Distribution of three non-essential trace metals (Cadmium, Mercury and Lead) in the organs of fish from Aiba Reservoir, Iwo, Nigeria

Allium sativum Essential Oil Supplementation Reverses the Hepatic Inflammation, Genotoxicity and Apoptotic Effects in Swiss Albino Mice Intoxicated with the Lead Nitrate

Prolonged lead (Pb) exposure impairs human health due to its interference with physiological and biochemical processes. Therefore, it is necessary to investigate natural therapeutics to alleviate Pb-induced intoxication. In the current investigation, essential oil extracted from the fresh bulbs of Allium sativum was considered as a natural remedy. Initially, in vitro antioxidant and anti-inflammatory activity of A. sativum essential oil (ASEO) were explored. The results reported that ASEO exhibits potent antioxidant and anti-inflammatory potential. Additionally, an in vivo study was conducted to elucidate its preventive role against Lead-nitrate (LN)-induced hepatic damage in Swiss albino mice. The experimental mice were allocated into six groups: Control, LN-intoxicated group (50 mg/kg), LN + ASEO (50 mg/kg), LN + ASEO (80 mg/kg), LN + Silymarin (25 mg/kg), and LN + vehicle oil control group. The entire duration of the study was of 30 days. From the results, it was determined that LN exposure elevated the Pb content in hepatic tissues which subsequently increased the serum biomarkers, inflammatory cytokines (NF-kB, TNF-α, IL-6) as well as apoptotic factors (caspase-3, BAX), all of which contribute to DNA damage. Meanwhile, it reduced anti-inflammatory (IFN-γ and IL-10) and anti-apoptotic factors (Bcl-2). Furthermore, Pb accumulation in hepatic tissues changed the histological architecture, which was linked to necrosis, central vein dilation, inflammatory cell infiltration and Kupffer cell activation. In contrast to this, ASEO administration decreased the Pb content, which in turn reduced the level of serum biomarkers, inflammatory and apoptotic factors. At the same time, it increased the anti-inflammatory and anti-apoptotic factors, thereby reduced DNA damage and restored the hepatic histology. In conclusion, exhaustive research is of the utmost demand to elucidate the precise defense mechanisms of ASEO against LN-induced hepatotoxicity.

Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework

An important provision of the Minamata Convention on Mercury is to monitor and evaluate the effectiveness of the adopted measures and its implementation. Here, we describe for the first time currently available biotic mercury (Hg) data on a global scale to improve the understanding of global efforts to reduce the impact of Hg pollution on people and the environment. Data from the peer-reviewed literature were compiled in the Global Biotic Mercury Synthesis (GBMS) database (>550,000 data points). These data provide a foundation for establishing a biomonitoring framework needed to track Hg concentrations in biota globally. We describe Hg exposure in the taxa identified by the Minamata Convention: fish, sea turtles, birds, and marine mammals. Based on the GBMS database, Hg concentrations are presented at relevant geographic scales for continents and oceanic basins. We identify some effective regional templates for monitoring methylmercury (MeHg) availability in the environment, but overall illustrate that there is a general lack of regional biomonitoring initiatives around the world, especially in Africa, Australia, Indo-Pacific, Middle East, and South Atlantic and Pacific Oceans. Temporal trend data for Hg in biota are generally limited. Ecologically sensitive sites (where biota have above average MeHg tissue concentrations) have been identified throughout the world. Efforts to model and quantify ecosystem sensitivity locally, regionally, and globally could help establish effective and efficient biomonitoring programs. We present a framework for a global Hg biomonitoring network that includes a three-step continental and oceanic approach to integrate existing biomonitoring efforts and prioritize filling regional data gaps linked with key Hg sources. We describe a standardized approach that builds on an evidence-based evaluation to assess the Minamata Convention's progress to reduce the impact of global Hg pollution on people and the environment.

