Heavy Metal Residues in Some Fishes from Manzala Lake, Egypt, and Their Health-Risk Assessment

Contaminant and residue profiles in Lebanese food: a comparative analysis with global standards

Lebanon's agricultural sector, known for its diverse crop and livestock production, faces challenges in the international market due to the presence of chemical residues and contaminants in its food exports. Recent rejections of these exports have raised global concerns about food safety, increasingly seen as vital for public health and economic prosperity. This review focuses on examining scientific studies about the levels of various chemical residues including pesticides, and veterinary drugs and contaminants like mycotoxins, and polycyclic aromatic hydrocarbons, and heavy metals in Lebanese food products. Findings indicate that these residues and contaminants often exceed both the maximum residue limits (MRLs) and maximum limits (MLs) set by the Codex Alimentarius and the European Union. The review concludes with recommendations for reducing these contaminants and residues to enhance Lebanon's food safety and quality, aligning with international standards, and mitigating the risk of export rejections.

Carcinogenic and non-carcinogenic health risks associated with the consumption of fishes contaminated with heavy metals from Manzala Lake, Egypt

Manzala Lake was sampled to assess the concentrations and possible ecological risks of heavy metals. The mean heavy metal levels in the muscles of Nile tilapia, Flathead grey mullets and African catfish were 0.01, 0.15 and 0.29 mg/kg, respectively, for mercury; 3.16, 4.25 and 4.74 mg/kg for arsenic; 1.01, 0.87 and 0.95 mg/kg for lead; and 0.05, 0.12 and 0.06 mg/kg for cadmium. The levels of heavy metals exceeded their maximum permissible limits in most samples. The EDIs of some metals were higher than their PTDIs or BMDLs. The THQs and TTHQs from metal intake were >1 for Hg and Cd. In addition, the TCR values of As in all fish species were higher than 1.0 × 10-4 indicating a potential health risks from consumption of fish species which need strict hygienic procedures to prevent fish contamination with heavy metals and ensure that their levels did not exceed the maximum permissible limits.

Biomonitoring of mercury and selenium in commercially important shellfish: Distribution pattern, health benefit assessment and consumption advisories

This study aims to explore the concentrations of Se and Hg in shellfish along the Gulf of Mannar (GoM) coast (Southeast India) and to estimate related risks and risk-based consumption limits for children, pregnant women, and adults. Se concentrations in shrimp, crab, and cephalopods ranged from 0.256 to 0.275 mg kg-1, 0.182 to 0.553 mg kg-1, and 0.176 to 0.255 mg kg-1, respectively, whereas Hg concentrations differed from 0.009 to 0.014 mg kg-1, 0.022 to 0.042 mg kg-1 and 0.011 to 0.024 mg kg-1, respectively. Se and Hg content in bamboo shark (C. griseum) was 0.242 mg kg-1 and 0.082 mg kg-1, respectively. The lowest and highest Se concentrations were found in C. indicus (0.176 mg kg-1) and C. natator (0.553 mg kg-1), while Hg was found high in C. griseum (0.082 mg kg-1) and low in P. vannamei (0.009 mg kg-1). Se shellfishes were found in the following order: crabs > shrimp > shark > cephalopods, while that of Hg were shark > crabs > cephalopods > shrimp. Se in shellfish was negatively correlated with trophic level (TL) and size (length and weight), whereas Hg was positively correlated with TL and size. Hg concentrations in shellfish were below the maximum residual limits (MRL) of 0.5 mg kg-1 for crustaceans and cephalopods set by FSSAI, 0.5 mg kg-1 for crustaceans and 1.0 mg kg-1 for cephalopods and sharks prescribed by the European Commission (EC/1881/2006). Se risk-benefit analysis, the AI (actual intake):RDI (recommended daily intake) ratio was > 100%, and the AI:UL (upper limit) ratio was < 100%, indicating that all shellfish have sufficient level of Se to meet daily requirements without exceeding the upper limit (UL). The target hazard quotient (THQ < 1) and hazard index (HI < 1) imply that the consumption of shellfish has no non-carcinogenic health impacts for all age groups. However, despite variations among the examined shellfish, it was consistently observed that they all exhibited a Se:Hg molar ratio > 1. This finding implies that the consumption of shellfish is generally safe in terms of Hg content. The health benefit indexes, Se-HBV and HBVse, consistently showed high positive values across all shellfish, further supporting the protective influence of Se against Hg toxicity and reinforcing the overall safety of shellfish consumption. Enhancing comprehension of food safety analysis, it is crucial to recognize that the elevated Se:Hg ratio in shellfish may be attributed to regular selenoprotein synthesis and the mitigation of Hg toxicity by substituting Se bound to Hg.

