Accumulation of trace elements in selected fish and shellfish species from the largest natural carp fish breeding basin in Asia: a probabilistic human health risk implication

Assessment of Water, Sediment, and Fish Contamination by Metals in the Lentic Ecosystems of a Mineral-Rich State in India

Jharkhand is a mineral-rich state and there are many possibilities in pisciculture. Fish is the staple food of Jharkhand because of its nutritional values. In the present study, water, sediment, and the most favorite fish species (Labeo rohita, Catla catla, Cirrhinus mrigala, Cyprinus carpio, and Ctenopharyngodon idella) were collected from the lentic reservoirs and analyzed for assessing the ecological and human health risk assessment. The mean concentrations of Cd, Cr, Cu, Pb, and Zn in water samples varied within the ranges of 0.001-0.004 mg/L, 0.02-0.04 mg/L, 0.004-0.007 mg/L, 0.023-0.081 mg/L, and 0.003-0.12 mg/L, respectively. In sediment samples, the metal concentrations were recorded within the following ranges: 109.15-411.48 mg/kg for Zn, 0.79-22.87 mg/kg for Cd, 22.71-34.79 mg/kg for Pb, 93.44-581.38 mg/kg for Cr, and 19.61-129.09 mg/kg for Cu. The average concentrations of metals in fish were observed as follows: 82.98 - 91.81 mg/kg of Zn, 20.91 - 31 mg/kg of Cd, 81.48 - 91.81 mg/kg of Pb, 442.68 - 482.50 mg/kg of Cr, and 35.91 - 68.57 mg/kg of Cu. Ecological health assessment based on sediment indices shows the prevalence of Cd in the lentic ecosystems and their bioaccumulation (biota-sediment accumulation factor > 2) in fish species. Among the four reservoirs, HD is the most contaminated site. Local population, especially, children of Ranchi district, consuming fish species are prone to health risk due to the metal contamination. Conclusively, this study provides valuable data on metal concentrations in fish species, supporting future ecotoxicology research and policymaking for any mineral-rich state.

Attenuating effects of vitamin C on lead (Pb)-induced toxicological and endocrine responses in male Wistar rats

The aim of this study was to investigate the attenuating effect of vitamin C (VC) on lead (Pb)-induced toxicity in male Wistar rats. Twenty-four mature male rats were divided into 4 groups consisting of 6 animals using a completely randomized design. Rats were treated orally with either 60 mg/kg body weight (BW) Pb acetate or 100 mg/kg BW VC singly or combination. Controls group received water (vehicle control). After 65 days exposure, testes and epididymis of the animals were measured for testicular weight, epididymal weight and sperm estimations, while blood and liver samples were collected for liver function, hormonal assays, and oxidative stress responses including transcript expression using real-time PCR. Lead initiated significant increases in expression and activities of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD,) glutathione peroxidase (Gpx) and levels of malondialdehyde (MDA) and nitric oxide (NO). Liver function enzyme activities for alkaline phosphatase (ALP,) aspartate aminotransferase (AST), and alanine aminotransferase (ALP) were also elevated in Pb exposed rats. In contrast, a significant decrease was noted in reproductive hormones testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH), sperm variables including motility, viability and counts, as well as testes and epididymis weights following Pb treatment. However, the oxidative stress responses and liver function enzymes were reduced in the combined Pb and VC exposure group, while reproductive hormones and sperm profile increased significantly compared to Pb alone. Data indicate that VC exerts an attenuating effect. Our findings showed the attenuating potential of VC on Pb-induced toxicity of male rats.

Exploring Potential Human Health Risks Linked to Heavy Metal(Loid)s in Dietary Fishes: Utilizing Data-Driven and Computational Modelling Approaches

There are significant concerns about the risks to human health posed by metal(loid) contamination in dietary fishes in Bangladesh. Therefore, this study aimed to evaluate heavy metal(loid) contamination in fish and their associated health risks using published data from 2000 to 2022. Additionally, the safe limit of fish consumption was estimated using the target hazard quotient (THQ) followed by computational modelling and artificial neural networks (ANN). Results showed that freshwater and herbivorous fishes pose the least non-cancer risks, whereas saltwater and carnivorous fishes pose the highest non-cancer risks to Bangladeshi consumers. However, freshwater and omnivorous fish consumption pose the highest cancer risks compared to all studied metal(loid)s. In particular, among the heavy metal(loid)s, As, Cr, Hg, and Ni pose significant cancer and non-cancer risks to Bangladeshi consumers. On the contrary, the ANN and Decision tree regression (DTR) characterized the dataset, simulation model, or data testing condition, reaching 94.7% accuracy and allowing us to measure the safest fish consumption limit. The herbivorous fishes are less contaminated and allow greater consumption (175.09 g day-1). Contrarily, the allowable intake rates of carnivorous and omnivorous fishes are 153.05 and 168.63 g day-1, respectively. Besides, the safe consumption rate of saltwater fishes was 156.51 g day-1, which was lower than freshwater (180.59 g day-1) and euryhaline fishes (182.17 g day-1). Therefore, this study will assist fish consumers in selecting less contaminated fish, ensuring safe consumption levels, and ultimately reducing health risks associated with metal(loid) contamination in fish.

Multi-compartmental risk assessment of heavy metal contamination in soil, plants, and wastewater: A model from Industrial Gazipur, Bangladesh

Heavy metal contamination in industrial-agricultural regions poses global challenges, yet comprehensive risk assessment models addressing both ecological and human health impacts are scarce. This study introduces a novel multi-compartmental risk assessment framework applied to the Saldha River region of Gazipur, Bangladesh, a rapidly industrialising area experiencing significant environmental stress. Here, we analysed eight heavy metals (Cr, Pb, Cu, Fe, Mn, Zn, Ni, and Cd) in soil, wastewater, and plant samples (spinach, wild rice, and nut grass) via atomic absorption spectrophotometry (AAS). Ecological risks were evaluated through contamination factor (CF), pollution load index (PLI), and geo-accumulation index (Igeo), while human health risks were assessed using hazard indices (HI). Results revealed severe Cd contamination (enrichment factor 2563.19), indicating substantial anthropogenic influence. Correlation analysis of wastewater samples showed strong associations between metal pairs, such as Cu-Zn (0.92), Cu-Fe (0.90) and Zn-Mn (0.87), indicating common industrial sources. Transfer factor (TF) analysis in plants demonstrated substantial variability in metal uptake, with Mn and Ni showing the highest bioavailability, increasing risks to local food chains. Human health risk assessments indicated hazard indices (HI) exceeding safety thresholds for both adults and children, underscoring the urgent need for mitigation strategies. This study offers a novel, integrative framework for assessing multi-source contamination and provides critical baseline data for future environmental policy development. The model is adaptable to industrial regions worldwide, such as textile hubs in Southeast Asia or metal processing zones in Europe and North America, offering new insights into contamination pathways and risk management.

