Effect of abiotic factors and environmental concentrations on the bioaccumulation of persistent organic and inorganic compounds to freshwater fish and mussels

Emission and risk of atmospheric hexachlorobutadiene might be underestimated globally

Ambiguous emission of new pollutants is a fundamental obstacle of risk prevention, such as hexachlorobutadiene (HCBD). To quantify the HCBD emission in China, we probed the emission factors for main sources based on analysis of 847 gas samples from field experiments. Considering treatment efficiency, emissions of 362 kinds of sources were measured. Results showed that 15115.34 tons HCBD were emitted in 2019, among which more than half was contributed by agricultural sources (53.85 %) that were overlooked in ongoing HCBD regulation. More industrial sectors were recognized to produce and emit HCBD with the cumulative contribution being 29.35 %, such as industrial coating, plastic and rubber products manufacturing industry. Residential coal and transportation contributed 11.03 % and 5.5 % to total HCBD emission. Significant occupational health threats in the chemical raw material manufacturing industry indicated that low emission did not mean low risk, since emission of this industry was low. Assessment of population-weighted non-occupational risk revealed a higher risk for residents in Central and Eastern China. High detection rate of HCBD in agricultural and industrial sources implied a probably underestimated emission and impact over the globe. The conclusions highlight the importance of emission factor localization and source full-coverage in new pollutants regulation.

Interactions of a PFOS/sodium nitrite mixture in Chinese mitten crab (Eriocheir sinensis): Impacts on survival, growth, behavior, energy metabolism and hepatopancreas transcriptome

Perfluorooctanesulfonic acid (PFOS) and sodium nitrite may have complex adverse effects on aquatic animals. This study assessed the interactive effects of PFOS and sodium nitrite on Chinese mitten crab (Eriocheir sinensis). A 2 × 3 factorial experiment with 0, 0.1, and 5 mg/L PFOS and 0, 3.50 mg/L sodium nitrite evaluated impacts on growth, behavior, oxygen consumption, health, energy metabolism, and hepatopancreas transcriptome. PFOS <0.1 mg/L with 3.50 mg/L nitrite significantly decreased PFOS accumulation in the hepatopancreas and improved feeding rates and hepatopancreas structure (P < 0.05). Under 5 mg/L PFOS and nitrite, survival, weight gain, hepatosomatic index, and feeding rate significantly decreased (P < 0.05). PFOS (0.1 mg/L) with nitrite significantly prolonged righting response time and increased locomotion speed (P < 0.05). PFOS (5 mg/L) significantly decreased serum triglyceride and lactate levels, while PFOS and nitrite decreased glucose, triglyceride, and glycogen levels and increased lactate in hepatopancreas (P < 0.05). Transcriptomic analysis indicated that PFOS affects p53 signaling, cell cycle and neurotransmission pathways, with notable changes in cell proliferation genes (pcna, ccna, cdk1, cdk2, rbx1) primarily downregulated by PFOS. Overall, PFOS disrupts neurotransmitter regulation and causes hepatopancreatic damage, while nitrite can reduce the toxicity of PFOS by decreasing its hepatopancreas accumulation. However, high levels of PFOS combined with sodium nitrite exacerbate toxicity, emphasizing the need for comprehensive assessment of environmental pollutant interactions.

Efficient removal of lipophilic compounds from sewage sludge: Comparative evaluation of solvent extraction techniques

