Health risk assessment of heavy metals in freshwater fish in the central and eastern North China

The Accumulation and Transformation of Heavy Metals in Sediments of Liujiang River Basin in Southern China and Their Threatening on Water Security

Heavy metal (HM) pollution in sediments is tightly related to the security of water quality in rivers, but the accumulation and conversion of HMs are poorly researched, so that a field study was conducted as an example in the Liujiang River Basin. Seven HMs were analyzed to determine between the overlying water and sediments. Moreover, the regulation of HMs speciation and environmental factors in their accumulation and conversion were identified. The obtained results suggested the HM concentrations in water are far below the primary standard of water quality, but in sediments, the contents of Cd and Zn are significantly higher than their corresponding baseline of soil. Only Cd and Pb are dominantly in non-residual form (carbonate-bound fraction and reducible fraction, respectively). The non-significant correlations suggested pH and Eh may be hard to influence HMs in water, while the significant correlations highlighted the regulations of Eh, organic matter and mean grain size on the accumulation of metals in sediments. The opposite correlations between EC, TDS, pH and Cd confirmed the emission of acid wastewater contributed to the accumulation of Cd in sediment. The conversion of metals between water and sediments were found to be significant only in specific forms of Cd, As, Cu, Zn and Pb, suggesting the conversion of HMs in sediments should be largely regulated by their specific forms. The very high risk disclosed by the higher values of Eri and RI are only found upstream, while the higher risk of Cd should be treated as a critical environmental threat.

The Bioaccumulation and Health Risk Assessment of Metals among Two Most Consumed Species of Angling Fish (Cyprinus carpio and Pseudohemiculter dispar) in Liuzhou (China): Winter Should Be Treated as a Suitable Season for Fish Angling

Wild fish caught by anglers were validated to be commonly polluted by metals, but their contamination status could be varied with changing seasons. To determine the seasonal variation in metal pollution and health risks in these fish, this study took Liuzhou City as an example to investigate the concentrations of eight metals in two dominant angling fishes (Cyprinus carpio and Pseudohemiculter dispar) collected, respectively, in winter and summer. The obtained results suggested the mean concentrations of metals in fish are overall lower in winter. Only Cr, Zn, and Cd in some fish were beyond the thresholds in summer. The significant correlations between fish length and weight and most metals suggested the biological dilution effect could exert its influence in winter. The similar distribution of metals in winter suggested that metal bioaccumulation should be manipulated by living habitats, while the inconsistent distribution of metals in summer may be related to the variation in feeding behavior. The metal pollution index (Pi) values were all below 0.2 in winter, which suggested no metal contamination in fish, but most fish were found to be mostly contaminated by Cr and Cd in summer, which was confirmed by their Pi > 0.2. The fish could be consumed freely in winter due to the total target hazard quotient (TTHQ) below 1, while the consumption of fish was not entirely safe in summer, particularly for children, due to TTHQ values that were generally beyond 1. Given the higher weekly recommended consumption of fish in winter, winter should be treated as a suitable season for fish angling.

Effect of Methylmercury Exposure on Bioaccumulation and Nonspecific Immune Respsonses in Hybrid Grouper Epinephelus fuscoguttatus × Epinephelus lanceolatus

Simple Summary

The head kidney was primary organ that accumulated methylmercury in hybrid grouper. Muscle tissue had lower methylmercury content than the head kidney and liver. Nonspecific immune responses and bioaccumulation of methylmercury were linked to hybrid grouper health.

Abstract

Mercury (Hg) is a dangerous heavy metal that can accumulate in fish and is harmful when consumed by humans. This study investigated the bioaccumulation of mercury in the form of methylmercury (MeHg) and evaluated nonspecific immune responses such as phagocytic activity and superoxide anion (O₂⁻) production in hybrid grouper (Epinephelus fuscoguttatus × E. lanceolatus). The hybrid grouper leukocytes were incubated with methylmercury chloride (CH₃HgCl) at concentrations of 10–10,000 µg/L to determine cell viability, phagocytic activity, and O₂⁻ production in vitro. Subsequently, the grouper were exposed daily to CH₃HgCl mixed in the experimental diets at concentrations of 0, 1, 5, and 10 mg/kg for 28 days. The bioaccumulation of MeHg in the liver, head kidney, and muscle tissue was measured, and the phagocytic activity and O₂⁻ production were evaluated. In vitro results indicated that cell viability was significantly lower than that of the control group at concentrations > 500 µg/L. The phagocytic rate and O₂⁻ production at concentrations ˃ 500 and ˃ 200 µg/L, respectively, were significantly lower than those of the control group. The dietary exposure demonstrated that MeHg accumulated more substantially in the liver and head kidney compared with the muscle tissue in the treatment groups. Moreover, the cumulative concentration significantly increased with higher concentrations and more days of exposure. The phagocytic rate and O₂⁻ production in the treatment groups were significantly lower than those in the control group from days 2 and 1, respectively. In conclusion, hybrid grouper accumulated significant MeHg in the liver and head kidney compared with the muscle tissue, and higher concentrations and more exposure days resulted in decreased cell viability, phagocytic activity, and O₂⁻ production.

Ozonized biochar filtrate effects on the growth of Pseudomonas putida and cyanobacteria Synechococcus elongatus PCC 7942

BACKGROUND

Biochar ozonization was previously shown to dramatically increase its cation exchange capacity, thus improving its nutrient retention capacity. The potential soil application of ozonized biochar warrants the need for a toxicity study that investigates its effects on microorganisms.

RESULTS

In the study presented here, we found that the filtrates collected from ozonized pine 400 biochar and ozonized rogue biochar did not have any inhibitory effects on the soil environmental bacteria Pseudomonas putida, even at high dissolved organic carbon (DOC) concentrations of 300 ppm. However, the growth of Synechococcus elongatus PCC 7942 was inhibited by the ozonized biochar filtrates at DOC concentrations greater than 75 ppm. Further tests showed the presence of some potential inhibitory compounds (terephthalic acid and p-toluic acid) in the filtrate of non-ozonized pine 400 biochar; these compounds were greatly reduced upon wet-ozonization of the biochar material. Nutrient detection tests also showed that dry-ozonization of rogue biochar enhanced the availability of nitrate and phosphate in its filtrate, a property that may be desirable for soil application.

CONCLUSION

Ozonized biochar substances can support soil environmental bacterium Pseudomonas putida growth, since ozonization detoxifies the potential inhibitory aromatic molecules.

Health Risk Assessment and Levels of Heavy Metals in Farmed Nile Tilapia (Oreochromis niloticus) from the Volta Basin of Ghana

Heavy metals (Pb, Cd, As, Mn, Fe, Zn, Cu, Ni, and Cr) are some of the most toxic elements that can bioaccumulate from sources linked to human activities, such as industry and agriculture. This study quantifies the concentrations of several heavy metals in caged tilapia found in Ghana’s Volta Basin and assesses the associated health risks. The levels of heavy metals in the tissues of Oreochromis niloticus from three cage farms (N = 52) were determined using Atomic Absorption Spectrometry (AAS). The implication for human health was assessed using several risk assessment techniques. Fe (50.11 ± 10.22 mg/kg) and Cr (0.31 ± 0.07 mg/kg) had the highest and lowest accumulated metal concentrations, respectively. Heavy metal concentrations in tilapia tissue from fish farms were ordered as follows: Fe > Mn > Zn > Ni > Cr (farm A), Fe > Zn > Ni > Mn (farm B), and Fe > Mn > Zn > Ni > Cr (farm C). All metals had an estimated daily intake (EDI) below the threshold, and mean differences between sample farms were not statistically significant. Similarly, the values of target hazard quotients (HQs) and hazard indices (HIs) were less than one. According to the risk assessment results, eating tilapia from farms posed no risk to human health. The presence of Mn, Fe, and Ni concentrations above the maximum level in the fish, on the other hand, suggests that they may affect fish health.

