Occurrence, distribution and possible sources of polychlorinated biphenyls (PCBs) in the surface water from the Bay of Bengal coast of Bangladesh.

Full profile of polychlorinated biphenyls (PCBs) in the coastal surface water from Bangladesh were analyzed by GC-MS/MS to explore the status of contamination, spatiotemporal distribution and to trace their potential sources. The total concentrations of dissolved PCBs (∑PCBs, sum of all congeners) varied from 32.17 to 160.7 ng/L and 46.45-199.4 ng/L in winter and summer, respectively, and the ranges were comparable to or higher than those recorded in the surface water from the coastal areas of India, China, Japan, Italy, Belgium and USA. The difference in the levels of PCBs between the two seasons was not statistically significant (p > 0.05). However, spatial distribution revealed that the areas with recent urbanization and industrialization (Chittagong, Cox's Bazar and Sundarbans) were more contaminated with PCBs than the unindustrialized area (Meghna Estuary). Lightly to moderately chlorinated (2-6 Cl) homologs dominated the PCB profiles. Our analyses (congener profile and homolog composition) elucidated that the past and on-going use of PCB-containing equipment (e.g. capacitors and transformers) as well as the anthropogenic activities such as urban developments, commercial and industrial establishments (e.g. ship breaking and port activities) might be the potential sources of PCB emission in Bangladesh. A set of congeners based on their detection frequencies and abundance were identified and categorized as potential environmental marker PCBs, which can be used for the future selective monitoring studies regarding reasonable limitations on full congener assessment. According to the existing national and international water quality guidelines/standards, PCB concentrations recorded in this study could potentially cause biological damage. Essentially, the findings of this first comprehensive report on the PCB contamination in the surface water in Bangladesh may provide a reference to future studies of these compounds in the Bay of Bengal.

Trophodynamics and parabolic behaviors of polycyclic aromatic hydrocarbons in an urbanized lake food web, Shanghai.

Understanding the trophic movement and trophic magnification factor (TMF) of polycyclic aromatic hydrocarbons (PAHs) is an important criterion to assess their fate and potential effects in an aquatic ecosystem. This study investigated concentrations and trophodynamics of 16 priority PAHs in food webwb (food web comprising whole bodies) and food webm (food web containing only muscles) of total 14 species ((including plankton, shrimp, whitebait, mussels, snails, red-eared terrapin and seven other fish species) from the Dianshan Lake. Values of δ13C and δ15N were determined to assign trophic levels to organisms. In general, there was no evidence of biomagnification because of biological degradation of PAHs compounds, but only 9 PAH compounds in food webm showed a statistically significant negative relationship between trophic level and lipid normalized concentration compared to the 6 PAHs congeners in food webwb. However, TMF values of PAHs in food webm ranged from 0.32 for pyrene to 0.68 for phenanthrene compared to TMF values of food webwb ranged from 0.34 for pyrene to 0.74 for fluorene. Because of two opposing scientific views for biomagnification and biodilution of PAHs in the food web, albeit based on a rather limited number of studies, our study investigated that there is parabolic behavior of most of the PAHs. Concentrations of PAHs in the red-eared terrapin (Trachemys scripta elegans) were biodiluted which showed that this species metabolises such compounds. There was no particular relationship between Kow and TMFs of PAHs in the Dianshan Lake. Hepatobiliary system (such as gall bladder and liver) in the whole body considered to have higher bioaccumulation potential of organic compounds than extrahepatic tissue (muscles).

Distribution, Source Apportionment, and Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in the Surficial Sediments from the Coastal Areas of Bangladesh.

The surficial sediments were collected in winter and summer (2015) from the coastal areas of Bangladesh and analyzed for 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs). The total concentration of PAHs (∑PAHs) were 349.8-11,058.8 and 199.9-17,089.1 ng/g dry weight (dw) in winter and summer, respectively. Sediements from the areas with recent urbanization and industrialization (Chittagong, Cox's Bazar, and Sundarbans) were more contaminated with PAHs than the unindustrialized area (Meghna Estuary). The concentrations of ∑PAHs were slightly higher in summer than those in winter, but the seasonal variations were not statistically significant (p > 0.05). Molecular ratios suggested mixed sources of PAHs in the Bangladeshi coastal areas with a slight imposition of pyrolytic inputs closely related to shipping and fishing activities as well as industrial and municipal sewage discharge. According to ecological risk assessment, the measured levels of sedimentary PAHs exceeded some of the existing national and international environmental quality guidelines/standards, and thus might cause acute biological damage in the studied areas of the Bay of Bengal coast of Bangladesh.

