Health risk of Hg, Pb, Cd, Zn, and Cu to the inhabitants around Huludao Zinc Plant in China via consumption of vegetables

Huludao Zinc Plant in Huludao City, China is the largest zinc smelting plant in Asia. Heavy metals have contaminated its neighboring environment seriously. We collected 20 vegetables and the corresponding soil samples from eight sampling plots near Huludao Zinc Plant to investigate health risk of Hg, Pb, Cd, Zn, and Cu to the inhabitants around Huludao Zinc Plant in China via consumption of vegetables. Transfer factor (TF) values of Hg, Pb, Cd, Zn, and Cu from soil to vegetable and the target hazard quotients (THQs) to the possible health risks to local population through the food chain transfer were calculated accordingly. TF values of heavy metals from soil to vegetable decrease in the order of Cd>Zn>Cu>Pb>Hg. These TF values of leaves are higher than other tissues. Daily intakes of Hg, Pb, Cd, Zn, and Cu through the consumption of vegetables are 1.322, 574.3, 301.4, 5263, and 292.5 microg, respectively, for adults, and 1.029, 446.8, 234.5, 4095, and 227.6 microg, respectively, for children around Huludao Zinc Plant. This would lead to potential health risk, especially for children, since Cd or Pb individual THQ is high than 1. The total metal THQs (TTHQs) due to consumption of vegetables for adult and child are 5.79-9.90, 7.6-13.0, respectively. Comparing TTHQs in the sampling plots of different distances to Huludao Zinc Plant, it indicate that the health risks to inhabitants close to Huludao Zinc Plant (<500 m) is the highest, and at >1000 m distance is relatively higher than in 500-1000 m distance. However, the inhabitants who lived in 500-1000 m distance to Huludao Zinc Plant is also experiencing the adverse health risk due to TTHQ being higher than 1.     

Population health risk due to dietary intake of heavy metals in the industrial area of Huludao City, China

For most people, diet is the main route of exposure to trace metals, so the assessment risks of these elements to human via dietary intake is important. The non-carcinogenic health risk of Hg, Pb, Cd, Zn and Cu to the adults and children via dietary intake in the industrial area of Huludao city, northeast of China was estimated. The industrial area of Huludao has been contaminated seriously by heavy metals due to heavy metals smelting. The target hazard quotients (THQs) and hazard index (HI) were calculated to evaluate the non-carcinogenic health risk from individual heavy metal and combined heavy metals due to dietary intake. Target hazard quotients for individual heavy metal from consuming individual foodstuff in the industrial area of Huludao were all less than one, indicating that health risk associated with the intake of a single heavy metal through consumption of only one kind of foodstuffs (e.g. vegetable) was the relative absent. However, consumption of the entire foodstuff would lead to potential health risks for children and adults, since hazard indexes (HIs) for heavy metals due dietary intake were higher than one. The relative contributions of Hg, Pb, Cd, Zn and Cu to the HIs were 1.7%, 11.7%, 24.0%, 23.4%, and 39.6% for adults, and 1.5%, 11.7%, 21.8%, 26.1%, and 38.8% for children. Cereal, sea product, and vegetable were the main sources of heavy metal intake from foodstuff for adults and children, but fruit, milk, bean, and egg were secondary contributors.     

Health risk from heavy metals via consumption of food crops in the vicinity of Dabaoshan mine, South China

Heavy metal contamination of soils resulting from mining and smelting is causing major concern due to the potential risk involved. This study was designed to investigate the heavy metal (Cu, Zn, Pb and Cd) concentrations in soils and food crops and estimate the potential health risks of metals to humans via consumption of polluted food crops grown at four villages around the Dabaoshan mine, South China. The heavy metal concentrations in paddy and garden soils exceeded the maximum allowable concentrations for Chinese agricultural soil. The paddy soil at Fandong village was heavily contaminated with Cu (703 mg kg^− 1), Zn (1100 mg kg^− 1), Pb (386 mg kg^− 1) and Cd (5.5 mg kg^− 1). Rice tended to accumulated higher Cd and Pb concentration in grain parts. The concentrations of Cd, Pb and Zn in vegetables exceeded the maximum permissible concentration in China. Taro grown at the four sampled villages accumulated high concentrations of Zn, Pb and Cd. Bio-accumulation factors for heavy metals in different vegetables showed a trend in the order: Cd > Zn > Cu > Pb. Bio-accumulation factors of heavy metals were significantly higher for leafy than for non-leafy vegetable. The target hazard quotient (THQ) of rice at four sites varied from 0.66-0.89 for Cu, 0.48-0.60 for Zn, 1.43-1.99 for Pb, and 2.61-6.25 for Cd. Estimated daily intake (EDI) and THQs for Cd and Pb of rice and vegetables exceeded the FAO/WHO permissible limit. Heavy metal contamination of food crops grown around the mine posed a great health risk to the local population through consumption of rice and vegetables.     

