Wastewater-irrigated Vegetables Research Articles

Comprehensive Assessment of Heavy Metal Contamination in Soil-Plant Systems and Health Risks from Wastewater-Irrigated Vegetables

A research study examined the origins, human health impacts, and risks associated with pollutants in vegetables grown in soil irrigated with wastewater. The study analyzed 164 samples from water sources, irrigated soil, and harvested vegetables for eight heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) using atomic absorption spectrophotometry. The focus was on the potential health effects of consuming heavy metal-contaminated vegetables grown in wastewater-irrigated soil. The findings revealed significant accumulation of heavy metals in soil and plants from Mianwali, Pakistan, posing potential health risks to consumers. When compared to vegetables produced with freshwater irrigation, the concentration levels of heavy metals in the soil irrigated with untreated wastewater were significantly greater (P≤0.001) and above the recommended limits set by the World Health Organization (WHO). The results showed that heavy metals in the soil had significantly increased, and crops had subsequently absorbed these metals. Produce raised in soil watered with wastewater showed higher levels of heavy metals than the US Environmental Protection Agency (EPA) and the WHO recommended. Among the veggies, lead (Pb) and cadmium (Cd) were found to have higher Hazardous Quotient Indices (HRIs) than one. This indicates that both adults and children may have been exposed to dangerous levels of these metals. Additionally, for Brassica oleracea, Raphanus sativus, and Spinacia oleracea, nickel (Ni) surpassed HRIs larger than 1, indicating a significant health risk connected to these veggies' ingestion.

Contribution of wastewater irrigated vegetables to the prevalence of soil-transmitted helminth infection among female farmers in Addis Ababa, Ethiopia

BackgroundUntreated or inadequately treated wastewater carrying human feces can host helminth eggs and larvae, contaminating the soil and plants that are irrigated with it. In Addis Ababa, farmers use untreated wastewater to grow vegetables; however, there are little data currently available published on vegetables' contribution to the prevalence of helminth among female farmers along the Akaki River, in Addis Ababa, Ethiopia.MethodsA cross-sectional study was conducted in Addis Ababa City in February 2022. A stratified random sampling method was used to sample farming households. The sample size for each district was determined by a proportional allocation to the total number of households in the area. Two hundred and fifty-two composite vegetable samples and 101 farmers’ stool samples were collected and analyzed for helminth prevalence. Data on socio-demographics were collected by trained data collators using a structured questionnaire. Kato-Katz concentration was used to detect STH from a stool sample. Stata version 14.0 was used to process the data. Poisson regression was used to identify the association between STH prevalence in the vegetable and the farm's stool.ResultsHelminths were found in 67.5% of vegetables sampled and 20.8% of female farmers' stools. Ascaris lumbricoides eggs (vegetable 48.4% and stool 9.9%) were identified in all analyzed samples. Hookworm eggs (vegetable 13.1% and stool 8.9%) and Trichuris trichiura eggs (vegetable 5.9% and stool 2%) were also isolated. The total number of helminth eggs present in wastewater-irrigated vegetables and female farmers’ stool had a positive association (p < 0.05) with a regression coefficient of 1.92 (95% CI = 1.56–2.28).ConclusionsThe study found a significant prevalence of helminth infections, particularly Ascaris lumbricoides, in stool and vegetable samples irrigated with wastewater. A clear association was found between vegetable production and a higher prevalence of helminth infections among female farmers. Therefore, it is important to ensure that farmers are educated in the importance of food washing and sanitation/hygiene practices when using wastewater irrigation for vegetable crops.Graphical

Cadmium accumulation in wastewater-irrigated vegetables: Exploring factors, thresholds, health implications, and transfer modeling