Distribution of polycyclic aromatic hydrocarbons (PAHs) in commonly consumed seafood from coastal areas of Bangladesh and associated human health implications.

Levels, distribution, possible sources and potential risks of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) were investigated comprehensively in frequently consumed seafood species collected from the coastal areas of Bangladesh. Samples were collected in winter and summer, 2015. The total concentration of PAHs (∑PAHs) in the examined seafood was 184.5-2806.6 ng/g wet weight (ww) in winter and 117.9-4216.8 ng/g ww in summer, respectively. The levels of ∑PAHs were comparable to or higher than those reported from other coastal areas. Seasonal variation was not significant for the majority of the monitored PAHs. Spatial distribution revealed that the seafood collected from areas with recent urbanization and industrialization (Chittagong, Cox's Bazar and Sundarbans) was more contaminated with PAHs than those from the unindustrialized area (Meghna Estuary). Low-molecular-weight isomers dominated the PAH composition. Molecular ratios suggested the abundance of mixed sources of PAHs in the Bangladeshi coastal areas with a slight imposition toward the petrogenic origin. A preliminary evaluation of human health risk indicated that the dietary PAH exposure from consumption of Bangladeshi seafood would certainly induce adverse health effects. This finding suggests the need to enhance risk management regarding seafood consumption through public advisory in Bangladesh.

Occurrence and ecological risk of pharmaceuticals in river surface water of Bangladesh.

Pharmaceutical contamination in the aquatic environment is a global issue that affects aquatic animals, micro-organisms and human health. The occurrence and preliminary ecological risk of 12 (11 antibiotics and 1 antiepileptic drug) pharmaceuticals were investigated for the first time in the surface water of the old Brahmaputra River, where open-water-fed aquaculture activities are being practiced in Bangladesh. The pharmaceuticals were quantified by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS), operated with positive electrospray ionization (ESI+) and a multiple reaction monitoring (MRM) mode. Nine pharmaceuticals were detected in the river surface water, whereas three were below the limit of detection (LOD). Metronidazole was detected in all the samples with concentrations ranging from 0.05 to 13.51 ng L-1. Trimethoprim had the second highest frequency of detection (95%) with the highest concentration (17.20 ng L-1). The ranges of concentration and detection frequency of sulfonamides and macrolides were

The concentration, source and potential human health risk of heavy metals in the commonly consumed foods in Bangladesh.

Seven food items, namely, meat, egg, fish, milk, vegetables, cereals and fruits were collected from Bogra district, Bangladesh to evaluate the levels of heavy metal and associated health risk to the adults and children. The samples were analyzed for the quantification of selected heavy metals (Cr, Ni, Cu, As, Cd and Pb) on inductively coupled plasma mass spectrometer followed by acid digestion. In general, the highest concentrations of the studied metals were detected in vegetables, cereals, and fruits. The range of Cr, Ni, Cu, As, Cd, and Pb in the foods were 0.058-10, 0.036-25, 0.045-40, 0.005-7.1, 0.001-5.5 and 0.005-13 mg/kg fw, respectively. Multivariate principal component analysis (PCA) revealed three major groups of the studied metals and showed significant anthropogenic contributions of the Ni, Cu, and As in foods. Health risk assessment was evaluated in terms of target hazard quotient and target carcinogenic risk (TR) which showed that the intake of some metals through foods were higher than the recommended values, consequently consumption of the foods may be associated with non-carcinogenic health risks. Nonetheless, elevated levels of As and Pb were also found to be associated with lifetime carcinogenic risk to the consumers.

Metal speciation in sediment and their bioaccumulation in fish species of three urban rivers in Bangladesh.

