Acute toxicity bioassay of mercury and silver on Capoeta fusca (black fish)

Emerging bioanalytical sensors for rapid and close-to-real-time detection of priority abiotic and biotic stressors in aquaculture and culture-based fisheries

Abiotic stresses of various chemical contamination of physical, inorganic, organic and biotoxin origin and biotic stresses of bacterial, viral, parasitic and fungal origins are the significant constraints in achieving higher aquaculture production. Testing and rapid detection of these chemical and microbial contaminants are crucial in identifying and mitigating abiotic and biotic stresses, which has become one of the most challenging aspects in aquaculture and culture-based fisheries. The classical analytical techniques, including titrimetric methods, spectrophotometric, mass spectrometric, spectroscopic, and chromatographic techniques, are tedious and sometimes inaccessible when required. The development of novel and improved bioanalytical methods for rapid, selective and sensitive detection is a wide and dynamic field of research. Biosensors offer precise detection of biotic and abiotic stressors in aquaculture and culture-based fisheries within no time. This review article allows filling the knowledge gap for detection and monitoring of chemical and microbial contaminants of abiotic and biotic origin in aquaculture and culture-based fisheries using nano(bio-) analytical technologies, including nano(bio-)molecular and nano(bio-)sensing techniques.

Co-exposure of zinc oxide nanoparticles and multi-layer graphenes in blackfish (Capoeta fusca): evaluation of lethal, behavioural, and histopathological effects

Zinc oxide nanoparticles (ZnO NPs) and multi-layer graphenes (MLGs) are widely used, and due to the lack of appropriate wastewater treatment may end up in the aquatic environment, with unknown consequences to biota. The main purpose of this study was to assess the acute toxicity, histopathological and behavioural changes caused by the exposure of ZnO NPs and MLGs, alone and combined, to the blackfish Capoeta fusca. The estimated mean 96 h-LC₅₀ for ZnO NPs was 4.9 mg L^-1 and 68.4 mg L^-1 for MLGs. In combination, MLGs increased the acute toxicity of the ZnO NPs. The effects of the different NPs on the gills included hyperplasia, aneurisms, and fusion of the lamellae. In the intestine, exposure to the NPs resulted in an increase in the number and swelling of goblet cells and tissue degeneration. Loss of balance, restlessness, erratic and abnormal swimming patterns were the most common behavioural changes seen in the ZnO NPs' exposed blackfish. In contrast with the acute toxicity findings, MLGs decreased the histopathological and behavioural effects of the ZnO NPs on both gills and intestinal tissues as well as fish behaviour. Our experimental results illustrated insights into the simultaneous exposure assessment of metal-based NPs and carbon nanomaterials, although further research is needed on the interactions exposure of these substances to interpreting the toxicological effects of metal-based nanomaterials seen in exposed organisms.

Multivariate statistical evaluation of heavy metals in the urine of opium individuals in comparison with healthy people in Western Iran

The current study aimed to evaluate the levels of some toxic and essential elements (Pb, Cd, Cu, Ti, Ni, Cr, Co, Fe, Ca, Hg, Mn, Se, and Zn) in the urine of opium-addicted compared to non-addicted cases. In this study, 126 participants were recruited and their fasting urine samples were collected (63 opium-addicted and 63 non-addicted subjects served as the reference group). ICP-MS was utilized to detect the concentration of trace elements. Results exhibited that the concentration of all elements than Ni, Cu, and Zn was markedly different between the addicted and non-addicted groups. Compared to controls, the Cd, Cr, Co, Hg, Mn, Pb, Se, and Ti levels were higher among opium-addicted cases (p < 0.05) whereas the Fe and Ca concentrations were higher among controls (p < 0.05). Robust regression analysis showed no statistically significant effect of gender on element levels. It revealed that age was associated with the levels of Ni and Cu only and also the route of administration was related to the urinary levels of Co, Cr, Hg, and Mn. In conclusion, results confirmed that it is opium consumption that affects the concentration levels of most elements.

