Health risk assessment of hazardous metals for population via consumption of seafood from Ogoniland, Rivers State, Nigeria; a case study of Kaa, B-Dere, and Bodo City

Evaluation and health risk assessment of arsenic and potentially toxic elements pollution in groundwater of Majha Belt, Punjab, India

Concentrations of potentially toxic elements (PTEs) like arsenic, uranium, iron, and nitrate in the groundwater of the Majha Belt (including Tarn Taran, Amritsar, Gurdaspur, and Pathankot districts) in Punjab, India were measured to evaluate the health risks associated with its consumption and daily use. The average concentrations of these elements in some locations exceeded the WHO-recommended values. Arsenic and iron toxicity levels were found to be higher in the Amritsar district, while uranium toxicity was more prevalent in Tarn Taran. The Trace Element Evaluation Index suggests that Amritsar is one of the districts most affected by toxic elements. According to the US Environmental Protection Agency's (USEPA) guidelines, the HQ values of U, Fe, and nitrate were less than one, indicating that there is no non-carcinogenic health risk for adults and children. However, the hazard quotient (HQ) value for arsenic was greater than one, indicating a higher possibility of health risk due to arsenic in the study area. The total hazard index values of 44.10% of samples were greater than four for arsenic, indicating that people in the Majha Belt are at a very high health risk due to the usage of water for drinking and domestic purposes. The cancer risk assessment values for arsenic in children (5.69E + 0) and adults (4.07E + 0) were higher than the accepted limit of USEPA (10-4 to 10-6) in the Majha Belt. The average radiological cancer risk values of U for children and adults were 8.68E-07 and 9.45E-06, respectively, which are well below the permissible limit of 1.67 × 10-4 suggested by the Atomic Energy Regulatory Board of DAE, India. The results of this study confirm that the residents of the Majha Belt who use contaminated groundwater are at a serious risk of exposure to arsenic in the Amritsar district and uranium in Tarn Taran district.

Heavy metals contamination of seafood from the crude oil-impacted Niger Delta Region of Nigeria: A systematic review and meta-analysis

This study aims at computing the pooled mean estimate (PME) and health risks of heavy metals in seafood obtained from the Niger Delta Region of Nigeria (NDRN), using data from existing literatures. Pubmed, Scopus and Google Scholar were searched to retrieve articles that investigated the heavy metal contents of edible seafood from the NDRN. Search hits were screened against predetermined criteria following which relevant data were extracted from eligible articles. The PME for each metal was computed by performing a maximum likelihood random effect model meta-analysis using the R Studio Software. Outcome from the meta-analysis involving 58 studies and a total of 2983 seafood samples revealed the following PMEs (mg/kg dry wt seafood) for the investigated heavy metals: As (0.777), Cd (0.985), Co (4.039), Cr (2.26), Cu (11.45), Fe (143.39), Hg (0.0058), Mn (13.56), Ni (5.26), Pb (4.35), and Zn (29.32). The health risk assessment suggests that seafood from this region poses considerable carcinogenic and non-carcinogenic risks to human consumers. Our finding calls for urgent actions aimed at identifying and eliminating point sources of heavy metals pollution of the NDRN marine environment. Inhabitants of NDRN are encouraged to reduce seafood consumption while diversifying their protein sources to include non-seafood options.

Phycoremediation of crude oil polluted water from selected water sources in Ogoniland, Rivers State, Nigeria

Crude oil exploitation in the Niger Delta, particularly in Ogoniland, brought environmental devastation occasioned by petroleum pollution, as farmlands and water sources were destroyed. This study was designed to remediate crude oil contaminated water obtained from water sources in Ogoniland using two green algal species. Thirty water samples were collected from eight different water sources. The samples were analysed for total petroleum hydrocarbon (TPH) using gas chromatography/flame ionization detector (GC/FID). Algal samples were collected from Ogba River and at wetland in Military Hospital Benin, Edo State, Nigeria. The algal samples were identified, screened, optimized and grown in Bold basal medium. Results obtained from the determination of TPH showed that the infiltrated pond (Exc) sample site had the highest concentration among all the sites sampled with 198.8329 μg/L, R2 with 134.1296 μg/L, R1 with 108.9394 μg/L, R3 with 105.8011 μg/L, R4 with 98.442 8 μg/L, the hand-dug wells (Wll) had 9.6586 μg/L while the borehole (Bhl) had the lowest with 1.8310 μg/L. It was deduced that pollution of water sources was principally because of pollutants washed from the soil environment into the open surface water sources via run-off rather than through the seepage from the underground aquifers, incriminating illegal oil mining and artisanal refining. Results obtained from the analysis of algal growth medium indicated that the two algal species were able to absorb the hydrocarbon contaminants, albeit at different rates, corresponding with the algal growth rate. Analysis of algal biomass after 4 weeks of remediation showed that from the initial 10.27 μg/20 mL added to the growth medium, the highest TPH mean value of 0.490 μg/20 mL was extracted from Ulothrix zonata (F.Weber & Mohr) Kützing biomass grown in Exc compared to 0.344 μg/20 mL of TPH extracted from Chlorella sorokiniana Shihira & R.W.Krauss grown in the same sample site. Also, Ulothrix zonata had higher TPH yield 0.023 μg/20 mL in Bhl compared to Chlorella sorokiniana 0.021 μg/20 mL of TPH from the same water source. This result indicated Ulothrix zonata had superior TPH phycoremediation ability to Chlorella sorokiniana. While the present study calls for deployment of the algal species for field trial, it is strongly recommended that crude oil pollution should be discouraged.