Municipal sewage sludge, a by-product of wastewater treatment plants, presents environmental challenges due to its complex composition. Particular concern is the lipophilic and aliphatic compounds that pose risks to the environment and human health. This study focuses on the efficient removal of those compounds from sewage sludge using several organic solvents (hexane, toluene, chloroform, dichloromethane, acetone, hexane-methanol mixture, ethanol, and methanol) and ionic liquids (ILs) like tetrakis(hydroxymethyl)phosphonium chloride and 1-ethyl-3-methylimidazolium acetate by solvent extraction techniques. To determine optimal conditions, various factors such as solvent types, contact time, and temperature were examined. The results reveal that solvent polarity significantly impacts extract composition, with non-polar solvents like hexane and toluene yielding profiles characteristic of lipid-type compounds. An in-depth analysis of contaminants present in the sewage sludge was studied by Fourier-transform infrared spectroscopy (FTIR). Additionally, nuclear magnetic resonance (NMR) was used to identify the extracted compounds, including triglycerides, aliphatic esters, aliphatic alcohols, and free carboxylic acids. NMR provides data on the composition of the sewage sludge and indicates that among all the solvents used, tetrakis(hydroxymethyl) phosphonium chloride was the most suitable solvent for removing lipophilic and aliphatic compounds. Regeneration potential and reusability of the IL were conducted and verified by NMR. The results showed that tetrakis(hydroxymethyl) phosphonium chloride ionic liquid could be used for several extraction cycles. Identifying these compounds in the extracted mixture demonstrates that it adds value and potential for various applications. Towards environmental sustainability and circular economy, this effort develops strategies for the safe management, disposal, and recyclability of sewage sludge and, the reduction in environmental and health hazards associated with organic compounds.

Trace metal accumulations in commercially important fish and crab species from impacted tropical estuary, India: implications on human health risk assessment

Despite the beneficial role of aquatic food, bioaccumulation of trace metals can increase health risk for consumers. We conducted a comprehensive study to understand the levels of various trace metals (Cd, Co, Cr, Cu, Fe, Ni, Pb, Zn and Mn) in fish (Nematalosa nasus, Gerres filamentosus, Arius arius, Gerres erythrourus, Sardinella fimbriata, Caranx ignobilis, Etroplus suratensis, Mugil cephalus, Sillago sihama, and Euryglossa orientalis) and crab (Portunus pelagicus and Scylla serrata) species collected from Netravathi-Gurupur estuary, India and evaluated the potential health risks to humans by measuring target health hazard (THQ), hazard index (HI), estimated daily (EDI) and weekly (EWI) intake and cancer risk (CR). The hierarchy of toxic metal content in studied species was Fe>Pb>Cr>Mn>Zn>Cu>Ni>Cd>Co. The concentration of heavy metals were distinctly lower than the threshold value as suggested by World Health Organization and Food Safety and Standards Authority of India, except for Cr and Pb in few species. THQ values were below the acceptable limit. However, the estimated mean HI values were >1 for children, indicating they may be vulnerable to health risk due to continuous consumption of contaminated aquatic species from the study area. In contrast, the cancer risk for Cr, Cd, and Pb was below the acceptable range. Principal component analysis (PCA) discerned nearby petrochemical industry, electroplating industry, pesticides and fertilizer from agricultural runoff, as the potential sources of metal bioaccumulation in different tissues. Although the study reveals that metal contamination in aquatic species does not pose any immediate human health effect, continuous monitoring of the study area is recommended, as some metals have demonstrated their ability to accumulate in the tissues.

Incorporating habitat use and life history to predict PCB residues in wild fish in an urban estuary

Owing to the heterogenous distribution of contaminated sediments in urban estuaries, contaminant residues, such as polychlorinated biphenyls (PCBs), in fish tissue can vary widely. To investigate the relationship between PCBs in fish tissue and heterogeneity of PCBs in sediment, we developed a geospatial Biota-Sediment Accumulation Factor (BSAF) model for an urban estuary. The model predicts whole fish total PCB residues at a scale of 0.1 km2 by incorporating sediment chemistry, fish home range, and habitat type. The model predicted concentrations from across the estuary ranging from 0 to 161,456 ng/g lipid. An estuary-wide (50+ km2) and a project-scale (1+ km2) field validation of the model demonstrated it produced values that were slightly skewed to low concentrations; performance improved with increased sediment data spatial coverage. We conclude this approach has potential for determining PCBs "hot spot," estimating remediation project footprints, and evaluating potential remediation improvements to the quality of a fishery.

