Consumption Of Heavy Metals Research Articles

Eco-friendly and stable silver bismuth disulphide quantum dot solar cells via methyl acetate purification and modified ligand exchange

Abstract From the point of view of environmentally-friendly, non- or less toxic photovoltaic material and fabrication method are desired by both the academia and industrial community. However, most efficient quantum dot solar cells have been fabricated based on heavy metal and toxic solvent consumption, which could cause serious ecological problems. Quantum dot solar cells were studied and explored based on lead-free active material silver bismuth disulphide, less toxic solvent purification of methyl acetate and lab-developed ligand exchange process. Twice ligand exchanges with tetramethylammonium iodide were applied for every deposited quantum dot layer kept in static. Methanol rinse was applied to the quantum dot film after each ligand exchange process to promote the ligand exchange and clean the organic residuals. Decent power conversion efficiency and good stability were demonstrated for the fabricated silver bismuth disulphide quantum dot solar cells. The best power conversion efficiency of 4.57% was achieved, with open-circuit voltage of 0.445 V, short-circuit current of 18.87 mA/cm2 and fill factor of 54.4%. Over 95% of the original power conversion efficiency was maintained after 150 days both in N2-filled glove box and ambient atmosphere with relative humidity of 30%. This work demonstrated fabrication of quantum dot solar cells based on non- or less-toxic quantum dots and solvent consumption. Which would benefit the development and commercialization of quantum dot solar cell technology.

Physics analysis of new TRU recycling options using FCM and MOX fueled PWR assemblies

Abstract In this work, new multi-recycling options of TRU nuclides using PWR fuel assemblies comprised of MOX and FCM (Fully Ceramic Micro Encapsulated) fuels are suggested and neutronically analyzed. These options do not use a fully recycling of TRU but a partial recycling where TRUs from MOX fuels are recycled while the ones from FCM fuels are not recycled due to their high consumption rate resulted from high burnup. In particular, additional external TRU feed in MOX fuels for each cycle was considered to significantly increase the TRU consumption rate and the finally selected option is to use external TRU and enriched uranium feed as a makeup for the heavy metal consumption in MOX fuels. This hybrid external feeding of TRU and enriched uranium in MOX fuel was shown to be very effective in significantly increasing TRU consumption rate, maintaining long cycle length, and achieving negative void reactivity worth during recycling.

Chemical characteristics and health hazards of heavy metals in shallow groundwater: case study Anloga community, Volta Region, Ghana

Five water samples each were collected from six shallow wells which serve as source of drinking water at different locations within the Anloga community of the Volta Region in Ghana. Samples were analyzed for physicochemical characteristics, and human health risk associated with the consumption of heavy metals in the samples was also assessed. The results showed that pH, EC, water hardness, fluoride and sulfate levels were below the maximum permissible levels recommended by the WHO for drinking but chloride and nitrate levels in well A6 were above their respective WHO limits. Concentration of heavy metals showed Cd and Pd toxicities in some of the wells since their concentrations were higher than the WHO accepted limit for drinking water. Estimated non-carcinogenic health risks of the metals through ingestion were less than 1 in some of the wells, indicating small to no health hazard; however, high non-carcinogenic risk was recorded in well 2, 3 and 5 indicating a potential health hazard to the local residents. Health risk through dermal injection of the metals was found to be less than 1, indicating no health risk associated with water samples via dermal absorption. Cancer risk computed for Cd ranged from 1.82E−02 in well A5 to 9.09E−02 in well A1 and A6, indicating that consumption of water from these wells could result in an excess of 2–9 cancer cases per 100 people. The risk of developing cancer from Pb as a result of consuming water from wells A1, A2 and A5 was estimated to be 3.69E−06.

Electrochemical detection of lead and cadmium in UHT-processed milk using bismuth nanoparticles/Nafion®-modified pencil graphite electrode

Pencil graphite electrodes (PGEs) were modified with bismuth nanoparticles and Nafion® using the drop-coating method. Simultaneous detection of trace cadmium (Cd2+) and lead (Pb2+) in ultrahigh-temperature-processed milk samples were done via anodic stripping voltammetry using the modified PGE as the working electrode. Scanning electron microscopy and energy-dispersive x-ray analyses were conducted for the morphological characterization of the modified PGE. The limit of detection was found to be 7.31 μg/L for Cd2+ and 31.07 μg/L for Pb2+. Trace quantities of Cd2+ and Pb2+ in the milk samples were detected. Results showed that all milk samples have tolerable daily intake less than the World Health Organization's permissible daily consumption of trace heavy metals of 0.83 μg/kgbw based on the average adult body weight (60 kg) and estimated volume of daily milk consumption (0 .5 L).

