Hg Bioaccumulation Research Articles

Seasonal riverine inputs may affect diet and mercury bioaccumulation in Arctic coastal zooplankton

Climate change driven increases in permafrost thaw and terrestrial runoff are expected to facilitate the mobilization and transport of mercury (Hg) from catchment soils to coastal areas in the Arctic, potentially increasing Hg exposure of marine food webs. The main aim of this study was to determine the impacts of seasonal riverine inputs on land-ocean Hg transport, zooplankton diet and Hg bioaccumulation in an Arctic estuary (Adventfjorden, Svalbard). The Adventelva River was a source of dissolved and particulate Hg to Adventfjorden, especially in June and July during the river's main discharge period. Stable isotope and fatty acid analyses suggest that zooplankton diet varied seasonally with diatoms dominating during the spring phytoplankton bloom in May and with increasing contributions of dinoflagellates in the summer months. In addition, there was evidence of increased terrestrial carbon utilization by zooplankton in June and July, when terrestrial particles contributed substantially to the particulate organic matter pool. Total (TotHg) and methyl Hg (MeHg) concentrations in zooplankton increased from April to August related to increased exposure to riverine inputs, and to shifts in zooplankton diet and community structure. Longer and warmer summer seasons will probably increase riverine runoff and thus Hg exposure to Arctic zooplankton.

Associations between total mercury, trace minerals, and blood health markers in Northwest Atlantic white sharks (Carcharodon carcharias)

The ecology and life-histories of white sharks make this species susceptible to mercury bioaccumulation; however, the health consequences of mercury exposure are understudied. We measured muscle and plasma total mercury (THg), health markers, and trace minerals in Northwest Atlantic white sharks. THg in muscle tissue averaged 10.0 mg/kg dry weight, while THg in blood plasma averaged 533 μg/L. THg levels in plasma and muscle were positively correlated with shark precaudal length (153–419 cm), and THg was bioaccumulated proportionally in muscle and plasma. Nine sharks had selenium:mercury molar ratios in blood plasma >1.0, indicating that for certain individuals the potential protective effects of the trace mineral were diminished, whereas excess selenium may have protected other individuals. No relationships between plasma THg and any trace minerals or health markers were identified. Thus, we found no evidence of negative effects of Hg bioaccumulation, even in sharks with very high THg.

Bioaccumulation and translocation of Hg and Cr by tobacco in Sichuan Province, China: understanding the influence of soil pH.

The present study investigated the bioaccumulation and translocation of mercury (Hg) and chromium (Cr) in Yunyan 87 flue-cured tobacco (Nicotiana tabacum) and assessed the influence of soil pH on the metal uptake by plant organs at the field scale. The study was conducted in 4 different regions selected from Sichuan Province, China: Guangyuan, Luzhou, Panzhihua, and Yibin. The results revealed that Hg highly contaminated Yibin soils at 0.29 mg kg-1 and by Cr at 147 mg kg-1, which is above the permissible limit. The levels of Hg in tobacco plant organs were predominantly in the order of leaves > root > stem. The overall trend for Cr contents in tobacco organs was in the order of root > leaves > stem. The results of an index of bioaccumulation (IBA) and translocation factor (TF) showed that the values observed in Panzhihua and Guangyuan tobacco leaves were generally higher, despite the low levels of soil contamination. The linear mixed model (LMM) demonstrated that the log of Hg IBA in tobacco organs was likely to decrease with soil pH increase, whereas the log of Cr IBA only decreased in the root but gradually increased in the aerial parts with soil pH increase. The total random variation in the log of metals' IBA due to regions indicated that for Hg, 33.42% of the variation was explained by regional differences, while for Cr, only 13% was accounted. The results suggested that Yibin and Luzhou need to correct the soil acidity if they are set to reduce Hg contamination in tobacco-growing soils. Guangyuan and Panzhihua need efforts to keep the soil pH on track to avoid high contamination levels, and effective measures of soil nutrients supply are required to produce high tobacco leaf quality free from heavy metal content. The findings of this study may be used to ascertain regional differences in heavy metals, particularly Hg and Cr uptake by tobacco plant organs, and to prevent the cultivation areas contamination through soil pH monitoring.