Daily intake of TBT, Cu, Zn, Cd and As for fishermen in Taiwan

The consumption of contaminated seafood has been reported as an important route of human exposure to metals in Taiwan. We consider the concentrations of TBT, Cu, Zn, Cd, As, and the consumption of oysters of Taiwanese to be the important information related to public health in Taiwan. Therefore, the aim of this study was to evaluate the public health risks associated with TBT, Cu, Zn, Cd and As from shellfish for the general population and fishermen of Taiwan. In general, TBT concentrations in various oysters ranging from 0.32 to 1.51 microg/g dry wt. varied with sampling locations. The highest TBT, Cu, and Zn geometric mean (GM) concentrations in oysters of 1.51, 1180 and 1567 microg/g dry wt. were obtained from the Hsiangshan coastal area. The values of oyster consumption for fishermen were 94.1 and 250 g/day for typically and maximally exposed individuals, respectively. In particular, the highest intake (250 g/day) from fishermen was almost two times greater than that of the general population (139 g/day). The THQ (target hazard quotient) values of Hsiangshan's fishermen are 3.87 and 20.50 for TBT and Cu for maximally exposed individuals are higher than other oyster culture areas. It is interesting that those consuming oysters from Hsiangshan, Lukang, Taishi caused abnormally high THQs of TBT and other metals (100% over 1.0), and TBT was attributed to only 3-21% of the total THQs in different fishermen of Taiwan. Our results suggest that current environmental levels of TBT and other metals are associated with a significant potential threat to human health for fishermen resident in coastal areas of Taiwan.     

Heterogeneity of cadmium concentration in soil as a source of uncertainty in plant uptake and its implications for human health risk assessment

The major route of exposure of humans to the toxic element cadmium (Cd) is via the consumption of vegetables homegrown on Cd contaminated soil. It is well known that soil pH is one of the main soil properties controlling bioavailability of Cd in plants. This is acknowledged in human health risk assessment models that incorporate pH dependant concentration factors (CF=plant Cd/soil Cd). However, variation in spatial heterogeneity of nutrients and heavy metals in soil can have a profound effect on plant performance and uptake of nutrients and heavy metals. Here we show for lettuce (variety Crispino) that variation in plant-scale heterogeneity of Cd in soil affects bioavailability and hence CF by a factor of 2. Plant yield is also significantly affected. This has important implications for both human health risk assessment, as variation in CF affects predicted exposure, and for phytoremediation where an optimal combination of plant yield and contaminant accumulation is required.     

Heavy metals in wheat grain: assessment of potential health risk for inhabitants in Kunshan, China

Heavy metals (HMs) may cause deleterious effects on human health due to the ingestion of food grain grown in contaminated soils. Concentrations of HMs (Hg, As, Cr, Cu, Ni, Pb, Zn and Cd) in wheat grains were investigated in different areas of a developed industry city in Southeast China (Kunshan city), and their potential risk to health of inhabitants was estimated. The results showed that concentrations of HMs in the top soil (0-15 cm) were in this order: Zn>Cr>Ni>Pb>Cu>As>Hg>Cd. The Zn, Cr, Ni Cd and Hg concentrations of several soil samples exceeded the permissible limits of China standard. In addition, concentrations of HMs in wheat grain decreased in the order of Zn>Cu>Pb>Cr>Ni>Cd>As>Hg. There were 1, 6 and 10 wheat samples whose Zn, Pb and Cd concentrations were above the permissible limits of China standard, respectively. In relation to non-carcinogenic risks, Hazard Quotient (HQ) of individual metal presented values inside the safe interval. However, health risk due to the added effects of eight HMs was significant for rural children and rural adults, but not for urban adults and urban children. HQ (individual risk) and HI (Hazard Index of aggregate risk) to different inhabitants due to HMs followed the same sequence of: country children>country adults>urban children>urban adults. Amongst the HMs, potential health hazards due to As, Cu, Cd and Pb were great, and that due to Cr was the minimum. It was suggested to pay more attention on the potential added threat of HMs to the health of country inhabitants (both children and adults) through consumption of wheat in Kunshan.     

