Toward sustainable environmental quality: Priority research questions for Europe.

The United Nations' Sustainable Development Goals have been established to end poverty, protect the planet, and ensure prosperity for all. Delivery of the Sustainable Development Goals will require a healthy and productive environment. An understanding of the impacts of chemicals which can negatively impact environmental health is therefore essential to the delivery of the Sustainable Development Goals. However, current research on and regulation of chemicals in the environment tend to take a simplistic view and do not account for the complexity of the real world, which inhibits the way we manage chemicals. There is therefore an urgent need for a step change in the way we study and communicate the impacts and control of chemicals in the natural environment. To do this requires the major research questions to be identified so that resources are focused on questions that really matter. We present the findings of a horizon-scanning exercise to identify research priorities of the European environmental science community around chemicals in the environment. Using the key questions approach, we identified 22 questions of priority. These questions covered overarching questions about which chemicals we should be most concerned about and where, impacts of global megatrends, protection goals, and sustainability of chemicals; the development and parameterization of assessment and management frameworks; and mechanisms to maximize the impact of the research. The research questions identified provide a first-step in the path forward for the research, regulatory, and business communities to better assess and manage chemicals in the natural environment. Environ Toxicol Chem 2018;37:2281-2295. © 2018 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Toxicity of five antibiotics and their mixtures towards photosynthetic aquatic organisms: implications for environmental risk assessment.

The individual and combined toxicities of amoxicillin, erythromycin, levofloxacin, norfloxacin and tetracycline have been examined in two organisms representative of the aquatic environment, the cyanobacterium Anabaena CPB4337 as a target organism and the green alga Pseudokirchneriella subcapitata as a non-target organism. The cyanobacterium was more sensitive than the green alga to the toxic effect of antibiotics. Erythromycin was highly toxic for both organisms; tetracycline was more toxic to the green algae whereas the quinolones levofloxacin and norfloxacin were more toxic to the cyanobacterium than to the green alga. Amoxicillin also displayed toxicity to the cyanobacterium but showed no toxicity to the green alga. The toxicological interactions of antibiotics in the whole range of effect levels either in binary or multicomponent mixtures were analyzed using the Combination Index (CI) method. In most cases, synergism clearly predominated both for the green alga and the cyanobacterium. The CI method was compared with the classical models of additivity Concentration Addition (CA) and Independent Action (IA) finding that CI could accurately predict deviations from additivity. Risk assessment was performed by calculating the ratio between Measured Environmental Concentration (MEC) and the Predicted No Effect Concentration (PNEC). A MEC/PNEC ratio higher than 1 was found for the binary erythromycin and tetracycline mixture in wastewater effluents, a combination which showed a strong synergism at low effect levels in both organisms. From the tested antibiotic mixtures, it can be concluded that certain specific combinations may pose a potential ecological risk for aquatic ecosystems with the present environmentally measured concentrations.

Combined phytoremediation of metal-working fluids with maize plants inoculated with different microorganisms and toxicity assessment of the phytoremediated waste.

The aim of this study was to validate the effectiveness of a phytoremediation procedure for metal-working fluids (MWFs) with maize plants growing in hydroponic culture in which the roots grow on esparto fibre and further improve bioremediation potential of the system with root beneficial bacteria, seeking a synergistic effect of the plant-microorganism combination. Chemical oxygen demand (COD), pH, total and type of hydrocarbons measured after phytoremediation indicated that the process with maize plants was successful, as demonstrated by the significant decrease in the parameters measured. This effect was mainly due to the plant although inoculated microorganisms had a relevant effect on the type of remaining hydrocarbons. The success of the phytoremediation process was further confirmed by two toxicity tests, one of them based on chlorophyll fluorescence measurements on maize plants and another one based on cyanobacteria, using a bioluminescent toxicity bioassay; both tests demonstrated that the phytoremediated waste was significantly less toxic than the initial non-phytoremediated MWFs.

Physicochemical characterization and ecotoxicological assessment of CeO2 nanoparticles using two aquatic microorganisms.