Pacific salmon as vectors of environmental contaminants: An experimental test confirms synoptic surveys in natural streams

Pacific salmon transfer large quantities of material to tributaries during their spawning migrations, including carcass tissue and labile nutrients but also persistent organic pollutants (POPs) and heavy metals. We conducted a Before-After-Control-Intervention experiment by adding salmon carcasses and eggs to a Michigan (USA) stream that had never received inputs from non-native salmon to understand the bioaccumulation and persistence of biotransported contaminants. Our experimental outcomes were compared to previous studies using meta-analysis. Coincident with the introduction of salmon, the PCB and DDE burden of resident trout significantly increased. However, we did not observe changes in total mercury (Hg). Two years after the salmon addition experiment concluded, resident trout POP concentrations had returned to pre-addition levels, with no difference between the treatment and control reaches. Analysis of effect sizes suggested that the contaminant response observed in our experiment is consistent with field survey observations. Our study suggested that the consumption of salmon eggs drove the increase in POP burden of resident trout while Hg bioaccumulation was influenced by watershed sources. Critically, our study suggests that ecosystems are capable of quickly recovering from POP inputs from species migrations if contaminant sources are removed.

Heavy metal toxicity in poultry: a comprehensive review.

Arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg) have been recognized as most toxic heavy metals that are continuously released into the environment, both from natural sources and from anthropogenic production of fertilizers, industrial activities, and waste disposal. Therefore, As, Cd, Hg, and Pb are found in increasing concentrations in bodies of water, fodder, feed, and in the tissues of livestock, including poultry, in the surroundings of industrial areas, leading to metabolic, structural, and functional abnormalities in various organs in all animals. In poultry, bioaccumulation of As, Pb, Cd, and Hg occurs in many organs (mainly in the kidneys, liver, reproductive organs, and lungs) as a result of continuous exposure to heavy metals. Consumption of Cd lowers the efficiency of feed conversion, egg production, and growth in poultry. Chronic exposure to As, Pb, Cd, and Hg at low doses can change the microscopic structure of tissues (mainly in the brain, liver, kidneys, and reproductive organs) as a result of the increased content of these heavy metals in these tissues. Histopathological changes occurring in the kidneys, liver, and reproductive organs are reflected in their negative impact on enzyme activity and serum biochemical parameters. Metal toxicity is determined by route of exposure, length of exposure, and absorbed dosage, whether chronic and acute. This review presents a discussion of bioaccumulation of As, Cd, Pb, and Hg in poultry and the associated histopathological changes and toxic concentrations in different tissues.

Hg bioaccumulation in the aquatic food web from tributaries of the Three Gorges Reservoir, China and potential consumption advisories

The Three Gorges Reservoir (TGR) holds the distinction of being China's largest reservoir, and the presence of pollutants in the fish from the reservoir have a direct impact on the health of local residents. Thus, 349 fish specimens of 21 species and 1 benthos (Bellamya aeruginosas) were collected from four typical tributaries of the TGR from 2019 to 2020. These specimens were analyzed for the concentrations of total mercury (THg) and methylmercury (MeHg), and some representative samples were tested for δ13C and δ15N values to reveal the characteristics of bioaccumulation and biomagnification. The maximum safe daily consumption was estimated based on the oral reference dose (0.1 μg kg−1 bw/day according to US-EPA, 2017). The results showed that the mean THg and MeHg concentrations in fish from the TGR tributaries were 73.18 ± 49.21 ng g−1 and 48.42 ± 40.66 ng g−1, respectively, with the trophic magnification factors (TMFs) of THg and MeHg being 0.066 and 0.060, respectively. Among all the fish species in the tributaries, the highest daily maximum safe consumption amount was 1253.89 g for S. asotus consumed by adults, while the lowest was 62.88 g for C. nasus consumed by children.