Quantificational exposure,sources, and health risks posed by heavy metals in indoor and outdoor household dust in a typical smelting area in China

Contamination of metals in household dust remains a concern for human health. However, few studies to date have been conducted on the contribution of both indoor and outdoor environments to the health risks posed by metals. This study was carried out to assess the potential health risks from both indoor and outdoor household dust and the respective contribution to the health risks for children. The results showed that household dusts were heavily polluted by metal(loid)s, which were up to 30 times higher than the relative background level, and were attributed to smelting activity. However, there are other pollution sources in indoor environments, since the I/O ratio values of Pb, Cd, and As were significantly higher than 1. HI values of Pb and As exceeded the threshold of (1) and accounted for approximately 60% and 24% to the HIt, respectively. The HIts of Zn, Cr, Mn, Hg, and Cu were mainly attributable to indoor dust exposure, particularly for Hg (73.44%), indicating non-carcinogenic health risks could be attributed more to the indoor dust exposure. This study highlights the potential risks of metal contamination in household environment, particularly indoor environment, on the health of children who live in the vicinity of smelting activity.     

Arsenic and heavy metal contamination of vegetables grown in Samta village,Bangladesh

Drinking of arsenic (As) contaminated well water has become a serious threat to the health of many millions in Bangladesh. However, the implications of contamination of agricultural soils from long-term irrigation with As-contaminated groundwater for phyto-accumulation in food crops, and thence dietary exposure to As, and other metals, has not been assessed previously in Bangladesh. Various vegetables were sampled in Samta village in the Jessore district of Bangladesh, and screened for As, Cd, Pb, Cu and Zn by inductively coupled plasma emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). These local food products are the basis of human nutrition in this region and of great relevance to human health. The results revealed that the individual vegetables containing the highest mean As concentrations microg x g(-1)) are snake gourd (0.489), ghotkol (0.446), taro (0.440), green papaya (0.389), elephant foot (0.338) and Bottle ground leaf (0.306), respectively. The As concentration in fleshy vegetable material is low. In general, the data show the potential for some vegetables to accumulate heavy metals with concentrations of Pb greater than Cd. Some vegetables such as bottle ground leaf, ghotkol, taro, eddoe and elephant foot had much higher concentrations of Pb. Other leafy and root vegetables, contained higher concentrations of Zn and Cu. Bioconcentration factors (BCF) values, based on dry weight, were below 1 for all metals. In most cases, BCF values decreased with increasing metal concentrations in the soil. From the heavily As-contaminated village in Samta, BCF values for As in ladies finger, potato, ash gourd, brinjal, green papaya, ghotkol and snake gourd were 0.001, 0.006, 0.006, 0.014, 0.030, 0.034 and 0.038, respectively. Considering the average daily intake of fresh vegetables per person per day is only 130 g, all the vegetables grown at Samta had Pb concentrations that would be a health hazard for human consumption. Although the total As in the vegetables was less than the recommended maximum intake of As, it still provides a significant additional source of As in the diet.     

Heavy metal contamination of water, soil and produce within riverine communities of the Río Pilcomayo basin, Bolivia

The Río Pilcomayo heads on the Cerro Rico de Potosí precious metal-polymetallic tin deposits of Southern Bolivia. Mining of the Potosí deposits began in 1545 and has led to the severe contamination of the Pilcomayo's water and sediments for at least 200 km downstream of the mines. This investigation addresses the potential human health affects of metal and As contamination on four communities located along the upper Río Pilcomayo by examining the potential significance of human exposure pathways associated with soils, crops and water (including river, irrigation and drinking water supplies). The most significantly contaminated agricultural soils occur upstream at Mondragón where Cd, Pb and Zn concentrations exceed recommended guideline values for agricultural use. Further downstream the degree of contamination decreases, and metal concentrations are below Dutch, German and Canadian guideline values. Metal and As concentrations in agricultural products from the four communities were generally below existing guidelines for heavy metal content in commercially-sold vegetables. Thus, the consumption of contaminated produce does not appear to represent a significant exposure pathway. A possible exception is Pb in carrots, lettuce and beetroots from Sotomayor and Tuero Chico; 37% and 55% of the samples, respectively, exceeded recommended guidelines. Most communities obtain drinking water from sources other than the Río Pilcomayo. In general, dissolved concentrations of metals and As in drinking water from the four studied communities are below the WHO guideline values with the exception of Sb, which was high at Tasapampa. The inadvertent ingestion of contaminated water from irrigation canals and the Río Pilcomayo represents a potential exposure pathway, but its significance is thought to be minimal. Given the degree of soil contamination in the area, perhaps the most significant exposure pathway is the ingestion of contaminated soil particles, particularly particles attached to, and consumed with vegetables. The risks associated with this pathway can be reduced by thoroughly washing or peeling the vegetables prior to consumption. Other exposure pathways that are currently under investigation include the consumption of contaminated meat from livestock and poultry, which drink polluted waters and the ingestion of contaminated wind-blown dust.     