Six trace metals (chromium [Cr], nickel [Ni], copper [Cu], arsenic [As], cadmium [Cd] and lead [Pb]) were measured in sediments and soft tissues of three commonly consumed fish species (Channa punctatus, Heteropneustes fossilis, and Trichogaster fasciata) collected from three urban rivers around Dhaka City, Bangladesh. The abundance of total metals in sediments varied in the decreasing order of Cr > Ni > Pb > Cu > As > Cd. Sequential extraction tests showed that the studied metals were predominantly associated with the residual fraction followed by the organically bound phase. The range of metal concentration in fish species were as follows: Cr (0.75-4.8), Ni (0.14-3.1), Cu (1.1-7.2), As (0.091-0.53), Cd (0.008-0.13), and Pb (0.052-2.7 mg/kg wet weight [ww]). The rank of biota-sediment accumulation factor for fish species were in the descending order of Cu > As > Pb > Ni > Cr > Cd. Metal concentrations in fish exceeded the international permissible standards suggesting that these species are not safe for human consumption.

Metal speciation in soil and health risk due to vegetables consumption in Bangladesh.

This study was conducted to investigate the contamination level of heavy metals in soil and vegetables, chemical speciation, and their transfer to the edible part of vegetables. Metals were analyzed using inductively coupled plasma mass spectrometer (ICP-MS). The ranges of Cr, Ni, Cu, As, Cd, and Pb in agricultural soils were 3.7-41, 3.9-36, 3.7-46, 2.3-26, 0.6-13, and 4.5-32 mg/kg, respectively. The metals were predominantly associated with the residual fractions of 39, 41, 40, 40, 34, and 41 % for Cr, Ni, Cu, As, Cd, and Pb, respectively. Considering the metal transfer from soil to the edible part of vegetables, the mean transfer factors (TFs) were in the descending order of Cu > Ni > Cr > Pb > As > Cd. In the edible tissues of vegetables, the concentrations of As, Cd, and Pb in most vegetable samples exceeded the maximum permissible levels, indicating not safe for human consumption. Total target hazard quotient (THQ) of the studied metals (except Cr) from all vegetables were higher than 1, indicated that if people consume these types of vegetables in their diet, they might pose risk to these metals. Total values of carcinogenic risk (CR) were 3.2 for As and 0.15 for Pb which were higher than the US Environmental Protection Agency (USEPA) threshold level (0.000001), indicating that the inhabitants consuming these vegetables are exposed to As and Pb with a lifetime cancer risk.

Trace elements in different land use soils of Bangladesh and potential ecological risk.

Bogra city is highly susceptible to environmental pollution due to overpopulation, rapid industrialization, and urbanization during the last decades. The levels of six trace elements (chromium, nickel, copper, arsenic, cadmium, and lead) in seven different land use soils in Bangladesh were assessed. The ranges of Cr, Ni, Cu, As, Cd, and Pb in studied soils were 6.3-256, 8.3-271, 13-279, 7.5-87, 0.09-29, and 5.3-624 mg/kg, respectively. The pollution load index (PLI) values for all land uses were higher than 1, indicating the progressive deterioration of soil due to trace elements contamination. In view of the potential ecological risk (PER), soils from all land uses showed moderate to very high potential ecological risk. Among the elements, As and Cd showed a higher potential ecological risk than the others.

Trace elements in two staple cereals (rice and wheat) and associated health risk implications in Bangladesh.