Unmasking heavy metal contamination: Tracing, risk estimating and source fingerprinting from coastal sediments of the Payra River in Bangladesh

The Payra River, cicual for fish breeding, feeding and nursery in coastal Bangladesh, faces heavy contamination from industrial activities, agricultural runoff and poor waste management. This study used ICP-MS to assess metal contamination levels, risk status and potential sources in river sediment. The findings showed that the mean concentrations (mg/kg) of metals followed the decreasing order: Mn (434.24 ± 75.91) > Zn (66.42 ± 12.86) > Cr (44.59 ± 8.98) > Ni (40.30 ± 7.43) > Cu (34.07 ± 6.84) > Co (15.72 ± 2.84) > Pb (14.60 ± 5.56) > As (4.70 ± 0.72) > Hg (0.28 ± 0.21) > Cd (0.10 ± 0.03) with Mn significantly exceeding the recommended guidelines. Although contamination factors (CF < 1) and the pollution load index (PLI < 1) indicated low pollution, Hg and Cd posed greater ecological risks. However, the Risk Index (RI < 150) showed overall low pollution risk. Sediment ranged from uncontaminated to moderately contaminated (Igeo = 0-1). Non-carcinogenic risks were minimal (HQ < 1), but children were more vulnerable to As (HI = 2.40E-01) and Cr (HI = 2.17E-01). Carcinogenic risks were also higher for children, particularly from As (CR = 8.37E-06) and Pb (CR = 6.10E-06). Pearson correlation, principal component analysis (PCA), cluster analysis (CA) and spatial analyses indicated shared sources for As, Hg, and Cd, with Mn likely from different sources. The PMF model identified three pollution sources: natural agricultural activities (23.7 %), anthropogenic activities (54.43 %), and industrial activities (23.74 %).

Microplastic characterization and factors influencing its abundance in coastal wetlands: insights from the world's largest mangrove ecosystem, Sundarbans

Water and sediment samples were collected from 20 sampling sites within two major river systems within the world's largest mangrove ecosystem. The primary objectives of the study were to determine MPs' abundance, composition, and potential ecological risks and to identify the factors influencing their distribution and characteristics. Results revealed MP abundances, ranging from 2 to 53 items/m3 in water and 17 to 177 items/kg in sediment. The most prevalent types of MPs were films, fragments, foams, and fibers, with the most abundant fragments. Transparent MPs of various colors, such as red, green, blue, white, and yellow, were commonly observed. Additionally, sizes of MPs ranged from < 0.5 to 5 mm, with particles < 0.5 mm dominating in water and 4-5 mm particles prevailing in sediment. Six major polymers were identified, including polystyrene (PS), polyamide (PA), Polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), and ethylene propylene diene monomer (EPDM), with PS being the most abundant in both river systems. Linear mixed effect models showed that factors, such as distance from Mongla port and water velocity impacted MP abundance in water, while distance from Mongla port, total organic carbon (TOC), and total phosphorus (TP) contents affected their distribution in sediment. The Shannon-Weaver Index revealed a higher MP diversity in the Shela River compared to the Pasur. Overall, the pollution load index (PLI) and polymeric hazard index (PHI) indicated that MPs impacted both river systems, but the finding from the ecological risk index (ERI) was negligible at the individual sites. Our study recommends the long-term monitoring of MP abundance and implementation of strict regulations to reduce MPs in aquatic environments and proposes various engineering and biotechnological approaches for effective MP remediation. Further research is needed to identify both point and non-point sources of MPs and develop comprehensive strategies and policies to mitigate plastic pollution in the mangrove ecosystem.

Occurrence, bioaccumulation, and partitioning of phthalate acid esters in the third largest freshwater lake (Lake Taihu) in China

Phthalate acid esters (PAEs) are a category of plasticizers that are ubiquitous in freshwater environments attributable to extensive utilization. We collected water, suspended particulate matter (SPM), surface sediments, phytoplankton, and zooplankton from 23 sampling sites to investigate and complement the occurrence, bioaccumulation, and partitioning of five PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), and di (2-ethylhexyl) phthalate (DEHP) in the third largest freshwater lake (Lake Taihu) of China. PAEs were extracted using Soxhlet extraction and solid phase extraction, and determined by gas chromatography-mass spectrometry. The average concentrations of the five PAEs in the water column, SPM, sediments, phytoplankton, and zooplankton of Lake Taihu were 1.93 ± 1.57 μg L-1, 765 ± 766 μg g-1, 1.68 ± 1.47 μg g-1, 1358 ± 1877 μg g-1, and 72.7 ± 134 μg g-1, respectively. DBP and DEHP were the dominant PAE congeners in the five environment compartments. The logarithmic concentrations of DBP, BBP, and DEHP in the SPM were negatively correlated with the logarithmic content of the SPM. Biodilution significantly impacted the occurrence of PAEs in the plankton. Bioaccumulation of PAEs was found in the plankton with log BCF (bioconcentration factor) in the phytoplankton ranging from 1.78 ± 0.86 to 4.13 ± 1.23 and log BAF (bioaccumulation factor) in the zooplankton varying from -0.10 ± 0.26 to 3.04 ± 0.64. Biomagnification of the PAEs from phytoplankton to zooplankton was not observed. DMP, DEP, and BBP migrated from sediments to water. DBP was in dynamic equilibrium in the sediment-water system. DEHP transferred from water to sediments. Our results provide crucial complementary knowledge on bioaccumulation and transfer of PAEs in planktonic food web, and their partitioning in different compartments of waters.

Assessment of heavy metal concentrations, environmental risks and human health implications in marine sediments along the coastal ecosystems of the Republic of Congo

The aim of this study is to assess the level of heavy metals (HMs) in surface sediments along the coastal estuaries of the Republic of Congo. A variety of approaches were employed, integrating elemental analysis (Atomique Absorption Spectroscopy), environmental, ecological, health risk assessment, and source identification techniques to evaluate the distribution, origin, environmental, ecological and health risks of potentially toxic element (PTE) contamination in sediments. The ascending mean concentration (mg/kg) of Cd (0.4) < Cu (18.6) < Pb (28.8) < Zn (62.1) < Mn (107) < Mg (569.6) complied with the local background, except for Cd and Pb. However, notable variations across sampling points and sites were observed, with a strong relationship between metals and organic matter. The comparing of PTEs with USEPA international standards and sediment toxicity guidelines showed compliance. The assessment of environmental risk parameters, based on the calculation of the geo-accumulation index, concentration factor and pollutant load indices showed low pollution of sediments. The ecological risk assessment, on the other hand, revealed a low level of pollution of biota and a low toxicity risk of ecosystems related to Cd and Pb and then to Cu in some sites. Regarding human health risk assessment, related to the PTEs, the cancerogenic effect indices were calculated for Cd and Pb through ingestion and inhalation pathways, and the non-cancerogenic effect indices were calculated for all HMs through ingestion, inhalation, and cutaneous contact routes, for children and adults, and showed that the results comply with the international standards set by USEPA, ranging from 10-4 to 10-6 and less than 1, respectively, where children were more sensitive and vulnerable than adults to the effects of the PTEs. Ultimately, this study revealed sediment lithology, anthropogenic activities, and mixed origins of HMs, with a large contribution from industrial activities. However, no significant impacts are discernible in the study area. In addition to the importance of this study, it forms part of the region database and could serve as a reference for future monitoring studies, since no data are available in th Congolese coastal environment.