Association between trace elements in cancerous and non-cancerous tissues with the risk of breast cancers in western Iran

This study aimed to assess the tissue content of essential and toxic metals including lead (Pb), cadmium (Cd), arsenic (As), silver (Ag), aluminum (Al), chromium (Cr), copper (Cu), iron (Fe), selenium (Se), and zinc (Zn) in the breast cancerous tissues compared to the non-cancerous tissue. The biopsy specimens of 63 breast cancers along with 63 adjacent healthy tissues in Kurdistan Province, Iran, were collected from 2019 to 2020 and assayed using ICP-MS (Agilent 7900). The results of the Mann-Whitney test illustrated that the concentration of Pb, Cd, As, Cr, Cu, and Se were significantly elevated in cancerous tissue (p < 0.05), while Zn was the only trace element with higher levels in healthy subjects (p < 0.05). Moreover, weak to moderate correlations between elements were observed in the cancerous group including Al-Cr (r=0.60), As-Cu (r=0.52), and Cu-Se (r=0.56). In contrast, no correlation over 0.50 was found between trace elements in the non-cancerous group. Raw risk differences (RDs) accounted for a significant effect for Pb, Cd, As, Ag, Cr, Se, and Zn on the development of breast cancer. In conclusion, elevated levels of As, Cd, Cu, Pb, and Se may contribute to enhancing the risk of breast cancer.

Efficacious bioremediation of heavy metals and radionuclides from wastewater employing aquatic macro- and microphytes

Cytotoxic, mutagenic, and carcinogenic contaminants, such as heavy metals and radionuclides, have become an alarming environmental concern globally, especially for developed and developing nations. Moreover, inefficient prevalent wastewater treatment technologies combined with increased industrial activity and modernization has led to increase in the concentration of toxic metals and radioactive components in the natural water bodies. However, for the improvement of ecosystem of rivers, lakes, and other water sources different physicochemical methods such as membrane filtration, reverse osmosis, activated carbon adsorption, electrocoagulation, and other electrochemical treatment are employed, which are uneconomical and insufficient for the complete abatement of these emerging pollutants. Therefore, the application of bioremediation employing aquatic macrophytes and microphytes have gained considerable importance owing to the benefits of cost-effectiveness, eco-friendly, and higher energy efficiency. Thus, the present review aims to enlighten the readers on the potential application of algae, cyanobacteria, plant, and other aquatic micro- and macrophytes for the elimination of carcinogenic metals and radioactive isotopes from wastewater. Additionally, the use of transgenic plants, genetically modified species, algal-bacterial symbiosis for the enhancement of removal efficiency of mutagenic contaminants are also highlighted. Furthermore, species selection based on robustness, mechanism of different pathways for heavy metal and radionuclide detoxification are elucidated in this review article.

Biochemical, physiological (haematological, oxygen-consumption rate) and behavioural effects of mercury exposures on the freshwater snail, Bellamya bengalensis

The widespread occurrence of Mercury (Hg) and its derivatives in the aquatic environment and risks to the health of local populations has necessitated investigations into its toxic effects on sessile species. The toxicity of Mercury was observed sequentially from 96 h acute exposure regime (behavioural endpoints) to chronic durations (haematological and biochemical toxicity endpoints) in Bellamya bengalensis. Time-dependent lethal endpoints for acute toxicity (LC50) of mercury i.e., 24,48,72 and 96 h were estimated as 0.94, 0.88, 0.69 and 0.40 mg/l respectively. Threshold effect values i.e., LOEC (Lowest Observed Effect Concentration), NOEC (No Observed Effect Concentration) and MATC (Maximum Acceptable Toxicant Concentration) at 96 h were found to be 0.10, 0.05, 0.039 mg/l respectively. The study of oxygen consumption rate and behavioural changes during acute toxicity and haematological and biochemical responses during chronic toxicity to sublethal concentrations (10% and 20% of 96 h LC50) of mercury to the snail were also conducted. The organisms showed initial elevation at 24 h but later gradual decrease in oxygen consumption rate with the increase of concentration of mercury and time of exposure. For behavioural studies, variable test concentrations from 0.00 to 1.00 mg/l were used for 24, 48, 72 and 96 h. The crawling activity and clumping tendency decreased with the progress of time at all treatment periods and stopped ultimately at 96 h of exposure from 0.7 mg/l onwards whereas touch reflex was not observed at 96 h exposure at all treatments except at 0.09 mg/l. In haemocyte count, no significant variation was observed among control values between various exposure periods (p > 0.05) though variations were observed in sub-lethal concentrations versus control at all treatment duration (7, 14, 21, 28d, p < 0.05). In biochemical response study, the protein content in hepatopancreas of the snails treated at sublethal concentrations of mercury (10% and 20% of 96 h LC50) reduced significantly versus control after 21d of exposure (p < 0.05). In gonads, the protein content of the treated snails significantly reduced at all treatment concentrations versus control at all exposure times (p < 0.05). Based on the safe levels indicated above, the concentration of 0.01 to 0.04 ppm of mercury can be considered safe for Bellamya bengalensis and any less-hardy aquatic species. These responses elicited by our molluscan model will not only help in biomonitoring of environmental mercury contamination in water bodies but will also provide support to ecological health and risk assessment.