Selenium and mercury concentration, Se/Hg molar ratio and risk-benefit assessment of marine fish consumption: Human health risks and protective role of Se against Hg toxicity

This study aimed to explore the concentrations of Se and Hg in marine fish along the Gulf of Mannar (southeast coast of India) and to assess related risks and risk-based consumption limits for children, pregnant women, and adults. Se concentrations in pelagic and benthic fish ranged from 0.278 to 0.470 mg/kg and 0.203 to 0.294 mg/kg, respectively, whereas Hg concentrations ranged from 0.028 to 0.106 mg/kg and 0.026 to 0.097 mg/kg, respectively. Se and Hg contents in demersal fish (Nemipterus japonicus) were 0.282 and 0.039 mg/kg, respectively. The lowest and highest Hg concentrations in pelagic fish were found in Scomberomorus commersoni and Euthynnus affinis whereas the lowest and highest Se concentrations in benthic fish were found in Scarus ghobban and Siganus javus. Se concentrations in marine fishes were found in the following order: pelagic > demersal > benthic whereas Hg concentrations were found in the following order: pelagic > benthic > demersal. The presence of Se in fish was positively correlated with trophic level (TL) and size whereas that of Hg was weakly correlated with TL and habitat and negatively correlated with size. Se risk-benefit analysis, the AI/RDI (actual intake/recommended daily intake) ratio was > 100 % and the AI/UL (upper limit) ratio was < 100 %, indicating that all fish have sufficient levels of Se to meet daily requirements without exceeding the UL. Hg level was below the maximum residual limit (MRL) of 0.5 mg/kg for most fish but it was 1 mg/kg in E. affinis and Lethrinus lentjan. The target hazard quotient (THQ < 1) and hazard index (HI < 1) imply that the consumption of fish poses no noncarcinogenic health risks. However, all examined fish had a mean Se/Hg molar ratio > 1, indicating that human intake of fishwas rather safe relative to Hg content. Health benefit indexes (Se-HBV and HBVse) with high positive values in all fish supported the protective effect of Se against Hg toxicity, suggesting the overall safety of fish consumption. The high Se/Hg ratio in fish could be attributed to the replacement of Se bound to Hg, thereby suppressing Hg toxicity and maintaining normal selenoprotein synthesis. This insight is useful for a better understanding of food safety analysis.

Mercury and selenium in three fish species from a dam 20 months after a mine-tailing spill in the SE Gulf of California ecoregion, Mexico

During January 2013, a mining spill occurred in the Santa Maria mining region, releasing around 300,000 m3 of tailings on Los Remedios river, which was transported through the San Lorenzo river and finally to El Comedero (EC) dam. Twenty months later, we examined the concentrations of Hg and Se in the muscle, liver, gills, and guts of three fish species (Cyprinus carpio, Oreochromis aureus, Micropterus salmoides) captured in the EC dam to assess the performance of the cleaning operations. A high Se concentration in the liver of all species (carp, 1.2 ± 0.4; tilapia, 3.9 ± 2.1; bass, 3.5 ± 1.1 µg g-1 ww) was consistently observed, while this behavior was only found in the blue tilapia for Hg (0.15 ± 0.11 µg g-1 ww). Tilapia (benthic-detritivorous) exhibited the highest Se concentrations compared to the carp (omnivore) and the largemouth bass (piscivore). In contrast, the largemouth bass had the highest Hg levels in the muscle compared with the other fishes. Such differences could be related to the different metabolism and feeding habits among species. Compared to a tilapia study carried out three months after the mine spill during a mortality event, a decrease was evident in the liver for Se and Hg by 7.2 and 4.7 times, respectively. This reveals that cleaning operations were more efficient for Se and less for Hg, and that a prolonged period was required for the partial recovery of the element levels in fish from sites impacted by mining. Considering the Mexican consumption scenarios for each fish species, it could be concluded that there will be no non-cancer risk by exposure to Hg or Se.

