Assessment Of Heavy Metal Toxicity Research Articles

Assessment of heavy metal toxicity in fish and its impact on human health: A review

Assessment of heavy metal toxicity in fish and its impact on human health: A review

Study on preparation of glass-ceramics from municipal solid waste incineration (MSWI) fly ash and chromium slag

In order to realize the harmless treatment of municipal solid waste incineration (MSWI) fly ash and chromium slag, the CaO–SiO2–Al2O3 glass-ceramics were successfully prepared by the one-step method using a mixture of lead-zinc tailings and coal gangue as a flux. The results showed that the mixture successfully reduced the melting temperature of MSWI fly ash with a maximum blending ratio of 70% at 1450 °C, and realized the co-sintering of chromium slag and the base glass of MSWI fly ash. In addition, according to the analysis results of XRD, SEM, and EDS, combined with heavy metal leaching data measured by the TCLP method, diopside ferrous crystals exerted a better solidification effect on Zn and Cd than did gehlenite crystals. Uvarovite crystals exhibited an effective solidification effect on Cr owing to the participation of Cr in its formation, and the toxicity assessment of heavy metals in all samples satisfied the demand of the EPA and the CN GB 5058.3. This work provides a consult for the low-cost, green and efficient treatment of chromium slag, MSWI fly ash, coal gangue, and lead-zinc tailings.

Comparison of acid volatile sulphide, metal speciation, and diffusive gradients in thin-film measurement for metal toxicity assessment of sediments in Lake Chaohu, China.

The toxicity of heavy metals in sediments is inseparable from their forms in the environment. Traditional sediment toxicity assessment systems, such as total metals, dissolved metals in pore water, metals extracted by the Community Bureau of Reference procedure, and acid volatile sulphide (AVS)-simultaneously extracted metal (SEM), have their own limitations. This study revealed the horizontal and vertical distribution characteristics of AVS and SEM in Lake Chaohu and three typical groups of two-dimensional profiles of diffusive gradients in thin-film (DGT)-labile S(-II) were obtained at representative sampling sites. There was a positive correlation between DGT-labile S(-II) and AVS due to sulphate-reducing bacteria and a negative correlation due to the high sulphate reduction rate induced by high total organic carbon. Moreover, there was no correlation between DGT-labile S(-II) and AVS when bioturbation was dominant in the sediments. To realise the application of DGT measurement in toxicity assessment of heavy metals in sediment through the sandwich relationship of DGT-labile metals vs. metals speciation vs. sediment toxicity assessment, the key relationship of DGT-labile metals vs. metals speciation was explored. DGT-labile Ni showed potential to reveal this relationship.

A novel gas production bioassay of thiosulfate utilizing denitrifying bacteria (TUDB) for the toxicity assessment of heavy metals contaminated water.

This study reports for the first-time the possibility of deploying gas production by thiosulfate utilizing denitrifying bacteria (TUDB) as a proxy to evaluate water toxicity. The test relies on gas production by TUDB due to inhibited metabolic activity in the presence of toxicants. Gas production was measured using a bubble-type respirometer. Optimization studies indicated that 300mg NO3--N/L, 0.5mL acclimated culture, and 2100mg S2O32-/L were the ideal conditions facilitating the necessary volume of gas production for sensitive data generation. Determined EC50 values of the selected heavy metals were: Cr6+, 0.51mg/L; Ag+, 2.90mg/L; Cu2+, 2.90mg/L; Ni2+, 3.60mg/L; As3+, 4.10mg/L; Cd2+, 5.56mg/L; Hg2+, 8.06mg/L; and Pb2+, 19.3mg/L. The advantages of this method include operational simplicity through the elimination of cumbersome preprocessing procedures which are used to eliminate interferences caused by turbidity when the toxicity of turbid samples is determined via spectrophotometry.