Metal bioaccumulation and genotoxicity in Oreochromis niloticus reared in farming pools influenced by mining activities in Napo, in the Ecuadorian Amazon

Mining areas may suffer long-term metal contamination and represent harmful remnants of former mining activities. In the northern Amazon of Ecuador, former mining waste pits are used in Oreochromis niloticus (Nile tilapia) fish farming. Given the high consumption of this species by the local population, we aimed to estimate human consumption risks by determining Cd, Cu, Cr, Pb, and Zn tissue bioaccumulation (liver, gills, and muscle) and genotoxicity (micronucleus essay) in tilapia cultivated in one former mining waste pit (S3) and compare the findings to tilapias reared in two non-mining areas (S1 and S2); 15 fish total. Tissue metal content was not significantly higher in S3 than in non-mining areas. Cu and Cd were higher in the gills of tilapias from S1 compared to the other study sites. Higher Cd and Zn were detected in the liver of tilapias from S1 compared to the other sampling sites. Cu was higher in the liver of fish from S1 and S2, and Cr, in the gills of fish from S1. The highest frequency of nuclear abnormalities was observed in fish from S3, indicating chronic exposure to metals at this sampling site. The consumption of fish reared at the three sampling sites results in a 200-fold higher Pb and Cd ingestion than their maximum tolerable intake thresholds. Calculated estimated weekly intakes (EWI), hazard quotients (THQ), and Carcinogenic Slope Factors (CSF_ing) denote potential human health risks, indicating the need for continuous monitoring in this area to ensure food safety not only in areas affected by mining, but in general farms in the region.

Environmental and health risks assessment of n-alkanes and BTEX in Eze Iyi River at oil spill site in Isuikwuato, Abia State, Nigeria

The environmental and health risks of n-alkanes and benzene, toluene, ethylbenzene, and xylene (BTEX) in Eze-Iyi River at Isuikwuato oil spill site were evaluated. The water samples (60) were collected from upstream and downstream during the dry and rainy seasons. Concentrations of n-alkanes and BTEX were determined using a gas chromatograph coupled with a flame ionization detector. The percentage recovery of 87.3% and 92.0% was obtained for n-alkanes and BTEX in the water sample. The environmental risk analysis for n-alkanes and BTEX showed 80% of the water samples had a ratio greater than 1 indicating environmental risk in the area. Hydrocarbon source identification using biomarkers indicates that the n-alkane (nC16) dominant during the dry and rainy seasons was from anthropogenic/biogenic source, while nC14 and nC17 were from microbial and marine algae biogenic sources, respectively. The benzene levels in 100% (downstream) and 80% (upstream) of samples in the dry season and 40% (upstream) and 100% (downstream) of samples in the rainy season were above the WHO permissible limit of 0.01 mg/L for drinking water. The health risk index of n-alkanes during the dry season for children (upstream) was greater than 1 signifying adverse health risk. Therefore, consumption of water from the river should be discouraged and routine monitoring by regulatory authorities maintained to checkmate the build-up of BTEX and n-alkanes.