Fate and impact at molecular level of diatrizoic acid and iohexol contrast agents in Dreissena polymorpha mollusks

Iodinated contrast media (ICMs) used in X-ray imaging for medical diagnostics are released into wastewater and then encountered in river water at concentrations ranging from several dozen to hundreds of µg/L, and even thousands of µg/L in hospital effluents. ICMs are considered as emerging pollutants as their occurrence and impact on ecosystems and the environment are poorly documented. Even if they are considered inert for humans, aquatic organisms are continuously exposed to ICMs, and their potential deleterious effects are therefore questioned as we have recently demonstrated that they enter into organisms such as the zebra mussels. To answer this question, Dreissena polymorpha were exposed to two ICMs of different osmolality, diatrizoic acid and iohexol, at an environmental concentration (100 µg/L) for 21 days before a depuration phase of 4 days. The occurrence, fate, and impact of both ICMs in these organisms were studied using a metallomic approach. Thus, iodine as well as endogenous copper and zinc were quantified and analyzed in cytosolic extracts of digestive glands, gills, and gonads of mussels by size exclusion chromatography coupled to ICP MS. This work shows that a subcellular fractionation is necessary to distinguish variations in total element content. The cytosolic iodoprotein chromatographic pattern was consistent for the three organs and confirmed the presence of ICMs in cytosols. Additionally, this exploratory work tends to show a weak biological effect of ICMs with a substantial variation of the profile of Cu-binding proteins mostly in the gill cytosol and to a lesser extent, in the digestive gland cytosol.

Single and combined toxicity of tadalafil (Cilais) and microplastic in Tilapia fish (Oreochromis niloticus)

The joint impact of tadalafil (Cilais) as a pharmaceutical residue and microplastics on fish is not well comprehended. The current study examined haematological, biochemical, and antioxidant parameters, along with immunohistochemical and histological indications in tilapia (Oreochromis niloticus) after being exposed to tadalafil, polyethylene microplastics (PE-MPs), and their mixtures for 15 days. The fish were distributed into 1st group control group (The fish was maintained in untreated water without any supplements); 2nd group exposed to 10 mg/L PE-MPs;3rd group exposed to 20 mg/l tadalafil (Cilais); 4th group exposed to 20 mg/l tadalafil (Cilais) + 10 mg/LPE-MPs (in triplicate). The levels of creatinine, uric acid, glucose, AST, ALT, and albumin in fish treated with tadalafil alone or in combination with PE-MPs were significantly higher than those in the control group. Fish exposed to PE-MPs, tadalafil, and tadalafil plus PE-MPs showed significantly lower levels of RBCs, Hb, Ht, neutrophils, and lymphocytes compared to the control group. Serum levels of total antioxidant capacity and reduced glutathione (GSH) were notably lowered in fish groups subjected to PE-MPs, tadalafil, and tadalafil + PE-MPs combinations in comparison to the control group. Malondialdehyde (MDA) serum levels were notably elevated in fish groups subjected to PE-MPs, tadalafil, and tadalafil + PE-MPs combinations compared to the control group. The most severe impact was observed in the tadalafil + PE-MPs combination group. Interleukin-6 (IL-6) levels were significantly increased in liver tissues following exposure to both tadalafil and microplastics compared to tissues exposed to only one substance or the control group. Changes in the gills, liver, and renal tissues were seen following exposure to PE-MPs, tadalafil, and tadalafil + PE-MPs combination in comparison to the control group of fish. Ultimately, the mixture of tadalafil and PE-MPs resulted in the most detrimental outcomes. Tadalafil and PE-MPs exhibited showed greater adverse effects, likely due to tadalafil being absorbed onto PE-MPs.

Hazardous radical-coupled transformation products of benzophenone-3 formed during manganese dioxide treatment

Radical-coupled transformation products (TPs) have been identified as the byproducts of various transformation processes, including both natural attenuation and artificial treatments, of phenolic micropollutants. Benzophenone-3 (BP-3), an organic UV filter of emerging concern, has been previously reported with ubiquitous occurrence in the natural environment and water bodies. Current research has demonstrated how TPs are formed from BP-3 when it is treated with manganese oxide (MnO2). The ecological and toxicological risks of these TPs have also been assessed. Polymerization of BP-3 through radical coupling was observed as the major pathway by which BP-3 is transformed when treated with MnO2. These radical-coupled TPs haven't shown further degradation after formation, suggesting their potential persistence once occurred in the environment. In silico experiments predict the radical-coupled TPs will increase in mobility, persistence and ecotoxicity. If true, they also represent an ever-increasing threat to the environment, ecosystems and, most immediately, aquatic living organisms. In addition, radical-coupled TPs produced by MnO2 transformation of BP-3 have shown escalated estrogenic activity compared to the parent compound. This suggests that radical coupling amplifies the toxicological impacts of parent compound. These results provide strong evidence that radical-coupled TPs with larger molecular sizes are having potential adverse impacts on the ecosystem and biota.