The physicochemical properties of nanoparticles determine their interaction with living organisms. Four different cerium oxide nanoparticles, including commercial materials, were characterized and compared with a micron-sized ceria. The formation of aggregates as well as ζ-potential, surface area, and chemical composition were determined. The formation of primary particle aggregates was a slow process that led to different particle sizes depending on the composition of the medium. In this paper, we describe the toxicity of cerium oxide for the self-luminescent cyanobacterial recombinant strain Anabaena CPB4337 and the green alga Pseudokirchneriella subcapitata. The toxicity for Anabaena exposed to nanoparticles in pure water for 24 h ranged from 0.27 to 6.3 mg/l; P. subcapitata EC(50) (yielded effective concentration of nanoparticles that inhibits the cellular function of interest by 50%) values in the 2.4-29.6 mg/l range. Images of both organisms showed membrane disruption and highly damaged cells. Free cerium was highly toxic for both organisms, but the negligible amount found dissolved in the nanoparticle suspensions could not explain the observed toxic effect of nanoceria on the aquatic organisms; the dissolution of zinc could contribute to the toxicity of bulk material but could not explain the toxic effect of nanoceria either. We found no evidence of nanoparticle uptake by cells, but our observations suggested that their toxic mode of action required direct contact between nanoparticles and cells; in the case of the cyanobacterium, cells completely coated by layers of ceria nanoparticles were observed. Cell damage most probably took place by cell wall and membrane disruption; further research is needed to find out whether the oxidative activity of ceria could be responsible.

Ecotoxicological assessment of surfactants in the aquatic environment: combined toxicity of docusate sodium with chlorinated pollutants.

The toxicity of perfluorinated surfactants perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorobutane sulfonate (PFBS) and PF-656 as well as the sulfosuccinate surfactant docusate sodium has been examined using two bioluminescence inhibition assays based on the marine bacterium Vibrio fischeri and the self-luminescent cyanobacterial recombinant strain Anabaena CPB4337. We also determined multigenerational toxicity towards the growth of the algae Pseudokirchneriella subcapitata. With EC(50) values in the 43-75 mg/L range, docusate sodium exhibited a higher toxicity towards the three organisms than PFOS, PFOA, PF-656 and PFBS. We investigated the toxicological interactions of the most toxic surfactant, docusate sodium, with two chlorinated compounds, triclosan and 2,4,6-trichlorophenol (TCP), in their binary and ternary mixtures using the method of the combination index based on the median-effect equation. In general, the binary mixture of the chlorinated compounds triclosan and TCP exhibited antagonism, which was stronger for the growth test using P. subcapitata. Except for the green alga, the binary mixtures of docusate sodium with TCP or triclosan showed synergism at medium to high effect levels; the synergistic behaviour predominating in the ternary mixture and in the three tested species. This result highlights the potential toxicological risk associated with the co-occurrence of this surfactant with other pollutants.

Ecotoxicity assessment of lipid regulators in water and biologically treated wastewater using three aquatic organisms.

BACKGROUND, AIM, AND SCOPE: The high consumption of blood lipid regulators is leading to frequent reports of the occurrence of fibrates in natural streams and wastewater effluents. This paper describes a study undertaken to evaluate the acute toxicity of bezafibrate, clofibric acid, gemfibrozil, and fenofibric acid, a metabolite of fenofibrate whose ecotoxicity has not been previously reported. MATERIALS AND METHODS: The bioassays used were based on Vibrio fischeri, Daphnia magna, and Anabaena CPB4337 tests. Anabaena CPB4337 is a novel bioassay based on Anabaena sp. PCC 7120 strain CPB4337 bearing in the chromosome a Tn5 derivative with luxCDABE from the luminescent terrestrial bacterium Photorhabdus luminescens. RESULTS: The higher toxicity corresponded to fenofibric acid, with EC(50) as low as 1.72 mg/l for V. fischeri. Gemfibrozil was also toxic for Anabaena sp. with EC(50) of 4.42 mg/l. The study reports the results from toxicity tests using fortified real wastewater samples taken from the effluent of a wastewater treatment plant. The wastewater itself was found to be very toxic to Anabaena CPB4337 (84% of bioluminescence inhibition) whereas it did not have any negative effect on D. magna or V. fischeri. On the contrary, V. fischeri luminescence exhibited a stimulatory effect in wastewater. DISCUSSION: Except for fenofibric acid, the Anabaena bioassay was more sensitive than the D. magna and V. fischeri bioassays to bezafibrate, clofibric acid, and gemfibrozil. For the three toxicity tests, fortification resulted in lower measured toxicity for the four compounds, probably indicating a reduced bioavailability due to the interaction with other chemicals in the wastewater or with particulate matter. The observed decrease in toxicity associated to the use of a wastewater matrix was higher for the more hydrophobic compounds reaching one order of magnitude for bezafibrate and gemfibrozil. CONCLUSIONS: The Anabaena CPB4337 bioassay revealed a certain risk associated with the three less toxic compounds tested. Based on V. fischeri and D. magna bioassays, bezafibrate and gemfibrozil would have been considered non-toxic and harmful, respectively. The use of EC(50) data measured in wastewater increases the risk estimation. RECOMMENDATIONS AND PERSPECTIVES: Cyanobacteria, as primary producers with a key role in the carbon and nitrogen cycles, are a substantial component of the microbial food webs. Any detrimental effect on this group may have a negative impact in nutrient availability to organisms of higher trophic levels and should be considered in ecotoxicity assessment tests.