Manuscript Click here to download Manuscript: Manuscript_ESPR.docx Click here to view linked References 1 2 3 4 5 Human Health Risk Assessment of Heavy Metals in Tropical Fish and Shell Fish Collected 6 7 From the River Buriganga, Bangladesh 8 9 10 11 12 Md. Kawser Ahmeda, Mohammad Abdul Bakib, Md. Saiful Islamc, Goutam Kumar Kundua, Md. 13 14 Habibullah –Al- Mamuna,c,*, Santosh Kumar Sarkard and Md. Muzammel Hossainb 15 16 17 18 19 20 21 a Department of Fisheries, University of Dhaka, Dhaka-1000, Bangladesh. 22 23 b Department of Zoology, Jagannath University, Dhaka-1100, Bangladesh. 24 25 26 c 27 Department of Risk Management and Environmental Sciences, Graduate School of Environment 28 and Information Sciences, Yokohama National University, Yokohama, Kanagawa-240-8501, 29 30 Japan. 31 32 d Department of Marine Science, Calcutta University, India. 33 34 35 36 37 38 39 40 41 42 43 44 45 * Corresponding author at: Department of Risk Management and Environmental Sciences, 46 47 Yokohama National University, Yokohama, Kanagawa-240-8501, Japan. Tel.: +818079366622. 48 49 E-mail address:
[email protected] (M.H. Al-Mamun) 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65
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ABSTRACT Although fish, crustacean and shellfish are significant sources of protein, they are currently affected by rapid industrialization activities, resulting in increased concentrations of heavy metals. Accumulation of heavy metals (V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Sb, Ba, and Pb) and associated human health risk were investigated in three fish species namely; Ailia coilia, Gagata youssofi, Mastacembalus pancalus,
one crustacean (prawn); Macrobrachium
rosenbargii, and one gastropoda; Indopanorbis existus collected from Buriganga river, Bangladesh. Samples were collected from the professional fishermen. Cu was the most accumulated metal in M. rosenbargii. Ni, As, Ag and Sb were in relatively lower concentrations whereas, relatively higher accumulation of Cr, Mn, Zn and Se were recorded. Mn, Zn, Pb were present in higher concentration than the guidelines of various authorities. There were significant differences in metal accumulation among different fish, prawn or shelfish species. Target Hazard Quotient (THQ) and Target Cancer Risk (TR) were calculated to estimate the non-carcinogenic and carcinogenic health risk respectively. The THQ for individual heavy metals were below 1 suggesting no potential health risk. But combined impact, estimated by Hazard Index (HI) suggested health risk for M. pancalus consumption. Although consumption of fish at current accumulation level is safe but continuous and excess consumption for a life time of more than 70 years has probability of target cancer risk. Keywords: Fish, Heavy metal, Bioaccumulation, Target Hazard Quotient, Target Cancer Risk
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1. Introduction The increasing usage of heavy metals in industry has led to serious environmental pollution through effluents and emanations during the past several decades (Sericano et al., 1995). Subsequently, these activities have increased the release of harmful heavy metals into the aquatic environment (Agusa et al., 2005, 2007; Hajeb et al., 2009) which are well known environmental pollutants (Gulec et al., 2004). Heavy metals are a global concern, due to their potential toxic effect and ability to bioaccumulate in aquatic ecosystems (Goldstein, 1990). Pb, Ba, Cd, Hg, Cr, and As are classified as toxic heavy metals and maximum residual levels have been prescribed for humans (FAO, 1983; EC, 2001; FDA, 2001) and have no established role in biological system (Canli and Atli, 2003). Whereas metals such as Cu, Na, K, Ca, Mn, Se, Fe, and Zn are essential metals for fish metabolism but may also bioaccumulate and reach toxic levels and that can potentially destroy the ecological environment (Agusa et al., 2005, 2007; Hajeb et al., 2009). The bioaccumulation of