Assessment of potential ecological risk of heavy metal contamination of agricultural soils in Kazakhstan

Accumulation of heavy metals in soil can lead to the deterioration of soil quality, reduce soil fertility and crop yields, and thus threaten human and animal health. The study aimed to assess the potential ecological risk of heavy metal contamination of agricultural soils in Kazakhstan. The study was carried out in 2021 on the soils of the Zhdanovskoye owner-operated farm in the Sokolovsko-Sarybai district of the Kostanay region. The quantitative content of heavy metals, such as lead (Pb), mercury (Hg), arsenic (As), and cadmium (Cd), was determined, and concentrations of trace elements, such as zinc (Zn), copper (Cu), iron (Fe), and manganese (Mn), were calculated for the considered contaminated lands. The potential ecological risk index (RI) proposed by L. Hakanson was used in the study concerning heavy metal contamination of soil. As a result, the presence of trace elements and heavy metals in the considered areas of the Kostanay region was shown. The RI values for all sites ranged from 137 to 447, corresponding to the level of ecological risk grading from low to high. The average RI for As, Cd, Hg, Pb, Zn, Ni, and Cu amounted to 328, which indicates a high ecological risk. Detected levels of As, Cd, Zn, and Pb in long-term abandoned mining areas were well above national thresholds, indicating the impending need to fully investigate and assess the suitability of the land for further agricultural use. The availability of such data will allow predicting cluster-based development of processing infrastructures in the vicinity of agricultural lands.

Triazophos-induced Respiratory and Behavioral Effects and Development of Adverse Outcome Pathway (AOP) for short-term Exposed Freshwater Snail, Bellamya Bengalensis

The physiological effects of triazophos were examined using respiratory and behavioral endpoints in Bellamya bengalensis under a 96-hour acute exposure regime. Physiological manifestation of respiratory stress was measured using the rate of oxygen consumption while behavioral toxicity was measured using crawling reflexes, touch response, and mucus production. The threshold effect values for LOEC (Lowest Observed Effect Concentration), NOEC (No Observed Effect Concentration), and MATC (Maximum Acceptable Toxicant Concentration) at 96 h were 0.40, 0.60, and 0.075 mg/l, respectively. Definitive 96 h acute exposures for both respiratory and behavioral endpoints tests were determined using a control group and concentrations ranging from 0.40 to 1.60 mg/l monitored for 24, 48, 72, and 96 h. Test organisms irrespective of exposure concentration demonstrated an initial rise in oxygen consumption rate after 24 h, followed by a progressive decrease in toxicant concentration and exposure period. The in silico structural analysis presents triazophos as having an electrophilic toxic structure similar to choline esterase inhibitors, and also capable of inducing oxidative stress. The AOP highlighted neurotoxicity and oxidative stress as plausible pathways of triazophos toxicity in mollusk species.

Cadmium effects on the freshwater teleost Prochilodus lineatus: Accumulation and biochemical, genotoxic, and behavioural biomarkers

In order to evaluate the effects of Cd, juveniles of the Neotropical fish Prochilodus lineatus were exposed to 1 and 10 μg L^-1 Cd, for 24 and 96 h. Fish exposed to Cd showed metal accumulation in the gills, kidney, and liver, an increase in DNA damage in erythrocytes, and an increase in lipid peroxidation (LPO) in the kidney. Cd exposure also caused a reduction in catalase activity, metallothionein induction, and LPO in the liver. Cd stimulated the swimming activity of exposed fish, resulting in longer swimming times and distances travelled, especially for the shortest exposure time. Changes in acetylcholinesterase activity (AChE) in the muscle and brain are probably related to these behavioural responses. These results show that Cd affects the functioning of several organs in P. lineatus, which is indicated by the genotoxic damage and changes in the AChE and swimming pattern of the exposed fish.