The Introduction of cadmium (Cd) into the soil-crop system through wastewater (WW) irrigation poses a significant challenge to environmental safety. However, the understanding of the relationship between Cd phytoavailability in WW-irrigated soil and its uptake characteristics in edible vegetables remains largely unknown. This study aims to analyze the influence of WW irrigation on the accumulation characteristics and health risks associated with Cd in the soil-vegetables system. Soil and corresponding vegetable samples were collected from 12 vegetable farms including cabbage, lettuce, green beans, and pepper were studied under wastewater (WW) and freshwater (FW) irrigation. WW irrigation led to a significant increase in soil Cd levels, with enrichment factor, and contamination factor values ranging from 2.9 to 3.1 and 2.7 to 3.3 times higher, respectively, compared to the control. Across the study farms, WW irrigation increased Cd concentrations in cabbage, green beans, lettuce, and pepper by 62–220%, 55–100%, 25–68%, and 29–80%, respectively, compared to FW-irrigated farms. The average hazard quotient (HQ) and carcinogenic risk (CR) scores for Cd in WW-irrigated vegetables indicated low risk (0.1 < HQ) and fell within the permissible range (1.00E-06 < CR < 1.00E-04) for children and adults. The soil DTPA-extractable Cd thresholds for WW-irrigated farms cultivating cabbage, lettuce, green beans, and pepper were 0.62, 0.72, 0.85, and 0.83 mg kg−1, respectively. The results provide insight into the management strategies along with developing sustainable production practices for common leafy vegetables in Cd-enriched soil resulting from WW irrigation.

Wastewater-Irrigated Vegetables Are a Significant Source of Heavy Metal Contaminants: Toxicity and Health Risks.

Water contaminated with heavy metals constitutes an important threat. This threat is a real problem with a negative impact in some developing countries where untreated industrial effluents are used for irrigation. The present study examines heavy metals in wastewater-irrigated vegetables (apple gourd, spinach, cauliflower, sponge gourd, and coriander) water, and soil from Chenab Nagar, Chiniot, Pakistan. In particular, the metals quantified were cadmium (Cd), chromium (Cr), cobalt (Co), nickel (Ni), lead (Pb), and manganese (Mn). Among them, Cr and Co in crops irrigated -wastewater exceeded the levels recommended by the World Health Organization (WHO). In contrast, Ni, Cu, Pb, and Mn concentrations were in line with WHO standards. Compared with the limits established by the Food and Agriculture Organization of the United Nations (FAO), all the study vegetables presented higher (thus unsafe) concentrations of Cd (0.38 to 1.205 mg/Kg). There were also unsafe concentrations of Cr in coriander, sponge gourd, and cauliflower. Pb was found at an unsafe concentration (0.59 mg/Kg) in cauliflower. Conversely, Ni and Mn concentrations were below the maximum permissible limits by WHO, and FAO in all of the analyzed samples. The contamination load index (CLI) in soil, bioconcentration factor (BCF) in plants, daily intake of metals (DIM), and health risk index (HRI) have also been evaluated to estimate the potential risk to human health in that area. We have found an important risk of transitions of Pb, Cd, Cr, and Co from water/soil to the edible part of the plant. The highest HRI value associated with Cd (6.10-13.85) followed by Cr (1.25-7.67) for all vegetable samples presented them as high health risk metal contaminants. If the issue is not addressed, consumption of wastewater-irrigated vegetables will continue posing a health risk.

Human health risk hazards by heavy metals through consumption of vegetables cultivated by wastewater

Need for irrigated agriculture is rising daily, but quality water for irrigation is on the decline, necessitating the use of urban wastewater as alternative source, particularly in low or middle income countries. This study assessed the effect of urban wastewater irrigation on the quality of groundwater, soil and vegetables in farms around Faisalabad, Pakistan. Human health risks of heavy metals were investigated through consumption of wastewater irrigated vegetables. Samples of soil, vegetables and water were obtained and analyzed for heavy metal concentrations (cadmium, Cd; lead, Pb; manganese, Mn; nickel, Ni; cobalt, Co; and zinc, Zn). The groundwater could be declared safe for consumption in the present state, as concentration of heavy metals standards. But wastewater-irrigated vegetables had higher Pb, Cd and Mn than the permissible limits. In wastewater-irrigated vegetables, highest HRI-Pb was recorded in mustard leaf and cabbage and was >1. EF for Zn and Mn in all vegetable plants, Ni in potato and cauliflower, Pb in mustard leaf and cabbage were >1.5, suggesting that the metals were generated by anthropogenic processes (such as wastewater irrigation). Long-term irrigation of farmlands with the wastewater will result to heavy metal contamination of groundwater, soil and vegetables in the study area. Therefore, strategies to save the groundwater from future contamination are necessary.