Heavy Metals in the Fish Tenualosa ilisha Hamilton, 1822 in the Padma-Meghna River Confluence: Potential Risks to Public Health

Hilsa shad (Tenulosa ilisha) is Bangladesh's most important single-species fishery that contributes to 11% of total catch and employment for millions of people. However, heavy metals (HMs) toxicity in the edible organs of T. ilisha and their plausible public health threats have received weak attention. To provide insights on this issue, we determined, using ICP-MS, the concentration of Zn, Cu, Cr (VI), Pb, and Cd in the edible organs of five different sizes of T. ilisha and the surface water collected from the Padma-Meghna River confluence, Chandpur (Bangladesh). Multivariate analysis indicated that T. ilisha gills and liver contained higher HMs than muscle, and the surface water was below the safety limits. The study revealed that only Cr crossed the safety limits and bioaccumulated in the smaller-sized gills and liver. To assess the public health risks, target hazard quotient (THQ), total THQ (TTHQ) and carcinogenic (CR) risks were calculated. Only Cr imposed non-carcinogenic risks to consumers, while TTHQ showed higher chronic health risks. There was no CR risk measured for consumers, except for the largest-sized gills for children. Randomly positive relations between HMs and sizes were found; whereas, consistently positive relations were found among the tissue types. The outcomes of our study may aid policymakers in managing pollutants, especially the Cr sources in the greater Chandpur regions.

Continental-scale spatial distribution, sources, and health risks of heavy metals in seafood: challenge for the water-food-energy nexus sustainability in coastal regions?

Rare information on the seafood safety and the coastal water-food-energy nexus sustainability in terms of seafood safety is available. This study investigated the distribution of heavy metals in 3 kinds of seafood (bivalve molluscs, fish, and crustaceans) collected from coastal areas along the 18,000 km coastline of China. Risk assessment and source apportionment of heavy metals, and the coastal water-food-energy nexus sustainability in terms of heavy metal pollution were also performed. The results showed that total concentrations of 8 heavy metals (Cu, Pb, Zn, Cd, Cr, Hg, As, and Ni) in seafood varied with sampling sites and species by following the order of bivalve molluscs > crustaceans > fish. Estimated daily intake (EDI) analysis indicated that it was safe for humans to consume seafood in all sampling sites. Non-cancer risks posed by heavy metals were acceptable for 99.1% of adult and 97.7% of children. However, Cr and As in 72% of fish samples caused high cancer risks for children. The farmed fish posed relatively low risk in comparison with the wild fish suggested that it might be safer to consume farmed fish than wild fish. Source apportionment demonstrated that the fossil energy consumption (coal combustion and vehicle exhaust), seawater, and metallurgic dust might serve as the possible main sources of heavy metals in seafood. Based on the policy scenario analysis, the fossil-energy-controlling policy and clean coastal water action were beneficial to the seafood safety by reducing target heavy metals in seafood. These findings provided comprehensive information on seafood safety and the water-food-energy nexus sustainability in coastal regions at continental-scale in terms of heavy metal pollution.

Ecological and health risk assessments and water quality criteria of heavy metals in the Haihe River

Heavy metal pollution is an issue of wide concern owing to the toxic and bioaccumulative properties of many heavy metals and their tendencies to persist in the environment. The Haihe River is an important river in the Beijing-Tianjin-Hebei region, and heavy metal pollution of the basin has attracted considerable attention. This study determined the concentrations of 14 heavy metals (As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, and Zn) in water, sediments, and fish samples from the Haihe River basin. The results showed that the concentrations ranged from 0.08 μg L^-1 to 60.49 μg L^-1 in water, 0.11 mg kg^-1 to 229.20 mg kg^-1 in sediments, and 0.01 mg kg^-1 to 11.72 mg kg^-1 in fish. We derived the ambient water quality criteria (AWQC) value of each heavy metal with respect to human health, and then performed a comprehensive risk assessment according to the native parameters. The human health AWQC values for the assessed 14 heavy metals ranged from 0.16 μg L^-1 to 726.53 μg L^-1. The health risks posed by As, Cr, Hg, and Sb and the ecological risks associated with Ni, Cu, Cr, Zn, Cd, Co, Hg, and Sn were found to be issues of concern. The results of a sensitivity analysis revealed that the highest contributing parameter was i) the concentration in water (Cw) for Cd, Co, Mn, Sb, and Sn; ii) the intake rate of water (IR_w) for As, Ba, Cr, Hg, Ni, Pb, and Se; and iii) the concentration in fish (C_f) for Cu and Zn. The results of this research could contribute to the information required for water quality assessments and the development of water quality standards.

Heavy metals in processed seafood products from Turkey: risk assessment for the consumers

In this study, concentrations of 6 different elements (copper (Cu), tin (Sn), zinc (Zn), iron (Fe), cadmium (Cd) and lead (Pb)) in 9 different processed seafood (marinated and smoked mackerel, smoked mackerel, marinated octopus tentacles, marinated octopus salad, marinated squid salad, salted and dried mackerel, marinated and smoked anchovy, smoked salmon and smoked bonito) randomly taken from markets in Mugla province (West Anatolia, Turkey) were determined with the method of inductively coupled plasma mass spectroscopy (ICP-MS) after microwave wet digestion process. In addition, risk assessment for consumer health was conducted by the determination of estimated daily intake (EDI), target hazard quotient (THQ), total target hazard quotient (TTHQ) and carcinogenic risk (CR). According to the obtained results, the seafood product samples with the highest concentrations of each metal were marinated and smoked anchovy for Fe (65.85 ± 16.03 mg kg^-1), marinated and smoked anchovy for Zn (64.58 ± 25.16 mg kg^-1), marinated octopus salad for Cu (26.33 ± 17.76 mg kg^-1), smoked mackerel for Sn (0.42 ± 0.18 mg kg^-1), smoked mackerel for Pb (0.28 ± 0.18 mg kg^-1) and marinated squid salad for Cd (0.31 ± 0.12 mg kg^-1). According to risk assessment for consumer health, it was found that EDI results did not exceed the tolerable daily intake (TDI) values. As a conclusion, any risk for consumer health in terms of CR, THQ and TTHQ values was not detected in the examined samples.

Dietary risk of milk contaminated with lead and cadmium in areas near mining-metallurgical industries in the Central Andes of Peru

The mining-metallurgical industry in the central Andes of Peru is a source of lead (Pb) and cadmium (Cd) contamination in milk, and there are no studies on the impact of their ingestion. Using flame atomic absorption spectrometry, we quantified the concentration of these metals in raw milk produced in agroecological zones near these industries, and estimated the exposure and dietary risk in people aged 2-85 yr with minimum, average and maximum daily milk intake. In 2018, 40 raw milk samples were collected from 20 cows at two times of the year. The mean Pb and Cd concentrations were 577 ± 18.2 and 18.35 ± 5.4 μg/kg, all samples exceeded the maximum limits (ML). Children aged 2-5 and 6-15 yr, with average milk consumption, had Pb weekly intakes (WI) of 2019 and 2423 μg, exceeding the risk value; values for Cd 64 and 77 μg were below the risk values. In those older than 20 years the WI for both metals are below the risk values. The Dietary Risk Coefficient (DRC) to Pb in children younger than 8 years was >3 due to higher milk consumption in relation to body weight; for children aged 9-19 years it was 1.7 and 2.9, being <1 for those older than 20 yr. Cd RDCs were <1 at all ages, with the exception of 2-year-olds in the high milk consumption scenario (RDC > 1). There was notable evidence of Pb and Cd exposure risk from consumption of milk produced near mining-metallurgical activities, predominantly for children under 19-year-olds. In Peru there are no regulations for Pb and Cd in fresh milk and milk products, we recommended that ML for heavy metals in food be established.

Health risk assessment and heavy metal accumulation in fish species (Clarias gariepinus and Sarotherodon melanotheron) from industrially polluted Ogun and Eleyele Rivers, Nigeria

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Concentration of Arsenic and Cadmium in the fish tissues exceed the limits set by the European Union.

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THQ values indicated likely adverse effects during a person’s lifetime with continuous exposure to Arsenic and Cadmium.

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As, Cd, and Nickel may pose cancer risk to consumer of fish from the two rivers over longtime exposure.

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Cancer risk due to long time consumption of fish from the rivers can be a major concern.

Ogun and Eleyele Rivers are in the Western part of Nigeria with a potential risk of heavy metal pollution because of many industrial wastes channeling through their courses. Therefore, in this study, the concentration of heavy metals and the possible human health risk of consuming Clarias gariepinus and Sarotherodon melanotheron collected from industrially polluted Ogun and Eleyele Rivers in Nigeria were evaluated.

The concentration of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), manganese (Mn), nickel (Ni), and lead (Pb) in tissues (gill, muscle, and liver) of fish was measured using Atomic Absorption Spectroscopy (AAS) and compared with the maximum permissible. The Estimated Daily Intake (EDI), Targeted Hazard Quotient (THQ), and Carcinogenic Risk (CR) of the metals were estimated for the determination of human health risk. Probabilistic predictions of the health risk were performed with Oracle Crystal Ball software.

