Spatiotemporal distribution and pollution assessment of trace metals in the Buriganga River, Bangladesh.

The Buriganga River plays a key role in the socioeconomic structure of Dhaka, the capital of Bangladesh. However, this river is severely polluted and is considered one of the most polluted in the world. Therefore, this study aimed to assess the concentrations of various metals in the Buriganga River. A study was conducted from August 2019 to February 2020 to determine the concentrations of 16 metals in water samples (n = 210) collected from 10 distinct sites in the Buriganga River. The mean values for the concentrations of Cr, Mn, Ni, Zn, As, Se, Cd, Sb, and Pb in river water were above the guideline values prescribed by the WHO, Japan, and Bangladesh. Moreover, the fraction ratios of Be, Cr, Co, Ni, Cu, Zn, Se, Mo, Ag, Cd, Sb, and Pb were high (>0.85); consequently, these metals could accumulate at high concentrations in river sediments. Assessment using the single-factor pollution index allowed the classification of the pollution level as 'serious pollution' for Sb and 'heavy pollution' for Cd, Ni, and Pb. The trace metal concentrations in this river imply that crops cultivated along the river using river water may also be contaminated with trace metals.

Occurrence, potential source, and cancer risk of PM2.5-bound polycyclic aromatic hydrocarbons and their halogenated derivatives in Shizuoka, Japan, and Dhaka, Bangladesh.

Because of their unintentional formation and low vapor pressure, polycyclic aromatic hydrocarbons (PAHs) and their halogenated derivatives (XPAHs) in the atmosphere are distributed primarily to aerosolized particles with an aerodynamic diameter less than 2.5 µm (PM2.5). However, no information is available regarding the occurrence of PM2.5-bound PAHs and XPAHs in Bangladesh, one of the most highly PM2.5-polluted regions worldwide. In this study, we investigated the occurrence of PM2.5-bound PAHs and XPAHs in the atmospheres of Dhaka in Bangladesh and Shizuoka in Japan (as a reference) and estimated their incremental lifetime cancer risks (ILCRs). In addition, we statistically estimated the potential sources of PM2.5-bound PAHs and XPAHs by using principal component analysis and positive matrix factorization. The median concentration of total PM2.5-bound PAHs and XPAHs in Bangladesh was 24.2 times that in Japan. The estimated potential sources of PAHs clearly differed between Japan and Bangladesh, whereas those of XPAHs were largely (>80%) unknown in both countries. The median ILCR in Bangladesh was 2.81 × 10-3, which greatly exceeded the upper limit of acceptable risk (10-4). These results indicate that comprehensive monitoring and control of atmospheric PM2.5-bound PAHs and XPAHs are needed urgently, especially in highly polluted countries.

Organophosphate flame retardants in the indoor air and dust in cars in Japan.

The concentrations of organophosphate flame retardants (OPFRs) in the indoor air and dust were measured in 25 unoccupied cars in Japan. In the indoor air of the cars, most OPFRs were neither detected nor found at a concentration lower than the method quantification limit. The highest concentration (1500 ng m-3) was obtained for tris(1-chloro-2-propyl) phosphate (TCIPP). By contrast, many OPFRs were detected in the dust samples collected from the interior of the cars. TCIPP and tris(2-ethylhexyl) phosphate (TEHP) were present at the highest concentrations at 390 µg g-1 (in dust from car seats) and 640 µg g-1 (in dust from car floor mats), respectively. The highest median concentrations (35 µg g-1 for car seats, 53 µg g-1 for car floor mats) were obtained for tris(2-butoxyethyl) phosphate (TBOEP). According to the results of our exposure assessment, the typical exposures to OPFRs via inhalation in car cabins ranged from 9.0×10-4 to 7.8×10-1 ng kg-bw-1 day-1. The typical exposures to OPFRs via dust ingestion ranged from 9.2×10-4 to 8.8×10-1 ng kg-bw-1 day-1. We compared these results with the ref-erence doses for OPFRs and found that, based on cur-rent information about the toxicities of OPFRs, exposure to OPFRs in car cabins via inhalation and dust ingestion is unlikely to have adverse human health effects.

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.

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.

Evaluation of the potentials of rice varieties and water management practices for reducing human health risks associated with polluted river water irrigated rice in Bangladesh.