Assessment of health risks associated with the consumption of wastewater-irrigated vegetables in urban areas

Assessment of health risks associated with the consumption of wastewater-irrigated vegetables in urban areas

Managing microbial risks in informal wastewater-irrigated agriculture through irrigation water substitution

On-farm measures can be used in multi-barrier schemes to manage microbial risks from consumption of wastewater-irrigated vegetables, especially where informality of the practice determines minimal external support for farmers. Evidence indicates that cessation of irrigation greatly reduces microbial contamination on leafy vegetables, but at the expense of produce quality. Replacing wastewater with higher-quality irrigation water during the last days of cultivation is an alternative to cessation of irrigation that does not compromise produce quality. This study evaluated the effect of wastewater substitution under on-farm conditions on different indicators of microbial contamination of lettuce. Lettuce was cultivated in experimental plots and irrigated with three water sources: spring water, water from a wastewater-polluted river and effluent from a primary wastewater treatment plant, but with the river water replaced by spring water in half the plots about two weeks before harvest. The experiment was repeated four times in different seasons. Irrigation water samples collected during cultivation and lettuce samples collected at harvest were analysed for helminth eggs, Escherichia coli and coliphages. Variables characterizing the irrigation practices and environmental conditions were recorded. There were no significant differences in helminth egg or E. coli concentrations on lettuce (medians ranged from −0.7 to −0.1 log10 eggs g−1 and 0.6–1.4 log10 cfu g−1, respectively) between any of the treatments involving wastewater irrigation; no statistical analysis was possible for coliphages because concentrations on lettuce were mostly at or below the detection limit (94% of samples). Variables associated with temperature and soil explained helminth egg and E. coli concentrations on lettuce, while number of days of irrigation with spring water (representing wastewater substitution) was significant only for E. coli. It was concluded that the experimental conditions were suboptimal for successful implementation of wastewater substitution for on-farm microbial risk management, but key variables for successful implementation were identified.

Cryptosporidium’s burden of disease attributable to consumption of wastewater-irrigated raw vegetables

Conventional wastewater treatment plants do not effectively remove parasitic protozoa resulting in their presence in wastewater effluent. Therefore, agricultural reuse of wastewater effluent could be a route of Cryptosporidium transmission into the food chain. Samples of secondary wastewater, wastewater-irrigated soil and vegetable samples were collected from an experimental field and analyzed using real-time PCR for quantification of Cryptosporidium oocysts. Quantitative microbial risk analysis (QMRA) was performed to determine the annual disease burden from Cryptosporidium associated with consumption of wastewater-irrigated vegetables. Detection of Clostridium perfringens spores as a potential indicator for the presence of Cryptosporidium was also performed. Cryptosporidium was observed in 64% of the effluent samples ranging from 16 to 162 oocysts L−1, whereas no oocysts were detected in wastewater-irrigated soil and the vegetable samples. The mean annual disease burden for consumption of lettuce (6.6 × 10−5 DALY per person per year (pppy)) was higher than spring onion (3.4 × 10−6 DALY pppy) which both exceeding the WHO guideline of 10−6 DALYs pppy. However, the disease burden was within the acceptable range considering the less stringent level of 10−4 DALY pppy. Clostridium spores were detected in 92% of the effluent samples with no relationship with the presence of Cryptosporidium. The results of this study suggest that agricultural reuse of treated wastewater may not be a major health concern of cryptosporidiosis in a semi-arid region. However, because of the higher risk from lettuce, the choice of an appropriate crop would be needed to completely meet the WHO recommendations for safe reuse of wastewater. The accuracy of the QMRA model could be improved by further investigating the decay rate of oocysts in the same region.

Quantification of human adenovirus in irrigation water-soil-crop continuum: are consumers of wastewater-irrigated vegetables at risk?