Risk Assessment of Heavy Metal Toxicity and Stress Marker Enzyme in Waste Water from Municipal Dam Site around Enugu Metropolis, Enugu State

Impact of waste water toxicity from collection ditches within Enugu metropolis, Enugu state was assessed in the present study. Risk impact of heavy metal recalcitrant was also determined in the present study as the waste water from the ditch were used by subsistence farmers around for irrigation purposes.  Physicochemical analysis of the soil irrigation with the domestic waste water was carried and revealed the following: pH 6.65, conductivity 792 respectively. Dissolved mineral contents were found in the following order: Cl>Ca>Fe>SO4>Mg>Cu>K>Pb>PO3 while heavy metals of Hg, As and Cd were found at below detectable limit range (BDL). Total organic carbon (TOC) and total organic matter (TOM) contents were found at 179.93 and 221 mg/kg in the various treatments. These varied significantly from the control treatment. Physicochemical properties of the domestic waste water were equally analyzed.  Soil enzymes showed the activity of the lipase, urease, peroxidase and catalase with an increased of lipase, urease and peroxidase after the irrigation with OD of 0.610, 0.677 and 0.712 respectively catalase activity was reduced downwardly. Health risks to human through utilization of the waste water by human were assessed by: estimated dietary intake (EDI), estimated weekly intake (EWI) and Target hazard quotient (THQ). EDI for the heavy metals of Pb, Cu and Fe were 3.98 x 10-3, 1.22 x 10-2 and 1.2 x 10-2 mg/g, respectively estimated while EDI of 1.36 x 10-3, 8.33 x 10-3 and 9.52 x 10-3 mg/g were obtained for Pb, Cu and Fe from the control experiments. EWI for heavy metals of Pb, Cu and Fe were 9.52 x 10-3, 583 x 10-2 and 6.7 x 10-2 mg/g, respectively. The results showed that the THQ for Fe and Cu were less than 1 while that of Pb was greater than 1. THQ were less than 1in all the analysed metals from the control experiment. The findings from this study show that there is a considerable health risks connected with utilization of waste water from our study locale and these waste water bioaccumulate heavy metal levels which are potentially poisonous to humans who consume them.

Multivariate statistical and GIS methods for the assessment of heavy metal toxicity in Ekulu River, Southeastern, Nigeria

Multivariate statistical and GIS methods for the assessment of heavy metal toxicity in Ekulu River, Southeastern, Nigeria

Health Risk Assessment of Heavy Metal Toxicity Utilizing Eatable Vegetables from Poultry Farm Region of Osun State

Heavy metals are present everywhere in the environment attributable to both geogenic and anthropogenic inputs and humans are vulnerable to them via various exposure pathways. Heavy metal accumulation in soils and plants is of grave concern because of the possible human health risks. This research article examined the seasonal concentrations of arsenic, cadmium, copper, iron, lead and zinc in leafy vegetables of Talinum triangulare and Vernonia amygdalina samples planted in some poultry farms and determine the risks involved in consumption of that vegetables. Flame Atomic Absorption Spectrophotometer was applied to evaluate the contents of the metals in the vegetables. Quality monitoring procedures comprised blank analysis, recovery test and calibration of standards. Descriptive and inferential statistics were adopted for data analyses. Hazard quotient, daily intake of metals, health risk index and transfer factor were also determined. The pattern of metals mean value in the soil was As > Fe > Zn > Pb > Cu > Cd while for vegetables was Fe > Zn > As > Cu > Pb > Cd. The TFs pattern for metals from soil to plant was Zn > Fe > Cd > As > Cu > Pb for Talinum triangulare and Fe > Zn > Cd > As > Cu > Pb for Vernonia amygdalina in both seasons. The sequence of the DIM value was Fe > Zn > As > Cu > Pb > Cd for both plants. The results indicated very high HRI and THQ values for As (22.60 and 61.00). This asserted that the intake of vegetables planted on the soil of the farms studied present a health risk for humans with regard to the evaluated metals.