Results of this study showed that the dry weight concentrations of the metals in the gills, liver, and muscle of the two fish species from the two sites were well below the permissible limits set by the joint FAO/WHO Expert Committee. Only the EDI for arsenic in gills of C. gariepinus obtained from the Ogun River exceeded the set limit. The THQ was >1 for As in the gills and liver of C. gariepinus and S. melanotheron obtained from the Ogun river suggesting non-carcinogenic risk to the consumers. The carcinogenic risk above 10⁻⁶ obtained for As, Cd, and Ni in the tissues of the two fish species suggested cancer risk to the consumers of fish from the two rivers. Consequent to our observation, consumption of fish from the study site presents some public health concerns. Therefore, this study advises routine heavy metal monitoring of fish along these rivers to implement regulatory standards by the government environmental health management agencies.

Impact of copper and zinc mixture on haematological parameters of rainbow trout (Oncorhynchus mykiss): acute exposure and recovery

Significant changes in composition of rainbow trout Oncorhynchus mykiss blood cells types were induced after 4-days exposure with mixture of Cu²⁺ and Zn²⁺ at 0.25, 0.125 and 0.06 parts of LC₅₀ in comparison to control group. The highest concentration of metal mixture (0.25 of LC₅₀) significantly induced elevation of the number of monocytes and poly-segmented neutrophils. Treatment with 0.125 parts of LC₅₀ concentration increased the number of thrombocytes, monocytes and non-segmented neutrophils. The most diluted mixture resulted in significant induction of thrombocytes, monocytes, non- and poly segmented neutrophils. Analysis of leucocyte cell types in the O. mykiss blood samples after 4-days of exposure at all applied mixture parts showed signs of monocytosis and neutrophilia. Comparison of different types of leucocytes' percentages (leukogram) in fish after 4-days exposure to metal mixture and after 4, 8, and 12-days recovery periods showed that, values of neutrophils even after the 12-days recovery period at all tested parts of LC₅₀, and monocytes after exposure with the highest (0.25) used part of LC₅₀ were not restored to control group levels. Depuration and recovery processes in treated fish are concentration and recovery period dependent.

The concentration of the potentially toxic elements (PTEs) in the muscle of fishes collected from Caspian Sea: A health risk assessment study

In the present study, the concentration of (potentially toxic element) PTEs in the five fish species from the Caspian Sea (from five coastal areas) was measured and compared. The target hazard quotient (THQ) and total THQ (TTHQ) were calculated using Monte Carlo simulations to determine the non-carcinogenic risk in both children and adults consumers. The highest concentration of PTEs was associated with chromium (Cr) measured in Cyprinus carpio, sampled from Bandar Anzali (1.56 ± 0.14 μg/g dw), and the minimum PTEs level was nickel (Ni) in Vimba from Astara (0.02 ± 0.01 μg/g d w). The rank order for PTEs based on THQ was mercury (Hg) > cadmium (Cd) > lead (Pb)> Ni > tin (Sn) > Total Cr. For adults, the fishes rank order based on TTHQ was: Cyprinus carpio (3.268) > Chelon saliens (2.89) > Rutilus frisii kutum kanesky (2.28) > Oncorhynchus mykis (1.39) > Vimba (0.25); and for children was Cyprinus carpio (15.25) > Chelon saliens (13.47) > Rutilus frisii kutum kanesky (10.63) > Oncorhynchus mykis (6.48) > Vimba (1.16). Overall this study showed that the levels of PTEs in investigated fish species had a potential non-carcinogenic risk for both children and adults (TTHQ>1).

Bioaccumulation and human health risk assessment of trace metals in the freshwater mussel Cristaria plicata in Dongting Lake, China

Trace metal contamination in water and bioaccumulation in aquatic organisms are human health risks of increasing concern. However, the bioaccumulation of trace metals in the organs of the mussel Cristaria plicata in Dongting Lake, China and the human health risks of mussel consumption are largely unknown. We investigated the concentrations of 15 trace metals and metalloids in surface water, sediments, and C. plicata organs (foot, gill, mantle, and visceral mass) and quantified the bioaccumulation and human health risk of these trace metals in specimens collected from Dongting Lake. The concentrations of most metals in surface water exceeded previously published background values. In contrast, the concentrations of most metals in sediments showed a decreasing trend. Overall, the metal concentrations in the gill and visceral masses of C. plicata were higher than those in the foot and mantle, and higher bioaccumulation capacities were observed for essential metals than for nonessential metals. The mean concentrations of the trace elements Zn, Pb, Cd, As, Cu, and Cr in C. plicata foot samples were lower than the threshold values established by international and Chinese organizations. The estimated daily intake (EDI) values of the essential metal Mn in C. plicata foot was higher than the recommended tolerable daily intake (TDI) values for juveniles. Only Mn for juveniles and As for both juveniles and adults may pose noncarcinogenic health risks through foot consumption. The hazard index (HI) values for adults and juveniles were higher than 1, suggesting significant risks of noncarcinogenic effects to humans by exposure to multiple metals.

Study of Heavy Metals Pollution and Vitellogenin Levels in Brown Trout (Salmo trutta trutta) Wild Fish Populations

The objectives of this research were, first, to determine the concentrations of certain heavy metals in the edible tissue of wild brown trout (Salmo trutta trutta) from two different rivers located in the Abruzzi region (Italy), and then, to investigate the levels of variation in vitellogenin (VTG) associated with the presence of metalloestrogens. VTG is an effective indicator for endocrine disturbance, and an increase in the vitellogenin levels in male fish is widely employed as a biomarker of estrogenic contamination in the aquatic environment. The muscles of the trout were analyzed for As, Cd, Co, Cr, Ni, Pb, Al, and Zn using an inductively coupled plasma-mass spectrometer (ICP-MS), and Hg was measured using a direct mercury analyzer (DMA-80). The calculated values of the condition factor confirmed a healthy status for this species, indicating that the aquatic habit in both rivers is suitable for brown trout life. No significant difference in the concentrations of each metal were reported between the trout from the two rivers, and no significant difference for VTG levels were found between male and female fish. It is interesting to note the high concentrations of Al/Zn, while the Pb, Cd, and Hg concentrations in all of the samples were lower than those established by the European Commission.

Effects of heavy metals speciations in sediments on their bioaccumulation in wild fish in rivers in Liuzhou-A typical karst catchment in southwest China

Although fish are widely confirmed to be susceptible to heavy metals (HMs) contamination in sediments, this bioconversion haven't been detailed. This is especially the case in karst areas, where HMs are less stably retained in the sediments and are more bioavailable. Therefore, we surveyed representative karst rivers in Liuzhou, China, in order to study the relationship between the speciations of seven HMs in the sediments with their bioaccumulation in wild fish. The results showed that the HMs in sediments are all below their permissible exposure limit (PEL), but Cd and Zn are significantly higher than soil basline. Most HMs are in residual fraction, while their exchangeable fractions are present in extremely low proportions. The concentration of Zn, Cr and Cd in some fish are above their maximum recommended limit (MRL). The concentrations of most of the HMs in the fish are significantly correlated with the levels in the sediments and given the higher correlation coefficients for their carbonate-bound phase, this phase can be seen to play a critical role in HMs bioconversion. However, the presence of this phase in low proportions enables other phases, especially oxidizable form, to play a greater role in HMs bioaccumulation. Apart from Do, HMs in the fish samples are significantly correlated with multiple environmental factors, demonstrating environmental fluctuations can manipulate HMs bioconversion from sediments; however, their significance depend heavily on the proportion of particular species. HMs in reducible and oxidizable fraction are more important in regulating, rather than promoting, their bioconversion during environmental fluctuations. Fluctuations in EC, TDS and pH can increase the impacts of HMs in carbonate-bound fraction on their bioconversion. Given the higher background values of EC and TDS and lower pH values during the monsoon period, careful attention should be paid to the increased bioconversion of HMs in karst rivers during this season.

