Heavy metal accumulation of edible vegetables cultivated in agricultural soil in the suburb of Zhengzhou City, People's Republic of China

Content of Cadmium and Nickel in Soils and Assimilatory Organs of Park Woody Species Exposed to Polluted Air

The rising level of pollutant emissions is becoming one of the most pressing environmental problems of our time. Therefore, this work is focused on evaluating Cd and Ni contamination of soils and assimilatory organs of two native (Acer platanoides L., Taxus baccata L.) and two non-native (Negundo aceroides Moench, Thuja occidentalis L.) woody species in urban parks of SW Slovakia. The contents of Cd and Ni in soils were determined by the AAS method and, in the assimilatory organs of trees, by the AAS-ETA method. The studied soils (Fluvisol, Phaeozem) have neutral soil reactions and a moderate organic matter content. Cadmium soil contamination is considerable to very high; in the case of Ni, it is moderate to low. Cadmium levels detected in leaves were 31% higher than in needles, while Ni levels were 27% lower. Significant ecological factors in relation to the studied woody species were evaluated using PCA. The first three principal components of PCA significantly correlated with Cd (PC1) and Ni (PC3) contents in soils and Cd content in assimilatory organs (PC2), thus suggesting that these elements could especially originate from industrial and vehicular sources. Knowledge of the factors affecting the accumulation of risk elements in the assimilatory organs of park woody species can be successfully used, especially in the assessment of the quality of the urban environment and the selection of suitable cultivars for planting in areas with air pollution.

Macronutrients, trace metals and health risk assessment in agricultural soil and edible plants of Mahshahr City, Iran

In this study, we evaluate the geochemistry of macro- (Fe, P, Ca, S, K, Na, Mg) and micronutrients (Mo, Cu, Pb, Zn, Co, Mn, Cd, Sr, Cr, Hg, Se), along with possible health risks of heavy metals contamination in agricultural soils and vegetables of the Mahshahr industrial port in Iran. Calculation of geochemical coefficients revealed the low pollution load of Mahshahr agricultural soils. Most of the investigated elements exhibited lower concentrations in soil than international standards. Element concentrations in plant samples were far below the permissible values set by environmental agencies. Based on permissible values, there was deficiency of several soil elements, including Cu, in vegetables because they are mostly present in the soil residual phase. An exception was Mn, which is the most mobile element in soil. The transfer factor (TF) of elements showed the following trend: K > Na > P > S > Mo > Hg > Se > Zn > Cd > Cu > Mg > Mn > Ca > Cr > Co ≈ Fe = Pb. There was high transfer of major elements from soil to plants, and lower values for micronutrients and heavy metals. The calculated daily intake (DIM) and health risk index (HRI) for ten plant species for adults were < 1, while the HRI was larger than 1 for Mn via radish consumption. According to geochemical investigations and statistical tests such as principal component analysis, Kruskal-Wallis, and correlation coefficient calculations, plant species play the most important role in elemental uptake by plants.

Health risk assessment of heavy metals via consumption of dietary vegetables using wastewater for irrigation in Swabi, Khyber Pakhtunkhwa, Pakistan

Health assumptions to the population due to the utilization of contaminated vegetables have been a great concern all over the world. In this study, an investigation has been conducted to ascertain metal concentrations in the wastewater, soil and commonly consumed vegetables from the vicinity of Gadoon Industrial Estate Swabi, Khyber Pakhtunkhwa Pakistan. Physicochemical parameters such as pH, electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS) and total solids (TS) and heavy metals such as Pb, Cr, Cd, Ni, Zn, Cu, Fe, Mn were determined using Atomic Absorption Spectrophotometer (AAS). Moreover, possible health risks due to the consumption of vegetables have also been estimated. pH and TSS in wastewater were found to be higher than the permissible limit set by WHO (1996). These results revealed that Cr concentration in the wastewater was above the permissible limits of United States Environmental Protection Agency (USEPA) which may lead to a detrimental effect on soil quality deterioration, ultimately leading to food contamination. ANOVA analysis demonstrated a significant difference in soil samples for Pb, Cr, Cd, Ni, Zn and Cu at p ≤ 0.001, for Mn at p ≤ 0.05 while no significant difference was observed for Fe respectively. ANOVA analysis also exhibited the highest mean value for Pb, Cr, Cd and Zn in vegetables. A substantial positive correlation was found among the soil and vegetable contamination. The transfer factor for Cr, Pb, Zn, Mn, Ni, Cd and Cu was greater than 0.5 due to contamination caused by domestic discharges and industrial effluents. Health assessment via consumption of dietary vegetables revealed a higher level than the permissible limit (HRI > 1) for Pb and Cd in children and adults. Enrichment factor (EF) due to consumption of vegetables was found higher for Pb and Cr respectively. Based on the findings of this study, there would be a significant risk to the consumers associated with consumptions of vegetables being cultivated in Gadoon Industrial Estate area of district Swabi. Therefore, strict regulatory control measures are highly recommended for the safety of vegetables originated from the study area.

