Estimated Heavy Metal Residues in Egyptian Vegetables in Comparison with Previous Studies and Recommended Tolerable Limits

Long-Term Impact of Wastewater Irrigation on Soil Pollution and Degradation: A Case Study from Egypt

There is consensus on the impact of wastewater irrigation on soil properties and heavy metal accumulation. The studies that show the impact of temporal changes as a result of different long-term additions of wastewater on the heavy metal accumulation and degradation of soil are extremely limited. This study was carried out to assess heavy metal contamination in soils irrigated with wastewater for more than 30 years in Egypt. A total number of 12 irrigation water samples and 12 soil profiles were collected during 2020 and were chemically characterized. The results showed that soils irrigated with wastewater over the long term contained significantly higher concentrations of heavy metals compared to fields irrigated with fresh water. Heavy metal levels in water and soil samples were within the permissible limits, with the exception of Cd concentration in water (0.03 mg L−1). Continuous cultivation for a long period of time (30 years) using raw urban wastewater application has led to the adverse effect of increasingly available Pb concentration (5.44 mg kg−1). Similar temporal behavior was seen for Cd and Fe, which increased by 0.98 and 11.2 mg kg−1, respectively, after 30 years. The heavy metals in wastewater-irrigated soils significantly increased in clayey soils, as compared to sandy soils irrigated from the same source. Our findings provide important information for decision makers in Egypt and similar countries for the development of a strategy for the use of wastewater in irrigation for sustainable agricultural management.

Uptake and accumulation of Cr in edible parts of Eruca sativa from irrigation water. Effects on polyphenol profile and antioxidant capacity

Metals in the environment have been an increasing research topic over the past decade, since they can be found in both natural and drinking water, including irrigation of crops and edible plants with contaminated water. The aim of this study was to investigate the uptake of Cr by arugula (Eruca sativa) in a greenhouse experiment, simulating the open field irrigation conditions. We also evaluate the toxic effects of Cr on oxidative stress by measuring the antioxidant capacity and polyphenol profile in the plant. The study examines the irrigation of arugula, during 15 and 21 days, with four Cr (VI) concentrations, ranging from 0 (control) to 250 μg. L⁻¹. Arugula plants were able to accumulate Cr when irrigated during 15 and 21 days in all the Cr concentrations evaluated. The estimated daily intake (EDI) shows that the amount of Cr accumulated by arugula plants does not represent a threat to human health.

Application of Cr levels induced some changes in content, profile and capacity of antioxidants depending on Cr concentration and time of exposure. Taking into account that E. sativa is consumed due to its polyphenol-related health benefits, the allowable Cr limits in irrigation water should be reviewed, in order to maximize health benefits associated with its consumption, and also to improve vegetable quality. Arugula is a valuable and nutritious food, that should not be excluded from a balanced diet. Chromium concentration in irrigation water as well as the speciation forms present in vegetables should be controlled.

Hazardous heavy metals contamination of vegetables and food chain: Role of sustainable remediation approaches - A review

This review emphasizes the role of toxic metal remediation approaches due to their broad sustainability and applicability. The rapid developmental processes can incorporate a large quantity of hazardous and unseen heavy metals in all the segments of the environment, including soil, water, air and plants. The released hazardous heavy metals (HHMs) entered into the food chain and biomagnified into living beings via food and vegetable consumption and originate potentially health-threatening effects. The physical and chemical remediation approaches are restricted and localized and, mainly applied to wastewater and soils and not the plant. The nanotechnological, biotechnological and genetical approaches required to more rectification and sustainability. A cellular, molecular and nano-level understanding of the pathways and reactions are responsible for potentially toxic metals (TMs) accumulation. These approaches can enable the development of crop varieties with highly reduced concentrations of TMs in their consumable foods and vegetables. As a critical analysis by authors observed that nanoparticles could provide very high adaptability for both in-situ and ex-situ remediation of hazardous heavy metals (HHMs) in the environment. These methods could be used for the improvement of the inbuilt genetic potential and phytoremediation ability of plants by developing transgenic. These biological processes involve the transfer of gene of interest, which plays a role in hazardous metal uptake, transport, stabilization, inactivation and accumulation to increased host tolerance. This review identified that use of nanoremediation and combined biotechnological and, transgenic could help to enhance phytoremediation efficiency in a sustainable way.

Risk assessment of human exposure to lead and cadmium in maize grains cultivated in soils irrigated either with low-quality water or freshwater

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Levels of lead and cadmium in agriculture soil were affected by its levels in irrigation water.

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Levels of lead and cadmium in maize grians irrigated with low-quality water were higher than that irrigated with freshwter (about 19-30 folds).

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Levels of Pb and Cd concentrations in maize grains irrigated with low-quality water were above the permissible limits as 0.2 and 0.1 mg kg-1, respectively according to WHO/FAO.

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The determined HRI values for both maize grains irrigated with low-quality water and freshwater were <1.