Water quality criteria for the protection of human health of 15 toxic metals and their human risk in surface water, China

In the absence of water quality criteria (WQC) support for the current water quality standard (WQS), systematic WQC studies have been carried out in recent years in China. WQC for the protection of human health is established to reflect long-term consumption safety of aquatic products and water. Human health WQC for 15 toxic metals and metalloids based on exposure factors of the Chinese population and 40 field bioaccumulation factors (BAFs) were developed and analyzed in this study. Moreover, age-specific (age 2-5, 6-8, 9-11, 12-14, 15-17, and adult) and region-specific (east, central and west China) WQC were analyzed to better understanding of the impact of specific parameter values on WQC. Human health WQC with consumption of fishes and water, consumption of fishes only, and consumption of water only were derived separately. WQC with consumption of water and organism for Hg, Cd, As, Sb, Se, Zn, Co, Cu, Ni, Pb, Mn, Sn, Ba, and Sr were 0.0264, 0.710, 0.827, 3.48, 22.1, 25.7, 32.2, 32.9, 35.5, 41.8, 72.1, 97.1, 206 and 2.20 × 10³ μg/L, and were 13.3 and 6.67 × 10³ μg/L for Cr(VI) and Cr(III) with consumption of water only. Comparison of age-specific and region-specific WQC showed that the protection for a specific population should be considered in the development of WQC and WQS, as well as cancer effect for carcinogenic metals. Health risk analysis showed that Cd, Cu, Zn, As, Hg and Mn average concentrations in 7, 5, 9, 22, 11 and 5 provinces exceeded the WQC values with consumption of water and aquatic product, showing potential long-term health risk (HQ ≥ 1) to the local population. Therefore, health risks posed by these metals from dietary intake related to surface water should be paying more attention.

Lemna minor, a hyperaccumulator shows elevated levels of Cd accumulation and genomic template stability in binary application of Cd and Ni: a physiological and genetic approach

In this study, to determine whether having potential to be used as hyperaccumulator for Cd and Ni, numerous experiments were designed for conducting assessments for physiological and genotoxic changes along with defining possible alterations on mineral nutrient status of Lemna minor L. by applying Cd-Ni binary treatments (0, 100, 200 and 400 µM). Our study revealed that there were increases in the concentrations of B, Cr, Fe, K, Mg, and Mn whereas decreases were noticed in the concentrations of Na and Zn and the levels of Ca were inversely proportional to Cd-Ni applications showing tendency to increase at the low concentration and to decrease at the high concentration. Randomly Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeat (ISSR) analyses revealed that rather than band losses and new band formations, mostly intensity changes in the band profiles, and low polymorphism and high genomic template stability (GTS) were observed. Although, to date, L. minor was defined as an efficient hyperaccumulator/potential accumulator or competent phytoremedial agent by researchers. Our research revealed that L. minor showing high accumulation capability for Cd and having low polymorphism rate and high genomic template stability is a versatile hyperaccumulator, especially for Cd; therefore, highly recommended by us for decontamination of water polluted with Cd. NOVELTY STATEMENTMany studies have been focused on the effects of individual metal ions. However, heavy metal contaminants usually exist as their mixtures in natural aquatic environments. Especially, Cd and Ni coexist in industrial wastes.In this study, the accumulation properties of Lemna minor for both Cd and Ni were investigated and the effects of Cd and Ni on the bioaccumulation of B, Ca, Cu, Fe, Mg, K, Mn, Na, Pb and Zn in L. minor were also determined. This study furthermore aimed to assess the genotoxic effects of Cd and Ni found in being extended concentrations on DNA using the Randomly Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) method.

Brominated flame retardants and heavy metals in common aquatic products from the pearl river delta, south china: Bioaccessibility assessment and human health implications

Aquatic products are an important source of environmental pollutants to humans. This study was conducted to assess the bioaccessibility of selected brominated flame retardants and heavy metals in common aquatic products from the Pearl River Delta, South China, as well as associated human health risks. Based on a questionnaire survey, ten of the most consumed aquatic products were collected from local markets. The bioaccessibility of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDDs), and heavy metals was assessed using an in vitro gastrointestinal model. Bioaccessibility of heavy metals (33.0-84.0%) and HBCDDs (38.5-68.4%) was significantly higher than that of PBDEs (13.4-65.4%). Total non-carcinogenic and carcinogenic risks from heavy metal consumption were much higher than the threshold values due to excessive abundances of arsenic in shellfish (HQ = 2.45, CR = 1.1 ×10^-3). Furthermore, middle-aged populations and females were subjected to greater health risks due to different intakes of aquatic products among age and gender groups. Significant difference in bioaccessibility among analytes indicated that bioaccessibility of pollutants is non-negligible in health risk assessment. This is the first study systematically investigating health risks of aquatic products consumption and concludes that shellfish is a great cause for concern for the PRD residents.

Spatial distribution, risk assessment, and source identification of heavy metals in water from the Xiangxi River, Three Gorges Reservoir Region, China

Heavy metals (HMs) contamination in rivers has attracted wide concern due to its persistence and potential risks to the natural environment and human health. In this study, eight HMs (As, Hg, Cu, Pb, Ca, Zn, Mn, and Ni) were measured by inductively coupled plasma mass spectrometry in 24 water samples to investigate HMs contamination levels in the Xiangxi River of the Yangtze River basin. A geographic information systems kriging interpolation method was used to reveal the spatial distribution of HMs contamination. The results indicate that most HMs occurred at acceptable levels below the Surface Water Quality Standard (GB 3838-2002), with the highest concentration (23.23 mg kg^-1) of Mn being observed at sampling site X20. The values of the potential ecological risk index (RI) suggest that high potential ecological risks were present at sampling sites X1, X3, X4, X14, X16, X17, and X24, which reached moderate risk level. The highest value of RI (279.56) was observed at site X17. HM spatial distributions show that upstream pollution is more severe than downstream. The hazard index was below 1 for all HMs except for Mn, indicating that HMs in Xiangxi River pose a low risk to human health. HM source identification was accomplished using principal component analysis and Pearson's correlation. Cu, Cd, Ni, and Hg originate primarily from agriculture, while Pb, Zn, and As originate primarily from transportation and mining. This research provides a reference on the risks posed by HMs in Xiangxi River and will support efforts to protect and improve water quality in Xiangxi River.

Heavy metals levels in raw cow milk and health risk assessment across the globe: A systematic review

This systematic review presents the potential toxicity of heavy metals such as lead (Pb), mercury (Hg), cadmium (Cd), iron (Fe), nickel (Ni), aluminum (Al), and copper (Cu) in raw cow milk, focusing on their contamination sources and on the assessment of the related human health risk. Multiple keywords such as "raw cow milk, heavy metals, and human health" were used to search in related databases. A total of 60 original articles published since 2010 reporting the levels of these metals in raw cow's milk across the world were reviewed. Data showed that the highest levels of Ni (833 mg/L), Pb (60 mg/L), Cu (36 mg/L) were noticed in raw cow milk collected in area consists of granites and granite gneisses in India, while the highest level of Cd (12 mg/L) was reported in barite mining area in India. Fe values in raw cow milk samples were above the WHO maximum limit (0.37 mg/L) with highest values (37.02 mg/L) recorded in India. The highest Al level was (22.50 mg/L) reported for raw cow's milk collected close to food producing plants region in Turkey. The Target Hazard Quotients (THQ) values of Hg were below 1 suggesting that milk consumers are not at a non-carcinogenic risk except in Faisalabad province (Pakistan) where THQ values = 7.7. For the other heavy metals, the THQ values were >1 for Pb (10 regions out of 70), for Cd (6 regions out of 59), for Ni (3 out of 29), and for Cu (3 out of 54). Exposure to heavy metals is positively associated with diseases developments. Moreover, data actualization and continuous monitoring are necessary and recommended to evaluate heavy metals effects in future studies.

Chronic exposure to environmental cadmium affects growth and survival, cellular stress, and glucose metabolism in juvenile channel catfish (Ictalurus punctatus)

Anthropogenic activities have led to the enrichment of cadmium in freshwater systems where it is a contaminant of concern for fisheries and aquaculture as it has no known biological function and is toxic at trace concentrations. Yet, knowledge gaps remain regarding effects of chronic exposure to environmentally relevant concentrations on freshwater fish. Thus, the objectives of the current study were to assess chronic impacts of cadmium on channel catfish (Ictalurus punctatus) including how tissue-specific bioaccumulation patterns relate to functions of those tissues over time. We focused on liver and kidneys, and expression of genes related to cellular stress, glucose metabolism, and steroidogenesis. Catfish were exposed to concentrations of 0.5 (control), 2 (low), and 6 (high) μg L^-1 Cd from fertilization to six months. Cadmium exposure negatively impacted channel catfish growth and was linked to bioaccumulation of tissue Cd, which followed a dose-related response, where concentrations in trunk kidney > liver = head kidney >> muscle. Differences in tissue Ca, Cu, Fe, and Zn concentrations were also observed between treatments. Following 3 months of exposure, expression of metallothionein (MT) and heat shock proteins (HSP) 70 & 90 increased relative to controls; however, no differences were detected at 6 months, suggesting compensation. Conversely, there were no differences in expression patterns for key genes in steroidogenesis, steroidogenic factor 1 (SF1), steroidogenic acute regulatory protein (StAR), and cytochrome P450scc (P450), which supports the observation that Cd did not affect the secondary stress response, evaluated via plasma cortisol and glucose concentrations following a low water stress event. As a function of length and weight, the high Cd treatment yielded fish that were significantly smaller than controls. In addition to the cellular responses in MT and HSPs noted, reduced growth in the high Cd treatment was likely due, at least in part, to elevated energetic demands. This is supported by observations of the upregulation of genes necessary for glucose metabolism. Hexokinase (HK), glucose-6-phosphatase (G6P), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were significantly elevated in the high treatment relative to controls at 3 months of exposure. Over the study period, exposure also reduced survival of channel catfish from 3 to 6 months. Reduced fitness, as a consequence of cadmium exposure, could be visible at the population level through altered life histories and growth patterns.