Trace Elements in Soils and Vegetables from Market Gardens of Urban Areas in Marrakech City

The consumption of vegetables grown on soils polluted by trace elements can cause a serious threat for animal and human health and disturb the functioning of the ecosystem. The aim of this work is to determine the concentrations of As, Cd, Co, Cr, Cu, Ni, Pb, Mn, and Zn in soils and different vegetables from market gardens of urban areas in Marrakech city in order to investigate human health risk through ingestion of contaminated vegetables. Plant transfer factor (TF), daily intake of metals (DIM), and health risk index (HRI) were calculated. The concentrations of all metals studied in the garden top soils were within the threshold values. The Cu, Zn, Co, Mn, and As concentration in the edible parts of vegetables were within the safe limits. However, Cd and Pb in Malva parviflora and Cd in Brassica rapa, and Cr and Ni in Coriandrum sativum exceeded their permissible limits. The TF for these nine metals varied between 0.01 and 1.35. The classification of TEs according to their TF is as follows: Cu > Zn > Cd > Ni > Cr > Pb > Mn > Co > As. The maximum value was recorded in Coriandrum sativum while the minimum value was recorded in Cynara cardunculus. The HRI values were within the safe limit (< one) except for Pb in Malva parviflora. This can lead to risks to the health of the human population, especially children, consuming contaminated plants. Thus, the monitoring and prevention of health risks related to the consumption of plants grown in (peri)urban areas are necessary and essential to propose recommendations to both gardeners and decision-makers.

Isotope tracers for lead and strontium sources in the Tieguanyin tea garden soils and tea leaves

The concentrations of Pb & Sr in Tieguanyin tea leaves and soils from 15 tea gardens of Anxi, China, were determined and the sources of Pb & Sr in soil and leaf samples were analysed using isotope tracing technology. The results showed pH in soils had significant correlations to both acid-extractable Pb & Sr in soils and new leaves. The Pb concentration in leaves was significantly lower than that in soils, especially the acid-extractable Pb in soils. The low Bio-concentration Factor (BCF) indicated the bioavailable Pb in soils could not easily be transferred to leaves. The contribution rates of parent material were 61%-100% and 45%-100% for total Pb isotope and acid-extractable Pb isotope in soils, respectively, indicating a low impact of human activity. A sizeable influence of parent material for leaves was also observed, suggesting that Pb may be present in the dust-fall. Although Sr concentrations in leaves were not high, they exceeded that in soils. The high BCF also indicated that tea has a high capacity to accumulate Sr, with the coincidence that Sr⁸⁷/Sr⁸⁶ in the acid-extractable isotope in soils were similar to new leaves. A Pb-Sr joint tracer indicated that Sr in old and new leaves may be influenced by parent material and anthropogenic sources, respectively.

Health risk assessment through determining bioaccumulation of iron in forages grown in soil irrigated with city effluent

The irrigation with sewage water can be useful if it has no negative effects on food crop yield, soil pollution, and health of humans. However, it includes various types of contaminants like heavy metals that pollute the soil and crops. In this regard, the aim of this study was to evaluate the possible health risks of heavy metals in forages. Forages both of summer and winter were grown with different water treatments (sewage water and tap water) in Department of Botany, University of Sargodha. The concentration of iron (Fe) in water, soil, and plant samples was determined. The Fe values in tap and sewage water were observed as 0.090 and 0.115 mg/L, respectively. The highest mean concentration of Fe was 9.608 mg/kg in the soil where Trifolium alexandrinum is grown, and the lowest mean concentration was 0.154 mg/kg which occurred in the soil where Trifolium resupinatum is grown in winter. The maximum mean concentration of Fe in the root samples of plants was observed as 2.483 mg/kg in Pennisetum typhoideum, and the minimum mean concentration occurred as 0.390 mg/kg in Zea mays grown in summer. The maximum bioconcentration factor value of Fe was observed for T. resupinatum (5.259) grown in winter. The maximum pollution load index value of Fe was observed for T. alexandrinum (0.1688). The maximum value of daily intake of metals was observed as 0.0731 in Medicago sativa, and the maximum health risk index value was determined as 0.1091 in P. typhoideum.