Heavy Metal Contamination of Selected Vegetables from Crude Oil and Non Crude Oil-Producing States in Nigeria: A Comparative Study

The aim of this study was to investigate and compare the heavy metal (HM) concentrations of selected vegetables harvested from crude oil-producing Rivers State and non-oil-producing Enugu State in Nigeria. Four vegetables;Telfaria occidentialis, Talinum triangulare, Ocimium gratissimum, and Murraya koenigii,were obtained from local farms in local government areas (LGAs) selected, each from the 3 senatorial zones in each state.The chemical analysis in mg/100g of the heavy metals (HMs) was conducted using standard methods. There mean values varied in the order: lead (Pb) > cadmium (Cd) > mercury (Hg) in mg/100g. Vegetable samples harvested from Rivers State had the highest toxicity level for both Pb (0.19 to 0.34) and Hg (0.01 to 0.03), while samples harvested from Enugu State had the highest toxicity level for Cd (0.07 to 0.25). The mean Pb contents forOcimium gratissimum(0.27) andTalinum triangulare(0.26), harvested from Rivers States were significantly (p < 0.05) higher than their counterparts harvested from Enugu State (0.19 and 0.21, respectively). Mercury had the least mean value than Pb and Cd in all the locations. All the vegetables from all the localities in this study had toxic levels of HM much above the FAO/WHO acceptable limits; 0.03 mg/100g for Pb, and 0.02 mg/100g for Cd in foods and 0.0001 mg/100g for Hg in mineral water. It can therefore be said that the public health importance for increased consumption of fruits and vegetables may equally mean increased HM consumption and bioaccumulation for the population in Rivers and Enugu States.

Evaluation of Arsenic, Cadmium, Lead and Mercury Contamination in Over-the-Counter Available Dry Dog Foods With Different Animal Ingredients (Red Meat, Poultry, and Fish).

Objectives: To examine the relative levels of heavy metals and arsenic content in commercial dog foods (arsenic, cadmium, lead and mercury) of 51 over-the-counter maintenance or all-life-stage dry dog foods. All products were chosen and segregated based on meat sources (fish, poultry, red-meat—17 products from each category) as animal protein sources being the primary contaminated ingredient due to bioaccumulation.Methods: Inductively coupled plasma mass spectrometry (ICP-MS) was performed on products that were classified as fish, red meat (beef, pork, venison, bison) or poultry (chicken, turkey, duck) based. A non-Gaussian data distribution for each heavy metal within category distribution led to non-parametric statistical testing and median (range) descriptive statistics. Comparison to average human consumption based on mg/megacalorie (Mcal)was also examined.Results: Based on caloric consumption, total arsenic and heavy metal consumption is higher in dogs than in humans; however chronic toxic exposure levels are highly unlikely. Fish-based diets had significantly higher arsenic, cadmium and mercury content than the poultry or red meat-based diets (p < 0.01). Red meat-based diets (beef, venison and bison) had higher lead concentrations than poultry and fish-based diets (p < 0.03).Clinical Significance: Based on the findings, commercial dog foods appear to be safe for chronic consumption and concentrations of the heavy metals were dependent on primary protein sources. Overall, poultry-based diets had relatively lower heavy metal and arsenic content than red meat and fish-based diets. Despite the safety of most pet foods occasional outliers for lead render some concern for chronic exposure based on other species toxicity data and a lack of data in dogs.

Health risk due to chronic heavy metal consumption via cow’s milk produced in Puebla, Mexico, in irrigated wastewater areas

ABSTRACTThe aim of this study was to determine the heavy metals content of milk from cows fed with forage irrigated with waste water from industrial sources and the health risk to children. Milk samples were taken from milk collection tanks of eight localities in the state of Puebla. On average, the heavy metals in the milk had the following order Zn> As> Pb > Cr> Cu > Ni. Pb (0.03 mg kg−1) exceeded the Codex limits. For As the hazard index was 8.0 ± 0.4, which is far above 1. On the other hand, the individual risk of cancer showed a descending order Cr> As > Pb, while the risk of total cancer (0.004 ± 0.002) indicated that the combined effect of heavy metals created a serious risk for girls and children.

