Is Atyaephyra desmarestii a useful candidate for lethal and sub-lethal toxicity tests on pharmaceutical compounds?

Metabolism of the aquatic pollutant diclofenac in the Lymnaea stagnalis freshwater gastropod

The metabolism of organic contaminants in Lymnaea stagnalis freshwater gastropod remains unknown. Yet, pharmaceuticals-like the NSAID diclofenac-are continuously released in the aquatic environment, thereby representing a risk to aquatic organisms. In addition, lower invertebrates may be affected by this pollution since they are likely to bioaccumulate contaminants. The metabolism of pharmaceuticals in L. stagnalis requires further investigation to understand their detoxification mechanisms and characterized the risk posed by contaminant exposure in this species. In this study, a non-targeted strategy using liquid chromatography combined with high-resolution mass spectrometry was applied to highlight metabolites formed in L. stagnalis freshwater snails exposed to 300 µg/L diclofenac for 3 and 7 days. Nineteen metabolites were revealed by this approach, 12 of which were observed for the first time in an aquatic organism exposed to diclofenac. Phase I metabolism involved hydroxylation, with detection of 3'-, 4'-, and 5-hydroxydiclofenac and three dihydroxylated metabolites, as well as cyclization, oxidative decarboxylation, and dehydrogenation, while phase II metabolism consisted of glucose and sulfate conjugation. Among these reactions, the two main DCF detoxification pathways detected in L. stagnalis were hydroxylation (phase I) and glucosidation (phase II).

Pharmaceuticals in the Aquatic Environment: A Review on Eco-Toxicology and the Remediation Potential of Algae

The pollution of the aquatic environment has become a worldwide problem. The widespread use of pesticides, heavy metals and pharmaceuticals through anthropogenic activities has increased the emission of such contaminants into wastewater. Pharmaceuticals constitute a significant class of aquatic contaminants and can seriously threaten the health of non-target organisms. No strict legal regulations on the consumption and release of pharmaceuticals into water bodies have been implemented on a global scale. Different conventional wastewater treatments are not well-designed to remove emerging contaminants from wastewater with high efficiency. Therefore, particular attention has been paid to the phycoremediation technique, which seems to be a promising choice as a low-cost and environment-friendly wastewater treatment. This technique uses macro- or micro-algae for the removal or biotransformation of pollutants and is constantly being developed to cope with the issue of wastewater contamination. The aims of this review are: (i) to examine the occurrence of pharmaceuticals in water, and their toxicity on non-target organisms and to describe the inefficient conventional wastewater treatments; (ii) present cost-efficient algal-based techniques of contamination removal; (iii) to characterize types of algae cultivation systems; and (iv) to describe the challenges and advantages of phycoremediation.

Mixture predicted no-effect concentrations derived by independent action model vs concentration addition model based on different species sensitivity distribution models

In the hazard assessment of mixtures, the mixture predicted no-effect concentration (mPNEC) is always derived by the concentration addition (CA) model (mPNEC_CA) to assess the risk of mixtures combined with exposure assessment. However, the independent action (IA) model, which is also widely used as the CA model in the prediction and evaluation of mixture toxicity, is always used to calculate the population fraction showing a predefined effect, not mPNEC, and this limits the application of IA model in the mixture risk assessment. In this study, we explored the process of mPNEC derived by the IA method (mPNEC_IA) based on the species sensitivity distribution (SSD) and compared mPNEC_IA with mPNEC_CA. Taking two common pesticides, dimethoate (DIM) and dichlorvos (DIC), exposed in the actual water environment as an example, their SSD models were constructed separately using nine distribution functions after toxicity data screening and quality testing. For both DIC and DIM, all different nine models had passed the Kolmogorov-Smirnov test. Then, the PNECs of two pesticides were derived based on SSD models. Finally, mPNEC_IA with different concentration ratios was derived and compared to mPNEC_CA based on 81 combinations of nine SSD models. Most mPNEC values derived by IA model were more conservative than those by CA. It is worth noting that the mPNEC_IA is more conservative than mPNEC_CA for the commonly used log-logit distribution (function 7), log-normal distribution (8), and log-Weibull distribution (9). This study provides a new direction for the application of IA in the risk assessment and enriches the framework of mixture risk assessment.