Risk assessment of toxic residues among some freshwater and marine water fish species

Egypt has several beaches, as well as the Nile River and a few lakes; therefore, it could compensate for the lack of protein in red meat with fish. Fish, however, may become a source of heavy metal exposure in humans. The current study was to assess the level of five toxic metals, lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), and aluminum (Al), in six species, namely, Oreochromis niloticus (O. niloticus), Mugil cephalus (M. cephalus), Lates niloticus (L. niloticus), Plectropomus leopardus (P. leopardus), Epinephelus tauvina (E. tauvina), and Lethrinus nebulosus (L. nebulosus), collected from the El-Obour fish market in Egypt. The residual concentrations of the tested toxic metals in the examined O. niloticus, M. cephalus, L. niloticus, E. tauvina, P. leopardus, and L. nebulosus species were found to be higher than the European Commission's maximum permissible limits (MPL) for Pb and Cd by 10 and 20%, 15 and 65%, 75 and 15%, 20 and 65%, 15 and 40%, and 25 and 5%. In contrast, 30% of L. niloticus exceeded the MPL for Hg. It was shown that the average estimated daily intake (EDI) and the target hazard quotient (THQ) in fish samples are below safety levels for human consumption and hazard index (HI < 1). From the human health point of view, this study showed that there was no possible health risk to people due to the intake of any studied species under the current consumption rate in the country.

Metal(loid)s (As, Cd, Cu, and Zn) in three fish species from a dam after a mine-tailing spill: differential bioaccumulation and potential health risk

The failure of a tailings dam occurred in January 2013 at the Santa María de Otáez mining region (Mexico) released a spill (~ 300,000 m3) on Los Remedios River, which was transported through the San Lorenzo River, and finally to El Comedero (EC) dam. The concentrations of metal(loid)s in the muscle, liver, gills, and guts of three fish species (Cyprinus carpio, Oreochromis aureus, Micropterus salmoides) collected from EC dam were examined twenty months later to assess the performance of the cleaning operations. The bioaccumulation patterns of the metal(loid)s in the tissues were different in the three fish species. Tilapia had the highest Cd (11.23 ± 8.53 µg g-1) and Cu (871 ± 1261 µg g-1) concentrations in the liver, as well as As concentration (83.6 ± 61.7 µg g-1) in the gut, while the highest Zn concentration (745 ± 356 µg g-1) was measured in the gills of the carp. Such variability can be caused by the variant bioavailability of the metal(loid)s and by the feeding habits of each species; and also by the fact that some metals are essential and better regulated by organisms than other non-essential. Compared to a study of tilapia carried out 90 days after mine spill, a decrease was evident in the liver for As, Cd, Cu, and Zn by 129, 5, 10, and 1.7 times, respectively. This revealed that cleaning operations were more efficient for As. The target hazard quotient and the hazard index were < 1, which indicates there will be no risk of consuming muscle in moderated rations of the three fish species.