Effects of diet composition on gut microbiome and mercury biotransformation in the gobyfish

Mercury (Hg) biotransformation (methylation and demethylation) could play a key role in affecting the final Hg speciation and level in fish. The gut microbiota was identified to be involved in this process. Diet is recognized to greatly influence the gut microbiome, whereas the impact of food composition on Hg biotransformation in fish has yet to be addressed. The study investigated the biotransformation and bioaccumulation of Hg in the gobyfish (Mugilogobius chulae) under different food choices (natural prey and artificial food) and evaluated the role of gut microbiome in these processes. The results showed that different diet composition significantly affected the gut microbiome and subsequently resulted in varied phenomenon of Hg biotransformation within fish body. Significant demethylation (0.33 % d−1) was only observed in the natural prey (brine shrimp) treatment, whereas methylation was occurred extremely slowly (0.013 % d−1) only in the artificial food (commercial dry pellets) treatment. Furthermore, the growth of demethylators was also enhanced in the natural prey treatment, which contributed to the demethylation process in fish. Furthermore, the gut microbial structure of gobyfish was greatly altered by different diet composition. This study highlights the significance of food choices in the minimization of Hg contamination in aquaculture. Incorporating natural prey into fish diets could be a better choice to balance the fish production and control MeHg levels. CapsuleDiet composition greatly affects the gut microbial composition, and natural prey could help to reduce the potential of MeHg accumulation by fish.

Bioaccumulation and trophic transfer of total mercury through the aquatic food webs of an African sub-tropical wetland system

Anthropogenic activities, including combustion of fossil fuels, coal, and gold mining, are significant sources of mercury (Hg) emissions into aquatic ecosystems. South Africa is a major contributor to global Hg emissions (46.4 tons Hg in 2018), with coal-fired power stations as the main source. Atmospheric transport of Hg emissions is the dominant cause of contamination, especially on the east coast of southern Africa where the Phongolo River Floodplain (PRF) is located. The PRF is the largest floodplain system in South Africa, with unique wetlands and high biodiversity, and provides essential ecosystem services to local communities who rely on fish as a protein source. We assessed the bioaccumulation of Hg in various biota, the trophic positions and food webs, as well as the biomagnification of Hg through the food webs in the PRF. Elevated Hg concentrations were found in sediments, macroinvertebrates and fish from the main rivers and associated floodplains in the PRF. Mercury biomagnification was observed through the food webs, with the apex predator tigerfish, Hydrocynus vittatus, having the highest Hg concentration. Our study shows that Hg in the PRF is bioavailable, accumulates in biota and biomagnifies in food webs.

High and diurnally fluctuating carbon dioxide exposure produces lower mercury toxicity in a marine copepod

Coastal waters have experienced fluctuations in partial pressure of carbon dioxide (pCO2) and mercury (Hg) pollution, yet little is known concerning how natural pCO2 fluctuations affect Hg biotoxicity. Here, a marine copepod Tigriopus japonicus was interactively exposed to different seawater pCO2 (ambient 400, steady elevated 1000, and fluctuating elevated 1000 ± 600 μatm) scenarios and Hg (control, 2 μg/L) treatments for 7 d. The results showed that elevated pCO2 decreased Hg bioaccumulation, and it was even more under fluctuating elevated pCO2 condition. We found energy depletion and oxidative stress under Hg-treated copepods, while combined exposure initiated compensatory response to alleviate Hg toxicity. Intriguingly, fluctuating acidification presented more immune defense related genes/processes in Hg-treated copepods when compared to steady acidification, probably linking with the greater decrease in Hg bioaccumulation. Collectively, understanding how fluctuating acidification interacts with Hg contaminant will become more crucial in predicting their risks to coastal biota and ecosystems.

In Vivo Mercury (De)Methylation Metabolism in Cephalopods under Different pCO2 Scenarios.

This work quantified the accumulation efficiencies of Hg in cuttlefish, depending on both organic (MeHg) and inorganic (Hg(II)) forms, under increased pCO2 (1600 μatm). Cuttlefish were fed with live shrimps injected with two Hg stable isotopic tracers (Me202Hg and 199Hg(II)), which allowed for the simultaneous quantification of internal Hg accumulation, Hg(II) methylation, and MeHg demethylation rates in different organs. Results showed that pCO2 had no impact on Hg bioaccumulation and organotropism, and both Hg and pCO2 did not influence the microbiota diversity of gut and digestive gland. However, the results also demonstrated that the digestive gland is a key organ for in vivo MeHg demethylation. Consequently, cuttlefish exposed to environmental levels of MeHg could exhibit in vivo MeHg demethylation. We hypothesize that in vivo MeHg demethylation could be due to biologically induced reactions or to abiotic reactions. This has important implications as to how some marine organisms may respond to future ocean change and global mercury contamination.