Impact of anthropogenic activities and the associated heavy metal pollution in Sundarbans waterways: threats to commercial fish and human health

The exposure of fish to heavy metals is a significant concern for human health and natural ecosystems. Despite being a critical issue, the extent of contamination in tropical fish from developing countries like Bangladesh remains somewhat unexplored. In this study, ten economically vital fish species (Osteogeneiosus militaris, Arius gagora, Harpadon nehereus, Mugil ephalus, Pseudapocryptes elongates, Apocryptes bato, Labeo bata, Tenualosa toil, Notopterus notopterus, and Pampus chinensis) from the Pasur River, Bangladesh, were analyzed by atomic absorption spectrometer for the concentrations of four concerned heavy metals, viz., As, Cr, Cd, and Pb, and the associated human health risks. The mean concentrations (mg/kg) followed the order of As (3.30 ± 1.43) > Pb (2.32 ± 0.73) > Cr (0.63 ± 0.29) > Cd (0.37 ± 0.24). Additionally, the bioaccumulation factor of the metals in the investigated fish species followed a decreasing trend of As (824.75) > Cr (781.25) > Cd (744) > Pb (385.83). While most species fell below the minimum bioaccumulation line, a few exceptions were noted for some species specific to metals. Health risk assessments indicated no significant carcinogenic and non-carcinogenic risks for both children and adults, although children exhibited greater vulnerability to both types of health effects. Multivariate analysis and local perceptions supported the conclusion that heavy metals primarily originated from anthropogenic sources related to development activities adjacent to the riverine areas.

Assessment of heavy metals and proximate composition in jellyfish (Lobonemoides robustus Stiasny, 1920) collected from Cox's Bazar coast: Human health risk assessment

Jellyfish are known for experiencing periodic blooms in population, which occur when their density increases suddenly. The present study assessed the level of heavy metals and proximate composition in the jellyfish Lobonemoides robustus collected from Cox's Bazar coast of Bangladesh. This is the first study conducted in Bangladesh. Most of the studied metals were not possible to detect in L. robustus samples because concentrations were below the detection limit. Ca, Na, Se, and Mg were found to have safe levels in the L. robustus while the amount of Pb was recorded 0.39 ppm. The findings of Target Hazard Quotient, and Carcinogenic Risk indicate that the L. robustus is safe for human consumption (both for children and adults). Hence, it is suitable for consumption and can be exported. This study emphasizes the need for regular marine environment monitoring to ensure that the seafood harvested from these waters is safe for consumption.

Impacts of Some Trace Metals in Cyprinus carpio (Linnaeus, 1758) and Tor soro (Valenciennes, 1842) on Human Health

Although fish are rich sources of various trace metals in their bodies, when these metals exceed health safety limits, it becomes a global concern. Fish exposed to trace metal pollution in their aquatic ecosystems can lead to bioaccumulation and transfer to consumers. Monitoring trace metal contamination of fish food is crucial because they can reach humans through the aquatic food chain, resulting in health problems. Therefore, a first attempt was made for the analysis of trace metals in two cyprinid fish species, namely Cyprinus carpio (Common carp) and Tor soro (Mahseer), which were abundantly found in Khanozai Dam and assessing their potential health impacts when consumed by humans. A total of 200 fish specimens were collected from this area. These specimens were divided equally between the two carp species, with 100 individuals from each species. The fish specimens were collected over 12 months, from June 2020 to May 2021 to determine the concentration of some trace metals, i.e. Manganese (Mn), Calcium (Ca), Iron (Fe), Potassium (K), and Zinc (Zn), Sodium (Na), Phosphorus (P), Magnesium (Mg), and Chlorine (Cl) using a Flame Atomic Absorption Spectrophotometer with a multi-element hollow cathode lamp. The obtained results from the trace metal analysis of Cyprinus carpio and Tor soro in this study revealed that both calcium and phosphorus were present in higher concentrations. However, iron, manganese, and zinc were not detected in both species. Additionally, magnesium was also not detected in C. carpio. For Cyprinus carpio, the arrangement was Ca > P > K > Na > Cl, while for Tor soro, it was Ca > P > Na > K > Cl > Mg in decreasing order. The health risks associated with fish consumption were assessed using factors like estimated daily intake (EDI), Target Hazard Quotient (THQ), and Total Target Hazard Quotient (TTHQ). The THQ values for all analyzed trace metals in both carp species exceeded the maximum value of 1.0, except for Cl in Tor soro. This suggests the potential for various health-related diseases in regular consumers due to their elevated levels. In both species, the TTHQ factor also surpassed the standard value of 1.0, indicating an acute health risk for humans. Although EDI values did not surpass the recommended daily allowance (RDA), continuous consumption of these contaminated fish from this area could lead to severe health complications. Therefore, these results strongly indicated that the elevated levels of trace metals found in the highly abundant cyprinid species of Khanozai Dam could pose serious health-related issues for the local inhabitants.

Heavy metals in afforested mangrove sediment from the world's largest delta: Distributional mapping, contamination status, risk assessment and source tracing

This study aims to assess seasonal and spatial variations, contamination status, ecological risks, and metal sources (Ni, Pb, Cr, Cu, Mn, and Zn) in human-afforested mangrove sediments in a deltaic region. Five sampling locations were sampled during dry and wet seasons. Heavy metal concentrations followed the order: Mn > Zn > Ni > Cr > Cu > Pb. Metal loads, except Cu and Pb, were higher during the dry season, aligning with national and international recommendations. Sediment quality guidelines, contamination factor, geoaccumulation index, enrichment factors, and pollution load index indicated uncontaminated sediment in both seasons. Potential ecological risk assessment showed low risk conditions in all sites. However, modified hazard quotient indicated moderate pollution risk from all metals except Pb. Analysis suggests anthropogenic sources, particularly evident near shipbreaking yards in Sitakunda. While initially uncontaminated, ongoing metal influx poses a potential risk to mangrove ecosystems.