Effects of diclofenac on the swimming behavior and antioxidant enzyme activities of the freshwater interstitial crustacean Bryocamptus pygmaeus (Crustacea, Harpacticoida)

Diclofenac (DCF) is one of the most widespread pharmaceutical compounds found in freshwaters as a pseudo-persistent pollutant due to its continuous release from point and diffuse sources, being its removal in Wastewater Treatment Plants incomplete. Moreover, DCF is particularly persistent in interstitial habitats and potentially toxic for the species that spend their whole life cycle among the same sediment grains. This study is aimed at offering a first contribution to the assessment of DCF effects on freshwater invertebrate species living in the interstitial habitats of springs, rivers, lakes and groundwaters. The Crustacea Copepoda are one of the main components of the freshwater interstitial communities, with the primacy taken by the worm-like and small-sized harpacticoids. A sub-lethal concentration of 50 μg L^-1 DCF significantly affected six out of the eight behavior parameters of the burrower/interstitial crustacean harpacticoid Bryocamptus pygmaeus recorded by video tracking analysis. DCF exposure reduced swimming speed, swimming activity, exploration ability and thigmotaxis, and increased swimming path tortuosity. The biochemical approach revealed a reduced level of the mitochondrial superoxide dismutase 2 in individuals exposed to DCF. It could be explained by a decline in mitochondrial performance or by a reduced number of functional mitochondria. Since mitochondrial dysfunction may determine ATP reduction, it comes that less energy is produced for maintaining the cell functions of the DCF-exposed individuals. In addition, the increasing energy demand for the detoxification process further contributes to decrease the total energetic budget allocated for other physiological activities. These observations can explain the changes we have observed in the swimming behavior of the copepod B. pygmaeus.

Effects of anti-inflammatory diclofenac assessed by toxicity tests and biomarkers in adults and larvae of Danio rerio

The entrance of the anti-inflammatory diclofenac in water bodies is a consequence of inappropriate use, incorrect disposal, and inefficiency of wastewater treatment plants (WWTPs) in removing this drug from sewage, among others. Effects of diclofenac on non-target aquatic organisms still need to be clarified. The objective of this work was to evaluate the toxic effects of the diclofenac on larvae and adults of Danio rerio. The LC₅₀ values were 5.49 mg/L and 5.22 mg/L for the adult and larvae, respectively. A set of biochemical and genotoxic biomarkers were evaluated in fish exposed to an environmentally relevant concentration of 2 μg/L DCF and a no observed effect concentration (NOEC) of 3 mg/L diclofenac. At the NOEC, an increase in activities of glutathione-S-transferase (GST) enzyme and an increase in ATP binding cassette (ABC) transporters in gills of adult fish was observed; also, an increase in lipoperoxidation (LPO) was seen in the gills of adults and whole larvae. These results indicate that diclofenac activates the fish detoxification processes and may affect fish health.

Mixture toxicity effects of chloramphenicol, thiamphenicol, florfenicol in Daphnia magna under different temperatures

Acute toxicities of chloramphenicol (CAP), thiamphenicol (TAP), and florfenicol (FLO) and their mixtures on Daphnia magna under two representative temperatures of the aquatic environment (20 and 25 °C) have been examined. Their toxicities depicted with an order of 72-h EC₅₀ values were as follows: CAP > FLO > TAP and CAP ≈ FLO > TAP under 20 and 25 °C, separately. Furthermore, the acute toxicity significantly increased with the rise of temperature from 20 to 25 °C in nearly all separate and mixture phenicol antibiotics. Meanwhile, the most toxic combination under two different temperatures was diverse. The nature of toxicological interactions of phenicol antibiotic mixtures was analyzed by Combination Index (CI) equation. In general, a dual synergism-antagonism effect was dominant in nearly all mixtures at both temperatures. The prediction suitability of Concentration Addition (CA), Independent Action (IA) models, and CI method was compared, suggesting that the CI equation seems to be more appropriate for predicting the toxicity values of phenicol drugs than CA and IA models. In brief, phenicol antibiotic mixtures with temperature variation may pose more significant hazards and risks to aquatic organisms; hence, the environment.