Because of health concerns regarding the presence of enteric viruses in wastewater effluents, this study was designed to investigate the occurrence of human adenovirus (HAdV) in the irrigation water-soil-crop continuum.Viral particles were extracted from wastewater and wastewater- or water-irrigated soil and crop samples and analyzed using real-time PCR. Concentration of fecal indicator bacteria (FIB) were also determined. Quantitative microbial risk assessment was performed to determine the HAdV illness risk associated with the consumption of wastewater-irrigated vegetables. HAdV-F was detected in 74% of wastewater effluent samples with a mean concentration of 38 Genomic Copy (GC)/mL. HAdV was also detected in wastewater-irrigated soil (2 × 102 GC/g) and crop (< 10 GC/g) samples, with no statistically significant difference in concentrations between wastewater- and freshwater-irrigated samples. The results showed no correlation between concentrations of FIB and HAdV in the analyzed samples. Mean probability of illness risk from consumption of wastewater-irrigated vegetables was 4 × 10-1 per person per year (pppy) which was about two orders of magnitude higher than the proposed value by WHO (10-3 pppy) for safe reuse of wastewater. This finding suggests that the wastewater reuse for irrigation of vegetables eaten raw could pose a threat to human health with respect to the risk of viral illness, signifying stricter management of wastewater reuse. However, because of uncertainties in the QMRA model, particularly the ratio of infectious to non-infectious virus particles, more data is required to validate the predicted risk. This information is especially important in arid and semi-arid regions where high temperatures, UV radiation intensity, and desiccation can efficiently inactivate microorganisms in the environment.

Assessment of heavy metal concentrations in waste water irrigated vegetables

Shortage of good quality irrigation water in present changing scenario of climate forces farmers to use waste water for growing vegetables in urban and peri-urban areas which resulted in buildup of heavy metal in the food chain. Three commonly grown vegetables of city Multan; Onion, Brinjal and Tomato irrigated with waste water were selected to examine the heavy metal contents. The vegetables samples were collected from Haji Block Industrial Estate areas irrigated by waste water due to shortage of canal water. Total thirty samples of three vegetable were collected and analyzed. The results showed that the vegetable samples were contaminated with Pb, Cd and Ni. This study suggests that in future, waste water should be used after treatment to save the health of the masses. The re-use of waste water will help in proper management of soil health and will also save the soil water resources under present climatic conditions.

Heavy Metals and Microbes Accumulation in Soil and Food Crops Irrigated with Wastewater and the Potential Human Health Risk: A Metadata Analysis

Wastewater is actively used for irrigation of vegetable and forage crops in arid lands due to water scarcity and cost advantages. The objective of this review was to assess the effect of wastewater (mixture sources) reuse in irrigation on soil, crop (vegetable and forage crops), animal products, and human health. The metadata analysis of 95 studies revealed that the mean of toxic heavy metals including nickel (Ni), chromium (Cr), cadmium (Cd), lead (Pb), and zinc (Zn) in untreated wastewater were higher than the world standard limits in wastewater-irrigated regions. Although heavy metals in treated wastewater were within the standard limits in those areas, the concentration of those toxic elements (Pb, Cd, Ni, Cr, and As) exceeded the allowable limits in both soil and vegetables’ edible parts. In fact, the concentration of heavy metals in vegetables’ edible parts increased by 3–9 fold when compared with those irrigated with fresh water. Escherichia coli in wastewater-irrigated soil was about 2 × 106 (CFU g−1) and about 15 (CFU g−1) in vegetables’ edible parts (leaf, bulb, tuber and fruit) while the mean total coliforms was about 1.4 × 106 and 55 (CFU g−1) in soil and vegetables’ edible parts, respectively. For human health risk assessment, the estimated daily intake (EDI) and human health risk index (HRI) ranged from 0.01 to 8 (EDI and HRI &gt; 1.0 associated with adverse health effects). Although the mean of EDI for heavy metals from wastewater-irrigated vegetables were less than 1, the HRI for Cd and Pb were above the limits for safe consumption. Overall, heavy metal levels in wastewater that used for irrigation of agricultural crops could be within the recommended levels by the world standards, but the long-term use of this reused water will contaminate soil and crops with several toxic heavy metals leading to potential carcinogenic risks to humans. Therefore, rigorous and frequent testing (wastewater, soil, and plant) is required in cultivated farms to prevent the translocation of heavy metals in the food chain.

Metal accumulation and health risk assessment in wastewater used for irrigation around the Agra Canal in Faridabad, India.