Biomonitoring-Health Risk Nexus of Potentially Toxic Metals on Cerithidea obtusa: A Biomonitoring Study from Peninsular Malaysia

The present study aimed to assess the human health risks of six potentially toxic metals (PTMs) (Cd, Cu, Fe, Ni, Pb and Zn) in 21 populations of popular mangrove snails, Cerithidea obtusa, collected from Malaysia. In general, the concentrations (mg/kg wet weight) of Cd (0.03-2.32), Cu (11.4-35.2), Fe (40.9-759), Ni (0.40-6.14), Pb (0.90-13.4) and Zn (3.11-129) found in the snails in all populations were lower than the prescribed maximum permissible limits (MPL)s for Cd, Cu, Ni, Pb and Zn. However, in the investigated snail populations, Cd (14%), Pb (62%), Cu (19%), and Zn (10%) were found in exceedance of the MPL of the respective metal. The target hazard quotient (THQ) values in all populations for Cu, Ni, Fe and Zn were all found to be below 1.00. However, for the THQ values of Cd and Pb, two populations exceeded 1.00, while others were below the threshold level. The estimated weekly intake (EWI) of all six metals for all populations was only 0.03-4.65% of the provisional tolerable weekly intake. This conclusively indicates that, based on the EWI, there are no health risks of the six PTMs in the consumption of snails from Malaysia since the assessments are dependent on the consumers' body weight and consumption rate. Nonetheless, the present results indicate that the amounts of snails consumed should be limited to minimize the potential health risks of PTMs to consumers. The relatively low and weak but positive correlations of Cu, Ni, Pb and Zn between C. obtusa and their habitat sediments indicate that C. obtusa can be a potential biomonitor for Cu, Ni, Pb and Zn. This is important for effective mangrove management from the perspective of the sustainable resources from the intertidal mangrove environment. Hence, the biomonitoring-health risk nexus of PTMs in mangrove snails is proposed in the present study.

Histopathological and health risk assessment of heavy metals in the straw-colored fruit bat, Eidolon helvum, in Nigeria

There is heightening concern regarding heavy metals environmental pollution requiring renewed global attention because of their bioaccumulation and toxicity at varying levels. The concern is most important in the highly migratory Eidolon helvum (E. helvum) that is very common and traverses wide geographical areas within the sub-Saharan Africa. The present study aimed to evaluate levels of cadmium (Cd), lead (Pb), and zinc (Zn) bioaccumulation in 24 E. helvum of both sexes from Nigeria to assess their indirect health risks to the human consumers of the bats in addition to their direct bioaccumulation and toxic damages in the bats themselves based on standard procedures. Lead, Zn, and Cd bioaccumulation concentrations were 2.83 ± 0.35, 0.42 ± 0.03, and 0.05 ± 0.01 mg/kg, respectively, with significant (p < 0.05) Pb bioaccumulation compared to either Cd or Zn in the affected bats. However, only Pb (markedly) and Cd (marginally) bioaccumulated above small mammals' critical threshold levels as there are no existing established threshold levels for bats. Sex played no major role in their bioaccumulation levels. The bioaccumulation levels posed no life-long non-carcinogenic nor carcinogenic risks to the human consumers of the bats at detected concentrations. The observed lungs, liver, and kidney histopathological changes suggested the possible direct effects of the metals in the bats. Nevertheless, other anthropogenic factors might be responsible as no significant (p > 0.05) correlation existed between cellular changes and the bioaccumulation levels. The presence of the heavy metals and their bioaccumulations above critical threshold levels suggested some levels of environmental contamination and pollution, which might have direct and indirect health implications to the bats and their human consumers.

The concentration of potentially toxic elements (PTEs) in drinking water from Shiraz, Iran: a health risk assessment of samples

The existence of potentially toxic elements (PTEs) in water bodies has posed a menace to human health. Thus, water resources should be protected from PTEs, and their effect on the exposed population should be investigated. In the present investigation, the concentrations of PTEs such as lead (Pb), mercury (Hg), manganese (Mn), and iron(Fe) in the drinking water of Shiraz, Iran, were determined for the first time. In addition, hazard quotient, hazard index, cancer risk, and sensitivity analysis were applied to estimate the noncarcinogenic and carcinogenic impacts of Pb, Hg, Mn, and Fe on exposed children and adults through ingestion. The mean concentrations (µg/L) of Pb, Hg, Mn, and Fe were 0.36, 0.32, 2.28, and 8.72, respectively, in winter and 0.50, 0.20, 0.55, and 10.36, respectively, in summer. The results displayed that Fe concentration was more than the other PTEs. PTE concentrations were lower than the standard values of the Environment Protection Agency and World Health Organization. Values of the degree of contamination and heavy metal pollution index for lead, mercury, manganese, and iron were significantly low (< 1) and excellent (< 50), respectively. Based on the Spearman rank correlation analysis, positive and negative relationships were observed in the present study. The observations of the health risk assessment demonstrated that mercury, lead, iron, and manganese had an acceptable level of noncarcinogenic harmful health risk in exposed children and adults (hazard quotients < 1 and hazard index < 1). The carcinogenic risk of lead was low (< E - 06), which can be neglected. Monte Carlo simulation showed that water intake rate and mercury concentration were the most critical parameters in the hazard index for children and adults. Lead concentration was also the most crucial factor in the cancer risk analysis. The results of the present study proved that the drinking water of Shiraz is safe and healthy and can be confidently consumed by people.