Trace elements in soil-vegetables interface: Translocation, bioaccumulation, toxicity and amelioration - A review

The contamination of soil and vegetables with trace elements is one of the most severe ecological problems in developing industrialized countries. Trace elements are released into the environment from natural and anthropogenic activities and accumulated in soil and vegetables through various pathways which ultimately affects the human health. The present review aimed at 1) discussing the anthropogenic sources in detail, 2) describing the bioaccumulation, absorption, and transportation of trace elements, 3) exploring the options to reduce the health risk due to consumption of contaminated vegetables, 4) identifying the research and policy gaps related to soil and vegetables contamination with trace elements. Besides these objectives, the present review also detailed the several factors which affect the rate of accumulation, toxicity mechanism, and effects of trace elements on vegetables and humans. Various toxicity indices for health risk assessment have also been described. It is suggested to evaluate the trace metals concentration in irrigation water and soil prior to plant the vegetable to minimize the possible contamination.

Assessment of Trace Metal and Metalloid Accumulation and Human Health Risk from Vegetables Consumption through Spinach and Coriander Specimens Irrigated with Wastewater

This study focused on evaluating the metal and metalloid contamination and associated risks in the two vegetables crops, coriander (Coriandrum sativum) and spinach (Spinacia oleracea) treated with three water regimes, canal water, groundwater and municipal wastewater. These vegetables are widely consumed by people and are also used in traditional medicine for treating various disorders. Metal and metalloid accumulation (Zn, Pb, Se, Cu, As, Mo, Fe, Ni) was found higher in vegetables treated with wastewater. Wastewater treated soil had high pollution load index. Fe, Zn, As and Pb had higher values in water, soil and vegetables as compared to other studied metals. Overall, metal correlation for soil and vegetables was significant and positive except for Fe and Cu in spinach. The highest value for daily metal intake was estimated for Fe while Se had the lowest value for the same index. It was thus concluded that trace metal and metalloid accumulation was a major health concern for the public consuming these vegetables.

Status of mercury accumulation in agricultural soil across China: Spatial distribution, temporal trend, influencing factor and risk assessment

Given its wide distribution in the natural environment and global transport potential, mercury (Hg) is regarded as a ubiquitous pollutant. In this study, we carried out nation-wide sampling campaigns across China to investigate the distribution of Hg in agricultural soils. Concentrations of Hg in the soils collected in 2011 and 2016 ranged from 0.04 to 0.69 and 0.06-0.78 mg kg^-1, respectively. Based on the data from 2016, the reserve of Hg in the surface arable soils (0-20 cm) in China was 4.1 × 10⁴ metric tons and Chinese cultivated soils accounted for 63.4-364 metric tons of Hg released to the global atmosphere. The soil Hg concentrations were significantly higher than the reference background level, highlighting the impacts of anthropogenic activities. The vertical distribution pattern showed a clear enrichment at the surface and a decrease with depth of the soils. Comparison of calculated geo-accumulation indexes among individual provinces showed that Northwest China had higher levels of Hg contamination than other regions of China, likely due to long-term energy related combustions in the area. Soil Hg level showed strong positive correlations with organic matter contents of soil, as well as the mean annual precipitation and temperature of the sampling locations. The non-carcinogenic human health risks of soil Hg were below the threshold level, but the general risk to the ecosystem was considerable. The increases in Hg accumulation from 2011 to 2016 at provincial level were found to relate to coal combustion, power generation and per capita GDP. This examination of energy consumption and socioeconomic drivers for China's soil Hg reserve increase is critical for direct Hg control by guiding policy-making and targets of technology development in era of rapid economic growth.

Metal accumulation in Raphanus sativus and Brassica rapa: an assessment of potential health risk for inhabitants in Punjab, Pakistan

Pakistan is an agricultural country and due to the shortage of clean water, most of the irrigated area (32,500 ha) of Pakistan was supplied with wastewater (0.876 × 109 m³/year). Concentrations of heavy metals in radish (Raphanus sativus) and turnip (Brassica rapa) taken from vegetable fields in Sargodha, Pakistan, were measured. Untreated wastewater was used persistently for a long time to irrigate these vegetable fields. A control site was selected that had a history of fresh groundwater irrigation. Mean metal concentrations were found for irrigation water, soil, and vegetables. In irrigation water, concentrations of Mo and Pb at three sites and Se at sites II and III were higher than the recommended limits. In vegetables, concentrations of Mo and Pb were above the maximum permissible limits. High bioconcentration factor was observed for Zn (12.61 in R. sativus and 11.72 in B. rapa) at site I and high pollution load index was found for Pb (3.89 in R. sativus and 3.87 in B. rapa) at site II. The differences in metal concentrations found in samples depended upon different soil nature and assimilation capacities of vegetables at different sites which in turn depended upon different environmental cues. The entrance of metal and metalloids to human body may happen through different pathways; however, the food chain is the chief route through which metals are transferred from vegetables to individuals. Health risk index observed for metals, (Mo, As, Ni, Cu, and Pb) higher than 1 indicated high risk through consumption of these vegetables at three sites.