heavy metals in living organisms and biomagnifications describes the processes and path- ways of pollutants from one trophic level to another. Heavy metals can enter the food web through direct consumption of water or organisms taken as food (zooplankton, phytoplankton and faunal of the bottom) or by uptake through the gills and skin and be potentially accumulated in edible fish in aquatic ecosystem. The acidic conditions of aquatic environment might cause free divalent ions of many heavy metals to be absorbed by fish gills (Part et al., 1985). Fish are widely used as bio-indicators of heavy metals contamination (Svobodova et al., 2004) because they occupy different tropic levels and are of different sizes and ages (Burger et al., 2002). Relationship between metal concentrations in fish and in the water has been studied in both, field and laboratories (Linde et al., 1996; Moiseenko et al., 1995; Zhou et al., 1998). Fish, shellfish and other aquatic organisms constitute a large part of daily meal of human population in countries like Bangladesh. Consumption of heavy metal contaminated fish for prolonged period results in accumulation of heavy metals in human. The River Buriganga running by the side of the Dhaka City, the capital of Bangladesh, which is a megacity of about 12 million people. City dwellers largely depend on the Buriganga river for sources of domestic water supply, serves as major transportation route and flood control and drainage outlet, used for agricultural, sanitary and industrial purposes (Alam, 2002). Intensive human intervention, rapid industrialization, unplanned urbanization and economic development
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has resulted in increased water pollution (Moniruzzaman et al., 2009). Earlier studies reported water flow (Ahmed et al., 2010) and ecological function of Buriganga river (Yousuf Ali, 2008) has been greatly influenced. It is increasingly being polluted with the city’s thousands of industrial units and sewerage lines dumping huge volumes of toxic wastes into it day and night (Islam et al., 2006). The Department of Environment (DoE) identified 249 factories along the river Buriganga (Sarker, 2005). However, River Buriganga received continuously wide variety of heavy metal which originate from industrial waste discharge, batteries, lead based paint and gasoline discharge from cargo, launch and mechanized boat, traffic and improper domestic waste discharge etc. The river Buriganga has become biologically and hydrologically dead due to indiscriminate dumping of domestic and industrial wastes, encroachment by unscrupulous people. Fish in Buriganga can also accumulate metals in its tissues through absorption, and humans can be exposed to these metals via the food web. Heavy metals, unlike organic pollutants, cannot be chemically degraded or biodegraded by microorganisms. Thus, their content has steadily increased in water and subsequently accumulated in sediments, plants, fishes, and even in humans ( Che et. al, 2006).The consumption of contaminated fish causes acute and chronic effects to humans (Nord et al., 2004). Although a number of studies have investigated heavy metal concentrations in fishes (Ahmed et al., 2010), water (Ahmed et al., 2010; Mohiuddin et al., 2011) and sediment (Ahmed et al., 2010; Mohiuddin et al., 2011) of Buriganga river but no research has been conducted on profile of heavy metal in the fish species, crustacean (prawn) and shellfish(molluska) of Buriganga river and evaluate the associated health risks. In this context, the present study was to designed to determine the accumulation profile of heavy metals, namely: V (Vanadium), Cr (Chromium), Mn (Manganese), Ni (Nickel), Cu (Copper), Zn (Zinc), As (Arsenic), Se (Selenium), Mo (Molybdenum), Ag (Silver), Cd (Cadmium), Sb (Antimony), Ba (Barium) and Pb (Lead) in fish species, crustacean (prawn) and shellfish (molluska) collected from the river Burganga and evaluate their health risk for humans.
