Parabens are recognized as emerging contaminants. Used in the pharmaceutical and cosmetic industries, they present significant ecological risks to aquatic ecosystems. This study evaluated the effects of two parabens—methyl 4-hydroxybenzoate (methylparaben) and propyl 4-hydroxybenzoate (propylparaben)—both individually and as a mixture on daphnids. Through a series of controlled exposure experiments, phenotypic endpoints, including mortality, feeding behaviour, and enzymatic activity, were measured. The results demonstrate that propyl paraben and the mixture of propyl and methyl paraben exhibit greater toxic potential compared to methyl paraben alone. We observed a dose-dependent impact on key enzymes, indicating significant metabolic disruption. These findings underscore the necessity of utilizing model systems to investigate the complex interactions and cumulative impacts of pollutant mixtures in aquatic environments. Furthermore, this study provides critical insights regarding the underlying toxicity mechanisms of parabens, highlighting the need for comprehensive water quality monitoring and risk assessment frameworks to address the challenges posed by emerging contaminants.

Humanity faces the great challenges arising from pollution and climate change which evidently lead to the irreversible effects observed on the planet. It is now more important than ever to monitor and safeguard the ecosystem as it has been highlighted by governments and scientists. Conventional approaches for water pollution rely on the detection of chemicals in the environment. However, these descriptive observations when compared against water quality standards used as metrics for pollution are unable to predict pollution early or capture the extent of its impact. This weakness is reflected in the legislation and the thresholds for emerging pollutants such as pharmaceuticals and nanomaterials. To bridge the gap and to understand the underlying mechanisms for toxicity, research in the field of molecular ecotoxicology shifts more and more towards the integration of model systems, in silico approaches and molecular information as endpoints. Focusing on the freshwater ecosystem, daphnids are key species employed in risk assessment which are characterised as highly responsive to pollutants and physical stressors. The translation of molecular information describing the physiology of these organisms provides novel and sensitive metrics for pollution assessment.

The levels of pharmaceuticals have been continuously increasing in aquatic ecosystems over the past decade due to their extensive use in human and veterinary medicine. Traditional water monitoring methods have been proven insufficient to capture pollution due to pharmaceuticals because of sensitivity limits, their inability to monitor every pollutant, and their failure to provide mechanistic insights into the actions of pollutants. To combat this, new approach methodologies (NAMs) are increasingly introduced as supplementary tools that can provide sensitive metrics for pollution assessment. In addition, NAMs can bridge the gap in ecotoxicological information regarding mixtures of pharmaceuticals, which are more commonly found in aquatic ecosystems versus pharmaceuticals existing alone. In this context, freshwater sentinel species, such as the water flea known as daphnids, were used to assess the acute effects of a typical pharmaceutical mixture on various physiological and molecular responses. In addition to mortality, phenotypic and molecular endpoints such as ingestion rate and enzyme activity were measured to determine the impact of a cocktail of commonly prescribed pharmaceuticals. Specifically, diclofenac, metformin, gabapentin, amoxicillin, trimethoprim, and erythromycin were mixed in equal amounts and tested at 0.1, 1, and 10 mg/L. Results showed differences in mortality, a decrease in feeding, and changes in enzyme activities, thus supporting a distinct pattern in the physiological responses of daphnids

An analytical quadrilateral p element is developed for solving the free vibrations of piezoelectric‐laminated plates. The formulations of the displacement and strain fields are based on first‐order shear deformation plate theory. The coupling effect between the electrical and stress fields is also considered. The Legendre orthogonal polynomials are used as the element interpolation functions, and the analytical integration technique is adopted. It is found that the present p element method gives high numerical precision results, fast and monotonic convergence rate. In the numerical cases, the effects of the number of hierarchical terms and mesh size on the convergence rate are investigated. Examples of square plates with different displacement and potential boundary conditions are studied. In the comparisons, the solutions of the present element are in good agreement with those obtained from other classical and finite element methods.

The assessment of pollution is a serious issue and a major consequence of the overgrowing human population and its activities. Focusing on the aquatic ecosystem, traditional approaches of water chemistry mainly provide minimal monitoring with the detection of pollutants, while they fail to produce mechanistic or predictive insight. As such, effect-based methods have gained significant attention for the better mechanistic understanding of aquatic pollution. Among the key species used, daphnids have acquired a central position in aquatic toxicology and ecology. In this study, a novel feeding assay was developed and applied in a battery of exposures to different pollutants. Furthermore, in combination with biochemical markers and sensitive metabolomic analyses, the responses of daphnids following exposures were uncovered in molecular detail. Specific categories of metabolites were identified as significant indicators to predict pollution.