Evaluating the potential health risk of toxic trace elements in vegetables: Accounting for variations in soil factors

Vegetable crop consumption is one of the main sources of dietary exposure to toxic trace elements (TEs). A paired survey of soil and vegetable samples was conducted in 589 agricultural sites in the Youxian prefecture, southern China, to investigate the effect of soil factors on the accumulation of arsenic, cadmium, mercury, and lead in different vegetables. A site-specific model was developed to estimate the health risk from vegetable consumption. The TE concentration varied in different plant species, and rape can be cultivated in contaminated areas for its potential use in restricting the transfer of TE from soil to edible plant parts. The accumulation of TEs in vegetables was governed by multiple factors, mainly element interaction, metal availability (extractable CaCl₂ fraction), and soil pH. Soil Zn may promote Cd accumulation in vegetables when soil Cd/Zn ratio>0.02. Cadmium is a major hazardous component. About 80.8% of the adult populations consuming locally produced vegetables had a daily Cd intake risk above the safe standard. Among investigated vegetables, radish is potentially hazardous for populations because of its high consumption rate and high Cd content but low Zn accumulation. The consumption of radish cultivated in highly acidic soil (4<pH≤5) and high Cd contamination (CaCl₂-Cd=1.0mgkg^-1) had a significant probability (89.4%) to be above the safe standard; while this risk was significantly decreased to 8.9% in soil of near-neutral pH (6<pH≤7). The wide range of TE concentrations and soil factors suggests that a site-specific risk assessment is needed for better and safer vegetable production.

Public Health Risk Assessment of Heavy Metal Uptake by Vegetables Grown at a Waste-water-Irrigated Site in Dhaka, Bangladesh

BACKGROUND

Wastewater is often used in developing countries for irrigation of crops. This wastewater often contains a number of heavy metals which are harmful to human health due to their non-biodegradable nature, long biological half-lives and their potential to accumulate in different body parts. There are many potential risks to human health from heavy metal contamination of vegetables grown at waste-water-irrigated sites.

OBJECTIVES

This study was carried out to assess the concentration of heavy metals and the risk to human health by heavy metals (lead (Pb), nickel (Ni) and arsenic (As)) through the intake of locally grown vegetables collected from wastewater irrigated agricultural fields. The objectives of the present study were to determine concentrations of heavy metals in vegetables collected from the wastewater-irrigated fields, to calculate daily intake of heavy metals from the consumption of vegetables for both adults and children, and to evaluate their potential health risk.

METHODS

Twenty-seven samples of nine different types of vegetables were analyzed by an Atomic Absorption Spectrometer (AAS) (Varian AAS 240 F S).

RESULTS

The range of various metals in waste-water irrigated vegetables were not detected (ND)-0.188, 0.072-1.069 and ND-0.076 mg/kg for Pb, Ni and As, respectively. The highest mean concentration of all metals was detected in jute leaf, except for Pb which was found in the stem amaranth leaf. The mean concentration of all metals in all vegetables was within the safe limits of the World Health Organization/Food and Agricultural Organization (WHO/FAO) and China's national standards. The health risk index was more than 1 for As in jute leaf for both adults and children. The metal pollution index was highest (0.16 mg/kg) in jute leaf, whereas green papaya showed the lowest metal pollution index (MPI) value (0.005 mg/kg). Among all vegetables tested, the highest intake values of Ni and As were from consumption of jute leaf and the highest intake values of Pb from consumption of stem amaranth leaf for both adults and children.

CONCLUSIONS

Higher values in the metal pollution index and health risk index indicate heavy metal contamination in wastewater-irrigated soils that present the potential for a significant negative impact on human health.

Uptake and translocation of metals in different parts of crop plants irrigated with contaminated water from DEPZ area of Bangladesh

Metal contamination in arable soils and crops grown in and around an industrial area of Bangladesh were measured, and the transfer factor from soils to crops was calculated accordingly. The highest concentration was observed for Fe and the order of metal concentration was Fe > Zn > Cr > Pb > Cu > Ni > Cd in soils. Bioaccumulation and translocation of metals from roots to edible parts of the crop plants were varied for almost all elements studied. Absorption of metals was significantly more in the roots compared to other plant parts. Accumulation of all metals in the edible parts of the plants was compared with the recommended maximum tolerable levels proposed by the Joint FAO/WHO Expert Committee on Food Additives. Bioconcentration factors values based on dry weights were below one for all metals except Cu in the rice roots and decreased in the order of Cu > Zn > Fe > Pb > Ni > Cd > Cr.