Accumulation of cadmium, mercury and lead by vegetables following long-term land application of wastewater

Several vegetable species which are part of the daily diet of Tehran's population were examined for potential uptake of cadmium, mercury and lead from soil following longterm land application of wastewater. The three study sites located in the south of Tehran have been receiving untreated domestic wastewater by flood irrigation for many years. Elevated levels of cadmium, mercury and lead were found in the upper layers of soil. Examined vegetables accumulated some cadmium, mercury and lead from treated soils, but accumulation was relatively low. Due to the low concentration of these metals and their poor absorption from the gastrointestinal tract (excluding absorption of lead in children), it does not appear that the short-term consumption of these contaminated vegetables would produce acute toxicity. However, since absorption of dietary lead in children is relatively high and children are very sensitive to lead toxicity, short-term consumption of these vegetables plus other environmental sources of these metals in Tehran may produce chronic effects in children.     

The use of town refuse ash in urban agriculture around Jos, Nigeria: health and environmental risks

This paper reports on a study that examines the health and environmental risks of using town refuse ash in urban vegetable production in Jos, Nigeria, in terms of heavy metal accumulation in the food chain. Soil and crop samples, collected from five study farms, and samples of the river water used for irrigation, were analysed for seven heavy metals Fe, Mn, Zn, Cu, Ni, Cd and Pb. On the basis of the field data the paper discusses: (1) the potential soil deficiencies and toxicities; (2) the probable links between soil heavy metal levels and fertilisation practices; (3) the heavy metal concentrations in crop tissue in relation to crop growth and human health. The findings suggest that soil concentrations of the seven metals fall within 'typical' soil levels, and that there should not be any problems of either toxicities or deficiencies for crop growth. There was evidence of slight accumulation of Zn, Cu and Cd on some of the farms with a history of town refuse ash use. However, in all farms lettuce crops contained very large concentrations of Fe, and Pb concentrations that were 20 to 40 times higher than the WHO/FAO maximum recommended level in leafy vegetables for human consumption. The Cd content of carrot tissue was 10 times higher than the WHO/FAO recommended limit. The relatively small number of soil and crop samples precluded any formal attempt at correlating the concentrations of heavy metals found in the vegetable crops with the farm levels. Nevertheless, the data suggested that these were not linked. The paper goes on to consider various potential sources of the metals found in the crops, including irrigation water, town refuse ash and air-borne dust, and discusses additional health and environmental risks pertaining to the use of town refuse ash. Undoubtedly, the heavy Pb and Cd contamination of certain crops indicates the urgent need for future studies to ascertain the precise source of these metals, and although the practice of using town refuse ash does not appear to have resulted in large-scale contamination of soil in the farming area, there are a number of unsafe practices associated with it that call for the identification of strategies for the safe utilisation of urban waste in Jos.     

Consumption of homegrown products does not increase dietary intake of arsenic, cadmium, lead, and mercury by young children living in an industrialized area of Germany

The dietary intake of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) was studied among young German children with different food consumption behaviour (consumption of own grown foodstuffs and of products from the supermarket). The study area comprised an industrialized and a rural area of West Germany. Dietary intake of contaminants was measured by the duplicate method according to the WHO guideline. A total 588 duplicate portions were collected daily from 84 individuals between May and September 1998. Intake of food groups was calculated from dietary records. Determination of As, Cd, Hg, and Pb was performed following high-pressure digestion of lyophilized samples by atomic absorption spectrometry (AAS). Geometric mean weekly intake [microg/(kgbw x week)] was as follows: As 1.4, Cd 2.3, Hg 0.16, and Pb 5.3. Geometric mean intake corresponded to the percentage of the provisional tolerable weekly intake (PTWI) as follows: As 9.7%, Cd 32%, Hg 3.3%, Pb 21%. As and Hg intake were mainly influenced by fish consumption. The amount of cereals and bakery wares mainly determined the Cd and Pb intake. Children living in the industrialized area with a substantial food consumption of own grown vegetables or products from domestic animals products had no increased dietary intake of the metals.     