Concentrations of fourteen trace elements (Cd, As, Pb, Cr, Ni, Zn, Se, Cu, Mo, Mn, Sb, Ba, V and Ag) in the composite samples of most frequently consumed two staple foods, i.e. rice and wheat (collected from 30 different agroecological zones for the first time in Bangladesh) were measured by ICP-MS. The mean concentrations (mg/kg fresh weight) of Cd, As, Pb, Cr, Ni, Zn, Se, Cu, Mo, Mn, Sb, Ba, V and Ag were found as 0.088, 0.321, 0.713, 0.183, 0.213, 13.178, 0.0256, 1.985, 0.102, 4.654, 0.0033, 0.144, 0.081 and 0.007 and 0.011, 0.281, 0.221, 0.352, 0.145, 15.472, 0.245, 1.894, 0.209, 22.077, 0.0012, 3.712, 0.023 and 0.0013 in rice and wheat samples, respectively. Dietary risk of human health (non-carcinogenic and carcinogenic risks) was assessed by USEPA deterministic approaches. Total target hazard quotient (THQ) values for As and Pb were higher than 1, suggesting that people would experience significant health risks from consuming rice and wheat. However, the THQ of other metals were all less than 1. Also, the estimation showed that the target carcinogenic risk (TR) of As and Pb exceeded the accepted risk level of 1 × 10(-6). Moreover, concerning the nutritional requirements of essential elements for a sound health, the recommended doses for the daily intake of Mn was conveniently supplied by the studied cereals; however, Cr, Zn, Se, Cu and Mo were below the recommend daily allowances (RDAs). Thus, the carcinogenic and non-carcinogenic risk of As and Pb with lower supplementation of essential elements via staple foods for Bangladeshi people is a matter of concern.

Trace metals in soil and vegetables and associated health risk assessment.

The objective of this study was to assess the contamination level of trace metals in soil and vegetables and health risk to the urban population in Bangladesh. The range of Cr, Ni, Cu, As, Cd, and Pb in agricultural soils was 158-1160, 104-443, 157-519, 41-93, 3.9-13, and 84-574 mg/kg, respectively. Sequential extraction tests revealed that the studied metals were predominantly associated with the residual fraction, followed by the organically bound phase. Concerning Cu, Ni, Cd, and Pb in vegetables, more than 50 % samples exceeded the FAO/WHO recommended permissible limits. Considering the transfer of metals from soil to vegetables, Cu and Cd exhibited higher transfer factor (TF) values than the other metals. Target hazard quotient (THQ) for individual metal was below 1, suggesting that people would not experience significant health hazards if they ingest a single metal from vegetables. However, total metal THQ signifies the potential non-carcinogenic health hazard to the highly exposed consumers. The carcinogenic risk (TR) of As (1.9 × 10(-4)) and Pb (2.3 × 10(-5)) through consumption of vegetables were higher than the USEPA threshold level (10(-6)), indicating potential cancer risks.

Using an internal body residue approach to assess acute pesticide toxicity in juvenile Chinook salmon (Oncorhynchus tshawytscha).

The use of internal body residues has the potential to improve toxicological assessments of hydrophobic pesticides. The acute toxicity of three classes of pesticides were assessed in juvenile Chinook salmon using internal body residues. Chinook salmon were exposed to two current-use pesticides bifenthrin and fipronil, and 4,4'- dichlorodiphenyldichloroethylene (DDE), which is a degradation product of the legacy pesticide dichlorodiphenyltrichloroethane (DDT). After 96-h of aqueous exposure to each pesticide, the pesticide content in whole-body Chinook salmon homogenates was measured using gas chromatography/mass spectrometry with methane negative chemical ionization. The wet-weight (ww) normalized lethal residue at 50% mortality (LR50) was lowest for bifenthrin (0.654 nmol/g ww), followed by fipronil (7.17 nmol/g ww) and the sum of fipronil and its sulfone, sulfide, and desulfinyl degradation products (8.72 nmol/g ww). No lethality was observed for DDE, even at the highest body residue (>116 nmol/g ww). LR50 estimates were also normalized to dry weight and lipid content and compared to field-caught fish to assess risk. The use of a risk quotient approach indicated that bifenthrin imparts the highest risk of acute toxicity in juvenile Chinook salmon among the three pesticides tested. In comparison to external dose metrics, the use of internal body residues has the potential to improve risk assessment by providing a more direct link between pesticide concentration at the receptor site and toxicological effects.

Antibiotics, antibiotic-resistant bacteria, and resistance genes in aquaculture: risks, current concern, and future thinking.