High accumulation of metals and metalloids in the liver of the blue tilapia (Oreochromis aureus) during a massive mortality event induced by a mine tailing spill

In this study, the concentration of six metal(loid)s was examined in the fish Oreochromis aureus collected from El Comedero dam during a massive mortality event induced by a mine tailing spill. A major spill (~ 300,000 m³) of waste was released into the San Lorenzo River System following a rupture in the tailing dam of a mining plant in NW Mexico; consequently, the discharged material flowed into El Comedero dam. The accumulation of metal(oid)s in the tissues of O. aureus showed higher levels in the liver than in the guts and muscle. Concentrations in the liver were high (As, 1.1-1063; Cd, 8.9-392; Cu, 372-59,129; Hg, 0.46-19.79; Se, 8.7-748; and Zn, 116-820 μg g^-1), revealing that these fish were exposed to high concentrations of these elements. The mortality of fish could have resulted from the combined effect of the six analyzed metal(loid)s, as well as other residues present in mine tailings.

Trace elements in Foodstuffs from the Mediterranean Basin-Occurrence, Risk Assessment, Regulations, and Prevention strategies: A review

Trace elements (TEs) are chemical compounds that naturally occur in the earth's crust and in living organisms at low concentrations. Anthropogenic activities can significantly increase the level of TEs in the environment and finally enter the food chain. Toxic TEs like cadmium, lead, arsenic, and mercury have no positive role in a biological system and can cause harmful effects on human health. Ingestion of contaminated food is a typical route of TEs intake by humans. Recent data about the occurrence of TEs in food available in the Mediterranean countries are considered in this review. Analytical methods are also discussed. Furthermore, a discussion of existing international agency regulations will be given. The risk associated with the dietary intake of TEs was estimated by considering consumer exposure and threshold values such as Benchmark dose lower confidence limit and provisional tolerable weekly intake established by the European Food Safety Authority and the Joint FAO/WHO Expert Committee on Food Additives, respectively. Finally, several remediation approaches to minimize TE contamination in foodstuffs were discussed including chemical, biological, biotechnological, and nanotechnological methods. The results of this study proved the occurrence of TEs contamination at high levels in vegetables and fish from some Mediterranean countries. Lead and cadmium are more abundant in foodstuffs than other toxic trace elements. Geographical variations in TE contamination of food crops clearly appear, with a greater risk in developing countries. There is still a need for the regular monitoring of these toxic element levels in food items to ensure consumer protection.

Estimation of Cadmium in Muscles of Five Freshwater Fish Species from Manzalah Lake, and Possible Human Risk Assessment of Fish Consumption (Egypt)

The Egyptian government devised a plan in 2016 to improve the unique ecological significance of northern lakes, which mentioned Manzalah Lake in the Egypt Vision 2030. In this regard, this study investigated cadmium (Cd) content in five freshwater fish species collected from Manzalah Lake in Egypt at 2018 by local fishermen. According to the findings, Clarias gariepinus recorded the highest concentration of Cd (1.40 ± 0.2 μg/g) and the lowest concentration was recorded in O. aureus (1.19 ± 0.2 μg/g). Cadmium contents of all species were largely above the permissible level of the Food Agricultural Organization (FAO)/World Health Organization (WHO) and Commission Regulation (EC). The estimated daily intake (EDI), the estimated weekly intake (EWI), and the percentages of provisional tolerable weekly intake (PTWI %) values for Cd in the C. gariepinus > Sarotherodon galilaeus > Tilapia zillii > Oreochromis niloticus > Oreochromis aureus which consumed by children, teenagers, and adults were much higher than the PTWI values established by FAO/WHO. In addition, C. gariepinus consumed by children showed the highest value of the target hazard quotient (THQ) (5.83 a day or 40.81 a week) while O. aureus that ingested by adults showed the lowest level (1.06 a day or 7.42a week). The target carcinogenic risk (TCR) of C. gariepinus in children had the greatest level (2.21 × 10-3 a day or 1.55 × 10-2 a week), whereas O. aureus in adults had the lowest level of TCR (4 × 10-4 a day or 2.81 × 10-3 a week). THQs values of Cd in the five studied species were found higher than one. Moreover, TCRs values of Cd in the five species were exceeded the US Environmental Protection Agency guideline USEPA permissible limits suggesting that a daily or weekly consumption of these species could lead to a high risk non-carcinogenic and carcinogenic for humans.