Ecological and public health risk assessment of potentially toxic elements in the surface sediments of the Pasur river estuary, Bangladesh

Potentially toxic elements (PTEs) in the surface sediments of the Pasur river estuary was investigated to assess its distribution, potential sources, and current dangers to ecological and public health. The Pasur River is a tidal, meandering, perennial river in south-western Bangladesh with a considerable number of fisheries and industrial activities. Sediment samples were collected from seven sampling points from January to December 2022 to assess the contamination level of six potentially toxic elements (Pb, Cr, Cd, As, Cu and Zn). Flame Atomic Absorption Spectrophotometer was utilized to detect the concentration of PTEs by following some sequential analytical procedure. Concentration of PTEs followed the reducing trend of Zn > Cr > Pb > As > Cu > Cd with the mean value of 61.04 > 49.15 > 26.58 > 10.28 > 6.28 > 1.59 mg/kg, respectively. The principle component and cluster analyses justified the anthropogenic source of the studied PTEs. The mean values of contamination factor (CF), geo-accumulation index (Igeo) and enrichment factor (EFc) showed that Pb and Cd were highly responsible for sediment (uncontaminated to moderate) contamination. Pollution load index (PLI) indicated higher pollution of sediments near the port areas. Potential ecological risk index (PERI) indicated low to moderate risks due to the contaminated sediment. However, the contamination of sediment was not associated with the non-carcinogenic (HQderm and HI < 1) and carcinogenic (CRderm < 10-6) risks due to the dermal contact. Although the risks were within the tolerable limit, regular monitoring is suggested to reduce the risk of PTEs contamination.

Assessing metal(loid)s-Induced long-term spatiotemporal health risks in Coastal Regions, Bay of Bengal: A chemometric study

Despite sporadic and irregular studies on heavy metal(loid)s health risks in water, fish, and soil in the coastal areas of the Bay of Bengal, no chemometric approaches have been applied to assess the human health risks comprehensively. This review aims to employ chemometric analysis to evaluate the long-term spatiotemporal health risks of metal(loid)s e.g., Fe, Mn, Zn, Cd, As, Cr, Pb, Cu, and Ni in coastal water, fish, and soils from 2003 to 2023. Across coastal parts, studies on metal(loid)s were distributed with 40% in the southeast, 28% in the south-central, and 32% in the southwest regions. The southeastern area exhibited the highest contamination levels, primarily due to elevated Zn content (156.8 to 147.2 mg/L for Mn in water, 15.3 to 13.2 mg/kg for Cu in fish, and 50.6 to 46.4 mg/kg for Ni in soil), except for a few sites in the south-central region. Health risks associated with the ingestion of Fe, As, and Cd (water), Ni, Cr, and Pb (fish), and Cd, Cr, and Pb (soil) were identified, with non-carcinogenic risks existing exclusively through this route. Moreover, As, Cr, and Ni pose cancer risks for adults and children via ingestion in the southeastern region. Overall non-carcinogenic risks emphasized a significantly higher risk for children compared to adults, with six, two-, and six-times higher health risks through ingestion of water, fish, and soils along the southeastern coast. The study offers innovative sustainable management strategies and remediation policies aimed at reducing metal(loid)s contamination in various environmental media along coastal Bangladesh.

Biomonitoring of mercury and selenium in commercially important shellfish: Distribution pattern, health benefit assessment and consumption advisories

This study aims to explore the concentrations of Se and Hg in shellfish along the Gulf of Mannar (GoM) coast (Southeast India) and to estimate related risks and risk-based consumption limits for children, pregnant women, and adults. Se concentrations in shrimp, crab, and cephalopods ranged from 0.256 to 0.275 mg kg-1, 0.182 to 0.553 mg kg-1, and 0.176 to 0.255 mg kg-1, respectively, whereas Hg concentrations differed from 0.009 to 0.014 mg kg-1, 0.022 to 0.042 mg kg-1 and 0.011 to 0.024 mg kg-1, respectively. Se and Hg content in bamboo shark (C. griseum) was 0.242 mg kg-1 and 0.082 mg kg-1, respectively. The lowest and highest Se concentrations were found in C. indicus (0.176 mg kg-1) and C. natator (0.553 mg kg-1), while Hg was found high in C. griseum (0.082 mg kg-1) and low in P. vannamei (0.009 mg kg-1). Se shellfishes were found in the following order: crabs > shrimp > shark > cephalopods, while that of Hg were shark > crabs > cephalopods > shrimp. Se in shellfish was negatively correlated with trophic level (TL) and size (length and weight), whereas Hg was positively correlated with TL and size. Hg concentrations in shellfish were below the maximum residual limits (MRL) of 0.5 mg kg-1 for crustaceans and cephalopods set by FSSAI, 0.5 mg kg-1 for crustaceans and 1.0 mg kg-1 for cephalopods and sharks prescribed by the European Commission (EC/1881/2006). Se risk-benefit analysis, the AI (actual intake):RDI (recommended daily intake) ratio was > 100%, and the AI:UL (upper limit) ratio was < 100%, indicating that all shellfish have sufficient level of Se to meet daily requirements without exceeding the upper limit (UL). The target hazard quotient (THQ < 1) and hazard index (HI < 1) imply that the consumption of shellfish has no non-carcinogenic health impacts for all age groups. However, despite variations among the examined shellfish, it was consistently observed that they all exhibited a Se:Hg molar ratio > 1. This finding implies that the consumption of shellfish is generally safe in terms of Hg content. The health benefit indexes, Se-HBV and HBVse, consistently showed high positive values across all shellfish, further supporting the protective influence of Se against Hg toxicity and reinforcing the overall safety of shellfish consumption. Enhancing comprehension of food safety analysis, it is crucial to recognize that the elevated Se:Hg ratio in shellfish may be attributed to regular selenoprotein synthesis and the mitigation of Hg toxicity by substituting Se bound to Hg.

Quantification, characterization and risk assessment of microplastics from five major estuaries along the northern Bay of Bengal coast

Microplastics (MPs) as hazardous contaminants has drawn the rapid attention of the general public due to their omnipresence and adverse impacts on ecosystems and human health. Despite this, understanding of MPs contamination levels in the estuarine ecosystems along the Bay of Bengal coast remains very limited. This research focused on the presence, spatial distribution, morpho-chemical characteristics and ecological implications of MPs in water and sediment from five key estuaries (Meghna, Karnaphuli, Matamuhuri, Bakkhali, and Naf rivers) within the Bengal delta. Out of the five estuaries, the Meghna exhibited the least amount of MPs in both surface water (150.00 ± 65.62 items/m3) and sediment (30.56 ± 9.34 items/kg). In contrast, the highest occurrence of MPs was recorded in Karnaphuli river water (350.00 ± 69.22 items/m3) and Matamuhuri river sediment (118.33 ± 26.81 items/kg). ANOVA indicated a statistically significant distinction (p < 0.01) among the examined estuaries. Most identified MPs were fibers and < 0.5 mm in size in both water and sediment samples. Transparent MPs were dominant in both water (42.28%) and sediment (45.22%). Besides violet, red, blue, pink and green colored MPs were also observed. Various polymer types, including PE, PP, PET, PS, Nylon, EVA, and ABS, were detected, with PE being the dominant one. Based on the polymer risk index (PHI), the estuaries were classified as hazard level V, signifying a severe level of MP contamination. However, the potential ecological hazardous index (PHI), potential ecological risk index (RI), and pollution load index (PLI) indicated moderate pollution levels. This study offers initial insights into the pollution caused by MPs in major estuaries of Bengal delta, which policymakers can utilize to implement suitable management strategies.