Aquaculture is remarkably one of the most promising industries among the food-producing industries in the world. Aquaculture production as well as fish consumption per capita have been dramatically increasing over the past two decades. Shifting of culture method from semi-intensive to intensive technique and applying of antibiotics to control the disease outbreak are the major factors for the increasing trend of aquaculture production. Antibiotics are usually present at subtherapeutic levels in the aquaculture environment, which increases the selective pressure to the resistant bacteria and stimulates resistant gene transfer in the aquatic environment. It is now widely documented that antibiotic resistance genes and resistant bacteria are transported from the aquatic environment to the terrestrial environment and may pose adverse effects on human and animal health. However, data related to antibiotic usage and bacterial resistance in aquaculture is very limited or even absent in major aquaculture-producing countries. In particular, residual levels of antibiotics in fish and shellfish are not well documented. Recently, some of the countries have already decided the maximum residue levels (MRLs) of antibiotics in fish muscle or skin; however, many antibiotics are yet not to be decided. Therefore, an urgent universal effort needs to be taken to monitor antibiotic concentration and resistant bacteria particularly multiple antibiotic-resistant bacteria and to assess the associated risks in aquaculture. Finally, we suggest to take an initiative to make a uniform antibiotic registration process, to establish the MRLs for fish/shrimp and to ensure the use of only aquaculture antibiotics in fish and shellfish farming globally.

Trace metals and organochlorine pesticide residues in imported fishes in Bangladesh and human health risk implications.

Substantial quantity of fish has been imported to Bangladesh without adequate food safety assessment which can pose a serious health risk to local people. This study analyzed the trace metals and organochlorine pesticides residues and the associated human health risk in 33 imported fishes (9 species) from four countries (India, Myanmar, Oman, and United Arab Emirates) collected from three different ports (Benapole, Bhomra, and Chittagong) of Bangladesh with invoice lists from the port authorities. Trace metal concentrations were determined using graphite furnace absorption spectrometry and flame absorption spectrometry. The two organochlorine pesticides (Aldrin and Chlordane) residues were determined by GC-MS and found as below detection level (BDL). The trace metal concentrations (mg/kg-ww) in imported fish samples ranged as As 0.008 to 0.558, Pb 0.004 to 0.070, Cr 0.010 to 0.109, Cd 0.00 to 0.083, Ni 0.011 to 0.059, Co BDL to 0.067, Mn BDL to 0.0780, Fe 1.780 to 10.77, Cu 0.055 to 0.632, and Zn 0.898 to 9.245. Concentrations of As and Cd were higher than the food safety guideline. Considering the source country of imported fishes, fish samples from Oman were mostly contaminated by the trace metals. The estimated daily intake (EDI) was higher for Cr. However, the target hazard quotient (THQ) for individual metal and total THQ for combined metals were lower than 1, indicating no apparent non-carcinogenic health risk for consumers. The cancer risk (CR) was within the acceptable range. But extensive monitoring of these toxic chemicals is needed prior to import these fishes to the country. Given the self-sufficiency in fish production, this study also argues whether Bangladesh needs to import the fishes at all.

Occurrence, spatial distribution and ecological risk assessment of trace elements in surface sediments of rivers and coastal areas of the East Coast of Bangladesh, North-East Bay of Bengal.

Coastal and estuarine ecosystems provide habitats for many organisms. Recently, the estuaries and coastal areas of the East Coast of Bangladesh have become heavily contaminated due to dumping of untreated wastewater into the rivers from a number of different industries. The current study analyzes potentially toxic elements contamination in surface sediments of the Karnaphuli, Sangu, Bakkhali and Naf Rivers, Kutubdia and Moheshkhali Channel, and St. Martin's Island, and assesses the consequent ecological risks. The pollution load index (PLI), geoaccumulation index (Igeo) and potential ecological risk (PER) indices show that the contaminated sediments have negative effects on the aquatic environments. The PLI values ranged between 0.45 and 1.67, which suggests the severity of trace-element contamination. The mean Igeo values showed the sediments range from uncontaminated to heavily contaminated state. The Enrichment Factor (EF) values suggested that the sediments were contaminated by anthropogenic sources, and PER values demonstrate that sites at Sangu, Naf and St Martin's Island are less contaminated compared to sites at Karnaphuli, Bakkhali, Kutubdia and Moheshkhali. Overall, results showed that Karnaphuli river is the most contaminated and St Martin's Island is the least based on the spatial distribution of PLI, Cd, PER and ∑TUs of trace metals in surface sediments. Comparing with the neighboring countries, the concentrations of Cd and Pb were found to be higher while Cr is lower in the East Coast of Bangladesh than the estuarine and coastal waters of the Bay of Bengal rim countries. The present study reveals that the lack of water quality guidelines in Bangladesh for the coastal, estuarine and marine water escalated the dumping of untreated wastewater. Immediate measures need to be taken to address the ecological risks so that an effective management program can be undertaken. A systematic approach for collecting pollutant data and use of isotopes to trace anthropogenic sources of contamination is recommended for pollutants like toxic metals, pesticides and other contaminants in sediment and aquatic products in the entire coastal waters of the Bay of Bengal.