Multiple metal(loid)s bioaccessibility from cooked seafood and health risk assessment

Seafood has been generally considered to be the main diet exposure source of metal(loid)s. We evaluated health risk of mercury (Hg), arsenic (As), cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni), copper (Cu), and zinc (Zn) through consumption of cooked seafood based on bioaccessibility, which was obtained by physiologically based extraction test method. Results showed that cooking practices could decrease metal(loid)s concentration from seafood (by 6.0-45.7%). Metal(loid)s release from seafood in this study followed the descending order of Hg > Zn > Ni > Cd > Pb > As > Cu > Cr. On average, cooking lowered the bioaccessibility of As, Hg, Cd, Pb, Ni, Cr, Cu, and Zn by 15.2, 26.1, 30.9, 30.7, 25.7, 31.2, 17.6, and 22.4%, respectively. Health risk calculation results showed that Cr, Ni, and Zn in seafood species in this study were within the human health benefits range. Hg, Cd, Pb, and Cu exposure from cooked seafood was within the safe dose. However, we found that there is a potential of having cancer (especially bladder and lung cancer) for people exposure to iAs from seafood based on bioaccessible contents the first time.

Heavy metal accumulation and health risk assessment of crayfish collected from cultivated and uncultivated ponds in the Middle Reach of Yangtze River

Crayfish, an aquatic food consumed globally, has been reported to accumulate heavy metal. To assess the health risk to the crayfish-consuming population, we investigated heavy metals (Cu, Pb, Zn, Fe, Mn, Cd, Cr, Ba, and As) in crayfish tissues (exoskeleton, abdominal muscle, gills, and hepatopancreas) and sediments from uncultivated and cultivated ponds in the middle reach of the Yangtze River. The metals, except for As, were measured by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and As was measured by atomic fluorescence spectrometry. The distribution of heavy metals differed significantly among tissues and concentrations were generally highest in the hepatopancreas. The average concentrations of heavy metals were higher in crayfish from uncultivated ponds than in crayfish from cultivated ponds. Heavy metal concentrations in crayfish correlated positively with sediment concentrations in uncultivated ponds, indicating that heavy metals can accumulate in crayfish. However, this positive correlation between sediment concentration and crayfish concentration was not observed in cultivated ponds. Source identification, using correlation analysis, indicated that heavy metals in the sediments derive from transportation and agriculture. Based on correlations between heavy metal concentration and body weight, and data on metal distribution in organs, heavy metals accumulate in the hepatopancreas of crayfish in uncultivated ponds, but not in cultivated ponds. Heavy metal concentrations were somewhat higher in female crayfish than in male crayfish and the difference was significant for Fe and Pb. The target hazard quotient (THQ) was used to evaluate non-carcinogenic health risk, with THQ < 1 considered to be safe. All THQ values were < 1, except for Cu in the hepatopancreas (THQ = 1.38) of cultured crayfish and Pb (THQ = 1.01) and Cd (THQ = 1.69) in the hepatopancreas of wild crayfish. Thus, the health risk posed by consuming crayfish, particularly cultured crayfish is low. Our research was designed to protect food safety and the results indicate that the health risk posed by heavy metals in crayfish is low.

Assessment of Heavy Metals Pollution in Noyyal and Chinnar Rivers, Western Ghats of Tamil Nadu, India with Reference to Crabs (Gecarcinucidae)-A Baseline Study

In the present study, heavy metals (Cd, Cu, Pb, and Zn) level in the water, sediment, and crabs were analyzed from Noyyal and Chinnar Rivers of the Western Ghats in Tamil Nadu, India. Based on our results, Noyyal River is considered as polluted environment due to the discharge of contaminants by various anthropogenic activities, whereas, Chinnar River maintained as unpolluted one due to its tributary nature of Noyyal River located in Western Ghats hills. The results showed that the heavy metals in water and sediments were higher in Noyyal River. Also, the level of bioaccumulation of studied metals and biochemical constituents were higher in the crab Spiralothelphusa hydrodroma sampled from Noyyal River than Barytelphusa cunicularis collected from Chinnar River. The present findings revealed that the crab sampled from Noyyal River had elevated heavy metals which lead to a significant increase in biochemical constituents to overcome the stress.

Accumulation of trace elements in selected fish and shellfish species from the largest natural carp fish breeding basin in Asia: a probabilistic human health risk implication

Intake of fish contaminated with non-essential hazardous trace elements poses a significant risk to human health. In this study, trace elements (As, Pb, Cd, Cu, Ni, and Zn) were measured in edible tissues of seven commercially important fish and shellfish species (Otolithoides pama, Pseudapocryptes elongatus, Macrobrachium rosenbergii, Liza parse, Notropis atherinoides, Apocryptes bato, and Rhinomugil corsula) from a natural carp breeding basin, Halda river, Bangladesh. The elements were detected by inductively coupled plasma-mass spectrometry (ICP-MS), and the hierarchy of elemental levels (mg/kg) was Zn (61.56) > Pb (30.45) > Ni (26.81) > Cu (21.09) > As (1.49) > Cd (0.24). Among the analyzed elements, Pb, Ni, and Zn for some fish species exceeded the permissible dietary limit, suggested by national and international agencies. In addition, results of bioaccumulation factor (BAF) indicated that most of the studied species were bioaccumulative in nature (BAFs > 1000), and the mean BAF of elements were found in the following order: Zn (3156.74) > Ni (1629.30) > Cu (1566.77) > As (997.14) > Pb (259.98) > Cd (216.52). However, the species, L. parse being omnivorous represented the highest BAF (stored higher concentrations of metals) as compared to other species. The growth pattern of all the species was negatively allometric, and the health condition of the species varied from poor to good state revealed from the estimated Fulton's condition factor (FC). For the evaluation of health hazards, estimated weekly (EWI), target hazard quotient (THQ), and carcinogenic risk (CR) were calculated for both adults and children. Results of EWI showed As, Pb, and Ni surpassed provisional tolerable weekly intake (PTWI)-recommended guidelines. The non-carcinogenic health effect (TTHQ) might not appear for both types of consumers (as TTHQ < 1), and CRs of all consumers were also in acceptable range (10^-6 to 10^-4). However, the probabilistic distribution through Monte Carlo simulation revealed that children were more vulnerable to non-carcinogenic (67.3%) and carcinogenic risk effect (47.3%) for Pb. Meanwhile, adults obtained the probability of 0.7% and 36% for THQ and CR effect, respectively, interpreting less vulnerable.

Heavy metal contamination in a highly consumed Brazilian fish: immunohistochemical and histopathological assessments

Due to industrial, rural, and domestic waste disposal, heavy metals such as cadmium (Cd), chromium (Cr), lead (Pb), zinc (Zn), copper (Cu), and iron (Fe) continually infiltrate aquatic environments. These pollutants do not degrade naturally and, thus, have a high capacity for bioaccumulation in tissues and organs. The present study uses histological and immunohistochemical analyses to evaluate the contamination status of Salminus franciscanus, a large and economically important fish. Levels of Cd, Cr, Pb, Zn, Cu, and Fe were evaluated by atomic absorption spectrometry in the liver and muscle of fish sampled from two tributaries of the upper São Francisco River Basin, Brazil: the Abaeté and Paraopeba Rivers. In addition, histopathological alterations and expressions of three environmental biomarkers were assessed: metallothionein (MT), heat shock protein-70 (HSP70), and cytochrome P450-1A (CYP1A). The results show that fish from the Paraopeba River are unsuitable for human consumption, with several metals being detected above the safe limits established by the World Health Organization. Histopathological alterations in the liver and spleen were also significantly more frequent in fish from the Paraopeba River than in those from the Abaeté River (P < 0.05). Significant differences in the expressions of environmental biomarkers were observed between the rivers. Fish from the Abaeté River presented significantly higher values of the gonadosomatic index (GSI) and lower levels of metal contamination in the liver and muscle.