Bioaccumulation and sources of metal(loid)s in fish species from a subtropical river in Bangladesh: a public health concern

Toxic metals and freshwater fish's metalloid contamination are significant environmental concerns for overall public health. However, the bioaccumulation and sources of metal(loids) in freshwater fishes from Bangladesh still remain unknown. Thus, the As, Pb, Cd, and Cr concentrations in various freshwater fish species from the Rupsha River basin were measured, including Tenualosa ilisha, Gudusia chapra, Otolithoides pama, Setipinna phasa, Mystus vittatus, Glossogobius giuris, and Pseudeutropius atherinoides. An atomic absorption spectrophotometer was used to determine metal concentrations. The mean concentrations of metal(loids) in the fish muscle (mg/kg) were found to be As (1.53) > Pb (1.25) > Cr (0.51) > Cd (0.39) in summer and As (1.72) > Pb (1.51) > Cr (0.65) > Cd (0.49) in winter. The analyzed fish species had considerably different metal(loid) concentrations with seasonal variation, and the distribution of the metals (loids) was consistent with the normal distribution. The demersal species, M. vittatus, displayed the highest bio-accumulative value over the summer. However, in both seasons, none of the species were bio-accumulative. According to multivariate statistical findings, the research area's potential sources of metal(loid) were anthropogenic activities linked to geogenic processes. Estimated daily intake, target hazard quotient (THQ), and carcinogenic risk (CR) were used to assess the influence of the risk on human health. The consumers' THQs values were < 1, indicating that there were no non-carcinogenic concerns for local consumers. Both categories of customers had CRs that fell below the permissible range of 1E - 6 to 1E - 4, meaning they were not at any increased risk of developing cancer. The children's group was more vulnerable to both carcinogenic and non-carcinogenic hazards. Therefore, the entry of metal(loids) must be regulated, and appropriate laws must be used by policymakers.

Contamination and ecological risk assessment of Cr, As, Cd and Pb in water and sediment of the southeastern Bay of Bengal coast in a developing country

Safe levels of heavy metals in the surface water and sediment of the eastern Bay of Bengal coast have not been universally established. Current study characterized heavy metals such as arsenic (As), chromium (Cr), cadmium (Cd) and lead (Pb) in surface water and sediments of the most important fishing resource at the eastern Bay of Bengal coast, Bangladesh. Both water and sediment samples were analyzed using inductively coupled plasma mass spectrometer. Considering both of the seasons, the mean concentrations of Cr, As, Cd, and Pb in water samples were 33.25, 8.14, 0.48, and 21.14 μg/L, respectively and in sediment were 30.47, 4.48, 0.20, and 19.98 mg/kg, respectively. Heavy metals concentration in water samples surpassed the acceptable limits of usable water quality, indicating that water from this water resource is not safe for drinking, cooking, bathing, and any other uses. Enrichment factors also directed minor enrichment of heavy metals in sediment of the coast. Other indexes for ecological risk assessment such as pollution load index (PLI), contamination factor (CF), geoaccumulation index (Igeo), modified contamination degree (mCd), and potential ecological risk index (PERI) also indicated that sediment of the coastal watershed was low contamination. In-depth inventorying of heavy metals in both water and sediment of the study area are required to determine ecosystem health for holistic risk assessment and management.

Distribution, characterization and contamination risk assessment of microplastics in the sediment from the world's top sediment-laden estuary

Microplastics (MPs) have gained a serious attention as an emerging contaminant throughout the world because of their persistence and possible risks to aquatic ecosystems and human well-being. However, knowledge on MPs contamination from sub-tropical coastal systems is limited, and no study has been conducted on the MPs contamination in sediment from one of the highest sediment-laden estuaries, Meghna River, in the world. This is the first study to examine the quantity, morpho-chemical characteristics and contamination risk level of MPs from this large scale river. MPs were extracted from the sediment samples of 10 stations along the banks of the estuary by density separation, and then characterized using a stereomicroscope and Fourier Transform Infrared (FTIR) spectroscopy. The incidence of MPs varied from 12.5 to 55 item/kg dry sediment with an average of 28.67 ± 10.80 item/kg. The majority (78.5%) of the MPs were under 0.5 mm in size, with fibers being the most (74.1%) prevalent MPs type. Polypropylene (PP) was found to be the predominant polymer (53.4%), followed by polyethylene (PE, 20%), polystyrene (PS, 13.3%), and polyvinyl chloride (PVC, 13.3%). The highest occurrence of PP indicted the MPs in the estuary might be originated from clothing and dying industries, fishing nets, food packages, and pulp industries. The sampling stations were contaminated with MPs as shown by the contamination factor (CF) values and pollutant load index (PLI), both of which were >1. This study exposed new insights on the status of MPs in the sediments of the Meghna River, laying the groundwork for future research. The findings will contribute to estimate the global share of MPs to the marine environment.

Assessment of environmental parameters effect on potentially toxic elements mobility in foreshore sediments to support marine-coastal contamination prediction

Potentially toxic elements (PTEs) presence in marine sediments can significantly affect the environmental quality and negatively influence economy and recreational activities in related areas. Accordingly, contamination monitoring and control in the marine environment is a fundamental task. In this work, four PTEs behavior (i.e. As, Hg, Pb, and Zn) in sandy foreshore sediments (SFSs) was thoroughly investigated at different pH, redox potential and temperature conditions of the marine water. For all the tests, the released As was 2.7-6 times higher than its initial concentration in water. Nonetheless, final mass balances showed that preferential release in the liquid phase occurred for Pb and Hg (up to 10 % and 9.1 %, respectively). Moreover, final Zn and Hg content increase in SFSs labile fractions indicated their higher bioavailability after the tests. The obtained results outline an approach useful to predict the contaminants behavior in marine matrices and support environmental monitoring and preservation strategies.