Maize is the third important cereal crop after wheat and rice, especially in Egyptian villages. It is used in baking as a substitution component in wheat products and a main component in snacks for children. The target of this study was to estimate the risk assessment of lead (Pb) and cadmium (Cd) in maize grains cultivated in the agricultural soil irrigated by the contaminated water in comparison with that irrigated by freshwater. Lead (Pb) and cadmium (Cd) levels in irrigation water, soils and maize grains collected from different sites in Egypt were determined using ICP-OES. The studied samples were collected from 5 agricultural sites irrigated with freshwater (Nile River water and groundwater) as well as 4 agricultural sites irrigated with low-quality water (contaminated by sewage and industrial wastewater). Results exhibited that the levels of Pb and Cd in soil and maize grains were significantly affected by their levels in irrigation water; where, the levels of Pb and Cd in soil and maize grains irrigated by low-quality water possessed the multiple concentrations in comparison with those irrigated by freshwater. Specific water sources such as Kafr-Dokhmais and Al-Nasiria sites, Kafr El-Sheikh governorate had the highest levels of metals in the samples of irrigation water, soil and maize grains (p < 0.05). Metals levels in water and soil samples were within the permissible limits except Cd in low-quality water samples. Levels of Pb in maize grains irrigated by low-quality water were above the permissible limits (0.20 mg kg⁻¹), while Cd levels were within the permissible limits (0.1 mg kg⁻¹) except Al-Nasiria samples. Levels of Pb and Cd in maize grains irrigated by low-quality water were 19–30 folds those of maize grains irrigated by freshwater. The risk assessment of Pb and Cd levels in maize grains was estimated by daily intake of metals (DIM) and health risk index (HRI). All determined HRI was <1 indicating a non potential health risk for both adults and children.

Exposure assessment of heavy metal residues in some Egyptian fruits

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Heavy metals Cu, and Ni were present in all fruit samples obtained from Egyptian governorates.

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Washing of grapes and peeling of orange samples greatly reduced the level of Cu and Ni.

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Estimated daily intake of the fruit samples were considered higher than that of the tolerable daily intake.

Heavy metals are considered a main public health hazards, they are known to accumulate in fruits, which are heavily consumed by humans because of their unique sweet taste and potential health benefits. Therefore, the aim of this study was to determine the possible contamination levels of cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb) and nickel (Ni) in some selected fruits obtained from four Egyptian governorates and to compare the contamination levels with those of the recommended permissible limits. Results revealed that Pb and Cd were absent in all fruit samples, while Cr was only detected in grapes obtained from Cairo and Fayoum governorates and exceeded the maximum permissible limit (0.10 mg kg⁻¹). Nickel and Cu were detected in all fruit samples. Nickel was reduced more than copper after washing process of grapes especially in samples obtained from Alexandria and Giza governorates. After peeling process, Cu was extremely reduced in orange samples obtained from the following governorates in descending order Cairo, Alexandria, El-Fayoum and Giza. Estimated daily intake of heavy metals in fruit samples were found to be higher than that of the tolerable daily intake, indicating potential risk to human health. Therefore, to decrease the risk to human health, fruits must be washed well before eating to decrease heavy metal concentrations.

Heavy metals content in some non-alcoholic beverages (carbonated drinks, flavored yogurt drinks, and juice drinks) of the Egyptian markets

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The studied samples (juices, flavored yogurts and carbonated drinks) were mostly free of Pb, Cd and Cr.

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Concentrations of Fe, Mn and Ni were above the recommended permissible limits in most of the beverage samples.

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Canned beverages were most contaminated by toxic elements as compared to the plastic bottled beverages.

Heavy metals are elements present in trace quantities in the environment and, in small concentrations, they play important roles for the living organisms yet it can cause toxicity if exceeded the recommended levels. Toxic metals contamination is an important environmental problem that was mainly manifested in the growing industrial cities where the levels in toxic metals exceeded the recommended levels leading to the increase of several health problems (that vary from memory disorder to carcinogenic diseases). The main sources of food contamination by toxic metals are the increase in petroleum fuels exhausts and the addition of fertilizers and metal-based pesticides during farming processes. Nowadays, the non-alcoholic drinks represent one of the highest consumption groups worldwide especially in the Middle East and Islamic countries. The current work aims to investigate the safety of some non-alcoholic beverages (carbonated drinks, flavored yogurt drinks and juice drinks) from toxic metal contamination in the Egyptian market. The study revealed that non-alcoholic beverage samples (juices, flavored yogurts and carbonated drinks) in the Egyptian market are mostly free of lead (Pb), cadmium (Cd) and chromium (Cr) contamination. On the other hand, the results of current beverage samples indicate that iron (Fe), manganese (Mn) and nickel (Ni), except Mn in juices and carbonated drinks, were presented in concentrations above the recommended permissible limits of both the World Health Organization (WHO) and Egyptian Ministry Health (EMH). Meanwhile, Cu was found in concentrations below the recommended permissible limits.