The health risk assessment of heavy metals to human health through the consumption of Tilapia spp and catfish caught from Lake Mariut, Egypt

This work assesses the concentration of As, Cd, Pb, Hg, and Al in three of Tilapia species and catfish caught from Lake Mariut. As well as the human health risk and muscle biochemical composition. Besides, the antioxidant responses of different species. The average metal concentration order was Pb> As> Cd> Al> Hg. The Cd and Pb levels in all species; besides, the Hg levels in Oreochromis niloticus and Oreochromis aureus exceeded the maximum limits set by FAO, European legislation, and FAO/WHO. The human health risk was assessed using estimated dietary intakes, the target hazard quotient (THQ), and the carcinogenic risk (CR). THQAs was >1 in all examined fishes and closer to 1 in THQCd, Hg. As well, CR level for As was higher than the permissible value. Tilapia zillii showed significant decreases in carbohydrates compared to Clarias gariepinus; also, ash content compared to C. gariepinus, O. niloticus, and O. aureus. Furthermore, water content compared to O. aureus. In contrast, significant increases of SOD in O. niloticus compared to C. gariepinus. In addition, CAT and GPx in O. aureus compared to C. gariepinus. Also, GR in both O. niloticus and O. aureus compared to C. gariepinus, and GSH in all of Tilapia spp. compared to C. gariepinus. Data obtained provide evidence of health risks to the consumers. Therefore, more caution is required.

Arsenic Exposure via Contaminated Water and Food Sources

Arsenic poisoning constitutes a major threat to humans, causing various health problems. Almost everywhere across the world certain “hotspots” have been detected, putting in danger the local populations, due to the potential consumption of water or food contaminated with elevated concentrations of arsenic. According to the relevant studies, Asia shows the highest percentage of significantly contaminated sites, followed by North America, Europe, Africa, South America and Oceania. The presence of arsenic in ecosystems can originate from several natural or anthropogenic activities. Arsenic can be then gradually accumulated in different food sources, such as vegetables, rice and other crops, but also in seafood, etc., and in water sources (mainly in groundwater, but also to a lesser extent in surface water), potentially used as drinking-water supplies, provoking their contamination and therefore potential health problems to the consumers. This review reports the major areas worldwide that present elevated arsenic concentrations in food and water sources. Furthermore, it also discusses the sources of arsenic contamination at these sites, as well as selected treatment technologies, aiming to remove this pollutant mainly from the contaminated waters and thus the reduction and prevention of population towards arsenic exposure.

Quantification of serum homoarginine, methylated arginine and inhibin-A levels in a high-risk pregnancy

The plasma levels of homoarginine (h-Arg) and methylated arginine have proven to be an independent cardiovascular risk factor. We aimed to determine the h-Arg and methyl arginine levels in serums of high-risk pregnancy causing potential complications. These participants were divided into four groups as the control group with quadruple test, the high-risk group quadruple test the control group with binary test, the high-risk group with quadruple test that have a positive result from second-trimester screening with a cut-off value of 1 in 300. The serum methyl arginine and homoarginine levels were analysed with liquid chromatography-tandem mass spectrometry. Serum h-Arg levels were found to be higher in high-risk groups compared to control groups and it was also detected higher in the groups with quadruple test than the groups with binary test (p < .05). H-Arg levels in the groups showed strong negative correlation with age and serum inhibin-A levels (r = -0.288, p < .001). Also, there was a strong negative correlation between serum asymmetric dimethylarginine (ADMA) and serum inhibin-A levels (r = -0.352, p < .001). H-Arg may be a new risk marker to detect high-risk pregnancies in early pregnancy. In addition to, methylated arginine such as ADMA has a key regulator in a physiological concentration of h-Arg.IMPACT STATEMENTWhat is already known on this subject? H-Arg levels decrease may be associated with preeclampsia, GDM, macrosomia, low birth weight, and preterm delivery in pregnancy.What do the results of this study add? Serum h-Arg levels were found to be higher in high-risk groups. Additionally, h-Arg levels and ADAM, one of the methylated arginines in the groups showed a strong negative correlation with serum inhibin-A levelsWhat are the implications of these findings for clinical practice and/or further research? H-Arg may be a new risk marker to detect high-risk pregnancies.