Determination of heavy metals and selenium contents in fish meat sold at Erbil City, Kurdistan Region, Iraq

Food contamination with heavy metals may pose a serious threat to human health. Fishes are the most common seafood globally. This study aimed to evaluate the levels of heavy metals in different fishes sold in Erbil city markets. The targeted heavy metal elements were cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), lead (Pb), mercury (Hg), manganese (Mn), nickel (Ni), selenium (Se), and zinc (Zn). Seventeen dorsal meat samples were digested and subjected to metal analysis by Inductively Coupled Plasma Optical Emission Spectrometry. Co, Mn, Cu and Se were detected in all samples, while cadmium was below the detectable level in all samples. The average concentrations of targeted trace elements were 0.03±0.016, 0.02±0.03, 0.07±0.08, 0.10±0.08, 0.03±0.03, and 2.90±3.33 mg/kg for cobalt, chromium, copper, manganese, nickel, and zinc, respectively. Lead was only found in one sample (5.88%). On the contrary, mercury was detected in all samples but in low concentration (0.14±0.07). All detected heavy metals with specified permissible limits by FAO/WHO were significantly lower than the permissible limits. Based on detected levels of targeted heavy metals, consumption of such fish has no potential risks to human.

Biomonitoring of Heavy Metal Pollution Using Acanthocephalans Parasite in Ecosystem: An Updated Overview

As a result of the global industrial revolution, contamination of the ecosystem by heavy metals has given rise to one of the most important ecological and organismic problems, particularly human, early developmental stages of fish and animal life. The bioaccumulation of heavy metals in fish tissues can be influenced by several factors, including metal concentration, exposure time, method of metal ingestion and environmental conditions, such as water temperature. Upon recognizing the danger of contamination from heavy metals and the effects on the ecosystem that support life on earth, new ways of monitoring and controlling this pollution, besides the practical ones, had to be found. Diverse living organisms, such as insects, fish, planktons, livestock and bacteria can be used as bioindicators for monitoring the health of the natural ecosystem of the environment. Parasites have attracted intense interest from parasitic ecologists, because of the variety of different ways in which they respond to human activity contamination as prospective indices of environmental quality. Previous studies showed that fish intestinal helminths might consider potential bioindicators for heavy metal contamination in aquatic creatures. In particular, cestodes and acanthocephalans have an increased capacity to accumulate heavy metals, where, for example, metal concentrations in acanthocephalans were several thousand times higher than in host tissues. On the other hand, parasitic infestation in fish could induce significant damage to the physiologic and biochemical processes inside the fish body. It may encourage serious impairment to the physiologic and general health status of fish. Thus, this review aimed to highlight the role of heavy metal accumulation, fish histopathological signs and parasitic infestation in monitoring the ecosystem pollutions and their relationship with each other.

Response patterns of biomarkers in omnivorous and carnivorous fish species exposed to multicomponent metal (Cd, Cr, Cu, Ni, Pb and Zn) mixture. Part III

Toxicity to fish of multicomponent metal mixtures at maximum-permissible-concentrations (MPC: Cd-0.005, Cr-0.01, Cu-0.01, Ni-0.01, Pb-0.005 and Zn-0.1 mg/L) set for EU inland waters was evaluated using the whole-mixture approach. An extended follow-up study on the biological effects of multicomponent metal mixtures on three ecologically different fish species, i.e. Perca fluviatilis, Rutilus rutilus, and Salmo salar is reported. The aim of this study was to assess response patterns of biomarkers (erythrocytic nuclear abnormalities (ENAs), metal accumulation and metallothioneins) in tissues of fish species after 14-day treatment with multicomponent metal mixtures at MPC and metal mixtures with one of its components at reduced MPC (↓). After treatments with Cu↓ and Cr↓, the lowest amount of Ni was found in all tissues (except the liver) of all fish species tested. After Zn↓ and Pb↓ treatments, the amount of Ni in muscle of all the tested fish species significantly decreased. The highest amounts of Cr in gills and Pb in muscle were detected in all fish species after treatments with Ni↓ and Cd↓ mixtures, respectively. R. rutilus accumulated significantly larger amounts of metals than P. fluviatilis and S. salar. The data obtained show that tissues of the omnivorous R. rutilus exposed to metal mixtures accumulated higher amounts of Cr, Cu, Ni and Zn, while tissues of carnivorous S. salar and P. fluviatilis higher amounts of Cd and Pb. The analysis of ENAs revealed concentration-dependent responses, indicating Cu↓ and Cr↓ treatments as causes of higher geno- and cytotoxicity levels.