Wpływ przygotowania marchwi do spożycia na stężenie metali ciężkich w konsumowanym produkcie

1. Anyszka Z. Metodyka integrowanej ochrony marchwi (Materiały dla doradców). Instytut Ogrodnictwa. InHort 2013. Google Scholar

Assessment of toxic metals in vegetables with the health implications in Bangladesh

This study was conducted to investigate the levels of heavy metals in twelve species of vegetables and assessment of health risk. Samples were analyzed using inductively coupled plasma mass spectrometer (ICP-MS). The ranges of Cr, Ni, Cu, As, Cd and Pb in vegetables species were 0.37-5.4, 0.03-17, 0.35-45, 0.01-2.6, 0.001-2.2, and 0.04-8.8 [mg/kg, fresh weight (fw)], respectively. The concentrations of As, Cd and Pb in most vegetable species exceeded the maximum permissible levels, indicating unsafe for human consumption. Health risks associated with the intake of these metals were evaluated in terms of estimated daily intake (EDI), and carcinogenic and non-carcinogenic risks by target hazard quotient (THQ). Total THQ of the studied metals from most of the vegetables species were higher than 1, indicated that these types of vegetables might pose health risk due to metal exposure. The target carcinogenic risk (TR) for As ranged from 0.03 to 0.48 and 0.0004 to 0.025 for Pb which were higher than the USEPA acceptable risk limit (0.000001) indicating that the inhabitants consuming these vegetables are exposed to As and Pb with a lifetime cancer risk. The findings of this study reveal the health risks associated with the consumption of heavy metals through the intake of selected vegetables in adult population of Bangladesh.

Dietary intake of heavy metals from eight highly consumed species of cultured fish and possible human health risk implications in Bangladesh.

Concentrations of five heavy metals (Pb, Cd, Cr, As and Hg) in eight highly consumed cultured fish species (Labeo rohita, Clarias gariepinus, Hypophthalmichthys molitrix, Cyprinus capio, Puntius sarana, Oreochromis mossambicus, Pangasius pangasius and Anabas testudineus) collected from four wholesale markets of Dhaka city, Bangladesh (Karwan Bazar, Mohammadpur Town Hall, Newmarket and Mirpur-1) were measured using atomic absorption spectrometry (AAS) in order to evaluate the potential human health risks from the consumption of fish. The estimated daily intake (EDI) of all the studied heavy metals calculated on the basis of mean fish consumption of 49.5g person-1 d-1 by Bangladeshi households indicated that no risk to people's health with respect to the EDI of investigated heavy metals through the consumption of the fish samples. From the human health point of view, the estimation of non-carcinogenic risk indicated that intake of individual heavy metal through the consumption of fish was safe for human health, whereas, consumption of combined heavy metals suggested potential health risk to highly exposed consumers. However, the estimation of carcinogenic risk of arsenic due to the consumption of fish indicated that consumers remain at risk of cancer.

Arsenic and heavy metal contaminations in the tube well water of Punjab, Pakistan and risk assessment: A case study

The present study for the first time highlighted the arsenic and heavy metals (HM) concentrations as well as their source of contamination in tube-well water and associated potential health risk to local residents of Tehsil Mailsi (Punjab), Pakistan. 44 samples were collected from Jala Jeem and Dunia Pur. Results revealed average concentrations of anion and heavy metals such as Iron (Fe), (Cadmium) Cd, (Lead) Pb, (Sodium) Na+, (Bicarbonate) HCO3−, (Sulfate) SO42− and Arsenic (As) exceeded the WHO limits in the tube well water. The calculated target hazard quotient (THQ) of metals from local tube well water above 1 was observed for As (36.5) and Cd (6.2), which employed highly potential health risk to local residents. The suitability of water for irrigation is evaluated based on residual sodium carbonate (RSC), sodium adsorption ratio (SAR), Kelly’s index (KI), Sodium percent (%Na) and Magnesium absorption ratio (MAR). Dominant ions in the study area are HCO3−, Ca2+ and Mg2+ and water chemistry of the area is Ca2+-Mg2+-HCO3− type. However, different statistical tools, including principal component analysis (PCA), hierarchical cluster analysis (CA) and correlation matrices revealed the contribution of both natural as well as anthropogenic activities towards the high level of arsenic and heavy metals contamination in the local tube well water. The results show that consumption of heavy metals contaminated groundwater poses an emerging health threat to the populations in the study area, and hence needs urgent remedial and management measures. Continued monitoring of heavy metals levels is recommended for future management strategies.