Nanoplastics potentiate mercury toxicity in a marine copepod under multigenerational exposure

The continuous fragmentation of plastics and release of synthetic nanoplastics from products have been aggravating nanoplastic pollution in the marine ecosystem. The carrier role of nanoplastics may increase the bioavailability and toxicity effects of toxic metals, e.g., mercury (Hg), which is of growing concern. Here, the copepod Tigriopus japonicus was exposed to polystyrene nanoplastics (PS NPs) and Hg (alone or combined) at environmental realistic concentrations for three generations (F0-F2). Then, Hg accumulation, physiological endpoints, and transcriptome were analyzed. The results showed that the copepod's reproduction was significantly inhibited under PS NPs or Hg exposure. The presence of PS NPs caused significantly higher Hg accumulation, lower survival, and lower offspring production in copepods relative to Hg exposure, suggesting an increased threat to the copepod's survivorship and health. From the molecular perspective, combined PS NPs and Hg caused a graver effect on the DNA replication, cell cycle, and reproduction pathways relative to Hg exposure, linking to lower levels of survivorship and reproduction. Taken together, this study provides an early warning of nanoplastic pollution for the marine ecosystem not only because of their adverse effect per se but also their carrier role for increasing Hg bioaccumulation and toxicity in copepods.

The mercury accumulation and its effects on antioxidant and immune responses in starry flounder, Platichthys stellatus exposed to dietary mercury

The purpose of this study is to investigate the effect of inorganic mercury (Hg) on fish. Inorganic Hg is less toxic than organic Hg, but it is used more in human daily life, such as manufacturing Hg batteries and fluorescent lamps. For this reason, inorganic Hg was used in this study. Starry flounder, Platichthys stellatus (mean weight 43.9 ± 4.4 g; mean length 14.2 ± 0.4 cm) were exposed for 4 weeks to the different levels of dietary inorganic Hg at concentrations of 0, 4, 8, 12 and 16 mg Hg/kg, and depuration was performed for 2 weeks after exposure. Bioaccumulation of Hg in the tissues was observed to increase significantly, in following order: intestine > head kidney > liver > gills > muscle. Antioxidant responses (superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST) and glutathione (GSH)) were significantly increased. Immune responses (lysozyme and phagocytosis activity) were substantially decreased. The results of this study suggest that dietary inorganic Hg induces bioaccumulation in specific tissues, increases antioxidant responses and decreases immune responses. After the depuration period for 2 weeks, it was effective to alleviate bioaccumulation in tissues. However, antioxidant and immune responses were limited to be attenuated for recovery.

Mercury methylation potential and bioavailability in the sediments of two distinct aquatic systems

This study explored mercury (Hg) methylation potential in two distinct aquatic systems. Fourmile Creek (FMC) was historically polluted with Hg effluents from groundwater as it is a typical gaining stream, where organic matter and microorganisms in streambed are continuously winnowed. The H02 constructed wetland only receives atmospheric Hg and is rich in organic matter and microorganisms. Both systems receive Hg from atmospheric deposition now. Surface sediments were collected from FMC and H02, spiked with inorganic Hg, and cultivated in an anaerobic chamber to stimulate microbial Hg methylation reactions. Total mercury (THg) and methylmercury (MeHg) concentrations were measured at each spiking stage. Mercury methylation potential (MMP, %MeHg in THg) and Hg bioavailability were assessed with the deployment of diffusive gradients in thin films (DGTs). During the methylation process and at the same incubation stage, FMC sediment showed faster increasing rates of %MeHg and higher MeHg concentrations than H02, demonstrating a stronger MMP in the FMC sediment. Similarly, higher Hg bioavailability was observed in FMC sediment compared to the H02 as indicated by DGT-Hg concentrations. In conclusion, the H02 wetland with high levels of organic matter and microorganisms presented low MMP. But the Fourmile Creek as a gaining stream and a historical site of Hg pollution showed strong MMP and high Hg bioavailability. A related study on microbial community activities characterized the microorganisms between FMC and H02, which is attributed to be the main reason for their different methylation capabilities. Our study further brought up the considerations on remediated sites from Hg contamination: Hg bioaccumulation and biomagnification can still be elevated and higher than the surrounding environment due to lagged changes in microbial community structures. This study supported the sustainable ecological modifications of legacy Hg contamination and raised the necessity of long-term monitoring actions even after executing a remediation plan.