Probabilistic Health Risk Assessment of Trace Elements in Baby Food and Milk Powder Using ICP-OES Method

This study was conducted to evaluate the concentration and health risk of trace elements in milk powder and baby food samples marketed in Iran using inductive couple plasma/optical emission spectroscopy (ICP-OES) method. The limit of detection (LOD) and limit of quantification (LOQ) were ranged from 1.80 × 10^-5 to 2.17 × 10^-3 and 6.00 × 10^-5 to 7.22 × 10^-3 mg/kg, respectively, with recoveries ranged from 92 to 105%. Zinc (Zn) was found in a high mean concentration (8.49 × 10^-1 ± 3.93 × 10^-2 mg/kg) in milk powder, and iron (Fe) was found in the highest mean concentration (2.04 ± 3.61 × 10^-2 mg/kg) in baby food. The Monte Carlo simulation results for the infants revealed that the rank order of the hazard quotient (HQ) index was mercury (Hg) > nickel (Ni) > arsenic (As) > cadmium (Cd) > aluminum (Al). Further, the result of non-carcinogenic and probability of carcinogenic risk was lower than the limits of safe risk (HQ > 1 and cancer risk (CR) > 1 × 10^-4). In conclusion, the toxic elements content in the tested products was sufficiently low, and all of the milk powder and baby food sold in Iran could be considered safe for infants and children.

Investigation of Bioaccumulation and Human Health Risk Assessment of Heavy Metals in Crayfish (Procambarus clarkii) Farming with a Rice-Crayfish-Based Coculture Breeding Modes

Due to the rapid development of the crayfish (Procambarus clarkii) industry in Chinese catering, people are paying more attention to the bioaccumulation of heavy metals in crayfish. To evaluate the health risks associated with the consumption of crayfish, nine types of heavy metals in both crayfish and abdominal muscles of crayfish were investigated. Crayfish samples were collected from rice-crayfish-based coculture breeding modes from different areas located in the middle and lower reaches of the Yangtze River. The average concentrations of heavy metals in the whole crayfish were much higher than the abdominal muscle of crayfish. The estimated daily intake (EDI) of heavy metals in the abdomen of crayfish was calculated to assess the noncarcinogenic risk and the overall noncarcinogenic risk including the target hazard quotient (THQ), the hazard index (HI) and carcinogenic risk (CR). The results of the present study showed that the consumption of crayfish may not present an obvious health risk to human associated with heavy metals. However, the THQ values of As in the abdominal muscles of crayfish for adults in EnShi (ES) and children in JiaYu (JY) should be of concern due to the higher contribution to the potential health risks of crayfish compared to other metals. Through X-ray photoelectron spectroscopy (XPS) detection of heavy metal As, it is found that As in crayfish culture environment mainly exists in the form of As3+.Therefore, the quality and quantity of crayfish consumption should be moderated to prevent the bioaccumulation of As. The results indicate that crayfish cultured in different areas may have similar pollution levels and/or emissions from the same pollution sources.

Trace Metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) and Stable Isotope Ratios (δ13C and δ15N) in Fish from Wulungu Lake, Xinjiang, China

Wulungu Lake is a vital fishery area in Xinjiang. However, the concentration, enrichment rules, and sources of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the aquatic organisms, have rarely been investigated. The results suggest that the concentrations of As, Ni, Pb, and Zn were higher than those recommended by the national standards for edible fish in some species. Hg, Ni, Cu, Pb, Cr, and Zn in the fish were dependent on the concentration of trace metals in the water environment (p < 0.05). The body weights of the fish were significantly negatively correlated with only Hg (p < 0.05); however, their body lengths were significantly positively correlated with As, Cu, Zn, and Hg contents. Values of δ¹³C ‰ (δ¹⁵N ‰) for the entire fish food web was found to range from -19.9‰ (7.37‰) to -27.7‰ (15.9‰), indicating a wide range of trophic positions and energy sources. Based on the linear correlation, As, Cu, Cd, and Zn contents were positively correlated with δ¹⁵N (p < 0.05), and bioaccumulation was observed in the fish. The target hazard quotient (THQ) of all fish species was less than 1, indicating the absence of potential risks to human health.