Risk assessment of excessive CO2 emission on diatom heavy metal consumption

Diatoms are the dominant group of phytoplankton in the modern ocean, accounting for approximately 40% of oceanic primary productivity and critical foundation of coastal food web. Rising dissolution of anthropogenic CO2 in seawater may directly/indirectly cause ocean acidification and desalination. However, little is known about dietary diatom-associated changes, especially for diatom heavy metal consumption sensitivity to these processes, which is important for seafood safety and nutrition assessment. Here we show some links between ocean acidification/desalination and heavy metal consumption by Thalassiosira weissflogii. Excitingly, under desalination stress, the relationships between Cu, Zn, and Cd were all positively correlated, especially between Cu and Zn (r=0.989, total intracellular concentration) and between Zn and Cd (r=0.962, single-cell intracellular concentration). Heavy metal consumption activity in decreasing order was acidification<acidification+desalination<desalination for Zn, acidification<desalination<acidification+desalination for Cu and Cd, i.e., heavy metal uptake (or release) were controlled by environmental stress. Our findings showed that heavy metal uptake (or release) was already responded to ongoing excessive CO2 emission-driven acidification and desalination, which was important for risk assessment of climate change on diatom heavy metal consumption, food web and then seafood safety in future oceans.

Presence of heavy metals in fruits and vegetables: Health risk implications in Bangladesh

The presence of toxic heavy metals such as As, Cd, Pb, Cr, Mn, Ni, Cu, and Zn in nationally representative samples of highly consumed fruits and vegetables was determined by inductively coupled plasma mass spectrometry (ICP-MS). Their concentrations exceeded the maximum allowable concentration (MAC) set by FAO/WHO for Pb in mango and Cd in tomato among the analyzed fruits and vegetables. Pb content in mango was found to be six times higher than the safe limit at production level. Health risks associated with the intake of these metals were evaluated in terms of estimated daily intake (EDI), and carcinogenic and noncarcinogenic risks by target hazard quotient (THQ) and hazard index (HI). EDI values of all the metals were found to be below the maximum tolerable daily intake (MTDI). The THQs of all metals were <1, suggesting no health hazards for adult population. However, total THQs of Mn and Cu were >1 through consumption of all vegetables, indicating significant health risks. HI was found to be <1 (0.825) for consumption of fruits; however, it was >1 (3.727) for vegetable consumption, suggesting adverse health effects from vegetable consumption only. The total carcinogenic risk (CR) of As was below the threshold level (10−6) and 9.82E-05 for Pb, suggesting no potential CR from As consumption, but indicating the risk of Pb-induced carcinogenesis. The findings of this study reveal the health risks associated with the consumption of heavy metals through the intake of selected fruits and vegetables in adult population of Bangladesh.

Distribution of Heavy Metals in Muscles and Internal Organs of Korean Cephalopods and Crustaceans: Risk Assessment for Human Health

Samples of seven species of cephalopods and crustaceans were collected from major fish markets on the Korean coast and analyzed for mercury (Hg) using a direct Hg analyzer and for the metals cadmium (Cd), lead (Pb), chromium, silver, nickel, copper, and zinc using inductively coupled plasma mass spectrometry. The distributions of heavy metals in muscles, internal organs, and whole tissues were determined, and a risk assessment was conducted to provide information concerning consumer safety. The heavy metals accumulated to higher levels (P < 0.05) in internal organs than in muscles for all species. The mean concentrations of Cd, which had the highest concentrations of the three hazardous metals (Cd, Pb, and Hg), in all internal organs (except those of blue crab) exceeded the regulatory limits set by Korea and the European Union. The Cd concentrations in all whole tissues of squid and octopus (relatively large cephalopods), red snow crab, and snow crab exceeded the European Union limits. The estimated dietary intake of Cd, Pb, and Hg for each part of all species accounted for 1.73 to 130.57%, 0.03 to 0.39%, and 0.93 to 1.67%, respectively, of the provisional tolerable daily intake adopted by the Joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives; the highest values were found in internal organs. The hazard index (HI) is recognized as a reasonable parameter for assessing the risk of heavy metal consumption associated with contaminated food. Because of the high HI (>1.0) of the internal organs of cephalopods and the maximum HI for whole tissue of 0.424, consumers eating internal organs or whole tissues of cephalopods could be at risk of high heavy metal exposure. Therefore, the internal organs of relatively large cephalopods and crabs (except blue crab) are unfit for consumption. However, consumption of flesh after removing internal organs is a suitable approach for decreasing exposure to harmful metals.