Mercury bioaccumulation in thresher sharks from the eastern tropical Pacific: Influences of body size, maturation stage, and feeding habitat

Sharks, as top order predators, provide a guidance on how contaminants such as mercury bioaccumulate in marine environments. This study assessed the bioaccumulation of mercury (total mercury, THg) in the muscle, liver, red blood cells (RBC), and plasma of pelagic and bigeye thresher sharks (Alopias pelagicus and A. superciliosus) from eastern tropical Pacific. Additionally, the concentration of methylmercury (MeHg) in muscle was also determined to assess risks for human consumption. For both species, muscle THg concentrations (4.05 ± 2.15 and 4.12 ± 1.84 μg g−1 dry weight for pelagic and bigeye thresher shark) were higher than that in other tissues. THg concentrations for all tissues were significantly correlated with precaudal length, with higher accumulation rates after maturity in pelagic than bigeye thresher sharks, suggesting an associated dietary shift at maturation. Correlations among tissues in both species suggested similar transportation and distribution patterns in internal tissues. The δ13C values in muscle, RBC and plasma suggested that habitat shifts influenced Hg accumulation, whereas trophic position, estimated by δ15N values, had limited effects on patterns of Hg bioaccumulation. Diet shifts towards prey more cephalopods that content higher Hg than small fishes (large fishes: 1.77 μg g−1; cephalopods: 0.66 μg g−1 and small fishes 0.48 μg g−1, dry weight) increased Hg accumulation rates in adult pelagic thresher sharks. Concentrations of MeHg in the muscle of both thresher shark (3.42 ± 1.68 μg g−1 in A. pelagicus and 3.78 ± 2.13 μg g−1 in A. superciliosus) exceeded the recommended levels for human consumption. This research provides insight into the factors influencing mercury bioaccumulation in thresher sharks, which are essential for the management and conservation of these species.

Prediction heavy metals accumulation risk in rice using machine learning and mapping pollution risk

Rapid and accurate prediction of metal bioaccumulation in crops are important for assessing metal environmental risks. We aimed to incorporate machine learning modeling methods to predict heavy metal contents in rice crops and identify influencing factors. We conducted a field study in Jiangsu province, China, collecting 2123 pairs of soil-rice samples in a uniform measurement and using 10 machine learning algorithms to predict the uptake of Cd, Hg, As, and Pb in rice grain. The Extremely Randomized Tree model exhibited the best performance for rice-Cd and rice-Hg (Cd: R2 = 0.824; Hg: R2 = 0.626), while the Random Forest model performed best for As and Pb (As: R2 = 0.389; Pb: R2 = 0.325). The feature importance analysis showed that soil-Cd and pH had the highest impact on rice-Cd risk, which is in line with previous studies; while temperature and soil organic carbon were more important to rice-Hg than soil-Hg. Then, based on another set of 1867 uniformly distributed paddy soil samples in Jiangsu province, the Cd and Hg risks of soil and rice were visualized using the established models. Mapping result revealed an inconsistent pattern of hotspot distribution between soil-Hg and rice-Hg, i.e., a higher rice-Hg risk in the northern area, while higher soil-Hg in south. Our findings highlight the importance of temperature on Hg bioaccumulation risk to crops, which has often been overlooked in previous risk assessment processes.

Is the inhalation influence on the level of mercury and PAHs in the lungs of the baltic grey seal (Halichoerus grypusgrypus)?

