Heavy metals are among the most persistent and bioaccumulative pollutants in marine ecosystems, posing significant toxicological threats to fish via complex molecular and cellular disruptions. This review synthesizes current knowledge on the cascade of mechanistic responses in marine fish following HM exposure, which includes oxidative stress, modulation of antioxidant responses, activation of detoxification systems, DNA damage, inflammation, apoptosis, neuroendocrine disruption, and ultimately, cellular energy imbalance. In addition to established pathways, the review highlights recent advances in mechanistic understanding and biomarker development, including cellular stress responses, epigenetic regulation, metal homeostasis mechanisms, and novel molecular indicators. These mechanisms support the development of an integrated biomarker framework that combines classical indicators (e.g., antioxidant enzymes, metallothionein) with next-generation endpoints (e.g., miRNA profiles, gene-level responses of metal transporters or stress chaperones, epigenetic alterations). The interpretation of biomarker responses requires consideration of the exposure context, environmental variables, and physiological status to ensure accurate assessment of sublethal toxicity in field settings. By bridging mechanistic understanding with biomonitoring relevance, this review provides a comprehensive foundation for advancing molecular tools in pollution monitoring and risk assessment. Special emphasis is placed on biomarkers specific to heavy metal exposure, enhancing their diagnostic value relative to general stress indicators.

This Research Communication reports analysis of 37 compounds comprising polycyclic aromatic hydrocarbons (PAHs), organochlorine and organophosphate pesticides (OCPS and OPPS) in milk powder (one brand each of commercial infant formulae, follow-on formulae and baby formulae purchased from a local supermarket in Romania). The selected analytes were investigated using gas chromatography–mass spectrometry (GC-MS), gas chromatography with electron capture detector (GC-ECD) and gas chromatography with thermionic sensitive detection (GC-TSD). The estimated limits of detection for most target analytes were in the μg/kg level (range 0·001–0·320 µg/kg). The purpose of the study was to determine the selected analytes, to assess the exposure of babies and infants and to produce data for comparison with tolerable limits according to the European Union Regulations. In most of the samples the organochlorine pesticides values were under the limit of detection. Exceptions were heptachlor epoxide and endosulfan sulphate, the last of which was found in all analysed samples at low concentrations. We also found detectable levels of ethoprophos, parathion-methyl, chlorpyrifos, prothiofos, guthion, disulfoton and fenchlorphos in most of the analysed samples. Benzo[a]pyrene, which is used as an indicator for the presence of PAHs, was not detected in selected samples. The low level of exposure to contaminants indicates that there are no health risks for the infants and babies that consume this brand of milk powder formulae.

The widespread use of Tebuconazole-based fungicides in phytosanitary treatments on a wide range of crops, on the one hand, and the lack of official reports on the amount of fungicide residues in nearby water basins, on the other hand, may lead to uncontrolled and hazardous contamination of water sources used by the resident population, and to serious effects on the environment and public health. Our study explores the acute toxicological risk of this fungicide on various organisms, from bacteria and yeast to fish, using a battery of tests (standardized Toxkit microbiotests and acute semi-static tests). By investigating the interaction between Tebuconazole and bacteria and yeast organisms, we observed that Gram-negative bacteria displayed a strong tolerance for Tebuconazole, while Gram-positive bacteria and yeasts proved to be very sensitive. The fish experiment was conducted on Chelon auratus juveniles exposed to five concentrations of the fungicide Tebustar EW (Tebuconazole, 250 g/L as active substance). After 96 h of exposure, the LC₅₀ for C. auratus was 1.13 mg/L. In the case of the Toxkit microbiotests’ application, the following results were recorded: Spirodela polyrhiza EC₅₀ = 2.204 mg/L (after 72 h exposure), Thamnocephalus platyurus EC₅₀ = 0.115 mg/L (after 24 h), and Daphnia magna EC₅₀ = 2.37 mg/L (after 24–48 h). With the exception of bacteria and yeast, the same response pattern was observed for all non-target species tested; the response range expressed by concentrations causing growth inhibition or mortality was small, ranging between very close values that are quite low, thereby demonstrating the high toxicity of Tebuconazole-based fungicides to the environment.

This study provides a comprehensive evaluation of contamination levels in the Romanian Black Sea within the framework of the Marine Strategy Framework Directive (MSFD). Over the course of five oceanographic expeditions between 2020 and 2022, data were gathered from 70 stations in transitional, coastal, shelf, and offshore waters of the Black Sea. Analyses were conducted on water, sediment, and biota samples for key contaminants: heavy metals (HMs), polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants (POPs) such as organochlorinated pesticides (OCPs) and polychlorinated biphenyls (PCBs). The assessment identified contamination hotspots near riverine inputs, urban runoff, harbor activities, and industrial discharges. Offshore waters also showed measurable pollutant levels, likely from diffuse sources and atmospheric deposition. The key findings reveal the widespread contamination of HMs, PAHs, and POPs across the Romanian Black Sea, with concentrations in certain areas exceeding acceptable environmental thresholds, highlighting ongoing challenges for regional pollution management. PAHs were prevalent in both nearshore and offshore regions, while OCPs and PCBs were detected across various matrices, with significant concentrations observed in water and biota samples. The study emphasizes the importance of integrated assessments within the MSFD framework, suggesting that future evaluations should complement the “one out-all out” (OOAO) approach with multi-metric tools, to enhance the robustness of pollution status reporting. Despite improvements in some areas, contamination remains a critical challenge, requiring strengthened regulations, improved waste management, and increased regional cooperation to mitigate the ongoing risks to marine ecosystems. The findings provide valuable data for the upcoming national MSFD assessment cycle (2018–2023) and highlight the need for sustained monitoring and coordinated efforts to ensure long-term marine sustainability.

The lysosomal membrane stability (LMS) of hemocytes in wild mussels (Mytilus galloprovincialis) as a biomarker of cellular stress for chemical pollution was tested by neutral red retention time (NRRT) assays. To assess the environmental contamination in the study area, seawater quality and pollutant bioaccumulation throughout the soft tissue of mussels were investigated. The samples were collected in July 2022 at four sites on the Romanian Black Sea coast considered to be differently affected by contamination. To support the suitability of LMS as a biomarker of contaminant-induced stress, the contaminant body burdens of the mussels were compared with the NRRT values. The results showed a significantly reduced NRRT in all investigated locations, particularly in port areas (mean retention time between 11 and 14 min). The elevated bioaccumulation of organochlorinated pesticides (OCPs) and polychlorinated biphenyls (PCBs) and low NRRTs were observed at the most contaminated sites (i.e., ports). The low lysosomal stability reflected stress and damage in the hemocytes of mussels and could be related to the body burdens of contaminants. LMS is an effective indicator of health status in mussels and could be considered a sensitive biomarker of cellular stress induced by contaminant exposure.