Assessing of distribution, mobility and bioavailability of exogenous Pb in agricultural soils using isotopic labeling method coupled with BCR approach

The contamination of Pb in agricultural soils is one of the most important ecological problems, which potentially results in serious health risk on human health through food chain. Hence, the fate of exogenous Pb contaminated in agricultural soils is needed to be deeply explored. By spiking soils with the stable enriched isotopes of (206)Pb, the contamination of exogenous Pb(2+) ions in three agricultural soils sampled from the estuary areas of Jiulong River, China was simulated in the present study, and the distribution, mobility and bioavailability of exogenous Pb in the soils were investigated using the isotopic labeling method coupled with a four-stage BCR (European Community Bureau of Reference) sequential extraction procedure. Results showed that about 60-85% of exogenous Pb was found to distribute in reducible fractions, while the exogenous Pb in acid-extractable fractions was less than 1.0%. After planting, the amounts of exogenous Pb presenting in acid-extractable, reducible and oxidizable fractions in rhizospheric soils decreased by 60-66%, in which partial exogenous Pb was assimilated by plants while most of the metal might transfer downward due to daily watering and applying fertilizer. The results show that the isotopic labeling technique coupled with sequential extraction procedures enables us to explore the distribution, mobility and bioavailability of exogenous Pb contaminated in soils, which may be useful for the further soil remediation.

Evaluation of possible health risks of heavy metals by consumption of foodstuffs available in the central market of Rajshahi City, Bangladesh

Considering the human health risk due to the consumption of foodstuffs, the concentrations of heavy metals (lead, manganese, chromium, cadmium, and arsenic) are investigated in vegetables, fruits, and fish species collected from the central market (called Shaheb Bazar) of Rajshahi City, Bangladesh. The foodstuffs examined for metal constituents are the basis of human nutrition in the study area. The highest concentrations of Mn and As in vegetables (onion and pointed gourd, respectively), Cr and Cd in fruits (black berry and mango, respectively), and Pb in fish (catla) are recorded. Health risks associated with these heavy metals are evaluated due to dietary intake. Target hazard quotient (THQ) and hazard index (HI) are calculated to evaluate the non-carcinogenic health risk from individual and combined heavy metals. The THQ values for individual heavy metals are below 1, suggesting that people would not experience significant health risks if they ingest a single heavy metal from one kind of foodstuff (e.g., vegetables). However, consumption of several of the foodstuffs could lead a potential health risk to human population since HI value is higher than 1. The relative contributions of vegetables, fishes, and fruits to HI are 49.44, 39.07, and 11.53 %, respectively. Also, the relative contributions of Pb, Cd, As, Mn, and Cr to HI are 51.81, 35.55, 11.73, 0.85, and 0.02 %, respectively. The estimation shows that the carcinogenic risk of arsenic exceeds the accepted risk level of 1 × 10(-6). Thus, the carcinogenic risk of arsenic for consumers is a matter of concern.

Accumulation and spatial distribution of Cd, Cr, and Pb in mulberry from municipal solid waste compost following application of EDTA and (NH4)2SO4