Nutritional profiling and contaminant levels of five underutilized fish species in Norway

Exploring and making use of underutilized marine resources can be a sustainable approach to achieve future demands of fish consumption by the ever-growing population. Five species, namely European plaice (Pleuronectes platessa), European flounder (Platichthys flesus), lemon sole (Microstomus kitt), megrim (Lepidorhombus whiffiagonis), and thornback ray (Raja clavate), often captured as by-catch in Norway, were characterized for their nutritional value and potential accumulation of hazardous components. The proximate composition, protein profile, fatty acid profile as well as essential and toxic trace elements and polychlorinated biphenyls (PCBs) were analyzed. Digestible indispensable amino acid (DIAA) ratios and scores (DIAAS) and contributions of omega-3 fatty acids to the diet were calculated. Analysis on proximate composition revealed low fat contents of 0.74 to 1.25% and sufficient protein contents between 16.9 and 24% in the five species. Results of DIAA indicate a profitable distribution, with contributions exceeding the daily intake recommendations for an adult person related to a 200 g fillet. Moreover, findings on the distribution of eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) showed remarkable results, considering that the investigated species are lean fish. All five investigated fish exceed the recommended average daily intake level (AI) of EPA + DHA in a 200 g portion. As to toxic trace elements and PCBs, no significantly elevated levels were found considering a portion size of 200 g. Consequently, the nutritional quality of the investigated fish can be regarded as profitable with overall low potential health risks.

Metal(loid)s and persistent organic pollutants in yellow European eel from the Raša River, Croatia

The anthropogenic impact on the aquatic environment of the Raša River (Croatia) was investigated through the analysis of seven polybrominated diphenyl ethers (PBDEs), seven polychlorinated biphenyls (PCBs), three DDT isomers, and 22 major and trace elements using yellow European eel (Anguilla anguilla L.) as a biological indicator of contamination. The obtained data indicated generally low contamination status in the surrounding area. Levels of all organic contaminants in muscle significantly increased with lipid content, length, weight and body condition. In both muscle and liver, most metal(loid)s decreased or remained unchanged with increasing size, while at downstream location only several elements (Cd, Cu, Fe, Na, Se, U, V, Zn) accumulated in the liver with fish growth. Spatial analysis revealed higher pressure of Ag, Cd, Cr, Mo, Tl, U, and V at the downstream location, revealing the potentially limited impact of historical coal mining industry on the lower reaches of the Raša River.

Level and risk assessment of selected polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and organochlorine pesticides in walnut and soil

It is unknown how hydrophobic organic contaminants (HOCs) are distributed and how they affect the environment in high-fat nuts and their planted soil. The profile of HOCs in walnut/soil system was investigated in this study. Polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) were found in walnuts at concentrations of 0.67, 127, and 116 μg/kg, respectively. The target hazard quotients (THQ) of 17 PCBs, 16 PAHs, and 21 OCPs from walnut consumption by human were 0.06, 0.01, and 0.11, respectively. The highest concentrations of HOC in the soil were found in Nap and toxaphene, with concentrations of 2580 and 902 μg/kg, respectively. Bioaccumulation factors (BAF) and biota-sediment accumulation factors (BSAF) in walnuts were ranged from <0.01 to 7.04 and <0.01 to 3.83, respectively. Concentrations of most individual HOCs in soil samples were significantly correlated with soil organic matter (SOM) (p < 0.01) and minerals (p < 0.01), with maximum correlation coefficients of 0.70 (OM-PCB81) and -0.84 (P-BaP). According to this study, high-fat walnuts do not have a high bioaccumulation of HOCs from soil, and the risk of consumption is within the safe range.