Toxic effects of NSAIDs in non-target species: A review from the perspective of the aquatic environment

The presence of pharmaceuticals in the aquatic environment, both in marine and freshwater reservoirs, is a major concern of global environmental protection. Among the drugs that are most commonly used, NSAIDs tend to dominate. Currently, being aware of the problem caused by drug contamination, it is extremely important to evaluate the scale and the full spectrum of its consequences, from short-term to long-term effects. The influence on non-target aquatic animals can take place at many levels, and the effects can be seen both in behaviour and physiology, but also in genetic alterations or reproduction disorders, affecting the development of entire populations. This review summarises all the advances made to estimate the impact of NSAIDs on aquatic animals. Multicellular animals from all trophic levels, inhabiting both inland waters, seas and oceans, have been considered. Particular attention has been paid to chronic studies, conducted at low, environmentally-relevant concentrations, to estimate the real effects of the present pollution. The number of such studies has indeed increased in recent years, allowing for a better insight into the possible consequences of pharmaceutical pollution. It should be stressed, however, that our knowledge is still limited to a few model species, while there are many groups of organisms completely unexplored regarding the effects of drugs. Therefore, the main aim of this paper was to summarise the current state of knowledge on the toxicity of NSAIDs in aquatic animals, also identifying important gaps and major issues requiring further analysis.

Disturbance of ecological habitat distribution driven by a chemical barrier of domestic and agricultural discharges: An experimental approach to test habitat fragmentation

Contamination is an important factor for determining the pattern of habitat selection by organisms. Since many organisms are able to move from contaminated to more favorable habitats, we aimed to: (i) verify if the contamination along the river Guadalete (Spain) could generate a chemical barrier, restricting the displacement of freshwater shrimps (Atyaephyra desmarestii) and (ii) discriminate the role of the contaminants concerning the preference response by the shrimps. A. desmarestii was experimentally tested in a multi-compartmented, non-forced exposure system, simulating the spatial arrangement of the samples just like their distribution in the environment. Water and sediment samples were chemically characterized by analyses of 98 chemical compounds and 19 inorganic elements. Shrimps selected the less contaminated water and sediment samples, with two marked preference patterns: (i) upstream displacement avoiding the sample located at the point of pollutant discharges and those samples downstream from this point and (ii) fragmentation of the population with spatial isolation of the upstream and downstream populations. The preference was related to the avoidance of artificial sweeteners, flame retardants, fragrances, PAHs, PCBs, pesticides, UV filters and some inorganic elements. The threat of contamination was related to its potential to isolate populations due to the chemical fragmentation of their habitat.

Lessons learned from more than two decades of research on emerging contaminants in the environment

In the last twenty years, thousands of research papers covering different aspects of emerging contaminants have been published, ranging from environmental occurrence to treatment and ecological effects. Emerging contaminants are environmental pollutants that have been investigated widely only in the last two decades and include anthropogenic and naturally occurring chemicals such as pharmaceuticals and personal care products and their metabolites, illicit drugs, engineered nanomaterials, and antibiotic resistance genes. The advancement in our knowledge on emerging contaminants has been the result of the appearance of highly sensitive and powerful analytical instrumentation that rapidly developed, allowing identification and trace quantification of unknown contaminants in complex environmental matrices. High efficiency chromatographic separations coupled to high-resolution mass spectrometers have become more common in environmental laboratories and are the pillars of environmental research, increasing our awareness and understanding of the presence of emerging contaminants in the environment, their transformation and fate, and the complex ecological consequences that they pose on exposed biological systems. This introductory paper for the Virtual Thematic Issue on Emerging Contaminants presents a brief literature overview on key research milestones in the area of emerging contaminants, focusing on pharmaceuticals and personal care products and endocrine disrupting compounds, and highlighting selected research papers previously published in the Journal of Hazardous Materials during the period of January 2012 to December 2015.