Municipal solid waste compost can be used to cropland as soil amendment to supply nutrients and improve soil physical properties. But long-term application of municipal solid waste (MSW) compost may result in accumulation of toxic metals in amended soil. Phytoremediation, especially phytoextraction, is a novel, cost-effective, and environmentally friendly approach that uses metal-accumulating plants to concentrate and remove metals from contaminated soils. Ethylenediaminetetraacetate (EDTA) was applied to metal-contaminated soil to increase the mobility and phytoavailability of metals in soil, thereby increasing the amount of toxic metals accumulated in the upper parts of phytoextracting plants. The objectives of this study were (1) to investigate the accumulation and spatial distribution of toxic metals (Cd, Cr, and Pb) in mulberry from MSW compost with the application of EDTA and (NH(4))(2)SO(4), (2) to examine the effectiveness of EDTA and (NH(4))(2)SO(4) applied together on toxic metals (Cd, Cr, and Pb) removal by mulberry under field conditions, and (3) to evaluate the potential of mulberry for phytoextraction of toxic metals from MSW compost. The tested plant-mulberry had been grown in MSW compost field for 4 years. EDTA solution at five rates (0, 50, 100, 50 mmol L(-1) + 1 g L(-1) (NH(4))(2)SO(4), and 100 mmol L(-1) + 1 g L(-1) (NH(4))(2)SO(4)) was added into mulberry root medium in September 2009. Twenty days later, the plants were harvested and separated into six parts according to plant height. Cd, Cr, and Pb contents in plant samples and MSW compost were analyzed using an atomic absorption spectrophotometer. In the same treatment, Cd, Cr, and Pb concentrations in mulberry shoot were all higher than those in root, and Cd and Pb concentrations in shoot increased from lower to upper parts, reaching the highest in leaves. Significant increases were found in toxic metal concentration in different parts of mulberry with increasing EDTA concentration, especially when combined with (NH(4))(2)SO(4). Mulberry exhibited high ability to accumulate Cd with bioconcentration factors (BCFs) higher than 1. EDTA application also significantly increased Cd BCFs. More than 30 % of metal uptake was concentrated in mulberry branches (stem of above 100 cm height) and leaves. Results presented here show that mulberry is a woody plant that has the potential of Cd phytoextraction from MSW compost by removing leaves and cutting branches. The application of EDTA combined with (NH(4))(2)SO(4) significantly enhanced the efficiency of mulberry in removing Cd from the compost medium. Adding (NH(4))(2)SO(4) into the compost will lower the risk of the exposure of environment to excessive non-biodegradable EDTA in a large-scale EDTA-assisted phytoextraction by reducing the dosage of EDTA. In China, the need for sod is increasing day by day. Sod is often produced on arable soil and sold together with soils. This would lead to the soil being infertile and the soil layer thin. After several times' production, the soil can no longer be used for cultivating crops and be destroyed. In order to fully utilize MSW compost resources and save valuable soil resources, MSW compost can be used to replace arable soil to produce sod after extraction of toxic metals in it.

Heavy metal accumulation in vegetables grown in a long-term wastewater-irrigated agricultural land of tropical India

In the present study, the magnitude of contamination of vegetables with heavy metals (Pb, Zn, Cd, Cr, Cu and Zn) was determined in a long-term wastewater-irrigated agricultural land. Heavy metal concentrations in vegetables were several folds higher in wastewater-irrigated site compared to clean water-irrigated area. The wastewater-irrigated crops analysed in this study are heavily contaminated with heavy metals. Concentrations of Pb, Zn, Cd and Cr in all the sewage-fed vegetables were beyond the safe limit of FAO/WHO and Indian standard. Contamination is at its highest level in radish and spinach. Daily intake values of Pb, Cd and Ni through consumption of sewage-fed vegetables exceeded the recommended oral dose of metal for both adult and children. The study concludes that wastewater irrigation led to accumulation of heavy metals in vegetables causing potential health risk to consumers.

Metal contamination of vegetables grown on soils irrigated with untreated municipal effluent

Metals in soils and vegetables irrigated with untreated municipal/industrial effluent, from four cities of Pakistan (Gujranwala, Sialkot, Hyderabad and Mirpurkhas) were assessed. The cadmium, copper, lead and chromium concentrations in the municipal/industrial effluent from all sites were above the recommended permissible limits. Similarly, cadmium, lead and nickel concentrations in almost all the soil samples were above the recommended permissible limits with chromium higher than the recommended permissible limits in 62% soils and copper higher in 26%. Cadmium and chromium concentrations were above the recommended permissible limits in all the examined vegetables and lead was exceeded in 90% of vegetables.

Concentration and potential health risk of heavy metals in market vegetables in Chongqing, China

Concentration and daily intake (DI) of heavy metals (Pb, Zn, Mn, Cu, Cd and Cr) in market vegetables in Chongqing of China are investigated and their potential health risk for local consumers is simultaneously evaluated by calculating the target hazard quotient (THQ). The results showed that the measured Pb and Cd concentrations exceeded the safety limits given by FAO/WHO and Chinese regulations, indicating serious contamination of market vegetables by these metals. As respective DI values for Pb, Mn and Cd were also above the international guideline bases, health risk to the consumers is obvious. The individual THQ for Pb and Cd in pakchoi and Cd in mustard, and the combined THQ for all metals in each vegetable species excluding cos lettuce were above the threshold 1.0, implying the obviously adverse effect on health. Therefore, attention should be paid particularly to the potential hazardous exposure to vegetable heavy metals, especially for Pb and Cd, over a lifetime for people in Chongqing.