Toxicity Assessment of Heavy Metals in Soils around Transformers in University of Port Harcourt, Choba, Nigeria

Toxicity Assessment of Heavy Metals in Soils around Transformers in University of Port Harcourt, Choba, Nigeria

Toluene induces hormetic response of soil alkaline phosphatase and the potential enzyme kinetic mechanism

Hormesis of soil enzyme that involved in heavy metal has been attracting much more attention for risk assessment of heavy metal toxicity, but insufficient studies were conducted to define the hormetic responses induced by toluene or other organic pollutions. The objectives of this study were to investigate the hormetic responses of soil enzyme induced by toluene and explore the potential enzyme kinetic mechanism. Soil alkaline phosphatase (ALP) activity was regarded as the endpoint to explore the hormetic responses under different doses of toluene (0.0, 0.1, 0.5, 1.0, 2.0, 3.0, 5.0, 10.0, 50.0 and 100.0 μL g−1). Subsequently, we conducted the experiments of enzymatic reaction kinetics and pure enzyme to further verify the potential mechanisms of soil ALP's hormesis. Results showed that ALP activities at 0.1–1.0 μL g−1 toluene were significantly increased in contrast to the control (0 μL g−1 toluene) (P < 0.05) at the exposure time of 30, 36, 48 and 54 h, with the maximum stimulation magnitudes of 24–43%. ALP activities were almost not affected by toluene (2–100 μL L−1) in the whole experimental period (6–54 h). Meanwhile, the values of catalytic efficiency (the radio Vmax/Km, Vmax: maximum reaction velocity and Km: Michaelis constant) and Vmax significantly increased compared with the control, but the value of Km decreased from 2.5 to 1.6. Overall, low dose toluene can induce hormesis of soil ALP. The potential reason is that low-dose toluene could enhance the combination of soil ALP and substrates. We believe that this study will provide a new viewpoint for ecological risk assessment of toluene contaminated soils.

Study of Toxicity Assessment of Heavy Metals from Steel Slag and Its Asphalt Mixture.

Steel slag has been used widely as an aggregate in road application, but it could pose a contamination risk for the environment due to considerable heavy metals (HMs). To explore the leaching behavior and contamination risk of HMs from steel slag and its asphalt mixture is of great significance. In this study, the physical-chemical features, batch leaching test and semi-dynamic test were conducted to determine the mobility capability and leaching characteristics of HMs. The results show that steel slag presents a low pollution risk in short-term leaching, whereas the cumulative release mass of Cd, Ni, As and Pb are more than or approach the limits, which indicates that steel slag exhibits environment impacts to a certain extent. Steel slag covered with asphalt binder results in As and Cu reduced by 3.64% and 4.83%. Diffusion is the main controlling mechanism of HMs in asphalt mixture and the mobility capability of most HMs were classed as “low mobility” (LI > 8). Asphalt stripping off can aggravate the release potential of HMs from asphalt mixture, but the pollution risk remains controllable.

Bioluminescent method for the rapid screening of toxic heayy metals in environmental samples using Photobacterium leiognathi strain AK-MIE.

Assessment of eco-toxicant using bioluminescent bacterial assay is a widely used and globally accepted method. In this work, a new luminescent bacterium was isolated from squid (Loligo duvauceli) and identified as Photobacterium leiognathi strain AK-MIE using 16S rRNA, phylogeny analysis. The predicted optimum conditions by RSM were 2.76% (w/v) NaCl, 2.28% (w/v) peptone, 0.34% (w/v) yeast extract, and pH 6.83 with 541,211.80 RLU of luminescent production whereas the predicted optimum conditions by ANN were 2.21% (w/v) NaCl, 2.27% (w/v) peptone, 0.39% (w/v) yeast extract, and pH 6.94 which produced 541,986.20 RLU. The validation analysis of both RSM and ANN show 0.60% and 0.69% deviation from the predicted results indicating that both models provided good quality predictions with ANN showing a superior data fitting capability for non-linear regression analysis. Toxicity tests show strain AK-MIE was sensitive to mercury (concentration causing 50% inhibition or IC50 of 0.00978mgL-1), followed by cadmium (IC50 of 0.5288mgL-1), copper IC50 of (0.8117mgL-1), silver (IC50 of 1.109mgL-1), and lead (IC50 of 10.71mgL-1) which are more sensitive than previously isolated luminescent bacteria, suggesting that strain AK-MIE has the potential to be used in toxicity assessment of heavy metals in the environment. Based on the field trial results, several sediment samples from industrial areas in Bangi, Selangor managed to inhibit the bioluminescence of strain AK-MIE. Validation method carried out using ICP-MS proved the presence of several toxic heavy metal elements.