Bioaccumulation and human health risk assessment of some heavy metals in sediments, Sparus aurata and Salicornia europaea in Güllük Lagoon, the south of Aegean Sea

In the current study, it was aimed to determine the sediment in Sparus aurata (Linnaeus 1758) tissues and Salicornia europaea L. Cu, Zn Fe, Hg, Cd, Pb and Mn concentration distributions in Güllük Lagoon which is located in the south of Aegean Sea and under the influence of anthropogenic activities by means of metal pollution and health indices and to investigate the effects of these metals on public health. The concentration range of Cu, Zn, Fe, Hg, Cd, Pb and Mn in sediment samples was determined as 12.16-26.00, 1.62-2.03, 7.77-8.36, 7.52-16.15, 0.071-0.40, 7.99-13.74 and 12.11-12.63 mg kg^-1, respectively. Cu and Hg concentrations in sediment were found to be higher than sediment quality guidelines standards. In addition, according to the enrichment factor (EF), Hg, Cd and Cu were found to show above moderate enrichment. Cu, Zn, Fe, Hg, Cd and Mn concentrations in S. aurata muscle tissue were 1.31 ± 2.30, 1.01 ± 0.24, 3.43 ± 0.75, 2.79 ± 0.85, 0.01 ± 0.01 and 1.80 ± 1.12 mg kg^-1, respectively. S. europaea heavy metals (HMs) concentrations were determined as Cu = 10.97 ± 3.20, Zn = 0.74 ± 0.62, Fe = 5.69 ± 0.22, Hg = 9.62 ± 8.84, Cd = 0.53 ± 0.33, Pb = 0.22 ± 0.26 and Mn = 8.61 ± 0.14 mg kg^-1. It was seen that Hg in S. aurata muscle tissue and Hg in S. europaea concentrations exceeded the limit values determined for consumption purposes. Target hazard quotient (THQ) and total target hazard quotient (TTHQ) values were found to be < 1 for S. aurata and S. europaea. When all these results were considered, it was determined that the metals that could pose a potential ecological and health risk were Hg, Cd and Cu in the study area.

Seasonal hydrocarbon and metal assessment of water and fish from oil producing communities along Orashi River, Nigeria

This study investigated the heavy metal and hydrocarbon pollution status of Orashi River in four communities of Imo and Anambra States of Nigeria. Water and fish (Oreochromis niloticus and Clarias gariepinus) samples were collected from the river in the dry and wet seasons. Hydrocarbon and physicochemical parameters were determined in water with standard methods. Water and fish muscles were digested and analysed for metals using atomic absorption spectrophotometry. Results of analyses indicated hydrocarbon pollution. Hardness, alkalinity, nitrate, chloride, phosphate, and sulphate were significantly higher (p < 0.05) in wet season samples. Arsenic was undetected in water samples, but higher cadmium and iron concentrations were recorded in the wet season samples. Lead concentrations in the wet season were higher at some sites than the World Health Organization guideline. Arsenic was detected in Clarias at three sites in both seasons, but iron concentrations were significantly higher (p < 0.05) than those of other metals. Lead concentrations in Clarias gariepinus were lower than the Codex limit (0.3 mg/kg) except in the muscle samples from four sites. Arsenic was undetected in Oreochromis niloticus muscle samples but concentrations for lead (0.851 ± 0.203-8.604 ± 1.264 mg/kg (dry season) and 0.627 ± 0.035-9.364 ± 0.786 mg/kg (wet season)) exceeded the Codex limits in all samples. Health risk indices for the species indicated potential risk to the population from the consumption of Oreochromis niloticus. However, hazard index and target carcinogenic risk values indicate that people in the communities do not face significant non-carcinogenic and carcinogenic risks from cadmium and lead intake by consuming the fish species.

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.

Heavy Metals and Health Risks Associated with Consumption of Herbal Plants Sold in a Major Urban Market in Southwest, Nigeria

BACKGROUND

Although herbal medicines play an important role as a source of medicine, concerns have been raised about the risks posed by consumption of these plants, especially if consumed above permissible levels.

OBJECTIVES

This study was undertaken to assess the level of exposure, toxicity and health risk associated with the consumption of herbal plants in Ado Ekiti urban market, Nigeria.

METHODS

Ten commonly consumed herbal plants sold in Ado Ekiti urban market were subjected to heavy metal analysis. Health risk assessment was carried out to determine the estimated daily intake (EDI) of heavy metals, health risk index (HRI), target hazard quotient for non-carcinogenic risk and estimation of cancer risk (ECR).