Trace metal exposure and human health consequences through consumption of market-available Oreochromis niloticus (L.) in Bangladesh

Using Oreochromis niloticus (L.), commonly known as tilapia, as a model, this study evaluated the exposure of trace metal and their risk assessment on human health. In addition, the status of amino acids, fatty acids, vital elements, and their benefits is also studied. Estimating the nutrient composition of fish muscle is necessary to ensure that it meets the requirements for human health, food regulations, and commercial specifications. The species examined contained appreciable concentrations of amino acids, fatty acid content, and minerals, suggesting that the fish species could be a good source of protein, fat, and minerals. Hazardous heavy metals were found to be lower compared to their corresponding maximum tolerable limits. The order of trace metals is Zn (22,709 µg/kg) > Fe (19,878 µg/kg) > Cu (1261 µg /kg) > Mn (1228 µg/kg) > Cr (474 µg/kg) > Ni (152 µg/kg) As (318 µg /kg) > Pb (281 µg/kg) > Co (24 µg /kg) > Cd (13 µg/kg) > Hg (5 µg/kg); a number of health-related indices, including estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI), as well as carcinogenic risk (CR) indices for adult and children, were calculated to evaluate the human health hazard of the heavy metals. The THQ and HI of heavy metals for tilapia are lower than 1, posing a non-carcinogenic threat to human health due to the biomagnifications of these deadly poisonous metals. Principal component, cluster, and correlation analyses delineated the common probabilistic sources of metal contamination origin and significant inter-parameter associations. Although no human health risks for the consumption of tilapia was found, more attention must be paid for the monitoring of Oreochromis niloticus before entering the market.

Health risk assessment of heavy metals (Zn, Pb, Cd, and Hg) in water and muscle tissue of farmed carp species in North Iran

This cross-sectional study was conducted to determine and compare the concentrations of heavy metals (Zn, Pb, Cd, and Hg) in carp-farming water and muscle of various carp species including common carp (Cyprinus carpio), bighead carp (Hypophthalmichthys nobilis), silver carp (Hypophthalmichthys molitrix), and grass carp (Ctenopharyngodon idella) collected from three major warm-water fish farms in Mazandaran Province (Iran) during March 2018 to March 2019. In addition, bioaccumulation of heavy metals (BCFs) and carcinogenic and non-carcinogenic risk assessments of consumers exposed to heavy metals through fish consumption were estimated. The water concentration of all metals in this study was lower than permissible limits. The concentration of Zn in the water (10.21-17.11 μg L^-1) was higher than that of other metals in all sites, followed by Pb > Cd > Hg. In fish muscle, Zn concentration in silver carp was the highest, and the lowest concentrations were related to Hg and Cd in common carp and grass carp, respectively. The target hazard quotients (THQ) indicated that the non-carcinogenic health risk to humans was relatively low by consuming four farmed carp species products. The carcinogenic risk of inorganic Pb was 1.24E-04 (common carp) to 2.11E-04 (grass carp) for adults, which is within the acceptable range. The values of BCFs for all metals demonstrated that farmed carp muscle could not be considered a bioaccumulative tissue for heavy metals. The results indicated that the concentrations of heavy metals in the farmed carp species in North Iran were relatively low and did not cause considerable human health risks.

Heavy Metals in Four Marine Fish and Shrimp Species from a Subtropical Coastal Area: Accumulation and Consumer Health Risk Assessment

Trace-element or heavy-metal pollution has emerged as a serious concern in terms of both environmental and human health issues. This study measured six trace and toxic heavy metals (Pb, Cd, Cr, Ni, Cu, and Zn) in four marine fish and shrimp species to assess their accumulation levels and evaluate the risks to human health. The mean concentrations of the metals in fish and shrimp species (Labeo bata, Sillaginopsis panijus, Platycepalus fuscus, and Penaeus monodon) followed the decreasing order of Zn (40.8 ± 9.7 μg/g) > Cu (17.8 ± 7.1 μg/g) > Pb (6.2 ± 1.8 μg/g) > Ni (0.4 ± 0.3 μg/g) > Cd (0.06 ± 0.02 μg/g > Cr (below detection level). Among the metals, only Pb in finfish and Pb, Cu, and Zn in shrimp samples exceeded the national recommended limits, representing possible risks to consumers. The mean metal concentrations in the studied fish/shrimp species followed the descending order of P. monodon > S. panijus > P. fuscus > L. bata, which implies that bottom dwellers and omnivores had higher levels of metals. However, the estimated daily intake (EDI) concentrations of Zn and Cu for the studied species were lower than the RDA (Recommended Daily Allowance). In addition, the Target Hazard Quotient (THQ) and hazard index (HI or TTHQ) values for all species were < 1, indicating that consumers might not experience carcinogenic health risks. A strong significant (p < 0.05) correlation between Cu and Pb (r = 0.623) and Zn and Cu (r = −0.871) indicated they were from the same source of origin. Cluster analysis (CA) and principal component analysis (PCA) demonstrated possible anthropogenic sources of toxic metals in the study area, specifically industrial wastes and agricultural chemicals.

Distribution and source apportionment of toxic and trace elements in some benthic and pelagic coastal fish species in Karnaphuli River Estuary, Bangladesh: Risk to human health

The Karnaphuli River is one of the prime and most important streams in the southeastern part of Bangladesh. The favorable water current and the geographic location have rendered the Karnaphuly River estuary a suitable habitat and a breeding ground for diverse fish species. Reversely, this estuary has been polluted by discharges from many point and non-point sources due to its location in the catchment area of a heavily industrialized area, Chattagram port city. However, published research concerning the status of toxic and trace elements in some commercially important benthic and pelagic coastal fish species in Karnaphuli River estuary was not found in the existing literature. Therefore, it's an important field of study on the assessment of toxic and trace elements concentration in the commercially important benthic and pelagic coastal fish species and their health taxation in the Karnaphuli River Estuary. Energy dispersive X-ray fluorescence (ED-XRF) was used to quantify trace metal concentration in edible parts of the fish species. This study revealed that the rank of the trace metals concentration was as follows (mg/kg): Zn (37.1) > Mn (16.12) > V (11.16) > Cu (9.49) > Rb (5.62) > Pb (2.98) > Cr (1.59) > Co (1.17). The F-test showed that a significant difference at 95 % confidence level in the distribution pattern of trace metals concentration among the examined fish species in the study area. The metal pollution index (MPI) in the muscle of fishes were found to be in the following order: L. bata > P. monodon > T. cirratus > M. bleekeri > O. pabda > H. nehereus > L. calcarifer > P. argenteus > P. paradiseus > T. toli, and the MPIs for most of the benthic fish species were higher compared to the pelagic fishes. On the other hand, the examined fish species were significantly bio-accumulative with the highest bio-accumulation factor value for benthic species. The multivariate analysis identified that the sources of the trace metals were associated with anthropogenic activities. For the human health risk assessment concern, estimated daily intake, target hazard quotient and cancer-causing risk were estimated. The results for non-cancer hazardous index values were found to be lower than unity. On the other hand, the total cancer risk data ranging from 1.24E-05 to 1.70E-05 were fallen within the range for the threshold values (1.0E-06 to 1.0E-04). However, considering the suggested values set by the environmental and regulatory agencies, it has been recommended that no significant non-carcinogenic and cancer-causing health risk for humans was seen due to the consumption of the studied fish species.