Health risk assessment of heavy metal exposure to street dust in the zinc smelting district, Northeast of China

Heavy metal contamination in the street dust due to metal smelting in the industrial district of Huludao city was investigated. Spatial distribution of Hg, Pb, Cd, Zn and Cu in the street dust was elucidated. Meanwhile, noncancer effect and cancer effect of children and adults due to exposure to the street dust were estimated. The maximum Hg, Pb, Cd, Zn and Cu contents in the street dust are 5.212, 3903, 726.2, 79,869, and 1532 mg kg^− 1, and respectively 141, 181, 6724, 1257 and 77.4 times as high as the background values in soil. The trends for Hg, Pb, Cd, Zn and Cu are similar with higher concentrations trending Huludao zinc plant (HZP). The exponential equation fits quite well for the variations of Pb, Cd, Zn and Cu contents with distance from the pollution sources, but not for Hg. The biggest contribution to street dust is atmospheric deposition due to metal smelting, but traffic density makes slight contribution to heavy metal contamination. According to the calculation on Hazard Index (HI), in the case of noncancer effect, the ingestion of dust particles of children and adults in Huludao city appears to be the route of exposure to street dust that results in a higher risk for heavy metals, followed by dermal contact. The inhalation of resuspended particles through the mouth and nose is almost negligible. The inhalation of Hg vapour as the fourth exposure pathway to street dust is accounting for the main exposure. Children are experiencing the potential health risk due to HI for Pb larger than safe level (1) and Cd close to 1. Besides, cancer risk of Cd due to inhalation exposure is low.     

Mercury contamination in the vicinity of a derelict chlor-alkali plant Part II: contamination of the aquatic and terrestrial food chain and potential risks to the local population

This study investigated the environmental impact and level of risk associated with mercury (Hg) contamination near a derelict chlor-alkali plant in Pavlodar, Northern Kazakhstan. Several species of fish were sampled from the highly polluted Lake Balkyldak and the nearby river Irtysh, to assess the extent of Hg bioaccumulation in the aquatic food chain and potential human health risks. A small number of bovine tissue samples, water samples, soil and plant samples from a nearby village were also investigated in order to make a preliminary assessment of potential impacts on the terrestrial food chain. Mercury levels in fish caught from Lake Balkyldak ranged from 0.16 to 2.2 mg kg(-1) and the majority of fish exceeded current human health criteria for Hg. Interspecies comparisons indicated that Hg is accumulated in the order dace>carp>tench. Site-specific bioaccumulation factors (BAF) were calculated for THg, and were estimated for MeHg. Fish from the river Irtysh and floodplain oxbow lakes contained between 0.075 and 0.159 mg kg(-1) of Hg and can be regarded as uncontaminated. Soils were found to be impacted by past atmospheric emissions of Hg. Cattle grazing in the surroundings of the factory are exposed to Hg from contaminated soils, plants and surface water, but the consumption of contaminated fish from the lake appears to be the main route of exposure for humans.     

Assessment of a remediation technique using the replacement of contaminated soils in kitchen gardens nearby a former lead smelter in Northern France

Vegetables cultivated in kitchen gardens that are strongly contaminated by heavy metals (Pb, Cd) may represent to consumers a means of exposure to these metals. This exposure is more problematic for those families that include a large quantity of home-grown vegetables in their diet. Researchers have shown that the majority of vegetables produced in kitchen gardens in the vicinity of the Metaleurop Nord smelter (Northern France) do not conform to European regulations. This study was carried out in three of these kitchen gardens. The concentrations of Cd and Pb in the topsoils were up to 24 and 3300 mg kg(-1) respectively. The method consisted of delineating a surface area of about 50 to 100 m(2) for each garden, then removing the contaminated soil and replacing it with a clean one. Seven species of vegetables were cultivated from 2003 to 2005 in the original contaminated soils and the remediated ones. The data showed a clear improvement of the quality of the vegetables cultivated in remediated soils, although 17% of them were still over the European legislative limits for foodstuffs. This suggested that there was a foliar contamination due to contaminated dust fallout coming from the closed smelter site and the adjacent polluted soils. In addition, the measurement of the Cd and Pb concentrations in the dust fallout showed that the substantial rise in metal concentrations in the remediated soil was not only due to atmospheric fallout. These results raise questions about possible technical, economic and sociological problems associated with this kind of remediation.     