Application of stable isotopes to the bioaccumulation and trophic transfer of arsenic in aquatic organisms around a closed realgar mine

The bioaccumulation and trophic transfer of As along food webs in freshwater ecosystems remain largely unknown. In this study, multiple environmental and biological samples were collected from a closed realgar mining area in South China. The As concentrations in the surface water, sediments and soils in the mining area were 0.62-3293 μg/L, 9.53-4543 mg/kg and 7.32-5008 mg/kg, respectively, and gradually decreased with distance from the central mining sites, indicating that historic As mining activities had an eminent impact on As contamination around the mine. The As concentrations in aquatic organisms ranged from 0.60 mg/kg to 45.75 mg/kg and varied markedly among sites and species, reflecting the influence of various physiologic and environmental factors. Arsenic species identified by liquid chromatography inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) were mainly organic, comprising 8% to 66% of the total As. Both the proportions and concentrations of inorganic As were positively correlated with total As. This correlation could be attributed to the higher assimilation and accumulation of inorganic As or the lower biotransformation ability of inorganic As with the increasing total As in the studied organisms. Values of δ¹³C and δ¹⁵N in aquatic organisms ranged from -30.59‰ to -15.07‰ and from 4.31‰ to 12.98‰, respectively, indicating multiple trophic levels and variety in the diet sources of these organisms. The δ¹⁵N increased distinctly in the order of planktivorous<herbivorous<omnivorous<carnivorous, which is generally consistent with the increasing trophic levels in the freshwater ecosystem. No significant correlation was observed between As concentrations and δ¹⁵N in the freshwater organisms, suggesting no biomagnification of As in the food web.

Metal concentrations in fish from nine lakes of Anhui Province and the health risk assessment

In the present study, to comprehensively investigate the metal contamination in the fish of Anhui Province, four fish species, Ctenopharyngodon idella, Cyprinus carpio, Hypophthalmichthys molitrix, and Hypophthalmichthys nobilis, were collected from nine lakes, and the levels of Zn, Pb, Cr, Cu, Ni, As, Hg, and Cd in the fish muscle were determined. The results showed that the highest concentrations of Zn (7.791 mg/kg), Pb (0.522 mg/kg), Cr (0.030 mg/kg), and Cu (0.767 mg/kg) were found in Tiangang Lake, Xifei Lake, Tiangang Lake and Baidang Lake, respectively. However, metals Ni, As, Hg, and Cd were not detected in all fish samples. In the fish species, the metal bioaccumulation ability was decreased with the following order: C. idellus > H. molitrix > H. nobilis > C. carpio. Furthermore, the target hazard quotient (THQ) was used to assess the health risk via fish consumption. The results indicated for co-exposure; C. idellus would pose a health risk to children at high exposure level (95th) as THQ value was higher than 1. It should be pointed out that Pb contributes most to the total THQs (the ratio was 88%); thus, the contamination of Pb should be paid more attention. This field investigation combined with health risk assessment would provide useful information on the heavy metal pollution in Anhui Province.

Heavy metals in aquatic products and the health risk assessment to population in China

In this paper, a total of 62,712 aquatic product samples were collected from 32 provinces of China during 2015-2017. By analyzing the spatial distributions and non-parametric tests of five heavy metals (lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr), and arsenic (As)) in four aquatic product (fish (n = 44,353), shrimp (n = 8453), crab (n = 5367), and shellfish (n = 4539)), it was found that the concentrations of the five heavy metals in the same aquatic product are significantly different in different regions. Furthermore, we calculated daily estimated intake (EDI) of each of the five heavy metals and assessed non-cancer risk and cancer risk using target hazard quotient (THQ) and target cancer risk (TR), respectively. The results showed that for mean exposure levels, the THQ values in four aquatic products were all below one, meaning that there was no non-carcinogenic risk. For high exposure levels, the hazard index (HI) value exceeded one in fish in North China, which means the potential non-carcinogenic risk should not be ignored. As for cadmium, most of the TR values in crab and shellfish exceed 1 × 10^-4 in North China, East China, and South China. For chromium, except for Northeast China, the TR values in fish in other regions exceed 1 × 10^-4; it indicated that the cancer risk caused by cadmium or chromium should not be ignored.

Investigation of toxic elements in Carassius gibelio and Sinanodonta woodiana and its health risk to humans

Increasing toxic metal content in aquatic products has become a universal burden due to the risks to aquatic organisms and human health associated with the consumption of these products. In this study, toxic metal distribution and accumulation in the organs of fish and bivalve species of economic and culinary importance from the lower reaches of the Yangtze River are examined, and the corresponding health risks are also investigated. In general, the viscera and gill show higher concentration of metals than other tissues. The order of the accumulation sequence of metals in muscle tissue of fish and bivalve is Zn > Cu > Mn > Cr > As > Hg > Pb > Cd and Mn > Zn > Cu > As > Cr > Pb > Cd > Hg respectively. Maximum accumulation of Mn (507.50 μg g^-1) and Pb (0.51 μg g^-1) in the gill tissues indicates the major uptake of these metals from the water column. According to the Hazard Index (HI) calculations (based on USEPA), the analyzed metals will not cause any harmful health effects to individuals for both normal and habitual fish consumers, except for Hg and As in habitual consumers, if these species are consumed at a larger amount. Compared to the Chinese Food Health Criterion and other international standards (WHO/FAO), metal concentrations in the edible muscle tissues of the studied species are lesser than the acceptable levels and found to be fit for human consumption.

Assessment of long-term effects from cage culture practices on heavy metal accumulation in sediment and fish

Fish cage farming has been generally banned in some regions since there is growing concern about adverse environmental issue caused by cage culture practices. This paper presents the long-term effects of past cage culture activities on heavy metal accumulation in sediment and fish in one historical cage culture lake (Changshou reservoir, Chongqing, China). Although cages were removed for over one decade in this studied lake, the average concentrations of heavy metals in sediments were still above 2 times higher than their background values, posing a moderate ecological risk. Higher levels of heavy metals appeared in demersal fish who is more susceptible to heavy metals exposure in sediment. Fish consumption would not lead to a significant health risk of most heavy metals. Hg levels in catfish posed a health risk to vulnerable group (children) and specific group (fishermen), whereas the presence of Se decreased Hg toxicity to a safety level. Therefore, it can be speculated that the cage culture activities could influence the heavy metal accumulation in sediment in the long term, however, consumption of current farmed fish in one lake used to carry out cage-culture is safe for local residents.

Arsenic, chromium, and other elements of concern in fish from remote boreal lakes and rivers: Drivers of variation and implications for subsistence consumption

Eating fish provides numerous health benefits, but it is also a dominant pathway for human exposure to contaminants. Many studies have examined mercury (Hg) accumulation in fish, but fewer have considered other elements, such as arsenic (As) and chromium (Cr). Recently, freshwater fish from several pristine boreal systems across northern Ontario, Canada, have been reported with elevated concentrations of As and Cr for reasons that are not well understood. Our goal was to investigate the ecological and environmental influences over concentrations of As, Cr, and other elements in these fish to better understand what affects metal uptake and the risk to consumers. We measured 10 elements (including As, Cr, Hg) as well as carbon (δ¹³C), nitrogen (δ¹⁵N), and sulfur (δ³⁴S) stable isotopes in 388 fish from 25 lake and river sites across this remote region. These data were used to determine the effect of: 1) trophic ecology; and 2) watershed geology on piscine elemental content. Overall, most element concentrations were low, often below provincial advisory benchmarks (ABs). However, traces of Hg, As, Cr, and selenium (Se) were detected in most fish. Based on their exceedance of their respective ABs, the most restrictive elements on fish consumption in these boreal systems were Hg > As > Cr. Arsenic and Se, but not Cr concentrations were related to fish size and trophic ecology (inferred from δ¹³C and δ¹⁵N), suggesting bioaccumulation of the former elements. Fish with enriched δ³⁴S values, suggestive of anadromous behaviour, had marginally lower Hg but higher Se concentrations. Modeling results suggested a strong effect of site-specific factors, though we found weak trends between piscine elemental content and geological features (e.g., mafic intrusions), potentially due to the broad spatial scale of this study. Results from this study address gaps in our understanding of As and Cr bioaccumulation and will help to inform fish consumption guidelines.