Wastewater application for irrigation is a traditional and economic tool in developing nations. Yet prolonged use of wastewater for agricultural activities contributes to the accumulation of metals in both soil and vegetables. This study investigated the accumulation and contamination of vegetables with heavy metals ensuing from the application of wastewater from the Agra Canal and the associated risks posed to human health. Three sites across the Agra canal were selected for sampling (CW-1, CW-2, and CW-3), where untreated wastewater is being used to irrigate vegetables (spinach, coriander, radish, and garlic crops), for which tube-well water (TW) from a village served as the control site. Water, soil, and vegetable samples were collected from all sites. The presence in them of various metals, such asAs, Pb, Cr, Mn, Cu, Zn, and Ni, was detected at all four sites. The greatest content of Mn was found in CW-1's water (7.91 mg/L), soil (633.77 mg/kg), and in spinach 368.12 (mg/kg) grown there. Significantly higher metal concentrations were observed in vegetables irrigated with wastewater than in tube-well-irrigated vegetables, with the metals ranked in accumulation as follows Mn > Zn > Ni > Cu > Cr > Pb > As. Our results also revealed that metal bioaccumulation varied enormously between foliar and non-foliar vegetables, as well as among the four sites. Daily metal intake (DMI) and health risk index (HRI) analyses suggested that children consuming contaminated vegetables are at higher risk than adults. The HRI for Mn, Ni, and Pb was above 1, which indicated significant health hazards to humans consuming the wastewater-irrigated vegetables. Moreover, the control site where tube-well water was used had an HRI below 1, signifying a negligible health risk for its consumption. Therefore, we may conclude that the extensive application of contaminated water for a longer duration would likely further increase metal accumulation in soil and vegetables that may be hazardous to living organisms.

Arsenic exposure through drinking groundwater and consuming wastewater-irrigated vegetables in Multan, Pakistan.

Arsenic (As) is one of the most toxic metalloids for humans. Above permissible levels of As cause severe health implications. Contaminated drinking water and food items may be the leading sources of As exposure to people all around the world. The current study assessed the levels of As in drinking water, vegetables, irrigation water, agricultural soils, and the human population (adult women and men) of rural and peri-urban areas of Multan (Pakistan). For a comparison between peri-urban (exposed site) and rural areas (control site), we sampled irrigation water, vegetables and vegetable-grown soils, drinking water, and human blood. In all sample types, As concentration was significantly higher at exposed site than at control site. Alarmingly, As concentration in drinking groundwater (34µg As L-1) of exposed site was 3.4-folds higher than the permissible limit (set by WHO). Among the studied vegetables, the cumulative daily dietary intake of As was recorded maximum by the consumption of okra (474ng d-1 on exposed site) and minimum by long melon (1ng d-1 on control site). However, As intake via drinking water was estimated to contribute ≥ 98% of total As intake at both sites. Hence, the health risks associated with drinking As-contaminated groundwater were recorded much higher than the health risks associated with the consumption of As-contaminated vegetables. Blood As levels in most of the subjects at exposed site exceeded the safe limit of 12µg L-1. Conclusively, the findings of the current study indicated that drinking contaminated groundwater may be the major cause of As-associated health risks in the region.

Heavy metals concentration in vegetables irrigated with municipal wastewater and their human daily intake in Erbil city

Assessment of heavy metals accumulation in vegetables and their levels in human is vital in countries where wastewater is used for irrigation. In this study, The aim of this research was to investigate the concentrations of highly toxic metals such as Nickel (Ni), chrome (Cr), lead (Pb), zinc (Zn), cadmium (Cd), and copper (Cu) in wastewater, farmlands soils and vegetables (chard, celery, cress and leek), and also their possible human health risk in the area of Erbil city. The heavy metals concentration in the vegetable, soil and water samples were analyzed by using an atomic absorption spectrophotometer. Bio-concentration factor (BCF), daily intake (DI) and health risk index (HRI) were calculated in order to estimate the human health risk. Overall, results indicated that the water, soil and vegetable samples were contaminated with Ni, Cd, Cr, Cu, Pb, and Zn. The trends of these metals concentrations were as follows: 0.613 > 0.316 > 0.162 > 0.065 > 0.041 > 0.028 mL/L for Ni, Cd, Pb, Cr, Cu, and Zn, respectively in the wastewater and 189.09 > 125 > 104.92 > 41.85 > 28.58 > 21.72 for Zn, Cr, Ni, Pb, Cu and Cd mgkg−1 in the soil. The mean concentrations (mg kg−1) in the vegetable samples ranged from 22.74 to 30.30, 5.18–9.19, 29.50–33.87, 39.42–64.78, 7.87–11.83 and 77.68–117.98 for Ni, Cd, Pb, Cr, Cu and Zn, respectively. In addition, the calculated BCFs value ranged from 0.21 to 71.295, with Pb having the highest BCF. The calculated DI for Ni, Cd and Pb exceeded WHO/FAW safe limits for adult and children. Furthermore, the HRI values of Cd and Pb exceeded the safe limit (1) for both adults and children, but the values for Ni (> 1) exceeded the safe limit only for children. These findings clearly indicate that the practice of irrigating the vegetables with untreated wastewater by local farmers have caused high accumulation of heavy metals in the soils and vegetables which are posing health risk to the population in the vicinity. Therefore, regular monitoring of these metals in the wastewater-irrigated vegetables is necessary.