Spatial and seasonal variation in heavy metals in the sediments and biota of two adjacent estuaries, the Orwell and the Stour, in eastern England

A study was made of the concentrations of the elements As, Cd, Cu, Hg, Mn, Ni, Pb and Zn in the sediments and biota of two adjacent estuaries, the Orwell and Stour, in eastern England. The Orwell Estuary, with its urbanized head, was more contaminated with heavy metals than the Stour Estuary. Generally, in both estuaries, concentrations of metals were highest towards the head and the mouth. Saltmarsh sediments accumulated higher concentrations of most metals than mudflat sediments. Metal concentrations in the biota showed marked interspecific differences; Mytilus edulis had higher concentrations of Cd, Littorina littorea higher concentrations of Cu and Mn and Arenicola marina higher concentrations of Hg. Invertebrates from the Orwell had higher metal concentrations than those from the Stour. Algae had generally lower levels of metals than invertebrates. Metal concentrations were greatest and more variable in the top 10 cm of sediment. Metals were at greatest concentrations in winter and lowest in summer in sediments, algae and invertebrates. Mercury concentration increased with size in the three invertebrate species studied, but Cd and Zn generally were at higher concentrations in younger animals. Comparisons of sediments with average shale values indicated anthropogenic enrichment with several metals but it was considered that only Pb, at some sites, and possibly Hg posed potential threats to the ecology of the estuaries.     

Soft metal preferences of 1,3-benzenediamidoethanethiol

Recent studies indicate that the sodium salt of 1,3-benzenediamidoethanethiol (BDET) is both economical and effective in precipitating mercury and other heavy metals from water. Because wastewaters and contaminated natural waters may contain a variety of heavy metals, it is important to determine how different heavy metals may interact with BDET, and whether free metals may displace those that are bound. To explore this possibility, Cd-, Cu-, Pb-, Mn-, Hg- and Zn-BDET were leached separately under a nitrogen purge for up to 240 h in pH 3 aqueous solutions containing 0.100 mmol of all five heavy metals. The leaching studies indicate that dissolved Hg has a strong tendency to displace Cd, Cu, Mn, Pb, and Zn from the BDET structure.     

Marine trace metal pollution assessment by fish as indicator species

Levels of eleven trace metals (Ag, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn and Hg) and four macronutrients (Na, K, Ca and Mg) were estimated in the edible muscle of six commercially exploited fish species using the atomic absorption spectrophotometric method. The fish included in the study were: Argyrops spinifer, Fistularia petimba, Bramnoplaties suppositus, Lepidotriqla omaneaisis, Pampus argentus and Sphyraena obtusata harvested from the south‐west coast of the Arabian Sea along the Karachi coast, Pakistan. All metals have shown substantial increase in their average levels over the past few years. Pampus argentus was found undesirable for human consumption as it contained elevated levels of five metals (As, Cr, Pb, Zn and Hg). This species could be used to monitor marine trace metal pollution since it was found to contain consistently enhanced levels of the industrial metals.     

The use of Micropogonias furnieri and Mugil liza as bioindicators of heavy metals pollution in La Plata river estuary, Argentina

This paper presents, the concentrations of total Hg, Cd and Zn in edible muscle tissue, and in the liver of the fish Micropogonias furnieri and Mugil liza from the Samborombon Bay, La Plata river estuary, Argentina. The highest accumulation of the three metals was observed in liver samples, whereas in muscle tissue concentrations they were always lower, values even lower than the detection limit of the analytical method used. A marked relationship between metal contents of the studied species and their trophic and ecological habits was observed. In all cases, metal levels found in edible muscle tissue were lower than the international standards of reference for organisms directed to human consumption. Finally, the validity of using these two species as bioindicators of heavy metal pollution in the assessed ecosystem was discussed.     

Heavy metal pollution in the Chao Phraya River estuary, Thailand

A study on heavy metal pollution in the Chao Phraya River estuary indicated that the accumulation of Cd, Cu, Cr and Pb in water in the river mouth vicinity was significant, which may have a long term impact on the aquatic environment through precipitation of heavy metals to the bottom sediments and bio-accumulation and bio-magnification of heavy metals in various food chains. Although the seasonal and spatial variations of heavy metals in the sediments and fish did not conform to a definite pattern, the heavy metal contents of samples were higher than those previously reported in the area and in some cases were higher than the mean world concentrations. Thus, Thai people may ingest Hg and Pb in fish in the Chao Phraya River estuary at quantities more than those reported for other countries.