RESULTS

The EDIs for lead (Pb), nickel (Ni), chromium (Cr), copper (Cu) and magnesium (Mn) were above the upper tolerable daily intake reference for all studied plant species in both children and adults, an indication that herbal use poses a short-term to long-term health risk to consumers of these herbal products. The EDI for children was significantly lower compared to that of adults, indicating higher risks for adult consumers of these herbal products. The HRI in children for Pb (Alstonia congensis, Terminalia avicennioides, Aframomum melegueta, Cymbopogon citratus and Napoleona vogelii) were greater than 1; HRI in Cu and Mn also showed an unusually high concentration, an indication that long term exposure to the consumption of these herbal plants poses a serious health risk. The HRI in children and adults follows the order Mn > Cu > Ni > Pb > Cr; cadmium (Cd) was not detected in any of the herbal plants. The ECR for Pb, Ni and Cr present in the herbal plants for children ranged between 10-6 (low) to 10-3 (high), while the ECR for Pb, Ni and Cr for herbal plants for adults ranged between 10-5 (acceptable) to 10-2 (unacceptable). For both children and adults, there is a call for concern due to ECRs above the acceptable range; the consumption of these herbal plants poses a long-term cancer risk.

CONCLUSIONS

In both children and adults, ECRs for some of the herbal plants in the present study above the acceptable range present a risk to human health. The consumption of such herbal plants poses a long-term cancer risk.

COMPETING INTERESTS

The authors declare no competing financial interests.

Environmental health risk assessment of heavy metal exposure among children living in an informal e-waste processing village in Viet Nam

This study was conducted to compare the exposure levels of five heavy metals via different pathways based on the field samplings and questionnaire surveys of children residing in an informal e-waste processing village and a reference village in Viet Nam. The findings revealed that levels of the total average daily intake (ADI) of the five heavy metals collected from a child at the exposed village were 3.90 times higher (p < 0.01) than that of a child at the reference village. Ingestion of cooked rice was the largest contributor to the total ADI of the children tested at both villages. However, the risks from water drinking and dermal contact of soil were negligible. The total non-carcinogenic risk and carcinogenic risk in an exposed child were significantly higher (p < 0.01) than their respective risks in a reference child. The non-carcinogenic risk to an exposed child was likely to occur, while the risk to a reference child was negligible. The carcinogenic risks found in children from both of the villages, however, were higher than the acceptable values, indicating the potential health risks to the children from both villages. The susceptibility of children to heavy metal contaminations shown in this study suggests that a mitigating measure need to be initiated jointly by a public agency and a private organization to prevent children from the risks of being exposed to the contaminants.

Elevated Concentrations of Metal(loids) in Seaweed and the Concomitant Exposure to Humans

While the consumption of seaweed and seaweed-based products is very common amongst East Asian nations, forming a notable component of the daily diet, relatively very few studies have concerned the concentrations of heavy metals in these together with potential effects on human health. The present study analyses the concentrations of 17 elements in locally resourced seaweed, also assessing potential noncarcinogenic and carcinogenic risks. The samples were ground, homogenized, and quantified using the ICP-OES technique. It has been found that the essential elements K, Ca, Mg, Zn, and Na typically show concentrations somewhat greater than a number of potentially toxic metals, in particular, Cd, Pb, Ag, and As, with exceptions being Ni, Cr-VI, and Si. Statistical analysis indicates all of the latter to have similar origin, with increased concentration of these metals within the marine ecosystem. While the daily estimated intake of most metals is seen to be within the daily dietary allowance level recommended by various international organizations, the noncarcinogenic risk shows a value greater than unity, estimated via the hazard quotient. This indicates a potential for adverse effects to health arising from consumption of the sampled seaweed. The carcinogenic risk resulting from nonessential elements shows values greater than the United States Environmental Protection Agency (US-EPA) reference limit of 10-4. Considering the nonbiodegradability of heavy metals and metalloids and their potential accumulation in seaweed, there is need for critical examination of metal levels in the seaweeds obtained from the present study locations, together with the introduction of practices of removal of heavy metals via bio-adsorbent techniques.