Effect of Heavy Metal Contaminated Waste Water Irrigation on Enzymatic and Non Enzymatic Antioxidants in Some Selected Vegetables

The study was conducted to investigate the bioaccumulation of heavy metals (As, Cd,Cr and Pb) and their effect on the antioxidant level and activity in vegetables Raphanus sativus, Spinacea oleracea, Brassica oleracea and Lycopersicum esculentum irrigated with heavy metal loaded waste water of Buddha Nullah. The results of the study revealed bioaccumulation of heavy metals in vegetables and the level of non-enzymatic antioxidants, ascorbic acid and proline and enzymatic antioxidants, catalase and peroxidase was found to be much higher in waste water irrigated vegetables in comarison to the level of bioaccumulation of heavy metals as well as antioxidants in same vegetables irrigated with normal borewell water as control. This indicates that heavy metals induce oxidative stress (ROS) in the plants at cellular level and to nullify the toxic effect these heavy metals the cell mechanism increase the production and activity of both non-enzymatic and enzymatic antioxidants.

Campylobacter risk for the consumers of wastewater-irrigated vegetables based on field experiments

Water scarcity is emerging as a major problem in water stressed regions such as Middle East countries which highlights the importance of agricultural reuse of wastewater as a valid alternative source. However, consumption of wastewater-irrigated crops has been implicated as a vehicle for transmission of bacterial infections such as campylobacteriosis. Understanding and minimizing public health threats associated with agricultural reuse of treated wastewater (TWW) are crucial elements in sustainable water resource management. To address this need, the present study was carried out to determine Campylobacter risk for the consumers of TWW-irrigated vegetables by field experiments as well as quantitative microbial risk assessment (QMRA) model. Campylobacter was monitored in secondary treated wastewater, TWW-irrigated soil and harvested vegetables by nested real-time PCR assay. Campylobacter was detected in 64% (16/25) of TWW samples, whereas analysis of TWW-irrigated soil and vegetable samples yielded no positive result for Campylobacter. The estimated mean annual Campylobacter disease burden ranged from 2.37 × 10−5 to 6.6 × 10−5 disability-adjusted life years (DALYs) per person per year (pppy) for vegetable consumers which was lower than the less stringent reference level of 10−4 DALYs pppy has been recommended by world health organization (WHO). Our results in regard to the QMRA estimates and field experiments suggest that the reuse of TWW for irrigation of vegetables doesn’t pose a considerable risk to human health from the viewpoint of Campylobacter infections in a semi-arid area.

Ecological risk assessment of heavy metals in vegetables irrigated with groundwater and wastewater: The particular case of Sahiwal district in Pakistan

The use of wastewater for irrigation is a common practice in the developing world. It is a major route of heavy metal contamination in vegetables. The groundwater, an alternative source for irrigation, is under threat of heavy metal contamination due to long-term use of wastewater. The present study investigated heavy metals contamination from irrigation with wastewater compared to groundwater in District Sahiwal situated in the vicinity of Lahore, Pakistan. Irrigated water, soil and vegetables were analyzed for Iron, Nickel, Lead, copper, Cadmium, Manganese and Zinc; Metal transfer factor (MTF); daily intake of metals (DIM) and health risk index (HRI) were calculated. Manganese (Mn) and Cd in wastewater irrigated soil, Pb, Cd, Mn and Fe in wastewater-irrigated vegetables and Pb, Mn and Fe in groundwater-irrigated vegetables exceeded the permissible limits (WHO, 1996), particularly in Mustard and Spinach. Generally, MTF was higher in wastewater than groundwater-irrigated vegetables, particularly with Fe followed by Ni. HRI was higher for wastewater-irrigated than groundwater-irrigated vegetables. Wastewater-irrigated Mustard and Spinach showed a HRI > 1 only for Mn. Quality control mechanisms need to be applied for long-term use of groundwater. Also, treatment of wastewater prior to application to plants must be considered to save crops from contamination.