Health risk of consuming Sphoeroides spp. from the Navachiste Lagoon complex due to its trace metals and organochlorine pesticides content

The Navachiste complex (NAV) is impacted by neighbored human activities and is located in the southwestern coastal zone of the Gulf of California. The study determines the trace metal (TM) and organochlorine pesticides (OCP) health risk content in the edible tissue of Sphoeroides spp. from NAV. The daily intakes (EDI), target hazard quotient (THQ), hazard index (HI), and carcinogenic and non-carcinogenic risks were calculated. Twenty OCP and seven TM were detected. Cd, Cu, Fe, Mn, Pb, and Zn were above MRLs. The γ‒Chlordane was the most frequent OCP. The highest average concentration was for α‒HCH, followed by γ‒chlordane. With the high ratios of γ‒HCH, p, p'‒ DDD and p, p'‒DDD, and the absence of p, p'‒ DDT, the higher ratios for dieldrin and endrin than for aldrin, α‒ chlordane, γ‒chlordane, heptachlor, and heptachlor epoxide indicates historical contamination. In contrast, the residual products of methoxychlor, endosulfan, and its isomers indicate endosulfan's recent use. The TM EDI, THQ > 1 (at 120 g day-1), and the ILCR (> 1 × 10-6) were above minimum levels, showing a high-risk potential for cancer development in the long term.

Broad toxicological effects of per-/poly- fluoroalkyl substances (PFAS) on the unicellular eukaryote, Tetrahymena pyriformis

Per-/Poly- fluoroalkyl substances represent emerging persistent organic pollutants. Their toxic effects can be broad, yet little attention has been given to organisms at the microscale. To address this knowledge shortfall, the unicellular eukaryote Tetrahymena pyriformis was exposed to increasing concentrations (0-5000 μM) of PFOA/PFOS and monitored for cellular motility, division and function (i.e., phagocytosis), reactive oxygen species generation and total protein levels. Both PFOA/PFOS exposure had negative impacts on T. pyriformis, including reduced motility, delayed cell division and oxidative imbalance, with each chemical having distinct toxicological profiles. T. pyriformis represents a promising candidate for assessing the biological effects these emerging anthropogenically-derived contaminants in a freshwater setting.

Spatial distribution and ecological risks of polychlorinated biphenyls in a river basin affected by traditional and emerging electronic waste recycling in South China

With development of e-waste related legislation in China, formal recycling activities are designated in some areas while informal ones are illegally transferred to emerging areas to avoid supervision. However, the resulting environmental impact and ecological risks are not clear. Here, we investigated the discharge of polychlorinated biphenyls (PCBs) to soil and aquatic environments by e-waste recycling activities in the Lian River Basin, China. The study area included a designated industrial park in the traditional e-waste recycling area (Guiyu, known as the world's largest e-waste center), several emerging informal recycling zones, and their surrounding areas and coastal area. A total of 27 PCBs were analyzed, and the highest concentration was found in an emerging site for soil (354 ng g^-1) and in a traditional site for sediment (1350 ng g^--1) respectively. The pollution levels were significantly higher in both the traditional and emerging recycling areas than in their respective upstream countryside areas (p = 0.0356 and 0.0179, respectively). Source analysis revealed that the traditional and emerging areas had similar PCB sources mainly associated with three PCB technical mixtures manufactured in Japan (KC600) and the USA (Aroclor 1260 and Aroclor 1262). The PCB pollution in their downstream areas including the coastal area was evidently affected by the formal and informal recycling activities through river runoff. The ecological risk assessments showed that PCBs in soils and sediments in the Lian River Basin could cause adverse ecotoxicological consequences to humans and aquatic organisms.