Heavy metal concentrations in sediments and Cyprinus carpio from Maqalika Reservoir -Maseru, Lesotho: An analysis of potential health risks to Fish consumers

The determination of heavy metal contaminants in fish is very important in monitoring health risks to humans who consume them. This study assessed the concentration of heavy metals (As, Pb and Zn) in sediments and gills of Common Carp fish (Cyprinus carpio) from Maqalika Reservoir in Maseru, Lesotho and their potential health risks to such fish consumers. Sediment and Cyprinus carpio samples were collected from upstream, midstream and downstream sites of Maqalika Reservoir and examined for As, Pb and Zn using atomic absorption spectrometer. Potential health risks were based on comparing the derived metal concentrations in gills of Cyprinus carpio with the World Health Organization (WHO) permissible limits for human consumption. The mean concentration levels of Zn, As and Pb in sediment were in the order: 78.5; 2.34; and 0.29 mg/kg respectively. In the gills of Cyprinus carpio the mean concentration levels were in the order 7.85; 1.29; and 0.33 mg/kg for Zn, As and Pb respectively. The magnitude of concentration of Zn, As and Pb by location in the reservoir varied spatially in the order of downstream > midstream > upstream in both sediment and gills of Cyprinus carpio. Significant differences (p < 0.05) in metal concentrations between upstream and downstream sites of the reservoir were observed. The metals concentration in gills of Cyprinus carpio were lower than those in sediments, but positively and significantly correlated (P < 0.05). As and Pb concentration levels in the gills of Cyprinus carpio were higher than the WHO permissible limits recommended for fish consumption of 1 mg/kg and 0.2 mg/kg respectively, suggesting that residents could experience significant health risks from the intake of individual metals through fish consumption. Measures should be taken to reduce heavy metal concentrations in sediment and Cyprinus carpio exposure in the general population in order to minimize the risk of human health adverse effects.

Metals and metalloid in gold mine pit lakes and fish intake risk assessment, Burkina Faso

This study aimed to determine the levels of metals and metalloid (arsenic) in pit lakes from a gold mining site and in their fishes and assess their potential health effect on the local human population, in order to evaluate whether pit lakes can be safely used for aquaculture. Water quality data were collected from two pit lakes, namely West Pit 1 (WP1) and West Pit 2 (WP2), and the Nakambé River (NR) in Burkina Faso. Fish consumption rates in different villages were assessed through a survey. Commonly available fish were sampled from the pit lakes and the NR. Fish from the pit lakes contained higher amounts of metals and metalloid than fish from the river (WP1 ~ WP2 < NR). Of the four species of fish considered, Oreochromis niloticus and Hydrocynus forskahlii had the highest metals and metalloid content and Bagrus bajad and Clarias anguillaris had the lowest. The results indicated that the consumption of the whole fish results in higher metals and metalloid intake than consumption of the fleshy part only. Due to the low fish intake of 5.34 ± 2.60 g/day/adult deduced from the nutritional survey, exposure to metals and metalloid was below referential doses. The highest arsenic intake comes from eating entire O. niloticus (0.058 mg/day/adult) from WP1. Eating O. niloticus and C. anguillaris exposes people to an arsenic intake of 0.01 mg/day/adult. The arsenic contents of H. forskahlii and B. bajad were below the method detection limit.