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2. Materials and Methods 2.1. Collection and preparation of samples: Samples were collected between August to September, 2013 from different stations of the river Buriganga near Kamrangir char (Figure 1) where fishing effort is high. Fish and prawn samples were collected from the professional fishermen while they were fishing in the river with using different gears. Special care was taken to make sure that the species were of similar size and weight. The samples were put in plastic bag/containers and transported to the laboratory. The biological information of the collected samples was recorded (Table 1). The collected species were divided into three groups: i. Fish (Ailia coila, Gagata youssufi and Mastacembalus pancalus, ii. Crustaceans (prawn; M. rosenbargii) and iii. Shell fish (molluska; gastropoda; snail; Indopanorbis existus). Whole body of fish, crustacean and molluska were used for analyses. A composite sample for each species was prepared and homogenized in a stainless steel blender cup. 50g test portions were stored at -20 0C for analytical methods. The metal contents were expressed as mg/kg wet wt. of fresh fish, prawn and molluska.
2.2. Analytical methods 2.2.1.
Reagents
All solutions were prepared with analytical reagent-grade chemicals and ultrapure water. SUPRAPUR® nitric acid (HNO3, 67% (v/v)) was purchased from Kanto Chemical Co, Japan and H2O2 was purchased from Wako Chemical Co, Japan. Standard stock solutions containing 10 µg/L of each element (Cd, As, Pb, Cr, Ni, Zn, Se, Cu, Mo, Mn, Sb, Ba, V and Ag and internal standard solutions containing 1.0 mg/L of indium (In), yttrium (Y), beryllium (Be), telium (Te), cobalt (Co) and titanium (Ti) were purchased from SPEXertificate® and were used to prepare calibration and internal standards. Working standards were prepared daily in 5% (v/v) HNO3 at 67% and were used without further purification. A solution of 10.0 mg/L multielement solution (Merck, Darmstadt, Germany) was used to prepare a tuning solution with several elements such as indium, uranium, barium and lithium, capable of covering a wide range of masses. Ultra-pure grade carrier (Argon (Ar)) was supplied from Air Liquide (Japan).
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2.2.2. Sample digestion A microwave (Berghof Microwave MWS-2, Germany) was used in preparation of samples to analyze various metals with ICP-MS (Agilent 7700, USA). The microwave digestion system has been designed to performed chemical digestion procedures under extreme pressure and temperature conditions in chemical laboratories. Digestion reagents that were used included 5 ml HNO3 acid (Kanto Chemical Co, Japan) and 2 ml H2O2 (Wako Chemical Co, Japan). The weighed samples of 0.2 g were then placed into the digestion reagent in a Teflon vessel. DAP60K
type
pressure
vessels
(Berghof,
Germany)
which
are
made
entirely
of
tetrafluoromethoxylene (TFM) were used in this study. Three step-digestion procedures were followed: 1) temperature and power were maintained at 180 ºC and 85% respectively for 15 min; 2) temperature was kept steady at 200 ºC for 15 min together with 90% of the power and 3) reduced temperature (100 ºC) and power (40%) were used for 10 min to cool down the Teflon vessels. After that, all Teflon vessels were kept in cold water to reduce the residual pressure inside the Teflon vessel. Samples were then transferred into a Teflon beaker and total volume was made up to 25 ml for water and 50 ml for sediments with MilliQ water (Elix UV5 and MilliQ, Millipore, USA). The digest solution then filtered (DISMIC® - 25HP PTTF syringe filter (pore size= 0.45 mm) Toyo Roshi Kaisha, Ltd., Japan), and stored in crew cap plastic tube. The samples were then subjected to analysis for various trace metals using ICP-MS followed by three times digestion for each sample. Afterwards, the vessels were cleaned by MilliQ water and dried with air. Finally, two blank digestions with 5 ml HNO3 following the said digestion procedures were carried out to clean up the digestion vessels (Berghof’s product user manual).
2.2.3. Quality assurance All test batches were evaluated using an internal quality approach and validated if they satisfied the defined Internal Quality Controls (IQCs). For each experiment, a run included blank, certified reference materials (CRM) as internal standard in samples and samples analyzed in duplicate to eliminate any batch-specific error. Multielement standard solution was used to prepare standard curve. Before starting the sequence, relative standard deviation (RSD,