Study of the genotoxicity of organic extracts from wastewater-irrigated vegetables using in vitro and in vivo biological tests.

The purpose of this study was to explore genotoxicity due to organic pollutants in wastewater-irrigated vegetables using biological and chemical analyses. Chinese cabbages from wastewater-irrigated farmland were taken as the research object. For the in vitro test, DNA damage was characterized in rat hepatocytes exposed to organic extracts from the cabbages using the comet assay. For the in vivo tests, mice were exposed to organic extracts from the cabbages. DNA damage was assessed in mouse peripheral blood lymphocytes (PBLs), and chromosome damage was assessed in bone marrow cells using the comet assay and micronucleus test, respectively. For the chemical analysis, gas chromatography-mass spectrometry (GC/MS) was used to analyze the organic compounds in the organic vegetable extracts. The in vitro test results showed that the comet tail lengths of the DNA in rat hepatocytes were significantly increased in the group dosed with 0.36g/ml (P<0.05), and the comet tailing rates of the hepatocytes were significantly increased in the groups dosed with 0.24 and 0.36g/ml (P<0.05). The in vivo test results indicated that the comet tail lengths of the DNA in mouse PBLs were increased in the low- and high-dose groups and that the comet tailing rate of the PBLs was increased in the high-dose group (P<0.05). The chemical analysis results showed that the total organic content in the organic vegetable extracts from the wastewater-irrigated area (1.355mg/kg) was significantly higher than the content in the cabbage samples from the clean-water-irrigated area (0.089mg/kg). This finding indicated that wastewater irrigation can cause organic pollution with genetic toxicity in vegetables. This study also showed that in vivo and in vitro biological tests can reflect the joint toxicity of organic pollutants, and the test results were in accordance with the chemical analysis of the organic pollutant compositions.

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

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

Assessment of potential health risks due to heavy metals through vegetable consumption in a tropical area irrigated by treated wastewater

Consumption of wastewater-irrigated vegetables is a common practice in developing countries including India. The wastewater irrigation gradually raises the contents of heavy metals in soils and vegetables. The consumption of heavy metal-rich vegetables may cause serious risk to the human health. Therefore, quantification of heavy metals in vegetables collected from wastewater-irrigated field is needed as proportion of farmers using wastewater for irrigation is increasing due to scarcity of water. The aim of the present study was to assess the heavy metal accumulation and the potential human health risks associated with consumption of contaminated vegetables irrigated with waste (WWT) and mixed wastewater (MWWT), grown in an agricultural area of Bhagwanpur, near Banaras Hindu University, Varanasi, India. Seven common vegetables growing at two differentially irrigated areas (WWT and MWWT) were considered for the study. At each site, three samples, each from water, soil and different vegetables, were taken. The samples after digestion were analysed for heavy metal contents using atomic absorption spectrophotometer. Heavy metal contents in soils, vegetables, transfer factor (TF) from soil to vegetables, metal pollution index (MPI) and their health risk in form of target hazard quotients (THQs) were calculated. Results showed significantly higher contents of heavy metals in water, soil and vegetable at WWT than MWWT. The TF value of Cd was notably greater in WWT compared to the MWWT. The values of THQ in children and adults were >1 for Pb and Cd in case of all vegetables at both WWT and MWWT. Among the vegetables, MPI was highest for B. vulgaris followed by B. botrytis, B. capitata, R. sativus, B. nigra, A. sativum and S. tuberosum. THQ for both categories were mostly higher for WWT compared at MWWT, suggesting a greater health risk to local residents from vegetable of the former than latter site. The present study suggests regular monitoring of water quality prior to discharge for irrigation uses and also points out to adopt better wastewater management strategies for proper utilization and disposal of wastewater.