Association between trace element concentrations in cancerous and non-cancerous tissues with the risk of gastrointestinal cancers in Eastern Iran

This study was conducted to investigate the association between trace elements including cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), nickel (Ni), selenium (Se), zinc (Zn), and arsenic (As) in gastrointestinal cancer tissue and non-cancerous tissue (suspected gastrointestinal cancer) in Eastern Iran. The samples of 63 gastrointestinal cancers (stomach (n = 20), esophageal (n = 19), and colorectal (n = 24) along with 63 controls in South Khorasan Province, Iran, were collected and analyzed using ICP-MS (Agilent 7900). Our results indicated that the concentrations of Co (1.3 ± 0.8, 1.3 ± 0.8 μg kg^-1), Cr (8.1 ± 7.3, 11.0 ± 14.8 μg kg^-1), Ni (29.0 ± 20.1, 39.5 ± 30.2 μg kg^-1), Pb (6.9 ± 4.0, 6.1 ± 4.6 μg kg^-1), and Zn (867.6 ± 159.1, 935.6 ± 196.2 μg kg^-1) were significantly higher among esophagus and colon cancer cases than controls (p < 0.05). Similarly, stomach cancer cases showed higher Co, Cr, Ni, Se, and Zn and lower Cu concentrations than their controls (p < 0.05). Moreover, the Spearman correlation between metals revealed a mostly low to moderate correlation between metals. Our finding illustrated that the significant risk differences of Cr, Ni, Pb, Se, and Zn metals on esophagus cancer when considered the single predictor unadjusted for other metals and covariates RD (95% CI) - Cr: -0.274 (-0.463, -0.086), Ni: -0.288 (-0.457, -0.118), Pb: -0.171 (-0.463, -0.086), Se: -0.243 (-0.434, -0.051), and Zn: -0.094 (-0.143, -0.045) respectively. This study suggests that the trace element's exposure may be associated with gastrointestinal cancer risk. Additional studies are needed to elucidate the mechanisms underlying trace element carcinogenesis further.

Environmental Chemistry and Ecotoxicology of Hazardous Heavy Metals: Environmental Persistence, Toxicity, and Bioaccumulation

Heavy metals are well-known environmental pollutants due to their toxicity, persistence in the environment, and bioaccumulative nature. Their natural sources include weathering of metal-bearing rocks and volcanic eruptions, while anthropogenic sources include mining and various industrial and agricultural activities. Mining and industrial processing for extraction of mineral resources and their subsequent applications for industrial, agricultural, and economic development has led to an increase in the mobilization of these elements in the environment and disturbance of their biogeochemical cycles. Contamination of aquatic and terrestrial ecosystems with toxic heavy metals is an environmental problem of public health concern. Being persistent pollutants, heavy metals accumulate in the environment and consequently contaminate the food chains. Accumulation of potentially toxic heavy metals in biota causes a potential health threat to their consumers including humans. This article comprehensively reviews the different aspects of heavy metals as hazardous materials with special focus on their environmental persistence, toxicity for living organisms, and bioaccumulative potential. The bioaccumulation of these elements and its implications for human health are discussed with a special coverage on fish, rice, and tobacco. The article will serve as a valuable educational resource for both undergraduate and graduate students and for researchers in environmental sciences. Environmentally relevant most hazardous heavy metals and metalloids include Cr, Ni, Cu, Zn, Cd, Pb, Hg, and As. The trophic transfer of these elements in aquatic and terrestrial food chains/webs has important implications for wildlife and human health. It is very important to assess and monitor the concentrations of potentially toxic heavy metals and metalloids in different environmental segments and in the resident biota. A comprehensive study of the environmental chemistry and ecotoxicology of hazardous heavy metals and metalloids shows that steps should be taken to minimize the impact of these elements on human health and the environment.