Seasonal behavior and accumulation of some toxic metals in commercial fishes from Kirtankhola tidal river of Bangladesh - A health risk taxation

Contamination of fish with heavy metals (Heavy metals) is one of the most severe environmental and human health issues. However, the contamination levels in tropical fishes from Bangladesh are still unknown. To this end, the evaluated concentrations of arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in 12 different commercially important fish species (Tenualosa ilisha, Gudusia chapra, Otolithoides pama, Setipinna phasa, Glossogobius giuris, Pseudeutropius atherinoides, Polynemus paradiseus, Sillaginopsis panijus, Corica soborna, Amblypharyngodon mola, Trichogaster fasciata, and Wallago attu) were collected from the Kirtankhola River assess human health risk for the consumers, both in the summer and winter seasons. Toxic metals surpassed the acceptable international limits in P. atherinoides, P. paradiseus, S. panijus, C. soborna, and W. attu. The target hazard quotient (THQ) revealed that non-carcinogenic health effects (HI < 1) for children and adults, and the carcinogenic risk (CR) indicated safety. Results show that children are more susceptible to carcinogenic and non-carcinogenic hazards from higher As. The multivariate analysis justified that heavy metals were from anthropogenic actions. The lessening of toxic metals might need strict rules and regulations as metal enrichment would continue to increase in this tidal river from both the anthropogenic and natural sources.

Toxic metal pollution and ecological risk assessment in water and sediment at ship breaking sites in the Bay of Bengal Coast, Bangladesh

Quantification of four toxic metals (As, Cr, Cd, and Pb) in water and sediments at the Sitakunda ship breaking area in Bangladesh was studied. Along with this, sediment quality and ecological risk were evaluated for the metal intrusion to the study area. A total sample number of 120 (water; n = 60 and sediment; n = 60) were analyzed for both winter and summer seasons using atomic absorption spectrophotometer (AAS). The trace metal concentration in both water and sediment showed decreasing trend as follows; Cr (mean-W: 0.118 mg/L; mean-S:121.87 mg/kg) > Pb (mean-W: 0.064 mg/L; mean-S: 65.31 mg/kg) > As (mean-W: 0.03 mg/L; mean-S: 32.53 mg/kg) > Cd (mean-W: 0.004 mg/L; mean-S: 4.81 mg/kg). However, in both segments, the concentrations of the toxic metals exceeded the recommended acceptable limits. As and Cd showed significant variation (water and sediment) between the seasons, while Pb and Cr had no seasonal impact. Metal pollution index (MPI) and contamination factor (CF) was evaluated and revealed that the study area exhibited the critical score of water quality (MPI > 100). The cumulative effect of the metal concentrations was high (CI > 3). The assessed mean geoaccumulaiton index (I_geo) revealed that the study area was moderate to strongly polluted except for Cr. According to the contamination factor (CF), the sediment samples were moderate to highly contaminated by Cd, Pb, and As. Moreover, the explored range of pollution load index (PLI) in all sampling sites in the ship breaking region was from 1.75 to 3.10, suggesting that the sediment in the study area was highly polluted by heavy metals (PLI > 1). The risk index and the potential ecological risk index (PERI) suggested that the study area was at high risk due to metals pollution. Therefore, it is obligatory to maintain some crucial efforts for the betterment of the surrounding environment near the investigated sites.

Assessment of contamination level, pollution risk and source apportionment of heavy metals in the Halda River water, Bangladesh

This study demonstrates the level of heavy metal pollution in the Halda River, the only natural breeding source of carps in Bangladesh. Water was collected from 12 different sampling points along the Halda River. Water at various locations was found satisfactory in terms of the assessed physicochemical parameters (pH, electrical conductivity, and total dissolved solids). The presence of various cations and anions was also studied using ion chromatography. Atomic absorption spectroscopy was used to identify and quantify various heavy metals in the collected water samples. Among the heavy metals, Cd, Cr, Fe, Pb, Cu, and As concentration exceeded the safe limit suggested by WHO. The calculated heavy metal pollution index and metal index were found higher than the critical index value. The single-factor assessment (P _i) and Nemerow's multi-factor index (P _N) of heavy metals was calculated to find out the degree of pollution in the Halda River. The maximum values of P _i (Cd), P _i (Pb), P _i (As), P _i (Cu), and P _i (Cr) were determined to be 26.67, 260.00, 17.00, 208.76 and 2.80 respectively. The maximum value of P _N was found to be 289.04. The discharge of effluents from various large and small industries near the Halda River is considered to be the major source of the identified heavy metals. Multivariate statistical analysis such as principal component analysis, Pearson correlation matrix and cluster analysis revealed that most of the heavy metals originated from different anthropogenic sources. Multivariate analysis also showed that Co, Mn, Cu, Cr, Pb, Cd, NH₄⁺, NO₃^- mainly came from artificial sources whereas Fe, Ca, As mainly originated from natural sources. Arsenic (As) also came from artificial sources with Cu.

Phytoremediation of Toxic Metals: A Sustainable Green Solution for Clean Environment

Contamination of aquatic ecosystems by various sources has become a major worry all over the world. Pollutants can enter the human body through the food chain from aquatic and soil habitats. These pollutants can cause various chronic diseases in humans and mortality if they collect in the body over an extended period. Although the phytoremediation technique cannot completely remove harmful materials, it is an environmentally benign, cost-effective, and natural process that has no negative effects on the environment. The main types of phytoremediation, their mechanisms, and strategies to raise the remediation rate and the use of genetically altered plants, phytoremediation plant prospects, economics, and usable plants are reviewed in this review. Several factors influence the phytoremediation process, including types of contaminants, pollutant characteristics, and plant species selection, climate considerations, flooding and aging, the effect of salt, soil parameters, and redox potential. Phytoremediation’s environmental and economic efficiency, use, and relevance are depicted in our work. Multiple recent breakthroughs in phytoremediation technologies are also mentioned in this review.