Bioaccumulation of Heavy Metals in the Mussel Mytilus galloprovincialis in the Changseon area, Korea, and Assessment of Potential Risk to Human Health

From 2008 to 2013, the mussel Mytilus galloprovincialis were collected from a major area of mussel production (Changseon area), which is a designated shellfish-cultivating area for export, located on the southern coast of Korea. The samples were analyzed for mercury (Hg) using a direct Hg analyzer and for other metals, such as cadmium (Cd), lead (Pb), arsenic (As), chromium, copper, nickel, and zinc, using inductively coupled plasma mass spectrometry. The concentrations and bioaccumulation of the heavy metals were determined, and a potential risk assessment was conducted to evaluate their hazards towards human consumption. The concentration and bioaccumulation ratio of Cd were the highest of the three hazardous metals (Cd, Pb, and Hg). The concentrations of hazardous metals in all samples were within the limits set by Korea and other countries. The estimated dietary intake (EDI) was compared to the provisional tolerable daily intake (PTDI) adopted by the Joint FAO/WHO Expert Committee on Food Additives and the U.S. Environmental Protection Agency. The EDIs of all heavy metals tested for mussel samples ranged from 0.01 to 4.99% of the PTDI; the highest value was measured for As. The hazard index (HI) can be used to assess the risk of heavy metal consumption associated with contaminated food. The HI for all samples was far less than 1.0, which indicates that the mussels produced in the Changseon area do not represent an appreciable hazard to humans and are fit for consumption.

Health Risk Assessment of Consumption of Heavy Metals in Market Food Crops from Sialkot and Gujranwala Districts, Pakistan

ABSTRACTThis study was performed to investigate the potential health risk of heavy metals (HMs) through consumption of market food crops (MFCs) in the Sialkot and Gujranwala districts, Pakistan. Both study areas are located in industrialized regions of the country, where atmospheric pollution is a problem and irrigation of food crops is mostly practiced on the use of wastewater/contaminated water. For the purpose of this study, MFCs samples were collected and assessed for HMs (Cr, Ni, Cd, Pb, Mn, Cu, Zn, and Fe) by using flame atomic absorption spectrophotometry. Concentration of HMs such as Pb and Cd exceeded the Food and Agriculture/World Health Organization's recommended limits in all MFCs, while Cr in most of the vegetables of the Sialkot and Gujranwala districts also exceeded that limit. The health risk index was >1 in Triticum aestivum for Pb and Cd intake in the Sialkot district and only Pb in the Gujranwala district. Therefore, this study suggests pretreatment of wastewater and its utilization for lawns and green belts irrigation, rather than for food crops. This study also suggests a regular monitoring of HMs in the irrigation water, subsequent soil, air, and MFCs in order to prevent or reduce health hazards.

Contents and Risk Assessment of Heavy Metals in Marine Invertebrates from Korean Coastal Fish Markets

The concentrations of the heavy metals cadmium (Cd), mercury (Hg), lead (Pb), chromium, silver, nickel, copper, and zinc in the edible portions of 105 marine invertebrates representing 16 mollusk and crustacean species were accurately determined to evaluate their hazard for human consumption. The samples were collected in 2011 from major fish markets on the coast of Korea and analyzed for Hg using a direct Hg analyzer and for other metals using inductively coupled plasma mass spectrometry. Estimated dietary exposure (EDE) was determined, and a risk assessment was made of the heavy metals to provide information concerning consumer safety. The Cd concentrations, which were the highest for the three hazardous metals (Cd, Hg, and Pb), were significantly higher (P < 0.05) in the bivalves and crabs than in the gastropods and cephalopods. However, the concentrations of these metals in all samples were within the regulatory limits set by Korea and other countries. The EDE was compared with the provisional tolerable daily intake (PTDI) adopted by the Joint FAO/WHO Expert Committee on Food Additives or the U.S. Environmental Protection Agency. The EDE of Cd, Hg, and Pb for each class of marine invertebrate were 0.07 to 2.64, 0.01 to 0.43, and 0.001 to 0.16% of the PTDI, respectively. The total EDE of Cd, Hg, and Pb for marine invertebrates accounted for 4.03, 0.96, and 0.21%, respectively, of the PTDI. The EDE of other metals in each class of marine invertebrate was less than 2% of the PTDI. The hazard index is a reasonable parameter for assessing the risk of heavy metal consumption associated with contaminated food. In the present study, the hazard index for all of the species was less than 1.0, which indicates that the intake of heavy metals from consumption of these marine invertebrates does not represent an appreciable hazard to humans.