Health Risk Assessment of Metals (Cu, Pb, Zn, Cr, Cd, As, Hg, Se) in Angling Fish with Different Lengths Collected from Liuzhou, China

Wild fish caught by anglers (WFAs) were confirmed to be usually contaminated with metals, and the contamination status is radically affected by the growth and length of the fish. To determine the contamination levels of metals and health risks in WFAs with different length ranges of fish, this study ascertained the concentration of eight metals, including Cu, Pb, Zn, Cr, Cd, As, Hg and Se, in 171 wild fishes collected from the watershed of Liujiang River. The assessment of metal pollution and health risks from the consumption of these fishes with seven length ranges were accomplished. The obtained results implied a relatively high concentration of Zn, Cr, and Cd up to 109.294 mg/kg, 4.226 mg/kg, and 0.196 mg/kg (wet weight), respectively, which exceed the corresponding Maximum Residue Limit (MRL). The negative correlation between Cu, Zn, Cr, and Cd was observed to be significant with fish length, signifying a possible occurrence of biological dilution on these metals. The WFAs were mostly contaminated with Cr and Cd irrespective of the length ranges of fish, which were denoted by the average pollution index (Pi) of Cr and Cd and were commonly found to be beyond 0.2. Based on the results of health risk assessment analysis, most of the target hazard quotient (THQ) values of Cr were below 1, implying that the consumption of wild fish for adults has insignificant health risk. For children, the total target hazard quotient (TTHQ) values of beyond 1 were found in fishes with the length range of <25 cm, particularly a TTHQ value 1.627 in the range of 10–15 cm, indicating that children are being prone to serious health risks owing to the consumption of WFAs. The weekly recommended consumption of WFAs with the length range of 10–15 cm for adults and children was 0.298 kg/week and 0.149 kg/week, respectively. These are substantially lower than the current rate of fish consumption (0.42 kg/week), and therefore, the wild fish with the length range of 10–15 cm should be avoided for consumption.

Levels and human health risk assessments of heavy metals in fish tissue obtained from the agricultural heritage rice-fish-farming system in China

China began to practice Rice-fish-farming system (RFFS) 1700 years ago. Nowadays, the widely spread of metals could be potential threats to the quality of RFFS fish. In this study, Pb, Cd, Hg, As and Cr as the top five most toxic heavy metals were determined in six species of RFFS fish meat obtained from 7 provinces in south China. The mean concentrations of metals in RFFS fish followed Pb (36.89 μg/kg) > As (33.36 μg/kg) > Cr (18.54 μg/kg) > Hg (16.35 μg/kg) > Cd (2.01 μg/kg), which were mostly lower in comparison with fish from traditional aquaculture systems raised by fish feeds. Grass carp obtained lower metal concentrations compared with other fishes, possibly indicating the importance of feeding habits of RFFS fish. Concentrations of metals in fish and RFFS sediment were in good correlations, and benthic fish obtained high pollution levels, suggesting the accumulation of metals through the direct contact with sediment. Risks assessments coupled with Monte Carlo simulation indicated the potential non-carcinogenic risks and carcinogenic risks decreased following As > Hg > Cr ≈ Pb > Cd, and As > Cr > Cd > Pb, respectively. These results suggested RFFS is still a successful mode of green agriculture.

Simultaneous reduction of nitrate and Cr(VI) by Pseudomonas aeruginosa strain G12 in wastewater

The interference of toxic heavy metals in the process of microbial aerobic denitrification is a hot issue in industry wastewater treatment in recent years. In this study, a multifunctional aerobic denitrifying bacterium - Pseudomonas aeruginosa G12 isolated from sewage sludge was used to explore the simultaneous removal ability to NO₃^--N and Cr(VI) in wastewater by a series of batch experiments. The results showed that G12 could effectively remove NO₃^--N (500 mg L^-1) and Cr(VI) (10 mg L^-1) by 98% and 93%, respectively. Meanwhile, the study found that the strain G12 had the potential to adapt to the complex external environment, including different carbon resources, nitrogen sources, and the coexisting heavy metals (Mn²⁺ and Cu²⁺). The strain G12 also had the considerable tolerance to initial NO₃^--N (100-700 mg L^-1) and Cr(VI) (1-20 mg L^-1) concentrations. The instrument analysis methods-Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), from the molecular level, further confirmed that the strain G12 could remove NO₃^--N by aerobic denitrification, and the reduced functional groups (amino group, amide group, hydroxyl group and carboxyl group) on the surface of bacteria could transform Cr(VI) to Cr(III) (mainly CrCl₃). This study will offer a promising new microbial resource for nitrogen and Cr(VI) removal in industry wastewater treatment.

Analysis and health risk assessment of toxic and essential elements of the wild fish caught by anglers in Liuzhou as a large industrial city of China

Most wild fish caught by anglers (WFAs) are likely to be contaminated by toxic metals, particularly the fish collected from the waterways in urban and suburban areas; hence, the determination of health risk caused by WFAs consumption associated with toxic metals is vital. Therefore, Liuzhou, one of the largest industrial cities in China, was considered as an example city in this study. Eight toxic elements were analysed to uncover the pollution status and consumption safety of WFAs. Moreover, the suitable angling waterways were identified in the urban and suburban areas. The obtained results suggested relatively high concentrations of Zn, Cr and Cd, which were also found to be beyond corresponding Maximum Residue Limit. Among all analysed elements, only the mean pollution indices of Cr and Cd were observed to be beyond 0.2, revealing that the observed WFAs were generally contaminated by these metals. However, the potential health risk of WFAs can be predominately attributed to Cr, confirmed by the significantly higher Target hazard quotients (THQ). For adults, all the THQ values were below 1, indicating no significant health risk being associated with WFAs consumption in the case of adults. On the contrary, all the THQ values for Children were beyond 1, suggesting children being susceptible to great health risks due to WFAs consumption. Furthermore, the weekly recommended consumption of WFAs in urban area is remarkably lower than the current rate of fish consumption observed among urban residents; therefore, the waterways in urban areas can be evaded for fish angling.

Health risk assessment and levels of toxic metals in fishes (Oreochromis noliticus and Clarias anguillaris) from Ankobrah and Pra basins: Impact of illegal mining activities on food safety

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Toxic metals analysis revealed that there were appreciable concentrations of Cadmium, Arsenic, Lead and Mercury in the fish samples (Oreochromis niloticus and Clarias anguillaris) and water samples from both rivers.

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All the examined fish species had toxic mineral concentrations within the E.U set limits except for Mercury (Hg) which exceeded the set limits of WHO.

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Human health risk assessment from lifetime metal exposure through fish consumption from the two rivers for both children and adults showed no significant non-carcinogenic adverse health risk to humans.

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Target Hazard Quotient (THQ) values calculated for both children and adult exposure to Cadmium and Mercury were >1 which implied a likely cause of adverse effects during such a person’s lifetime.

Arsenic (As), mercury (Hg), Cadmium (Cd) and lead (Pb) are toxic heavy metals that naturally occur in the ecosystem. Their levels are on the rise due to anthropogenic activities posing threat to aquatic wildlife and humans. In Ghana, pollution of some water bodies has led to unsafe consumption of riverine fishes as well as a shortage of treated potable water principally because the cost of treating polluted water has become expensive across the country. This study aimed to assess the As, Hg, Pb and Cd concentrations in water and fishes from rivers Pra and Ankobrah where activities of artisanal gold mining were carried out resulting in gross pollution of the water bodies.

An experimental study was performed to ascertain the levels of As, Hg, Pb and Cd in fish species of Nile tilapia (Oreochromis noliticus) and mudfish (Clarias anguillaris) and aquatic media (water) from the Pra and River Ankobrah basins using the Atomic Absorption Spectrophotometer (AAS) (Varian AA240FS).

Both river water samples recorded ranges of 0- 0.0040, 0.0060- 0.0387, 0 - 0.0020, 0.006-0.0093 mg/l for Cadmium, Lead, Arsenic and Mercury respectively. For Cadmium and Arsenic, their levels were comparable (p > 0.05). However, detected values for Lead and Mercury were no comparable (p < 0.05). Toxic metals concentrations in the rivers decreased in the order of Hg > Pb > Cd > As. For the fish samples, values ranged 0-0.08, 0.04-0.42, 0-0.04, and 0.40- 0.60 mg/kg for Cadmium, Lead, Arsenic and Mercury respectively. Generally, appreciably high values were obtained for Mercury. Toxic metals concentrations in the rivers decreased in the order of Hg > Pb > Cd > As.