Accumulation of Trace Metals in Indigenous Fish Species from the Old Brahmaputra River in Bangladesh and Human Health Risk Implications.

In this study, accumulation of the top six most toxic trace metals (Arsenic (As), Cadmium (Cd), Chromium (Cr), Mercury (Hg), Nickel (Ni) and Lead (Pb)) were assessed in six indigenous fish species (Barilius barila, Salmostoma acinaces, Gudusia chapra, Labeo bata, Corica soborna, and Sperata aor) collected from the Old Brahmaputra River in Bangladesh. Human health risk associated with these fish consumption was also evaluated. Metals were analyzed in whole body of fish by an atomic absorption spectrometer (AAS). Mean concentrations of metals (µg/g, wet weight) were in the range of As (< 0.02-0.278), Cd (< 0.002-0.005), Cr (0.239-0.761), Hg (0.008-0.057), Ni (< 0.02-0.044), and Pb (< 0.01-0.038). The metal contents varied significantly among the fishes regarding their feeding habits and living habitats. Concentrations of As, Cr, Hg, and Pb were significantly higher in omnivorous species, whereas the benthopelagic species showed significantly higher accumulation of As (p < 0.05). The target hazard quotient (THQ) for noncarcinogenic risk and target cancer risk (TR) for carcinogenic risk were calculated to estimate the probabilities of experiencing these adverse health effects for the fish consumers. Metal-specific THQ values were all below 1 indicating no potential human health risk. Nonetheless, the hazard index (HI) values to estimate the effects from exposure to all metals collectively elucidated chronic noncarcinogenic health risk particularly from G. chapra consumption. The TR values revealed that there was carcinogenic risk from exposure to As through consumption of the fish. This study finally suggests a systematic and continuous monitoring of trace metal contamination in fishes from the river to ensure the fitness of this food item regarding the safety for human health.

Total mercury and methylmercury in rice: Exposure and health implications in Bangladesh.

Rice methylmercury (MeHg) contamination has attracted global attention, especially in countries where rice is considered a staple food. The daily rice intake rate in Bangladesh ranks first in the world; however, no attention has been paid to rice MeHg contamination in Bangladesh. Total Hg (THg) and MeHg concentrations of commercial rice (n = 172) from Bangladesh were first analyzed to accurately evaluate both rice MeHg and inorganic Hg (IHg) exposure in different age-gender groups of Bangladeshis. The corresponding adverse health impacts and associated economic loss were also assessed. The results showed that THg concentration in all samples ranged from 0.42 to 14.4 ng/g, with an average of 2.48 ± 1.41 ng/g, while the MeHg concentration ranged from 0.026 to 7.47 ng/g, with an average of 0.83 ± 0.60 ng/g. The highest average MeHg and IHg were both recorded in rice from Chittagong. The highest mean MeHg and IHg exposures were observed in 2-5 years-old group and were 16.2% of the reference dose (RfD) of 0.1 µg/kg/day for MeHg and 7.09% of the provisional tolerable weekly intake (PTWI) of 0.571 µg/kg/day for IHg. Surprisingly, MeHg exposure of the 2-5 year-old children could be up to 93.7% of the RfD at a high percentile (P99.9). The total intelligence quotient reduction caused by rice MeHg exposure could be 54700 points, and the associated economic loss is approximately 42.5 million USD. To avoid high rice MeHg exposure, it was suggested that diet structure be improved. More attention should be paid to residents with long-term rice MeHg exposure, especially children in the 2-5 year-old group.

Bioaccumulation of trace metals in freshwater prawn, Macrobrachium rosenbergii from farmed and wild sources and human health risk assessment in Bangladesh.