Spatial variations of heavy metals in the soils of vegetable-growing land along urban-rural gradient of Nanjing, China

China has experienced rapid urbanization in recent years. The acceleration of urbanization has created wealth and opportunity as well as intensified ecological and environmental problems, especially soil pollution. Our study concentrated on the variation of heavy metal content due to urbanization in the vegetable-growing soil. Laws and other causes of the spatial-temporal variation in heavy metal content of vegetable-growing soils were analyzed for the period of urbanization in Nanjing (the capital of Jiangsu province in China). The levels of Cu, Zn, Pb, Cd and Hg in samples of vegetable-growing soil were detected. The transverse, vertical spatio-temporal variation of heavy metals in soil was analyzed on the base of field investigations and laboratory analysis. The results show that: (1) in soil used for vegetable production, the levels of heavy metals decreased gradually from urban to rural areas; the levels of the main heavy metals in urban areas are significantly higher than suburban and rural areas; (2) the means of the levels of heavy metals, calculated by subtracting the sublayer (15–30 cm) from the toplayer (0–15 cm), are all above zero and large in absolute value in urban areas, but in suburban and rural areas, the means are all above or below zero and small in absolute value. The causes of spatial and temporal variation were analyzed as follows: one cause was associated with mellowness of the soil and the length of time the soil had been used for vegetable production; the other cause was associated with population density and industrial intensity decreasing along the urban to rural gradient (i.e., urbanization levels can explain the distribution of heavy metals in soil to some extent). Land uses should be planned on the basis of heavy metal pollution in soil, especially in urban and suburban regions. Heavily polluted soils have to be expected from food production. Further investigation should be done to determine whether and what kind of agricultural production could be established near urban centers.

Heavy metal contamination in water, soil, and vegetables of the industrial areas in Dhaka, Bangladesh

Concentrations of Cu, Zn, Pb, Cr, Cd, Fe, and Ni have been estimated in soils and vegetables grown in and around an industrial area of Bangladesh. The order of metal contents was found to be Fe > Cu > Zn > Cr > Pb > Ni > Cd in contaminated irrigation water, and a similar pattern Fe > Zn > Ni > Cr > Pb > Cu > Cd was also observed in arable soils. Metal levels observed in different sources were compared with WHO, SEPA, and established permissible levels reported by different authors. Mean concentration of Cu, Fe, and Cd in irrigation water and Cd content in soil were much above the recommended level. Accumulation of the heavy metals in vegetables studied was lower than the recommended maximum tolerable levels proposed by the Joint FAO/WHO Expert Committee on Food Additives (1999), with the exception of Cd which exhibited elevated content. Uptake and translocation pattern of metal from soil to edible parts of vegetables were quite distinguished for almost all the elements examined.

Health risks of heavy metals in sewage-irrigated soils and edible seeds in Langfang of Hebei province, China

BACKGROUND

Human exposure to heavy metals is attributed to consumption of food crops grown in polluted soil environment. The objective of our study was to assess the health risks of heavy metals in edible seeds of crops grown in sewage-irrigated soils located in the Langfang of Hebei province, China. Here, heavy metal contents in soils and plants were determined using an internal standard and high-resolution inductively coupled plasma mass spectrometry.

RESULTS

There was a relative buildup of heavy metals in sewage-irrigated soils in the study area; in particular, all Cr and partial Zn and Cu showed higher concentrations than the limits proposed by the World Health Organization, European Union (EU) and UK. Heavy metal concentrations in edible seeds of plants grown in sewage-irrigated soils partly exceeded the permissible limits set by the EU, UK and the State Environmental Protection Administration in China. With the exception of Cu, health risk index values of each heavy metal investigated by intake of the edible seeds were less than 1. Here, a health risk index of < 1 is considered safe for human consumption.

CONCLUSION

The study indicated that there was a relative absence of health risks associated with the ingestion of sewage-irrigated edible seeds.

Health risk assessment of heavy metals via dietary intake of foodstuffs from the wastewater irrigated site of a dry tropical area of India

The present study was conducted to assess the risk to human health by heavy metals (Cd, Cu, Pb, Zn, Ni and Cr) through the intake of locally grown vegetables, cereal crops and milk from wastewater irrigated site. Milk is not directly contaminated due to wastewater irrigation, but is an important route of food chain transfer of heavy metals from grass to animals. Heavy metal concentrations were several fold higher in all the collected samples from wastewater irrigated site compared to clean water irrigated ones. Cd, Pb and Ni concentrations were above the 'safe' limits of Indian and WHO/FAO standards in all the vegetables and cereals, but within the permissible limits in milk samples. The higher values of metal pollution index and health risk index indicated heavy metal contamination in the wastewater irrigated site that presented a significant threat of negative impact on human health. Rice and wheat grains contained less heavy metals as compared to the vegetables, but health risk was greater due to higher contribution of cereals in the diet. The study suggests that wastewater irrigation led to accumulation of heavy metals in food stuff causing potential health risks to consumers.