Ethanol exacerbates manganese-induced oxidative/nitrosative stress, pro-inflammatory cytokines, nuclear factor-κB activation, and apoptosis induction in rat cerebellar cortex

Manganese (Mn) exposure is causing public health concerns as well as heavy alcohol consumption. This study investigates the mechanisms of neurotoxicity associated with Mn and ethanol (EtOH) exposure in the rat cerebellar cortex. Experimental animals received 30 mg/kg of Mn alone, 5 g/kg of EtOH alone, co-exposed with 30 mg/kg of Mn and 1.25 or 5 g/kg EtOH, while control animals received water by oral gavage for 35 days. Subsequently, alterations in the neuronal morphology of the cerebellar cortex, oxidative/nitrosative stress, acetylcholinesterase (AChE) activity, neuro-inflammation and protein expression of p53, BAX, caspase-3, and BCL-2 were investigated. The results indicate that Mn alone and EtOH alone induce neuronal alterations in the cerebellar cortex, decrease glutathione level and antioxidant enzyme activities, along with an increase in AChE activity, lipid peroxidation, and hydrogen peroxide generation. Mn alone and EtOH alone also increased neuro-inflammatory markers, namely nitric oxide, myeloperoxidase activity, interleukin-1β, tumor necrosis factor-α, and nuclear factor-κB (NF-κB) levels in the cerebellar cortex. Immunohistochemistry analysis further revealed that exposure of Mn alone and EtOH alone increases the protein expression of cyclooxygenase-2, BAX, p53, and caspase-3 and decrease BCL-2 in the rat cerebellar cortex. Furthermore, the results indicated that Mn co-exposure with EtOH at 1.25 and 5 g/kg EtOH significantly (p ≤ .05) increases the toxicity in the cerebellum when compared with the toxicity of Mn or EtOH alone. Taken together, co-exposure of Mn and EtOH exacerbates neuronal alterations, oxidative/nitrosative stress, AChE activity, pro-inflammatory cytokines, NF-κB signal transcription, and apoptosis induction in the rat cerebellar cortex.

Trace metal toxicity in some food items in three major markets in Ado-Odo/Ota LGA, Ogun State, Nigeria and associated health implications

BACKGROUND

Many of the markets in Nigeria are open, where foodstuffs are laid bare on flat trays and open baskets, directly exposing them to environmental contaminants. This study aimed at determining whether some food items on sale around an industrialized area of Ogun State are contaminated with trace metals.

METHODS

Seven different food items - Clarias gariepinus (roasted, fresh and smoked) Bos taurus (dried and fresh beef), zobo leaf (Hibiscus sabdariffa) and crayfish (Astacus leptodactylus) were sampled from three major markets, namely: Lusada, Atan and Ota in Ado-Odo/Ota LGA of Ogun State. They were analyzed for Lead, Cadmium, Nickel, Manganese and Zinc using Atomic Absorption Spectroscopy.

RESULTS

Cd was not detected in most of the food items across the markets. Pb, Ni and Mn were detected in very high concentrations above the maximum allowable limits by international regulatory agencies. Zn was the only metal that was generally below regulatory limits in food items across the three markets. The Estimated Daily Intake (EDI) and Target Hazard Quotient (THQ) values were generally higher than values acceptable in food.

CONCLUSION

Some of the food items consumed in this area are not entirely safe from metal toxicity and this may have serious health consequences.

Heavy Metals Bioaccumulation and Health Risks with Associated Histopathological Changes in Clarias gariepinus from the Kado Fish Market, Abuja, Nigeria

BACKGROUND

Aquatic pollution by heavy metals has become a global problem and is of great concern due to the detrimental effects on aquatic ecosystems and possible human uptake.

OBJECTIVES

The present study aimed to evaluate tissue bioaccumulations of heavy metals and possible human health risks in addition to associated cellular damages in fish for sale in a fish market in Abuja, Nigeria.

METHODS

Clarias gariepinus sold at the Kado Fish Market in Abuja, Nigeria, in March-April 2017 and March-April 2018 were randomly purchased and sampled. The heavy metal contents of the sampled fish were assayed and used to assess the extent of potential health risks to human consumers. The extent of histopathological changes associated with the bioaccumulations in the sampled fish were also evaluated according to standard procedures.

RESULTS

Levels of most heavy metals were above permissible limits, except for lower levels of zinc (Zn) in liver and muscle and higher levels of lead (Pb) in muscle in the sampled fish. Similarly, significant (p<0.05) liver bioaccumulation occurred for Zinc (Zn), chromium (Cr), iron (Fe), and copper (Cu) compared to their levels in muscle. The total hazard index (non-cancer risk across all metals) was 0.0415, which is very low and acceptable. The cancer risks ranged between the acceptable values of 1.98 × 10^-5 - 3.71 × 10^-6. Associated histopathological changes, which occurred in the sampled fish, differed between the various assayed tissues.

CONCLUSIONS

Most of the heavy metals were significantly bioaccumulated (p<0.05) and were above the permissible levels, particularly in liver samples. The levels of muscle heavy metal bioaccumulation in the sampled fish posed no apparent cancer or non-cancer health risks to human consumers. However, further efforts are needed to minimize heavy metal aquatic environmental pollution to safeguard the health of aquatic flora and fauna and human consumers because of the tendency of these pollutants to persist and bioaccumulate to toxic levels over time.