The consumption of arsenic and trace-metal-contaminated rice is a human health concern worldwide, particularly in Bangladesh. In this study, the effects of rice varieties and water management practices on the concentrations of arsenic and trace metals in rice grains were investigated to reduce human health risks related to rice consumption. In addition, the performance of risk reduction using the optimum combination of rice variety and water management practices was quantitatively assessed using Monte Carlo simulation, in which non-carcinogenic and carcinogenic risk distributions under the status quo and the optimum combination were compared. The experimental results revealed that Dular and BRRI dhan45 (rice varieties) cultivated under alternate wetting and drying (AWD) and continuous flooding (CF) conditions showed the lowest hazard quotient (HQ) values for copper, cadmium, and arsenic and the lowest target cancer risk (TR) for arsenic. In Dular and BRRI dhan45 (AWD and CF) varieties, the proportion of the population for which HQs exceeded 1.0 (the reference value) tended to decrease (except for arsenic), compared with populations for which the rice varieties and water management practices were not specified. These results suggest that the use of optimum combinations of rice varieties and water management practices could reduce non-carcinogenic and carcinogenic risks associated with arsenic and trace metals uptake via rice grain consumption by the Bangladeshi people.

Assessment of Heavy Metal Concentration in Water, Sediment and Common Fish Species of Dhaleshwari River in Bangladesh and their Health Implications.

The present study emphasized on evaluating the extent of pollution of Dhaleshwari River in Bangladesh due to the discharge of heavy metals from tanneries and other industries along with the health risks associated with the consumption of the heavy metals accumulated fish. For this purpose, three spots of Dhaleshwari River which are in the vicinity of the industrial outlet were selected for evaluating the seasonal status of heavy metals in water, sediment, and organs of three common fish species. Average concentrations of metals in water and sediment were in the order of Cr > Cd > Pb > Cu > As and Cr > Pb > Cu > As > Cd respectively. The average HM concentrations in water and sediment exceeded WHO and USEPA standards suggesting serious pollution to the aquatic environment. In fish organs, metal concentrations were in the order of Cu > Cr > Pb > Cd > As. Accumulation was highest in gills and lowest in muscles. Fish muscles had a relatively higher concentration of heavy metals (except As) exceeding the safe limits of FAO and WHO. Seasonal variation was also observed in water for all metals (p < 0.01), in sediment for Cu and As (p < 0.05), and in fish for Cr, Cd, and Cu (p < 0.05); higher concentrations were observed in winter. Bioconcentration factor analysis indicated that Cu, Pb, and Cr were more concentrated in fish. Health risk assessment reveals that the carcinogenic risk of Cr is associated with the consumption of contaminated fish species of the studied area.

Occurrence and assessment of perfluoroalkyl acids (PFAAs) in commonly consumed seafood from the coastal area of Bangladesh.

This study reports the first evidence of the occurrence of PFAAs in commonly consumed seafood from the coastal area of Bangladesh. Fifteen target PFAAs in 48 seafood samples (5 finfish and 2 shellfish species) were measured by HPLC-MS/MS. The ΣPFAAs in finfish and shellfish were in the range of 0.32-14.58 and 1.31-8.34 (ng/g wet weight), respectively. Perfluorooctanesulfonate (PFOS) in finfish (0.1-3.86ng/g ww), whereas perfluorooctanoic acid (PFOA) in shellfish (0.07-2.39ng/g ww) were the most abundant PFAAs. The results were comparable with other studies worldwide, particularly from China, Spain, Sweden, and USA. The majority of monitored PFAAs did not show clear seasonal variation. However, seafood from the southeast area (Cox's Bazar and Chittagong) showed relatively higher levels of PFAAs. Moreover, the dietary exposure assessment revealed that the daily intakes of PFAAs via seafood consumption were far less than the health-based guidelines, indicating low health risk for the Bangladeshi coastal residents.

Comprehensive study on effects of water matrices on removal of pharmaceuticals by three different kinds of advanced oxidation processes.