For many decades, mercury (Hg) has been recognized as one of the most dangerous environmental pollutants that negatively affects the ecosystem, including human health. Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic, toxic and potentially carcinogenic compounds. The process of respiration in addition to dietary intake is a significant source of these compounds to the human or marine mammalian body. Therefore, the aim of this study was to determine the sources of PAHs and labile forms of mercury in the lungs of dead seals found in the southern Baltic Sea. Of the PAHs: pyrene, fluoranthene and chrysene showed the highest concentrations. Considering the content of individual Hg fractions, the highest percentage was characterized by Hg labile 1b (related to organic matter). In a few specimens, deviations from the trend described above were observed: a higher proportion of Hg labile 1a (mainly halide-bound forms of mercury than the mean value which may indicate their origin from aerosols). Hg concentrations increased with seal age due to bioaccumulation and biomagnification of Hg from food; therefore, adsorption of atmospheric mercury on alveoli is probably of decreasing importance with seal age. Ratios obtained: FLA/PYR <1; B(a)A/CHR <1; FLA/(PYR + FLA) < 0.4 indicate a petrogenic source. In contrast, high correlations of B(a)A, FLA and PYR and CHR with Hg suggest a common source of PAHs and mercury - from food. Conversely, the presence of pyrogenic (combustion-derived) benzo(a)pyrene in the lungs of these mammals could indicate a respiratory route of entry. Mercury and PAHs in the lungs of the seals studied were mainly of trophic origin, but the results presented here make the hypothesis of an airborne influx of Hg and PAHs into the lungs from marine mammals plausible. This is of particular importance in juveniles (pups), who, at the initial stage of life, spend time on land and do not obtain food on their own.

Essential Trace Elements Prevent the Impairment in the Retention Memory, Cerebral Cortex, and Cerebellum Damage in Male Rats Exposed to Quaternary Metal Mixture by Up-regulation, of Heme Oxygynase-1 and Down-regulation of Nuclear Factor Erythroid 2-related Factor 2-NOs Signaling Pathways

In the present study, we examined adverse effects of metals and metalloids in the Cerebral cortex (CC) and Cerebellum (CE). Group 1 comprised from the controls while other four groups of male Wistar rats were treated with following pattern: Group II (Heavy Metal Mixture HMM only: PbCl2, 20 mg·kg−1; CdCl2, 1.61 mg·kg−1; HgCl2, 0.40 mg·kg−1, and NaAsO3,10 mg·kg−1), Groups III (HMM + ZnCl2); Group IV (HMM + Na2SeO3) and Group V (HMM + ZnCl2 + Na2SeO3) for 60 days per os. HMM promoted oxidative stress in the CC and CE of treated rats compared to controls; moreover, exposure to HMM led to increased activity of the AChE and pro-inflammatory cytokines; also, HMM promoted accumulation of caspase 3 and other transcriptional factors such as Nrf2 and decreased levels of Hmox-1. Essential metals reduced increased bioaccumulation of Pb, Cd, As and Hg in CC and CE caused by HMM exposure. Also, all mentioned adverse effects were diminished by essential metals treatment (Se and Zn). HMM exposed rats had considerably less escape dormancy than controls. Histopathological analysis revealed moderate cell loss at the intermediate (Purkinje cell) and granular layer.Zinc and selenium supplementations could reverse adverse effects of heavy metals at various cellular levels in neurons.

Banana peel extract alleviate inflammation and oxidative stress via modulation of the Nrf2/Hmox-1 and NF-κB pathways in thyroid of heavy metal mixture exposed female rats