COMPETING INTERESTS

The authors declare no competing financial interests.

Sentinel species for biomonitoring and biosurveillance of environmental heavy metals in Nigeria

Nigeria receives copious annual precipitation to nourish its forests and agriculture, it has an extensive river drainage system, and it possesses valuable mineral deposits that stimulate both commercial and artisan mining activities. The combination of these features complicates Nigeria's efforts to produce adequate amounts of healthy foods to support its population. Toxic heavy metals like lead, cadmium, and mercury, and toxic metalloids such as arsenic, are also present in its mineral deposits and they migrate gradually into the soil and water of Nigeria by natural means. However, mining activities can liberate higher levels of toxic metals, which adversely affect Nigerian ecosystems and its food chains. Thus, environmental pollution due to anthropogenic activities is a major public health concern in Nigeria. This review covers the importance of native Nigerian and African wild and cultivated plants along with livestock and wild animals as sentinel species to evaluate heavy metals as environmental stressors and the use of sentinel species for food safety monitoring and for predicting potential risks to human health.

A Review of the Health Implications of Heavy Metals in Food Chain in Nigeria

Heavy metals such as Zn, Pb, Fe, and Cu are abundant in the environment and contribute largely to the sustainability and equilibrium of ecosystem processes. However, because of their bioaccumulation, nondegradability, and the excessive amounts in which they exist, these metals contaminate the food chain and subsequently become a source of toxicity to human beings and the entire ecological function. This is a major issue of concern within the study of environmental science and geochemistry. Although there is a global significance to the issue, it seems more immediate for the developing countries (DCs) such as Nigeria, where the pressure of the teeming population escalates the exigency for human sustainability, food security, and total eradication of hunger. Within the Nigerian context, many studies have examined this all-important issue, but most of these studies are fragmented and limited within the purview of mostly individual states and localities within the country. Taken on a wider geographical scale, the discussions and perspectives of these studies on heavy metal contamination of the food chain offer insufficient insight and expose merely a snapshot of the actual situation. As a result of this, a country-wide knowledge base of the implications of heavy metals on the food chain is lacking. Thus, the present study synthesises existing literature and their findings to create a knowledge base on the vulnerability of the food chain in Nigeria. Aquatic foods, fruits, vegetables, and major staple food such as tubers are the major host of carcinogenic and mutagenic components of heavy metals in Nigeria. This study motivates the Standard Organisation of Nigeria (SON), along with other food and agricultural agencies, to intensify their efforts in monitoring and analysing food components, and we advise consumers to eat with certain degrees of caveat.

Toenail Metal Exposures in Fishermen from Bodo City, Nigeria

We conducted exposure assessment using toenails from 20 fishermen living in Bodo City, a community of the Niger delta region in Nigeria. This community has been affected by over 4000 oil spills and environmental disasters. Fishing is the primary source of food and income for individuals in this community. Previous research in Bodo City found elevated metal levels in fish. Toenails were used as a biomarker to investigate the feasibility for use in risk assessment studies in developing countries. The toenails collected had significantly higher manganese levels (median 5.8 µg/g) and lead levels (median 0.98 µg/g) than those reported in more developed countries, comparable levels to those from other low-middle incomes countries. These exposure levels are likely a direct result of exposures from the environmental disasters the community has experienced and would be related to increased risks for many diseases previously associated with heavy metal exposures.

Exposure to Heavy Metals in Soot Samples and Cancer Risk Assessment in Port Harcourt, Nigeria

BACKGROUND

Port Harcourt is an oil-rich city in Nigeria's Niger delta region. For over two years, Port Harcourt experienced black soot deposition in the environment. In November 2016, residents woke up to black soot covering cars, clothes, houses, plants, etc. Soot concentrations continued to increase until the first quarter of 2017. After public outcry, the frequency and concentration of soot deposition began to decline.

OBJECTIVE

The present study was carried out to determine the presence and levels of heavy metals in soot along with a cancer risk assessment of heavy metals exposure in Port Harcourt, Nigeria.

METHOD

Three residential locations were sampled: Aba road, Woji and Iwofe. Sampling was performed from 6:00 am to 6:00 pm, to simulate the estimated duration that most residents who do not work in offices are exposed to soot in places such as the open market and business areas. Five heavy metals (iron (Fe), nickel (Ni), chromium (Cr), cadmium (Cd) and lead (Pb)) were investigated. The data obtained were subjected to Pearson correlation and one-way analysis of variance using SPSS software to test the correlation and significant differences between metals concentrations.