Risk assessment of heavy metal toxicity by sensitive biomarker δ-aminolevulinic acid dehydratase (ALA-D) for onion plants cultivated in polluted areas in Kosovo

Biomarkers allow an integrated risk assessment of heavy metal pollution effects in living organisms. In this study, the biochemical effects of Cd, Cr, Ni, Pb and Zn pollution in agricultural soil and their accumulation in Alium cepa L. (onion) were evaluated with ALA-D enzyme response as a biomarker, along with δ-aminolevulinic acid (ALA) and total chlorophyll contents in leaves of this plant. Soil samples were randomly selected from agricultural areas in two regions, Mitrovica and Obiliqi, which are considered the most industrially polluted regions in Kosovo. Results show that Pb and Zn concentrations in soil samples from Mitrovica (1953-2576 mg kg −1) and Obiliqi regions (138-179 mg kg −1) and their bioaccumulation levels in onion were significantly higher in comparison with the control group. There was an adverse negative correlation between Pb or Zn concentration and ALA-D activity and total chlorophyll content, and a positive correlation with ALA content. This study indicates that ALA-D activity can be used as a very sensitive biomarker for evaluation of heavy metal pollution. The bioaccumulation of heavy metals from soil polluted areas poses a threat for food contamination and public health.

Assessment of heavy metal toxicity in soils contaminated by a former Pb–Zn mine and tailings management using flotation process, Jebel Ghozlane, Northern Tunisia

The present work aims to investigate the toxicity of heavy metals in soil samples collected from the vicinity of the former Pb–Zn mine of Jebel Ghozlane and to evaluate reprocessing performances of mine tailings. The research was undertaken using two ecotoxicity tests: (1) MetPAD™ biotest Kit and (2) standardized germination test using wheat seeds (Triticum durum). Water extraction test was carried out to evaluate the potential availability of Pb, Zn and Cd in soil samples. Although their total levels in soil were found to be high, their water extracted values were relatively low (Pb 7–100 µg L−1, Zn 15–238 µg L−1 and Cd 1–5 µg L−1). The high germination percentages (GPs) of wheat seeds indicate that all soil samples tested are not toxic. However, the toxicity of soil–water extracts, as determined by MetPAD™ biotest which is specific for heavy metal toxicity, showed that two of six soil samples exhibited moderate toxicity. The toxicity was related to the relatively high concentrations of water-extractable Zn, Pb and Cd in these two samples. Laboratory flotation tests were used to evaluate the separation ability of Pb and Zn minerals from the mine tailings materials. Results showed that this method allows satisfactory reduction of Pb (95% recovery) and, to a less extent, of Zn (42% recovery) from mine tailings, that could be used as a mitigation strategy for heavy-metal contaminated soil.

Toxicity assessment of heavy metals and organochlorine pesticides in freshwater and marine environments, Rosetta area, Egypt using multiple approaches

Egypt faces a rapidly increasing deterioration of its surface water owing to the discharges of contaminated effluents. The present study focuses on assessing the levels of toxic heavy metals and organochlorine pesticides (OCPs) in water, sediments and Phragmites australis of freshwater and marine environments at Rosetta area. Fourteen sites were sampled including 4 sites within the marine environment and 10 sites distributed along the Rosetta River Nile. Potential sources of pollution were spatially assessed using remote sensing and geographic information system techniques. To quantify the environmental impact of metals on the aquatic system, metal index (MI) in freshwater, heavy metal pollution index, and ecological risk index (Er) in sediments as well as bioaccumulation factor (BAF) in P. australis were calculated. Remote sensing results showed that drainage canals (954.8 km), cultivations (1252.4 km2) and urbanized zones (88.6 km2) are the major sources of contamination in the studied area. Results of MI indicated that water of the Rosetta area was moderately affected by the metal pollution. Er values for metals in the investigated sites showed low potential ecological risk (< 40). High values of Er were observed in coastal marine water and the nearby estuary. OCPs in water and sediment samples were below the detection limits. Mean Ni and Co concentrations of metals in P. australis were higher than the critical limits of these ions. Results of BAF and regression analysis recommend using P. australis in remediation of metals from the aquatic system in such settings worldwide. The present study shows that using integrated remote sensing and chemical analyses could provide a regional and cost-effective assessment tool of environmental toxicity in fresh-saline water interface.