Effects of cadmium at sub-lethal concentration on growth and biochemical parameters in rainbow trout (Oncorhynchus mykiss)

Cadmium (Cd), as one of heavy metals and an environmental stressor, may alter many physiological processes like growth and serum parameters in fish. The main objective of this study was to determine the effects of cadmium at sub-lethal concentrations (1 and 3 μg/l) on growth and serum biochemical parameters including enzymes, i.e. alkaline phosphatase (ALP), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), glucose, triglyceride, cholesterol and total protein in rainbow trout (Oncorhynchus mykiss). Trout were exposed to cadmium, and, at intervals of 1, 15, and 30 days, selected parameters were evaluated. Condition Factor (K), Specific Growth Rate (SGR) and Body Weight Gain (BWG) consistently decreased, while Food Conversion Ratio (FCR) increased at the end of experiment. Glucose was elevated in trout exposed to both Cd concentrations at day 15 and then returned to levels comparable to control fish. Triglyceride and cholesterol decreased transiently at day 15 and then increased at day 30. Total protein, AST, ALT and ALP increased linearly by time and Cd concentration. This investigation suggests that growth and serum biochemical parameters could be used as important and sensitive biomarkers in ecotoxicological studies concerning the effects of metal contamination and fish health.

Silver as antibacterial agent: ion, nanoparticle, and metal

The antibacterial action of silver is utilized in numerous consumer products and medical devices. Metallic silver, silver salts, and also silver nanoparticles are used for this purpose. The state of research on the effect of silver on bacteria, cells, and higher organisms is summarized. It can be concluded that the therapeutic window for silver is narrower than often assumed. However, the risks for humans and the environment are probably limited.

Metal concentrations in the water of Chah nimeh reservoirs in Zabol, Iran

The main objectives of this article were to monitor the metal concentrations of Fe, Cu, Pb, B, Ni, V, Cd, Se, As, and Cr in the water of Chah nimeh reservoirs in Zabol, south-eastern Iran; and to identify any relationships between metals. Metal concentrations in the water samples were analyzed using ICP-OES. The results indicated that there were a highly positive correlation between Cr and Se, Ni (p < 0.01), and, between As and Ni (p < 0.01). Also, there were significant differences between Cr, Ni, Pb, and Se in the water of Chah nimeh reservoirs.

Contaminations of metal in tissues of Siberian gull Larus heuglini: gender, age, and tissue differences

The objective of the present study was to investigate the levels of metals, namely cadmium, lead, and zinc, in Siberian gull (Larus heuglini) (n = 15), in order to: (1) examine the sex and gender related variation in trace metal accumulation, and (2) to determine the significant between metal concentrations in the kidney, liver, and pectoral muscle. The concentrations were different between the tissues of bird as well as among the interaction (sex × age), but this difference (except cadmium in liver and zinc in kidney) between the gender (male and female) and age (adult and juvenile) didn't exist. Results showed that the metal concentrations in the Siberian gull were decreased in sequence of kidney > liver > muscle. The cadmium, lead, zinc concentration overall means they were measured as 2.2 ± 0.7, 8.8 ± 2.5, and 91.1 ± 37. 1 μg/g for kidney, 1.1 ± 0.2, 5.1 ± 0.8, and 68.3 ± 27.8 μg/g for liver, and 0.8 ± 0.1, 3.4 ± 0.6, and 34.4 ± 23.2 μg/g for pectoral muscle, respectively.

Analysis of heavy metals concentration in water and sediment in the Hara biosphere reserve, southern Iran

This study determined the concentration of heavy metals (Al, Cr, Cu, and Zn) in water and sediments at nine sites in the Hara biosphere reserve of southern Iran during the summer and winter 2010. Determination of Al, Cr, Cu, and Zn in water was carried out by graphite furnace atomic absorption spectrometer (Shimadzu, AA 610s) and in sediment by flame atomic absorption spectrometer (Perkin Elmer, AA3030). Results showed that the heavy metal concentrations in the water samples decreased in the sequence of Zn > Al > Cu > Cr, while in sediment samples were Cr > Zn > Cu > Al. Data analysis indicated that with the exception of Al, there was a Pearson's correlation coefficient between pH and Cu, Zn, and Cr at α = 0.01, 0.05, and 0.001 in sediment (in winter), respectively. There were also significant differences between heavy metals of Cr, Cu, and Zn during the two seasons (p < 0.001) in the water and sediment.