The giant freshwater prawn, Macrobrachium rosenbergii, is an important species for Bangladesh's national economy, aquatic biodiversity, and employment opportunities; furthermore, human health risk associated to consumption of this species has become a crucial issue. Eight trace metals (Pb, Cr, Ni, Cd, Fe, Cu, Zn, and Mn) in different body parts of M. rosenbergii (U/10 as large and U/12 and U/15 as medium size), and water collected from farm and wild sources along with the human health risks were assessed in this study. Except Cd, all trace metals exceeded the maximum permissible limits proposed by different authorities. Elevated levels of Pb, Cr, Fe, Cu, Zn, and Mn were found in the wild-caught prawn, whereas Ni and Cd were higher in farmed prawn. A higher trace metal contamination was recorded from the cephalothorax part than the abdomen of both sized prawns. However, trace metal concentrations between two sizes of prawns were not statistically significant (p > 0.05). The estimated daily intakes (EDI) values were higher than the recommended and/or tolerable daily intake for Pb and Cr. Moreover, the target hazard quotient (THQ) values were > 1 for Pb, Cd, Cu, and Zn, elucidating non-carcinogenic risks to the consumers. In addition, the target cancer risk (TR) values of Pb and Ni were high and exceeded the acceptable guideline of 10-6, explicating the possibility of carcinogenic risks. Therefore, the study concludes that the consumption of the studied prawn species contaminated with elevated levels of toxic metals is associated with higher degree of potential health risks.

Polychlorinated biphenyls (PCBs) in commonly consumed seafood from the coastal area of Bangladesh: occurrence, distribution, and human health implications.

Dietary intake is the most important route of polychlorinated biphenyls (PCBs) exposure and seafood is the major dietary component for the coastal populations. It is, therefore, an urgent need to assess the levels of PCBs in seafood. A comprehensive congener-specific evaluation of PCBs was carried out for the first time in Bangladesh. All 209 congeners of PCBs in 48 seafood samples (5 finfish and 2 shellfish species) collected in winter and summer of 2015 were measured by GC-MS/MS. Regardless of season and site, the ∑PCBs (ng/g wet weight) in finfish and shellfish were in the range of 6.4-86.2 and 3.8-37.7, respectively. The results were comparable to or higher than those observed in other studies worldwide, particularly from Spain, China, Korea, Thailand, and Hong Kong. No significant seasonal variation was observed in the levels of ∑PCBs in the examined seafood (p > 0.05); however, interspecies differences were significant (p < 0.05). Nonetheless, spatial distribution revealed seafood collected from the areas with recent urbanization and industrialization (Chittagong, Cox's Bazar, and Sundarbans) were more contaminated with PCBs than the area unaffected by industries (Meghna Estuary). Moderately chlorinated (4-6 Cl) homologs dominated the PCB profiles. The congener profile and homolog composition revealed that the source origin of PCBs in the Bangladeshi seafood was related to mixtures of technical PCBs formulations. The dietary exposure assessment revealed that the coastal residents are sufficiently exposed to the dietary PCBs through seafood consumption which may cause severe health risk including dioxin-like toxic effects.

Heavy metals in sediment and their accumulation in commonly consumed fish species in Bangladesh.

Six heavy metals (chromium [Cr], nickel [Ni], copper [Cu], arsenic [As], cadmium [Cd], and lead [Pb]) were measured in sediments and soft tissues of eleven commonly consumed fish species collected from an urban river in the northern part of Bangladesh. The abundance of heavy metals in sediments varied in the decreasing order of Cr > Ni > Cu > Pb > As > Cd. The ranges of mean metal concentrations in fish species, in mg/kg wet weight (ww), were as follows: Cr, 0.11-0.46; Ni, 0.77-2.6; Cu, 0.57-2.1; As, 0.43-1.7; Cd, 0.020-0.23; and Pb, 0.15-1.1. Target hazard quotients (THQs) and target carcinogenic risk (TR) showed the intake of As and Pb through fish consumption were higher than the recommended values, indicating the consumption of these fish species is associated with noncarcinogenic and carcinogenic health risks.