Distribution and health risk assessment of cadmium, lead, and mercury in freshwater fish from the right bank of Senegal River in Mauritania

Clarias gariepinus (African catfish) and Oreochromis niloticus (Tilapia fish) from the right North bank of the Senegal River in Mauritania (Rosso, Boghé, and Kaédi) were sampled during 1-year monitoring and tested for lead (Pb), cadmium (Cd), and mercury (Hg) levels. Fishing from the Senegal River is an essential source of food for the local population and these two species are the most common. Muscle presents higher Hg concentrations than liver and gills for both species. Gill Hg concentrations from Kaédi are higher than Boghé and Rosso for both species. The Cd levels measured in gills were low in the different locations and revealed high variation throughout the 1-year study. No significant differences were observed between concentrations of Cd in Clarias gariepinus and Oreochromis niloticus parts. Statistical treatment did not show a considerable variation of Pb concentration between the different parts, revealing lower levels in gills from Boghé than the ones from Kaédi and Rosso. The associated human health risk was calculated from the concentration levels using the target hazard quotient (THQ) approach. Even though all the THQ values and the hazard index were lower than 1 for the determined trace metals when the exposure frequency was not greater than three times a week, eating frequency in the studied locations sometimes is greater than five, thus posing a health risk, especially at Kaédi and Boghé.

Replacing fish meal with insect meal in the diet of Atlantic salmon (Salmo salar) does not impact the amount of contaminants in the feed and it lowers accumulation of arsenic in the fillet

Insects are promising sources of protein and lipid in feeds for farmed animals. In the European Union, the use of insect meal (IM) and insect oil is permitted in fish feed. However, the European Food Safety Authority has highlighted the lack of data regarding the chemical safety of insects and products thereof. In this study, Atlantic salmon (Salmo salar) were fed diets in which fish meal (FM) was partially or fully substituted with IM, resulting in four diets with an FM replacement of 0%, 33%, 66% and 100% by IM. The IM was produced from Black soldier fly (Hermetia illucens) larvae fed media containing 60% seaweed (Ascophyllum nodosum). After 16 weeks of feeding, fish fillet samples were collected. The concentrations of undesirable substances, e.g., heavy metals, arsenic, dioxins, mycotoxins, pesticides, in the IM, the diets and fillets were determined. The concentrations of the analysed compounds in the IM were all below EU maximum levels for feed ingredients, except for arsenic. However, for complete feeds the concentrations of these compounds in the feeds, including arsenic, were all below EU MLs. Arsenic was transferred from seaweed to IM, resulting in arsenic levels in IM similar to what has been documented for FM. Transfer of arsenic from feed to fillet was observed; however, total arsenic concentrations in the fillet significantly decreased when fish were fed diets with more IM and less FM. Arsenic speciation analysis of the diets showed that although total arsenic levels were similar, the arsenic species were different. Arsenobetaine was the major organoarsenic species in the diets containing FM, while in diets containing IM several unidentified arsenic species were detected. The results suggest that the lower feed-to-fillet transfer of arsenic when FM is replaced by IM may be due to the presence of arsenic species with low bioavailability in the IM.

Bioaccumulation and potential sources of heavy metal contamination in fish species in River Ganga basin: Possible human health risks evaluation

This paper assesses the potential human health risks posed by five heavy metals (Zn, Pb, Cu, Cd, and Cr) found in seven most consumable fish species (Cirrhinus mrigala, Cirrhinus reba, Catla catla, Lebio rohita, Crossocheilus latius, Clupisoma garua, and Mystus tengara) collected from local markets of Varanasi, Allahabad, Mirzapur, and Kanpur of Uttar Pradesh, India. The Cu concentration was found at Varanasi (4.58 mg/l), Allahabad (2.54 mg/l), and Mirzapur (2.54 mg/l). Pb was recorded 0.54, 0.62, 0.85, and 0.24 mg/l at Kanpur, Allahabad, Mirzapur, and Varanasi, respectively. The Cd concentration was recorded 0.54, 0.68, 0.78, and 0.85 mg/l at Kanpur, Allahabad, Mirzapur, and Varanasi, respectively. The Cr, Cd, and Pb concentrations in the river water were observed over the prescribed safe limits at all sampling sites, while Cu concentration was higher than the standards at all sites except Kanpur. However, Zn was observed under the permissible limits (15 mg/l) at all sampling sites. In case of fish tissues, WHO reported the concentration of Pb, Cd, and Cr higher than the prescribed safe limits. The results determined that the highest heavy metals accumulation was found settled in the liver of all selected fish species. Zn ranked the highest quantity, which was found in fish tissues with the concentration of 32.41 ± 2.55 μg/g in the gill of C. catla and 4.77 ± 0.34 μg/g in the gill C. Reba. The metals followed the magnitude order of Zn > Pb > Cu > Cd > Cr in selected fish tissues.