Thiamine Deficiency in Cambodian Infants with and without Beriberi

To test the hypothesis that heavy metal toxicity and consumption of thiaminase-containing foods predispose to symptomatic thiamine deficiency. In a case-control study, thiamine diphosphate (TDP) blood concentrations were measured in 27 infants diagnosed with beriberi at a rural clinic, as well as their mothers and healthy Cambodian and American controls. Blood and urine levels of lead, arsenic, cadmium, mercury, and thallium were measured. Local food samples were analyzed for thiaminase activity. Mean TDP level among cases and Cambodian controls was 48 and 56 nmol/L, respectively (P = .08) and was 132 nmol/L in American controls (P < .0001 compared with both Cambodian groups). Mean TDP level of mothers of cases and Cambodian controls was 57 and 57 nmol/L (P = .92), and was 126 nmol/L in American mothers (P < .0001 compared with both Cambodian groups). Cases (but not controls) had lower blood TDP levels than their mothers (P = .02). Infant TDP level decreased with infant age and was positively associated with maternal TDP level. Specific diagnostic criteria for beriberi did not correlate with TDP level. There was no correlation between heavy metal levels and either TDP level or case/control status. No thiaminase activity was observed in food samples. Thiamine deficiency is endemic among infants and nursing mothers in rural southeastern Cambodia and is often clinically inapparent. Neither heavy metal toxicity nor consumption of thiaminase-containing foods account for thiamine deficiency in this region.

Effects of pulse current on energy consumption and removal of heavy metals during electrodialytic soil remediation

The aims of this paper were to investigate the possibility for energy saving when using a pulsed electric field during electrodialytic soil remediation (EDR) and the effect of the pulsed current on removal of heavy metals. Eight experiments with constant and pulse current in the different industrially polluted soils were performed. At a current density of 0.1mA/cm2 in soil 1 and 0.2mA/cm2 in soil 2, there was no difference on energy consumption and removal of heavy metals between pulse current and constant current experiments, but at higher current experiments (i.e., 0.2mA/cm2 in soil 1 and 0.8mA/cm2 in soil 2) the energy was saved 67% and 60% and the removal of heavy metals was increased 17–76% and 31–51% by pulse current in soil 1 and soil 2, respectively. When comparing the voltage drop at different parts of EDR cells, it was found that the voltage drop of the area across cation exchange membrane was the major contributor of energy consumption, and the pulse current could decrease the voltage drop of this part effectively. The overall removal of heavy metals in soil 1 (6–54%) was much higher than soil 2 (1–17%) due to the different acidification process and chemical speciation of heavy metals reflected by sequential extraction analysis. Among all experiments, the highest removal efficiency occurred in pulse current experiment of soil 1, where 54% of Cu and 30% of As were removed.

Lead contamination in tea garden soils and factors affecting its bioavailability

The consumption of heavy metals is detrimental to human health and most countries restrict the concentration of metals such as lead (Pb) in food and beverages. Recent tests have detected high Pb concentrations in certain commercial brands of tea leaves and this finding has raised concerns for both producers and consumers. To investigate what factors may be contributing to the increase in Pb accumulation in the tea leaves we collected tea leaves and soils from tea producing areas and analyzed them for Pb concentration, pH and organic matter content. The result showed the Pb concentration of 47% investigated tea leaves samples was beyond 2 mg kg −1, the permissible levels given by China. The total Pb concentration in the surface and subsurface soil layers averaged 36.4 and 32.2 mg kg −1, respectively which fall below of the 60 mg kg −1 limit provided for organic tea gardens in China. The pH of the tea garden soils was severely acidic with the lowest pH of 3.37. Soils under older tea gardens tended to have a lower pH and a higher Pb bioavailability which was defined as the amount of lead extracted by CaCl 2 solution than those under younger tea gardens. We found that the concentration of bioavailable Pb and the percentage of bioavailable Pb (bioavailable Pb relative to total Pb concentration) were positively correlated with soil H + activity and soil organic matter content, and the organic matter accumulation contribute more effects on Pb bioavailability in these two factors. We conclude that soil acidification and organic matter accumulation could contribute to increasing Pb bioavailability in soil and that these could increase Pb uptake and accumulation in the tea leaves.