Human health risk assessment from heavy metal exposure through fish consumption from the Rivers for both children and adults showed no significant non-carcinogenic adverse health risk to humans since all calculated values for Hazard Quotient (HQ) were <1. Nonetheless, Target Hazard Quotient (THQ) values calculated for children and adult exposure to Cadmium and Mercury were>1 which implied a likely cause of adverse effects during a person's lifetime.

Ecological risk assessment of heavy metal concentrations in sediment and fish of a shallow lake: a case study of Baiyangdian Lake, North China

The pollution levels of lakes vary in quantity and type of contaminants accumulated in their sediment and water. The second Chinese capital city will be built around Baiyangdian Lake in the near future, and thus, it is important to monitor pollution status of Baiyangdian Lake. This study mainly focused on the accumulated heavy metal concentrations in the surface sediment and in variety of fish bodies. Sediment pollution status and ecological risk were evaluated through geo-accumulation (I-geo), contamination factor (CF), pollution load index (PLI), potential ecological risk ([Formula: see text]), and mean probable effect concentration quotient (mPEC-Q). In addition, human health risks via fish consumption were also evaluated. Based on the results, the average sediment trace As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn concentrations were 9.53, 0.35, 56.37, 32.33, 617.05, 30.18, 19.17, and 84.24 mg/kg dry wt, respectively. Both I-geo and [Formula: see text] inferred low pollution levels and low ecological risks from all assessed trace metals except Cd. Cd posed moderate to high ecological risks. Based on sediment quality guidelines (SQGs), average Ni and Cr concentrations exceeded the threshold effect concentrations (TEC), but their [Formula: see text] are low as their average concentrations is below Hebei province pre-contaminations (30.8 mg/kg for Ni and 68.3 mg/kg for Cr). There is no cumulative toxicity from all the metals through mPEC-Q. Omnivorous fish accumulated statistically insignificantly higher amounts of metals than carnivorous fish, except for Hg. The intake of 12.22 g/person/day fish muscle for the entire life is safe from noncarcinogenic human health problems.

Bioaccumulation and human health risk of shellfish contamination to heavy metals and As in most rapid urbanized Shenzhen, China

Despite the benefits of shellfish consumption, the bioaccumulation of heavy metals in shellfish can endanger consumer's health. The consumption of seafood in Shenzhen (a fast-developing metropolis in China) has received more and more attention. Arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), and lead (Pb) in ten common shellfish species and associated health risks were analyzed for Shenzhen's consumers by evaluating estimated weekly intake (EWI), non-carcinogenic and carcinogenic health risks to children, adolescents, and adults. In this study, 50 shellfish samples were collected in total. The results showed that the levels of inorganic arsenic (iAs) in Babylonia areolata exceeded the maximum permissible limit set by the food safety guidelines (0.5 mg/kg), while other elements were below the limit in the present guidelines (Ministry of Health of the People's Republic of China, GB 2762-2012). EWI values of children, adolescents, and adults were all lower than provisional tolerable weekly intakes (PTWIs) of all shellfish species. The analysis of total target hazard quotients (TTHQ) showed that the ingested B. areolata in children, adolescents, and adults were all at non-carcinogenic risks; the consumption of Argopecten irradians and Chlamys farreri would pose non-carcinogenic risks for children only. In all age groups, the consumption of A. irradians, B. areolata, C. farreri, and Crassostrea ariakensis would lead to lifetime cancer risk due to Cd bioaccumulation, with toxicity of Pb and iAs to be acceptable and negligible.

Occurrence of priority trace metals in tomatoes (Solanum lycopersicum L.) from some areas of Uasin Gishu County, Kenya

This study determined the concentration of zinc, lead and cadmium in tomatoes consumed in some areas of Uasin Gishu, Kenya. Samples were taken in quintuplicate from Huruma and Bahati estates (Eldoret) and Chebaiywo (Kesses) and their metalliferous content were determined by atomic absorption spectroscopy. All samples had detectable levels of trace metals, with lead recording the highest concentration of 43.20 ± 0.31 mg/kg. Zinc concentrations were below WHO guidelines. Daily intakes ranged from 8.25 × to 2.59 × mg/kg/day. Though there are no probable cancer risks, hazard quotients indicated that deleterious health effects could arise from daily consumption of tomatoes.

Bioaccumulation of heavy metals in some commercially important fishes from a tropical river estuary suggests higher potential health risk in children than adults

The Karnaphuli River estuary, located in southeast coast of Bangladesh, is largely exposed to heavy metal contamination as it receives a huge amount of untreated industrial effluents from the Chottagram City. This study aimed to assess the concentrations of five heavy metals (As, Pb, Cd, Cr and Cu) and their bioaccumulation status in six commercially important fishes, and also to evaluate the potential human health risk for local consumers. The hierarchy of the measured concentration level (mg/kg) of the metals was as follows: Pb (13.88) > Cu (12.10) > As (4.89) > Cr (3.36) > Cd (0.39). The Fulton's condition factor denoted that fishes were in better 'condition' and most of the species were in positive allometric growth. The bioaccumulation factors (BAFs) of the contaminants observed in the species were in the following orders: Cu (1971.42) > As (1042.93) > Pb (913.66) > Cr (864.99) > Cd (252.03), and among the specimens, demersal fish, Apocryptes bato appeared to be the most bioaccumulative organism. Estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and carcinogenic risk (CR) assessed for potential human health risk implications suggest that the values were within the acceptable threshold for both adults and children. However, calculated CR values indicated that both age groups were not far from the risk, and HI values demonstrated that children were nearly 6 times more susceptible to non-carcinogenic and carcinogenic health effects than adults.

Effects of pollution on freshwater aquatic organisms

This paper presents the reviews of scientific papers published in 2018 issues on the effects of anthropogenic pollution on the aquatic organisms dwelling in freshwater ecosystem at global scale. The first part of the study provides the summary of relevant literature reviews followed by field and survey based studies. The second part is based on categories of different classes/sources of pollutants which affect freshwater organism. This is composed of several sections including metals and metalloids, wastewater and effluents, sediments, nutrients, pharmaceuticals, polycyclic aromatic hydrocarbons, flame retardants, persistent organic pollutants, pharmaceuticals and illicit drugs, emerging contaminants, pesticides, herbicides, and endocrine disruptors. The final part of the study highlights the reviews of published research work on new pollutants such as microplastics and engineered nanoparticles which affect the freshwater organisms. PRACTITIONER POINTS: Heavy metals concentrations should be assessed at nano-scale in aquatic environment. Air pollutants could have long-term effects on freshwater ecosystem. Future studies should focus on bioremediations of freshwater pollution.

Interrelationship of anthropogenic activity and parabens in fish from Taihu Lake during 2009-2017

Parabens are alkyl esters widely used as preservatives in foodstuffs, cosmetics, and pharmaceuticals. Taihu Lake is the third largest freshwater lake in China. However, there is no information available on the occurrence of parabens in Taihu Lake. To investigate contamination of parabens in Taihu Lake and the influence of human activities on contamination levels, 199 fish samples, comprising five species, were collected from Taihu Lake from 2009 to 2017. Five parabens, including methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), butylparaben (BuP), and benzylparaben (BeP), were quantitated using an isotope dilution LC-MS/MS method. The total concentrations of the five parabens ranged from 261 to 1710 pg/g wet weight (ww) with an average of 642 pg/g ww. The predominant compounds were MeP, EtP, and PrP, whose amounts accounted for more than 95% of the total amounts. No significant differences in the concentrations of parabens among the five fish species were observed, suggesting no interspecies differences in bioaccumulation of these compounds. Σ₅parabens in fish showed temporal variations with the means ranging between 532 and 772 pg/g ww during years. The levels of parabens were generally consistent with the economic development and urbanization rates of the regions surrounding Taihu Lake. The "typical" and "high" estimated daily intake (EDI) of parabens were 0.53 and 0.91 ng/kg-bw/day for children, and 0.46 and 0.79 ng/kg-bw/day for adults based on calculations using the means and the 95th concentrations, respectively. The EDIs were much lower than the reference dose values, suggesting that there are no obvious health risks posed by fish consumption.