Simple semi-theoretical models were developed to estimate the performance of three different kinds of advanced oxidation processes (AOPs) in the degradation of pharmaceuticals. The AOPs included the photo-Fenton process as an example of a liquid-liquid reaction, the TiO2 photocatalytic oxidation process as a solid-liquid reaction, and the combined ozone and hydrogen peroxide oxidation process as a gas-liquid reaction; the effects of the aqueous matrices (CESs: co-existing substances) of actual wastewater on the removal of pharmaceuticals (carbamazepine and diclofenac) was taken into account. By comparing the characteristic parameters of the models, obtained from the experiments using pure water and actual wastewater, the effects of CESs on the respective removal mechanisms could be separately and quantitatively evaluated. As a general tendency, the AOPs proceeded less effectively (were inhibited) in the matrices containing CESs, as observed with the use of a lower initial concentration of pharmaceuticals. The inhibition mechanisms differed for the three types of AOPs. In the photo-Fenton process, the Fenton reaction was improved by the incorporation of CESs, while the photo-reduction reaction was significantly inhibited. In the TiO2 photocatalytic oxidation process, competition between the pharmaceuticals and CESs for adsorption on the catalyst surface was a less significant inhibitory factor than the scavenger effects of the CESs. The combined ozone and hydrogen peroxide oxidation process was most strongly inhibited by CESs among the AOPs investigated in this study.

Occurrence and distribution of perfluoroalkyl acids (PFAAs) in surface water and sediment of a tropical coastal area (Bay of Bengal coast, Bangladesh).

This study reports the first evidence of perfluoroalkyl acids (PFAAs) in surface waters and sediments collected from the coastal area of Bangladesh. Fifteen target PFAAs, including C4-14-PFCAs (perfluoroalkyl carboxylates) and C4, C6, C8, and C10-PFSAs (perfluoroalkyl sulfonates), were quantified by HPLC-MS/MS. The ΣPFAAs in surface water and sediment samples were in the range of 10.6 to 46.8ng/L and 1.07 to 8.15ng/gdw, respectively. PFOA in water (3.17-27.8ng/L) and PFOS in sediment samples (0.60-1.14ng/gdw) were found to be the most abundant PFAAs, and these concentrations were comparable to or less than most other reported values, particularly those recorded from the coastal areas of China, Japan, Korea and Spain. The majority of the monitored PFAAs did not show clear seasonal variation. The southeastern part (Cox's Bazar and Chittagong) of the Bangladeshi coastal area was more contaminated with PFAAs than the southern (Meghna Estuary) and southwestern parts (Sundarbans). Industrial and municipal wastewater effluents, ship breaking and port activities were identified as potential sources of the PFAA contamination in this region. Field-based sediment water distribution coefficients (KD) were calculated and corrected for organic carbon content (KOC), which reduced the variability between samples. The values of log KD (1.63-2.88) and log KOC (4.02-5.16) were higher than previously reported values, which may indicate that the partitioning of PFAAs in a tropical coastal ecosystem is different from other ecosystems, such as temperate and sub-tropical regions. Although a preliminary environmental hazard assessment indicated that PFOA or PFOS levels do not currently exceed the acute safety thresholds, we should keep in mind that they are bioavailable and can accumulate in the food chain. Therefore, the ubiquity of PFAAs in the coastal area of Bangladesh warrants further studies characterizing their specific sources and the potential long-term risks they present to both humans and wildlife.

Trace metal contamination in commercial fish and crustaceans collected from coastal area of Bangladesh and health risk assessment.

Trace metals contamination in commercial fish and crustaceans have become a great problem in Bangladesh. This study was conducted to determine seven trace metals concentration (Cr, Ni, Cu, Zn, As, Cd, and Pb) in some commercial fishes and crustaceans collected from coastal areas of Bangladesh. Trace metals in fish samples were in the range of Cr (0.15 - 2.2), Ni (0.1 - 0.56), Cu (1.3 - 1.4), Zn (31 - 138), As (0.76 - 13), Cd (0.033 - 0.075), and Pb (0.07 - 0.63 mg/kg wet weight (ww)), respectively. Arsenic (13 mg/kg ww) and Zn (138 mg/kg ww) concentrations were remarkably high in fish of Cox's Bazar due to the interference of uncontrolled huge hatcheries and industrial activities. The elevated concentrations of Cu (400), Zn (1480), and As (53 mg/kg ww) were also observed in crabs of Cox's Bazar which was considered as an absolutely discrepant aquatic species with totally different bioaccumulation pattern. Some metals in fish and crustaceans exceeded the international quality guidelines. Estimated daily intake (EDI) and target cancer risk (TR) revealed high dietary intake of As and Pb, which was obviously a matter of severe public health issue of Bangladeshi coastal people which should not be ignored and concentrate our views to solve this problem with an integrated approaches. Thus, continuous monitoring of these toxic trace elements in seafood and immediate control measure is recommended.