Multi-elemental ionic liquid-based solvent bar micro-extraction of priority and emerging trace metallic pollutants (Cd, Ag, Pd) in natural waters

Transition metals Cd, Pd and Ag are toxic even at very low concentration. Cd is considered a priority substance; while, Pd and Ag are emerging pollutants. Membrane technologies have been applied for their extraction; however, they require important amounts of reagents, time and energy. Additionally, effective reagents for metal extraction in saline natural waters are limited. In this case, hollow fiber liquid phase micro-extraction with a configuration of solvent bar (SBME) using the ionic liquid Cyphos® 101 as extractant is proposed. Optimized conditions for SBME of Cd, Ag and Pd were 50% Cyphos® 101 in the organic solution, extraction time 30 min and 800 rpm stirring rate. Leaching was in all cases lower than 0.1%. Metallic concentrations were measured by flame atomic absorption spectroscopy. The method was applied to the extraction of Ag, Cd and Pd in natural water samples. Except for waste water, Pd extraction was higher than 90% in all cases. Cd (≈100%) and Ag (93-95%) offered their best results for saline samples. Concluding, the proposed system is a low cost and green methodology that allows a simple and fast extraction of trace pollutants such as Ag, Cd and Pd in different natural waters, including highly saline samples.

Survey on Heavy Metals Contamination and Health Risk Assessment in Commercially Valuable Asian Swamp Eel, Monopterus albus from Kelantan, Malaysia

This work investigates the metals concentration in the tissues of Asian swamp eel, Monopterus albus. Five selected tissues, including liver, gill, bone, skin, and muscle were examined for the concentration of Zn, Cu, Cd, Pb, and Ni. The concentrations of Cd and Pb were found high in the muscle tissues of the eels. Additionally, high amounts of Zn and Cu metals were observed in the liver, whereas the Cd, Pb, and Ni metals were highly detected in gill. The accumulation of Zn, Cu, Cd, Pb, and Ni in both skin and bone of the eel seems to vary between seasons. Low levels of Zn, Cu, and Ni were identified in the muscle tissues of the eels. This study revealed that the concentration of Cd and Pb in the muscle tissues of Asian swamp eels exceeded the permissible limits by the US EPA, suggesting the consumption of the muscle may be hazardous and can severely affect one’s health.

Coal mine effluent-led bioaccumulation of heavy metals and histopathological changes in some tissues of the catfish Clarias batrachus

Coal mining generates huge quantity of toxic effluent which consistently pollutes the neighboring wetlands where the local inhabitants regularly cultivate edible fishes. In the present study the concentration of heavy metals Fe, Zn, Cu, Mn, Ni, Cd, Pb and Cr were analyzed in the water and various tissues of edible catfish Clarias batrachus reared in a pond receiving effluents from Rajrappa coal mine, Jharkhand, India. The metal concentrations in the pond water were dramatically higher (Fe 350%, Zn 423%, Cu 12%, Mn 7029%, Ni 713%, Cd 1700%, Pb 4333% and Cr 588%) than the safe limit of Environmental Pollution Agency (2003) as well as the control tap water. Excessive amounts of metals in effluent caused their substantial transfer to the different tissues of the catfish reared in such ponds. Results showed that accumulation of metals in fish tissues were in the following order: liver > kidney > air breathing organ (ABO) > gills > skin > brain > muscles. Among the various tissues the highest accumulation of most of the metals was recorded in the liver (2.05-271.28 mg/kg dry weight) and lowest in the muscles (1.39-30.27 mg/kg dry weight), while the concentration of metals in other tissues ranged in between. The accumulation of heavy metals in tissues appears to cause remarkable histopathological alterations in skin, gills, ABO, liver and kidney that might be leading to deleterious effect on fish physiology and consequently impact the consumers of such fishes.

