of daily-use products such as personal care products (PCPs), including shampoos, after-shave lotions and sunscreens, pharmaceuticals, vehicle maintenance products, food packaging as well as many other industrial goods. In order to protect in the UV A and UV B light spectrum, usually UV-Fs are used in combination. Currently, these emerging pollutants are considered pseudo-persistent due to their continuous release into the environment, through direct inputs, as they are used during recreational activities, or indirectly through domestic and industrial sewage (Gago-Ferrero et al., 2013).

Some in vitro and in vivo studies have shown that many of these compounds produce adverse effects on reproduction, interfering the normal development on aquatic and terrestrial organisms (Weisbrod et al., 2007; Klammer et al., 2007). As an example, 4-methylbenzylidene camphor (4MBC) showed similar estrogenic effects than 17-β-estradiol in mammals and amphibious species (Klann et al., 2005). Similarly, ethylhexyl methoxycinnamate (EHMC), octocrylene (OC), benzophenone 3 (BP3) and its derivatives have shown estrogenic activity in Pimephales promelas (Kunz and Fent, 2006). The transformation products of the UV-Fs also constitute a focus of concern due to the possibility that their toxicity could increase the ecotoxicological risk. Despite that, ecotoxicity of most UV-Fs (chronic or acute) is unknown or few data are published (Seeland et al., 2012; Kim et al., 2011; Harris et al., 2007).

Nanotechnology entered in the production and application of PCPs, such as sunscreens, anti-aging creams, toothpastes and perfumes, many years ago. There are currently around 1000 PCPs on the global market that are nano-based products. Nanomaterials (NMs) are nanostructured components with one or more dimensional structure of less than 100 nm size. These substances occur in the environment as both the result of anthropogenic sources and natural events. They are extensively used in a wide range of applications besides cosmetics, for instance in automotive products (Franco et al., 2007), clothes (Fabrega et al., 2009) and biomedical tools (Sharifi et al., 2012). The properties of NMs differ from conventional materials given their high relative surface area and quantum effects associated (Farré et al., 2011). Carbon based NMs are slightly toxic at high concentrations, whereas the metallic ones (specially copper and silver) can pose a serious hazard even at low concentrations (Klaine et al., 2008). There is still very limited data regarding the toxicity effects of mixtures involving NMs and other common organic pollutants, despite NMs are found to display a “Trojan horse effect” acting as the best vehicle for organic compounds transport (DAUGHTON, 2004, MACCORMACK et al., 2013).

In order to fill the knowledge gap on the ecotoxicity of UV-Fs, this study aims to determine the EC₅₀ values of the selected UV-Fs through a series of toxicity assays on three aquatic species i.e. the micro-crustacean Daphnia magna, the alga Raphidocelis subcapitata and the aquatic bacterium Vibrio fischeri. Furthermore, we explored the possible additive effects of binary mixtures of both UV-F/UV-F and UV-F/NM on D. magna. The toxicity data estimated allowed us to assess the risk for the aquatic environment that the presence of UV-Fs may pose in urban groundwater from Barcelona by calculating Hazard Quotients (HQs).