Assessment of heavy metal toxicity using a luminescent bacterial test based on Photobacterium sp. strain MIE

Toxicity evaluation of wastewater, polluted sediment and water streams is a very crucial aspect of environmental pollution monitoring. In this work, a newly developed luminescent bacterial test using a tropical luminescent bacterium, Photobacterium sp. strain MIE was used to assess the toxicity of several heavy metals using a 15-min assay format. The assessment was carried out by exposing strain MIE to different concentrations of heavy metals ranging from 0.001 to 200 mg/L in a DTX microplate 96 wells. The toxicity result based on the inhibitory concentration (IC50) was Hg (0.053 mg/L) > Ag (0.12 mg/L) > Cu (0.85 mg/L) > Ni (12.32 mg/L) > Zn (18.72 mg/L) > Cr (26.02 mg/L). Principal Component Analysis (PCA) and Agglomerative Hierarchical Clustering (AHC) analyses showed the sensitivity (IC50) of strain MIE to several toxic heavy metals are comparable to the commercial luminescent assay, Microtox™ as both clusters together making it a good choice for an alternative near-real-time monitoring of heavy metals. The sensitivity of strain MIE towards heavy metals was proven through field trial works on several heavy metal-polluted sites in Malaysia. Thus, it is a good candidate as an early detection system for heavy metals in aquatic bodies in tropical countries.

A mediator-free whole-cell electrochemical biosensing system for sensitive assessment of heavy metal toxicity in water.

A bioelectrochemical sensing system (BES) based on electroactive bacteria (EAB) has been used as a new and promising tool for water toxicity assessment. However, most EAB can reduce heavy metals, which usually results in low toxicity response. Herein, a starvation pre-incubation strategy was developed which successfully avoided the metal reduction during the toxicity sensing period. By integrating this starvation pre-incubation procedure with the amperometric BES, a sensitive, robust and mediator-free biosensing method for heavy metal toxicity assessment was developed. Under the optimized conditions, the IC50 (half maximal inhibitory concentration) values for Cu2+, Ni2+, Cd2+, and Cr6+ obtained were 0.35, 3.49, 6.52, 2.48 mg L-1, respectively. The measurement with real water samples also suggested this method was reliable for practical application. This work demonstrates that it is feasible to use EAB for heavy metal toxicity assessment and provides a new tool for water toxicity warning.

Distribution and assessment of heavy metal toxicity in sediment cores from Bizerte Lagoon, Tunisia.

To examine the state of pollution of Bizerte Lagoon which is exposed to intense anthropogenic pressure, two sediment cores were taken at two sites, one undergoes the dual effects of both marine waters arriving from the Mediterranean Sea through the Channel, and also of freshwater from the Tinja River; the other core is located at the center of the lagoon where water depth is maximal (12m). Heavy metal concentrations in the two cores were assessed, with calculated enrichment factors and geo-accumulation indexes. Core sediments were also studied for chemical speciation and their monosulfide contents were measured. Results from enrichment factors and geo-accumulation indexes show an accumulation of Cd, Zn, Cr, and Pb, while chemical speciation revealed a risk only from Cd and Mn. Comparison of sequential extraction values with those of acid volatile sulfides revealed that non-toxic effects may be caused by any of the studied metals in the sediment.

Nonlinear biotic ligand model for assessing alleviation effects of Ca, Mg, and K on Cd toxicity to soybean roots.