The relevance of European Biota Quality Standards on the ecological water quality as determined by the multimetric macro-invertebrate index: A Flemish case study

European Biota Quality Standards (EQS_biota), for compounds with low water solubility and high biomagnification, were created to sustain water quality and protect top predators and humans from secondary poisoning. In reality, for multiple compounds, an exceedance of these standards is often reported in literature without a decrease in ecological water quality determined by biotic indices. In the present study, threshold concentrations were defined in biota (from 44 sampling locations throughout Flanders (Belgium)), above which a good ecological water quality, assessed by the Multimetric Macroinvertebrate Index Flanders (MMIF), was never reached. Threshold values were compared to current EQS_biota. Accumulated perfluoroctane sulfonate (PFOS), mercury (Hg), hexabromocyclododecane (HBCD), polybrominated diphenyl ethers (PBDEs), dioxins and polychlorinated biphenyls (PCBs) concentrations were measured in muscle tissue of European yellow eel (Anguilla anguilla) and perch (Perca fluviatilis). Fluoranthene and benzo(a)pyrene were also analyzed in translocated mussels (Dreissena bugensis, D. polymorpha and Corbicula fluminea). Threshold values could only be calculated using a 90th quantile regression model for PFOS (in perch; 12 µg/kg ww), PCBs (in eel; 328 µg/kg ww) and benzo(a)pyrene (in mussels: 4.35 µg/kg ww). The lack of a significant regression model for the other compounds indicated an effective threshold value higher than the concentrations measured in the present study. Alternatively, the 95th percentile of concentrations measured in locations with a good ecological quality (MMIF≥0.7), was calculated for all compounds as an additional threshold value. Finally, fish concentrations were standardized for 5% lipid content (or 26% dry weight content for PFOS and Hg). Threshold values for PFOS and benzo(a)pyrene and the 95th percentiles for dioxins and fluoranthene were comparable to the existing standards. For all other compounds, the 95th percentile was higher than the current EQS_biota, while for HBCD, it was lower. These results strongly advise revising and fine-tuning the current EQS_biota, especially for ∑PBDE and HBCD.

Enhanced trophic transfer of chlorpyrifos from resistant Hyalella azteca to inland silversides (Menidia beryllina) and effects on acetylcholinesterase activity and swimming performance at varying temperatures

Chlorpyrifos, an organophosphate (OP) insecticide, is prevalent in aquatic systems globally and is often implicated in aquatic toxicity during storm events. Chlorpyrifos induces toxicity by inhibition of acetylcholinesterase (AChE) activity, which has been related to alterations to fish swimming performance. Resistance to organophosphate insecticides, including chlorpyrifos, is prevalent in populations of the epibenthic amphipod Hyalella azteca in areas with known OP exposure. Previous studies have demonstrated an elevated bioaccumulation potential of insecticide-resistant prey items, however the potential for trophic transfer of chlorpyrifos from OP-resistant prey items and associated neurotoxic effects in fish predators has not been studied. Consequently, the present study aimed to determine the potential for trophic transfer of chlorpyrifos from OP-resistant H. azteca to a known predator, the inland silverside, Menidia beryllina at two temperatures (18 and 23 °C) to simulate temperature changes associated with global climate change (GCC). Fish were fed either ¹⁴C-chlorpyrifos-dosed H. azteca or control animals for 7 d, after which total bioaccumulation, percent parent chlorpyrifos, brain AChE activity and swimming performance (ramp-U_crit) were determined. Fish fed chlorpyrifos-dosed H. azteca bioaccumulated chlorpyrifos ranging from 29.9 to 1250 ng/g lipid, demonstrating the potential for trophic transfer. Lower bioaccumulation and greater biotransformation were observed in M. beryllina at 23 °C as compared to 18 °C, though this was not statistically significant. A significant 36.5% reduction in brain AChE activity was observed in fish fed chlorpyrifos-dosed H. azteca at 23 °C only, which may be attributed to increased biotransformation of parent chlorpyrifos to more potent AChE-inhibiting metabolites. Dietary chlorpyrifos exposure had no significant effect on swimming performance in M. beryllina, though ramp-U_crit was significantly increased by 25% at 23 as compared to 18 °C. These findings confirm the potential for trophic transfer of chlorpyrifos from OP-resistant prey to fish predators and the potential for elevated temperatures to exacerbate the neurotoxic effects of chlorpyrifos.