Introduction This is an evaluation of the effects of banana peel BP extract on the heavy metals’ mixture HMM mediated oxido-inflammatory effects in the thyroid of female albino rats. Methods Five groups (5 female rats/group) were treated as follows for 60 days: Group 1: Deionized water only; Group 2: (Pb, Hg, Mn and Al); Group 3: 200 mg/kg BP extract + HMM; Group 4: 400 mg/kg BP extract + HMM; Group 5: 800 mg/kg BP extract + HMM. On day 60 animals were euthanized, thyroid was harvested and used for, malondialdehyde MDA, nitric oxide NO, antioxidants, tumor necrosis factor alpha (TNF – α), interleukin 6 (IL – 6), Caspase-3, Nuclear factor erythroid 2- related factor 2 (Nrf2), Nuclear factor kappa B (NfkB) and Heme Oxygynase – 1 (Hmox-1) and histopathology. Results There was significant bioaccumulation of Pb, Al, Hg and MN; elevated IL-6 and Tnf-α, MDA and NO, caspase-3 and Nrf2, NF-κB and Hmox-1 in the HMM only group in comparison to the control. There was significant ( p &lt; 0.05) decrease in SOD, CAT GSH activities in HMM only exposed group in comparison to the control deionized water group, whereas BP co-treatment with HMM significantly ( p &lt; 0.05) increased SOD, CAT GSH activities. Co-treatment with BP extract also reversed most of these effects. Discussion and Conclusions BP extract may ameliorate HMM -induced thyrotoxicity in female albino rats by blunting oxido-inflammatory activities.

Ecological and Human Health Risk Assessment of Heavy Metal in Sediment and Demersal Fish Species in Western Offshore Nigeria, Gulf of Guinea

This study was focused to assess the contamination status of heavy metals in sediments, and human health risks associated with fish consumption from western Nigeria offshore in the Gulf of Guinea. Triplicate samples of demersal marine fish species and sediments were collected from five stations (fishing ground) and analysed for heavy metals [mercury (Hg), cadmium (Cd), and lead (Pb)] and metalloid [arsenic (As)] using ICP-OES (inductively coupled plasma optical emission spectrometry) adopted USEPA 200.7 standard method. The metals/metalloid concentrations in demersal fish species and sediment fell below the FAO/WHO permissible limits and sediment quality guidelines (SQG) [probable effect level (PEL) and threshold effect level (TEL)]. The ecological indices [probable contamination index (PCI), mean effect level quotients, newly modified hazard quotient (mHQ), and hazard quotient (HQ)] revealed low contamination level of heavy metals in sediment. The hazard index (HI) of metals in fish species associated with human health fell below the recommended threshold of 1 with no significant health risk to the consumers. The target cancer risk (TCR) of Cd and Pb in the fish species were below the regulation range of 1.0 × 10−6 to 1.0 × 10−4 set by the USEPA. The cluster analysis revealed two clusters. Cluster 1 (C1) showed that Cd was significantly accumulated in the sediment. Cluster 2 (C2) showed significantly low bioaccumulation of Hg, Cd, Pb, and As in fish species across all stations. The ecological and health risk assessment indices generally established low potential adverse effect on demersal marine fish species due to the overall low ecological severity risk associated with heavy metals/metalloids in sediment. Hence, consumers of fisheries resources from western off Nigeria coast are relatively safe from being exposed to any non-carcinogenic and carcinogenic health risk.

Zn and Se abrogate heavy metal mixture induced ovarian and thyroid oxido-inflammatory effects mediated by activation of NRF2-HMOX-1 in female albino rats

The thyroid is vital for the proper functioning of the female reproductive system since it regulates the metabolism and development of ovary. This is an evaluation of the essential trace elements ETE on the heavy metals mixture HMM mediated oxido-inflammatory effects in the ovary and thyroid of female albino rats. Five groups (5 female rats /group) were treated as follows for 60 days: Group 1: Deionized water only; Group 2: (Pb, Hg, Mn and Al); Group 3: HMM + ZnCl2, 0.80 mg/kg; Group 4: HMM + Na2SeO3, 1.50 mg/kg; Group 5: HMM + ZnCl2, 0.80 mg/kg and Na2SeO3, 1.50 mg/kg combined. On day 60 animals were euthanized, ovary and thyroid were harvested and used for, MDA, NO, antioxidants, TNF-α, IL-6, HMOX-1, Caspase-3, NF-KB, NRF2, HM and histopathology. There was significant bioaccumulation of Pb, Al, Hg and MN; elevated IL-6 and TNF-α, MDA and NO, caspase-3 and NRF2, NFKB and HMOX-1 with significant decrease in antioxidants in the HMM only group in comparison to the control. Co-treatment with ETE reversed most of these effects.ETE may ameliorate HMM -induced ovarian and thyrotoxicity in female albino rats by blunting oxido-inflammatory activities.