Bioaccumulation of heavy metals in fish species from the Meiliang Bay, Taihu Lake, China

In the present study, the bioaccumulation of heavy metals (Cr, Cu, Cd, Pb) content were determined in freshwater edible fishes Cyprinus carpio Linnaeus and Pelteobagrus fluvidraco, which were caught from the Meiliang Bay, Taihu Lake, a large, shallow and eutrophic lake of China. The results showed that the Cr, Cu, Cd and Pb content in the edible parts of the two fish species were much lower than Chinese Food Health Criterion (1994). However, the results showed marked differences in the four analyzed metal content between the two species and different tissues as well as significant variations. Pb content were the highest in the liver of fishes, Cd contents were almost the same in all organs of fishes, Cr contents mainly enriched in the kidney and liver, Cu contents were the highest in gills, However, the total metal bioaccumulation were greatest in the liver, gills and the lowest in the muscle. Although the total accumulations were highest in P. fluvidraco compare then C.carpio. This investigation indicated that fish products in Meiliang Bay, Taihu Lake were still safe for human consumption, but the amount consumed should be controlled under the Chinese Food Health Criterion to avoid excessive intake of Pb. Further, this is the first report on seasonal distribution of heavy metals and proximate compositions of commercialized important edible fishes from Meiliang Bay, Taihu Lake, China.

Exposure of the endangered Milky stork population to cadmium and lead via food and water intake in Kuala Gula Bird Sanctuary, Perak, Malaysia

The Milky stork is listed as an endangered species endemic to the Southeast Asia region. In Malaysia, the population is currently being reintroduced back into the wild. However, the increase of anthropogenic activity throughout the coastal area might expose the population to hazardous chemicals such as heavy metals. This study highlights the contamination of cadmium (Cd) and lead (Pb) in the Milky stork's diet. Additionally, this is the first time an integrated exposure model being used to assess heavy metal exposure risk to the population. Lead level (5.5-7.98 mg kg-1) in particular was relatively high compared to Cd (0.08-0.33 mg kg-1). This was probably related to the different niches occupied by the species in the aquatic environment. The results further show that the predicted exposure doses (through intake of both food and water) for all metals are much lower than the Tolerable Daily Intake (TDI) values. The total exposure dose for Cd was 0.11 mg kg-1 d-1 with TDI value of 0.54 mg kg-1 d-1 while Pb total exposure dose was 0.31 mg kg-1 d-1 with TDI value of 0.64 mg kg-1 d-1. Several possible factors that could lead to the observed pattern were discussed. In conclusion, there is an urgent need to improve the current habitat quality to protect the endangered species. The authors also emphasized on the protection of remaining Milky stork's habitats i.e. mudflats and mangroves and the creation of buffer zone to mitigate the negative impacts that may arise from pollution activity.

Tissue specific metal characterization of selected fish species in Pakistan

Concentration of various metals, i.e., zinc (Zn), copper (Cu), lead (Pb), nickel (Ni), iron (Fe), manganese (Mn), chromium (Cr), and silver (Ag), was evaluated in five indigenous fish species (namely, silver carp, common carp, mahseer, thela fish, and rainbow trout), by using atomic absorption spectrophotometer. It is proved from this study that, overall, mahseer and rainbow trout had high amount of zinc, whereas thela fish and silver carp had high concentration of copper, chromium, silver, nickel, and lead, while common carp had highest amount of iron contents. Furthermore, a tissue-specific discrimination among various fish species was observed, where higher metal concentrations were noticed in fish liver, with decreasing concentration in other organs like skin, gills, and finally the least contents in fish muscle. Multivariate data analysis showed not only a variation in heavy metals among the tissues but also discrimination among the selected fish species.