Adsorptivity of mercury on magnetite nano-particles and their influences on growth, economical, hemato-biochemical, histological parameters and bioaccumulation in Nile tilapia (Oreochromis niloticus)

Among toxic pollutants, Mercury (Hg) is a toxic heavy metal that induces harmful impacts on aquatic ecosystems directly and human being's health indirectly. This study confirmed the in vitro magnetic potential of magnetite Nano-Particles (Fe₃O₄ NPs) against waterborne Hg exposure-induced toxicity in Nile tilapia (Oreochromis niloticus). We further evaluate the safety profile of Fe₃O₄ NPs on fish growth, hemato-biochemical, histological parameters, bioaccumulation in muscles, and economy. Magnetite nanoparticles were characterized, adsorption loading to Hg ions was investigated, and testing different concentrations of Fe₃O₄ NPs (0.2, 0.4, 0.6, 0.8, and 1.0 mg/L) was applied to determine the highest concentration of adsorption. An in vivo experiment includes 120 fish with an average weight of 26.2 ± 0.26 g were randomly divided into 4 equal groups, each group had three replicates (n = 30 fish/group; 10 fish/ replicate). All groups were fed on a reference basal diet and the experiment was conducted for 30 days. The first group (G₁) was allocated as a control. The second group (G₂) received 1.0 mg/L aqueous suspension of Fe₃O₄ NPs. The third group (G₃) was exposed to an aqueous solution of Hg ions at a concentration of 0.025 mg/L. Meanwhile, the fourth group (G₄) acquired an aqueous suspension composed of a mixture of Hg ions and Fe₃O₄ NPs as previously mentioned. Throughout the exposure period, the clinical signs, symptoms, and mortalities were recorded. The Hg ions-exposed group induced the following consequences; reduced appetite resulting in reduced growth and less economic efficiency; microcytic hypochromic anemia, leukocytosis, lymphopenia, and neutrophilia; sharp and clear depletion in the immune indicators including lysozymes activity, immunoglobulin M (IgM), and Myeloperoxidase activities (MPO); significant higher levels of ALT, AST, urea, creatinine, and Superoxide dismutase (SOD); histological alterations of gill, hepatic and muscular tissues with strong expression of apoptotic marker (caspase 3); and a higher accumulation of Hg ions in the muscles. Surprisingly, Fe₃O₄ NPs-supplemented groups exhibited strong adsorption capacity against the Hg ions and mostly removed the Hg ions accumulation in the muscles. Also, the hematological, biochemical, and histological parameters were recovered. Thus, in order to assess the antitoxic role of Fe₃O₄ NPs against Hg and their safety on O. niloticus, and fill the gap of the research, the current context was investigated to evaluate the promising role of Fe₃O₄ NPs to prevent Hg-exposure-induced toxicity and protection of fish health, which ascertains essentiality for sustainable development of nanotechnology in the aquatic environment.

Integrated geospatial analysis linking metal contamination among three different compartments of Lake Edku ecosystem in Egypt to human health effects