Developing a nonlinear biotic ligand model (BLM) that considers the geometrical constraints for binding of different cations on biotic ligands will provide more reliable details about the hypothetical mechanism governing the alleviation of cadmium (Cd) toxicity by coexistent cations. Soybean seedlings under Cd stress produced by various activities of coexistent cations such as calcium (Ca2+), magnesium (Mg2+), and potassium (K+) were hydroponically assayed for Cd toxicity to soybean roots. The Cd2+ activity resulting in 50% reduction of root elongation (RE), EA 50, was used for assessing the Cd toxicity to the soybean seedling. Increasing Ca2+, Mg2+, and K+ activities resulted in a significant alleviation of Cd toxicity to soybean roots. This alleviation was markedly higher with increasing Ca2+ and K+ levels than with increasing Mg2+ level. In addition, EA 50 increased in nonlinear positive relationships with Ca2+ and Mg2+. The real data obtained from the soybean assay were thus used to develop the nonlinear BLM for Cd rhizotoxicity. Two parameters, competition equivalent and stability constant, indicated the profiles of the geometrical constraint and affinity of Ca2+, Mg2+, and K+ binding on the soybean root surface to alleviate Cd toxicity. Compared with the traditional linear BLM, the nonlinear BLM provided more precise predictions of relative root elongation (RRE) and EA 50. Therefore, adopting the nonlinear BLM approach will successfully improve the monitoring and assessment of heavy metal toxicity to terrestrial plants.

Sublethal Toxicity Endpoints of Heavy Metals to the Nematode Caenorhabditis elegans.

Caenorhabditis elegans, a free-living nematode, is commonly used as a model organism in ecotoxicological studies. The current literatures have provided useful insight into the relative sensitivity of several endpoints, but few direct comparisons of multiple endpoints under a common set of experimental conditions. The objective of this study was to determine appropriate sublethal endpoints to develop an ecotoxicity screening and monitoring system. C. elegans was applied to explore the sublethal toxicity of four heavy metals (copper, zinc, cadmium and chromium). Two physiological endpoints (growth and reproduction), three behavioral endpoints (head thrash frequency, body bend frequency and feeding) and two enzymatic endpoints (acetylcholine esterase [AChE] and superoxide dismutase [SOD]) were selected for the assessment of heavy metal toxicity. The squared correlation coefficients (R2) between the responses observed and fitted by Logit function were higher than 0.90 and the RMSE were lower than 0.10, indicating a good significance statistically. There was no significant difference among the half effect concentration (EC50) endpoints in physiological and behavioral effects of the four heavy metals, indicating similar sensitivity of physiological and behavioral effects. AChE enzyme was more sensitive to copper, zinc, and cadmium than to other physiological and behavioral effects, and SOD enzyme was most sensitive to chromium. The EC50 of copper, zinc, and cadmium, to the AChE enzyme in the nematodes were 0.68 mg/L, 2.76 mg/L, and 0.92 mg/L respectively and the EC50 of chromium to the SOD enzyme in the nematode was 1.58 mg/L. The results of this study showed that there was a good concentration-response relationship between all four heavy metals and the sublethal toxicity effects to C. elegans. Considering these sublethal endpoints in terms of simplicity, accuracy, repeatability and costs of the experiments, feeding is the relatively ideal sublethal toxicity endpoint of heavy metals to C. elegans.

Risk assessment of heavy metal toxicity through contaminated vegetable from sewage water: Implications for populace health

ABSTRACTThe present investigation was carried out to evaluate the levels of metals and metalloids in okra (Abelmoschus esculentus) irrigated with city wastewater. Soil and vegetable samples from two different sites irrigated with wastewater were wet-digested and analyzed. Arsenic (As) was found higher at both sites and Cr was many-fold lower at both sampling sites. Among all heavy metals, Mn and Zn were abundant. Highest value of coefficient factor was found for Cr and the lowest for Cd. The high transfer value was recorded for Cu at site-I and for Ni at site-II. Copper and Se showed negative and significant correlations between soil and vegetable, whereas Mn, Zn, As, Cd, Cr, and Ni showed positive but non-significant correlations. Pollution load index in this vegetable was found to be higher for Cd and lower for Cu. Health risk index at site-I was in the order of As > Mn > Mo > Pb > Cd > Ni > Zn > Se > Fe > Co > Cr > Cu, whereas the same order was observed at site-II of the sampling locations. Thus, the health risks of metals through ingestion of vegetables were of great concern in the study area.