Influence of temperature on toxicity of single pharmaceuticals and mixtures, in the crustacean A. desmarestii

Lethal and sublethal responses of the shrimp Atyaephyra desmarestii exposed to three pharmaceutical compounds, Diclofenac (DF), Ibuprofen (IB) and Carbamazepine (CBZ), individually and in mixtures, were evaluated under two temperature scenarios. LC50 (96h) values were obtained individually at 20° and 25°C. At 25°C, mortality in binary and ternary mixtures is higher than at 20°C. The toxicity of the mixtures was predicted on the basis of individual mortality data using two toxicity models: Concentration addition (CA) and Independent action (IA). Our results showed that neither CA nor IA unequivocally predicted the observed toxicity of binary and ternary mixtures. For sublethal toxicity, selected endpoints were: ingestion rate, osmoregulatory capacity and respiration rate. Regarding osmoregulatory capacity, no significant differences were found. The highest ingestion rates were recorded in organisms exposed at 25°C, irrespective of the compound, after 30 and 60min of exposure. At 20°C, there was a significant decrease in respiration rate (Dunnett́s test p<0.05) under conditions of severe anoxia (1mg O2L(-1)) in organisms exposed to 13.3μgL(-1) of DF. At 25°C a significantly lower respiration rate with respect to the control (Dunnett́s test p<0.05) was found in organisms exposed to 13.8μgL(-1) of CBZ under conditions of moderate hypoxia and well-oxygenated water (3 and 5mg O2L(-1), respectively). The respiratory independence of organisms exposed to the higher temperature (25°C) also decreased. This study shows that CBZ and DF individually, even at relatively low concentrations, may produce respiratory deficiencies in the freshwater shrimp, Atyaephyra desmarestii under certain temperature and water oxygenation conditions, thus reducing its ability to function.

Evaluation of acute effects of four pharmaceuticals and their mixtures on the copepod Tisbe battagliai

The individual and combined toxicities of acetaminophen, carbamazepine, diclofenac and ibuprofen have been examined in neonate nauplii (<24 h-old) of the harpacticoid copepod Tisbe battagliai. Based on acute toxicity data (LC50) obtained, diclofenac was the most toxic compound with an LC50 value of 9.5 mg·L(-1); this is between 5 and 7 times lower than the LC50 value for acetaminophen, carbamazepine and ibuprofen (67.8 mg·L(-1), 59 mg·L(-1) and 49.7 mg·L(-1) respectively). The environmental risk posed by the selected pharmaceuticals was assessed by calculating risk quotients (RQs) based on MEC (the highest exposure concentration of the compound in the medium)/PNEC (predicted no effect concentration) ratios. Results suggest that, at environmental concentrations, none of the compounds is harmful for the aquatic environment (low or no risk). Toxicity data obtained for mixtures were compared with predictions derived from three different models: Concentration Addition (CA), Independent Action (IA) and Combination Index (CI). The classical modeling approaches CA and IA failed to predict the observed mixture toxicity, thus indicating that single compound toxicity data are not sufficient to predict toxicity of drug mixtures on Tisbe species. However, the use of the CI seems to provide better predictions of pharmaceutical toxicity.

The effects of the psychiatric drug carbamazepine on freshwater invertebrate communities and ecosystem dynamics

Freshwater ecosystems are persistently exposed to pharmaceutical pollutants, including carbamazepine. Despite the ubiquity and recalcitrance of carbamazepine, the effects of this pharmaceutical on freshwater ecosystems and communities are unclear. To better understand how carbamazepine influences the invertebrate community and ecosystem dynamics in freshwaters, we conducted a mesocosm experiment utilizing environmentally relevant concentrations of carbamazepine (200 and 2000 ng/L). Mesocosms were populated with four gastropod taxa (Elimia, Physa, Lymnaea and Helisoma), zooplankton, filamentous algae and phytoplankton. After a 31 d experimental duration, structural equation modeling (SEM) was used to relate changes in the community structure and ecosystem dynamics to carbamazepine exposure. Invertebrate diversity increased in the presence of carbamazepine. Additionally, carbamazepine altered the biomass of Helisoma and Elimia, induced a decline in Daphnia pulex abundance and shifted the zooplankton community toward copepod dominance. Lastly, carbamazepine decreased the decomposition of organic matter and indirectly altered primary production and dissolved nutrient concentrations. Changes in the invertebrate community occurred through both direct (i.e., exposure to carbamazepine) and indirect pathways (i.e., changes in food resource availability). These data indicate that carbamazepine may alter freshwater community structure and ecosystem dynamics and could have profound effects on natural systems.