This study is the first in forming an integrated up-to-date spatial analysis linking heavy metal contamination among three different compartments of Lake Edku ecosystem to human health effects. The study determined the concentrations of iron (Fe), nickel (Ni), lead (Pb), chromium (Cr), and cadmium (Cd) in sediment and water samples collected from 12 stations covering the entire lake, as well as in the liver and muscle tissues of the three commercially edible fish species (African sharptooth catfish (Clarias gariepinus), Blue tilapia (Oreochromis aureus), and Redbelly tilapia (Tilapia zillii)), during winter 2019. Cartographic maps investigating the spatial contamination pattern of each metal in sediment and water samples along the entire lake, as well as correlation analysis between metal pairs, were generated. Moreover, the study examined the affinity of metal transfer among the three compartments and assessed the probability of being exposed to non-carcinogenic health hazards from the consumption of the abovementioned species. Results revealed that Fe and Cd recorded the highest and lowest mean concentrations, respectively, in sediment, water, and fish samples. The mean concentrations of Cd, Pb, and Ni in the water of Lake Edku, as well as the mean concentrations of Cd, Pb, and Cr in muscle tissues of the three examined fish species, exceeded the permissible limits. The northwestern part of the lake exhibited the highest concentrations of Fe, Ni, and Cr in Lake Edku's sediment with strong significant positive correlations recorded between Fe-Ni, Fe-Cr, and Ni-Cr pairs suggesting sharing the same contamination source. Concerning Lake Edku's water, the northwestern area displayed the highest concentrations for all metals. Moreover, Cd, Pb, and Cr exhibited nearly the same spatial contamination pattern with the hotspot located in the western part of the lake. Strong significant positive correlations were found between Cd-Pb, Cd-Cr, and Pb-Cr pairs in surface water, suggesting sharing the same origin of dispersion. The three fish species accumulated heavy metals from water several folds higher than from sediments, indicating that water is the main source of the intensive transfer of heavy metals to the three fish species. Based on the consumption of the three investigated fish species, children recorded the highest estimated daily (EDI) and weekly intakes (EWI) of heavy metals followed by adults. Regardless Pb, EWI values indicated that there are no significant health risks through fish consumption from the examined metals recommending that children should consume less than 85.227 g/day African sharptooth catfish muscle, 108.696 g/day Blue tilapia muscle, and 97.403 g/day Redbelly tilapia muscle to assure their health. Moreover, adults should consume less than 397.727 g/day African sharptooth catfish muscle, 507.24 g/day Blue tilapia muscle, and 454.54 g/day Redbelly tilapia muscle. The estimated hazard quotient (HQ) of all metals was lower than or close to the safe values of one for children and adults in the three investigated fish species indicating the absence of potential non-carcinogenic threats. The hazard index (HI) estimated for the five examined heavy metals in each of the investigated fish species was below one in adults only. Regarding the total hazard index estimated from consuming the three fish species, both children and adults may be subjected to non-carcinogenic risk.

Spatial profiles of perfluoroalkyl substances and mercury in fish from northern Lake Victoria, East Africa

There is an acute deficit of data on per- and polyfluoroalkyl substances (PFASs) and mercury (Hg) in the open waters of Lake Victoria, East Africa, relative to nearshore areas. We analyzed stable isotopes (δ¹⁵N and δ¹³C), PFASs and Hg in Nile Perch and Nile Tilapia muscle and liver samples from nearshore and open lake locations from the Ugandan part of the lake. The δ¹⁵N values of Nile Perch muscle indicated a higher trophic level for samples from the open lake than from nearshore locations. Averages of ∑PFAS concentrations in Nile Perch muscle and liver (0.44 and 1.75 ng/g ww, respectively) were significantly higher than in Nile Tilapia (0.24 and 0.50 ng/g ww, respectively). ∑PFAS concentrations in muscle of open lake Nile Perch were significantly higher than for nearshore samples. A similar observation was made for total mercury concentrations in muscle (THg_{_Muscle}) of Nile Perch. THg was dominated by methyl mercury (MeHg⁺, 22-124 ng/g ww) and mercuric mercury (Hg²⁺, <MDL-29 ng/g ww) in Nile Perch muscle. Strong correlation between MeHg⁺ and some PFASs (e.g. PFOS: r = 0.704, P = 0.016) suggested similar exposure routes or factors. Estimated human daily intake values of PFOS from fish consumption were below international limits whereas for MeHg^+, the US EPA reference dose was exceeded.