Vertical distribution and contamination assessment of heavy metals in sediment cores of ship breaking area of Bangladesh

Vertical heavy metal profiling reflects the history of the deposition of metals and helps to understand the characteristics of accumulation in various layers of the sediment. Nevertheless, no previous studies in Bangladesh had focused on the vertical distribution of heavy metals in core sediments. In this study, vertical distribution, contamination level and potential ecological risks of six heavy metals (Zn, Cu, Pb, Cr, Ni, Mn) from the core sediment of ship breaking were assessed and compared with the non-ship breaking area of Bangladesh. The concentration (µg/g) of heavy metals in the 0-10 cm (surface), 10-20 cm (middle) and 20-30 cm (bottom) of sediment cores was as follows, respectively: Zn (35.54-100.68, 37.27-258.02, 42.78-66.45); Cu (16.38-75.25, 30.64-92.02, 34.99-52.98); Pb (4.84-132.08, BDL-204.48, BDL-23.51); Cr (14.57-42.13, 25.31-42.71, 15.26-36.34); Ni (4.02-42.23, 4.94-43.70, 4.40-43.13); Mn (198.74-764.16, 257.77-980.50, 255.62-856.44). The heavy metal content of core sediment from the shipbreaking region was substantially higher than that of non-shipbreaking area. Except for Ni, heavy metal content was highest in the middle layer, followed by the upper and lower layers of the sediment core. Contamination exponents such as enrichment factor, contamination factor and geo-accumulation index (Igeo) revealed contamination by Zn, Cu and Pb while potential ecological risk factor ([Formula: see text]) and risk index suggested low ecological risk by studied heavy metals except for Pb. Correlation matrix, cluster analysis and principal component analysis indicated that all studied heavy metals could have similar anthropogenic origins.

Tracing the heavy metals zinc, lead and nickel in banana shrimp (Penaeus merguiensis) from the Persian Gulf and human health risk assessment

Seafood has long been considered a unique source of nutrition. However, increasing trends in consumption of marine products must be considered, especially in potentially polluted environments such as the Persian Gulf. This study was undertaken to analyse the level of heavy metal contamination of nickel (Ni), zinc (Zn), and lead (Pb) in shrimp (Penaeus merguiensis) captured from the northern Persian Gulf. The concentration of heavy metals in the muscle of shrimp followed the order Zn > Ni > Pb. The content of Zn and Ni was higher than recommended standard limits by the FAO/WHO. The combined impact of all metals was lower than the acceptable limit of 1 in shrimp. The carcinogenic risk for Ni was higher than the unacceptable value. In total, our finding indicated no potential health risk from the daily consumption of this species. However, long-term consumption of shrimp can pose a risk of carcinogenic effects of nickel. Continuous monitoring of these trace metals in seafood is necessary to ensure the quality of seafood and food safety.

Trophic transfer of heavy metals in the marine food web based on tissue residuals

Trophic transfer of metals has been well researched in aquatic food webs; however, most studies have examined the presence of metal residuals in the entire body of marine organisms and but not in specific tissues. In this study, we determined the concentrations of Cu, Cr, Pb, Zn, Cd, and Ni in various organs of 17 marine species, including crustaceans, gastropods, bivalves, and fishes, with different trophic levels (TLs), which were collected from the Liaodong Bay, China, in July 2019. Results showed that the liver, gill, and muscle tissues of marine species are ideal indicators for analyzing Cu, Cr, Pb, Zn, Cd, and Ni contamination in marine environments. When the entire bodies of these marine species were considered, a bio-dilution in Cu, Cr, Pb, Zn, Cd, and Ni was observed in the studied food web. In contrast, the metal tissue-specific bio-magnification in the entire studied food web showed different results. In the liver and gill tissues, negative correlations were found between the concentrations of cadmium and TLs, while copper bio-dilution was also observed in gill tissue. In the muscle tissues, Cu, Pb, and Ni showed bio-dilution and trophic magnification factors of Cu, Pb, and Ni ranged from 0.44 to 0.73. This study highlights the importance of tissue-specific considerations to obtain further accurate information on metal trophodynamics and trophic transfers in marine food webs, thereby enhancing the risk assessment of many elements in wildlife and human health.

Urban river pollution in Bangladesh during last 40 years: potential public health and ecological risk, present policy, and future prospects toward smart water management

River water is very much important for domestic, agriculture and industrial use in Bangladesh which is in critical condition from long time based on research data. During last 40 years, extreme pollution events occurred in peripheral rivers surrounding Dhaka city and Karnaphuli River in Chittagong city. Present data showed that other urban rivers are also in critical condition especially Korotoa, Teesta, Rupsha, Pashur and Padma. The pollutants flowing with water made a severe pollution in downstream areas of rivers. Metals concentrations in river water was found to be higher in dry season. Dissolve oxygen (DO) was nearly zero in Buriganga River and several points in Turag, Balu, Sitalakhya and Karnaphuli River. NO₃^-, NO₂^- and PO₄^3- pollution occurred in different rivers. Zn, Cu, Fe, Pb, Cd, Ni, Mn, As and Cr concentration was above drinking water standard in most of the river and some metals was even above irrigation standard in water from several rivers. Sediment data showed very much higher metal concentrations in most of the rivers especially peripheral rivers in Dhaka and Karnaphuli, Korotoa, Teesta, Rupsha and Meghna River. Metal concentrations in sediment was above US EPA threshold value in most of the rivers. Metal concentrations in fish and agricultural crops showed that bioaccumulations of metals had occurred. The concentration of metals showed the trend like: water<fish<sediment. Agricultural crops were found to contain toxic metals through polluted water irrigation. The calculated data of daily intake for the non-carcinogenic and carcinogenic showed that consumption of the contaminated foodstuff can cause serious health injuries.

Bioaccessibility-corrected health risk of heavy metal exposure via shellfish consumption in coastal region of China

A systematic investigation into bioaccessible heavy metals in shellfish Crassostrea ariakensis, Chlamys farreri, and Sinonovacula constricta from coastal cities Shenzhen, Zhoushan, Qingdao, and Dandong was carried out to assess the potential health risk to residents in coastal regions in China. The bioaccessible fractions of heavy metals were (μg‧g-1): Zn (0.63-15.01), Cu (0.10-12.91), Cd (0.01-0.64), As (0.11-0.33), Cr (0.07-0.12), Pb (0.01-0.03). The bioaccessibilities of heavy metals were Cr 61.86%, inorganic As (iAs) 60.44%, Pb 55.74%, Cu 46.83%, Zn 28.16%, and Cd 24.99%. As for child and adult, the bioaccessibility-corrected estimated daily intakes were acceptable and the non-carcinogenic risks posed by heavy metals were not obvious. The carcinogenic risks posed by bioaccessible heavy metals at the fifth percentile were 10-fold higher than the acceptable level (10-4), with iAs and Cd to be the major contributors, regardless of child or adult. The probabilistic estimation showed the low risk of shellfish consumption, which was verified by higher values of maximum allowable consumption rate and monthly meals at the 95 percentile; while some control of consumption rate and monthly meals was necessary for reducing heavy metal exposure of most shellfish samples, except for the safe consumption of S. constricta for both child and adult in Qingdao and Shenzhen, China.