Accumulation and translocation of toxic heavy metals in winter wheat (Triticum aestivum L.) growing in agricultural soil of Zhengzhou, China

A field experiment was conducted to study the accumulation of toxic heavy metals by winter wheat (Triticum aestivum L.) grown in the agricultural soil in the suburb of Zhengzhou City, China. The quantities of heavy metals (Cd, Cr, Pb, As, Hg) were determined in different parts of wheat plant. The content of five toxic metals was found significantly higher in roots than in the aerial parts of wheat (stems and leaves, and grains). Additionally, wheat roots were enriched in Cd, Pb, and Hg from the soil, while Cr and As were hardly taken up by the roots. On the other hand, the winter wheat transported five toxic heavy metals very weakly from root to grain in the various irrigation regions.

Accumulation of heavy metals in dietary vegetables and cultivated soil horizon in organic farming system in relation to atmospheric deposition in a seasonally dry tropical region of India

Increasing consciousness about future sustainable agriculture and hazard free food production has lead organic farming to be a globally emerging alternative farm practice. We investigated the accumulation of air-borne heavy metals in edible parts of vegetables and in cultivated soil horizon in organic farming system in a low rain fall tropical region of India. The factorial design of whole experiment consisted of six vegetable crops (tomato, egg plant, spinach, amaranthus, carrot and radish) x two treatments (organic farming in open field and organic farming in glasshouse (OFG)) x seven independent harvest of each crop. The results indicated that except for Pb, atmospheric deposition of heavy metals increased consistently on time scale. Concentrations of heavy metals in cultivated soil horizon and in edible parts of open field grown vegetables increased over time and were significantly higher than those recorded in OFG plots. Increased contents of heavy metals in open field altered soil porosity, bulk density, water holding capacity, microbial biomass carbon, substrate-induced respiration, alkaline phosphatase and fluorescein diacetate hydrolytic activities. Vegetable concentrations of heavy metal appeared in the order Zn > Pb > Cu > Ni > Cd and were maximum in leaves (spinach and amaranths) followed by fruits (tomato and egg plant) and minimum in roots (carrot and radish). Multiple regression analysis indicated that the major contribution of most heavy metals to vegetable leaves was from atmosphere. For roots however, soil appeared to be equally important. The study suggests that if the present trend of atmospheric deposition is continued, it will lead to a destabilizing effect on this sustainable agricultural practice and will increase the dietary intake of toxic metals.

Influence of some soil parameters on heavy metals accumulation by vegetables grown in agricultural soils of different soil orders

The main purpose of this research was to determine the levels of heavy metals in tomato, potato and lettuce, grown in agricultural soils of different soil orders (Alfisols, Endisols and Vertisols), located at Central Greece. Soil samples were analysed for available forms (after extraction with DTPA) and for total concentrations (after digestion with Aqua Regia) of metals. Zn, Cu, Cr and Ni were the common metals detected in the vegetables studied. Pb and Cd concentrations were low and in some cases not detectable. Significant correlations among metals concentrations and soil physicochemical parameters were obtained and discussed. The pH value and the percentage of clay content were found to determine the solubility of metals in the soil and their availability for uptake by plants.

An assessment of heavy metal contamination in vegetables grown in wastewater-irrigated areas of Titagarh, West Bengal, India

The effects of municipal wastewater irrigation on the accumulation of heavy metals (Pb, Zn, Cd, Cr, Cu and Ni) in soil and vegetables were investigated by monitoring wastewater-irrigated agricultural field of Titagarh, 24-Parganas (North), West Bengal, India. The mean concentrations of Pb, Ni, Cu in the irrigation water and the mean Cd content in soil were much above the recommended level. The concentrations of Pb, Zn, Cd, Cr and Ni in all the examined vegetables were beyond the safe limits. The study reveals that heavy metal-contaminated vegetables grown in wastewater-irrigated areas may pose public health hazards.

Uptake of toxic heavy metals by rice (Oryza sativa L.) cultivated in the agricultural soil near Zhengzhou city, People's Republic of China

Higher accumulation of toxic heavy metals in rice grown in agricultural soil may lead to health disorder. A field experiment was carried out to investigate uptake and translocation of Cd, Cr, Pb, As, and Hg by different parts of rice plant in various irrigation regions. The results showed the rice grain contained significantly lower amounts of five metals than straw and root in all sampling sites. Rice root accumulated Cd, As, and Hg from the paddy soil. Moreover, the rice plant transported As very weakly, whereas Hg was transported most easily into the straw and grain among studied heavy metals.