RESULTS

Lead was found to have a significant correlation with Cd (0.808), indicating that both metals originated from the same source. Concentrations of heavy metals were higher than control values and the World Health Organization's specifications for ambient air. Chromium concentrations were the lowest. The order of concentration of heavy metals was Fe > Pb > Cd > Ni > Cr.

CONCLUSIONS

Non-carcinogenic and carcinogenic health risks of these heavy metals were evaluated using the target hazard quotient (THQ) and the incremental lifetime cancer risk (ILCR). Obtained ILCR values were within the acceptable limits for cancer risks. However, the total ILCR values for Cd and Pb for children were 3 times higher than those for adults. This is a source of concern as their prevalence in ambient air puts children and residents in Port Harcourt metropolis at risk of various types of cancers.

COMPETING INTERESTS

The authors declare no competing financial interests.

Ethanol Exacerbates Manganese-Induced Neurobehavioral Deficits, Striatal Oxidative Stress, and Apoptosis Via Regulation of p53, Caspase-3, and Bax/Bcl-2 Ratio-Dependent Pathway

This study investigated the effects of ethanol (EtOH) on manganese (Mn)-induced striatal toxicity in rat by evaluating the neurobehavioral changes, biochemical and molecular events in rats exposed to Mn alone at 30 mg/kg, or their combination with EtOH at 1.25- and 5-g/kg body weight for 35 consecutive days. Locomotive and exploratory profiles were assessed using a video tracking software (ANY-Maze software) during a 5-min trial in a novel environment. Subsequently, acetylcholinesterase (AChE) activity, oxidative stress markers, histological morphology, and expression of apoptotic proteins (p53 and Bax and caspase-3) and anti-apoptotic protein (Bcl-2) were assessed in the striatum. Results showed that Mn, EtOH, and their combination induced locomotor and motor deficits. Track plot analysis indicated that EtOH exacerbated the Mn-induced reduction in exploratory profiles of exposed rats. Similarly, exposure of rats to Mn, EtOH, or combination of Mn and EtOH resulted in decreased activities of anti-oxidant enzymes, diminished level of reduced glutathione, downregulated Bcl-2 expression, increased AChE activity, enhanced hydrogen peroxide and lipid peroxidation levels, and upregulated expressions of p53, Bax, and caspase-3. Moreover, potentiation of Mn-induced striatal toxicity by EtOH co-exposure was dose dependent. Taken together, it seems that EtOH exacerbates Mn-induced neurobehavioral deficits, oxidative stress, and apoptosis induction via the regulation of p53, caspase-3, and Bax/Bcl-2 ratio-dependent pathway in rat striatum.

Ethanol via Regulation of NF-κB/p53 Signaling Pathway Increases Manganese-Induced Inflammation and Apoptosis in Hypothalamus of Rats

The diet is a major route of manganese (Mn) exposure for humans. Interestingly, several epidemiological data demonstrated an increase in the incidence of alcohol consumption globally. Chemical-chemical interaction subsequent to chemical mixtures exposure may result in a synergism or antagonism effects. The present study investigated the influence of co-exposure to ethanol (EtOH) and Mn on inflammation and apoptosis in the hypothalamus of rats. The study consisted of five groups of rats that were exposed to drinking water alone, EtOH alone at 5 g/kg, Mn alone at 30 mg/kg or co-expose with EtOH at 1.25 and 5 g/kg body weight by oral gavage for 35 consecutive days. The results indicated that the significant (p < 0.05) increases in pro-inflammatory cytokines, namely tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) as well as cyclooxygenase-2 (COX-2) and nuclear factor kappa B (NF-κB) activation in the hypothalamus following individual exposure to Mn and EtOH to rats were intensified in the co-exposure group. Moreover, immunohistochemistry analysis showed marked decrease in B cell lymphoma-2 (Bcl-2) protein expression as well as the increases in the apoptotic proteins, namely Bax and caspase-3 along with p53 in the hypothalamus of rats treated with Mn or EtOH alone were intensified in the co-exposure group. Taken together, these findings highlight that EtOH exacerbated the induction of inflammatory and apoptotic biomarkers via regulation of NF-κB/p53 signaling pathways in the hypothalamus of rats. These alterations may have profound disrupting effects on the hypothalamus functions such as impairment of it metabolic and autonomic nervous system functions.

Levels of Some Heavy Metals and Health Risks Assessment of Three Different Species of Catfishes in Ikoli Creek, Bayelsa State, Nigeria

Heavy metals are the most common form of aquatic pollutants and are of great health risk to consumers of contaminated sea food. This study investigated the level of heavy metals in three species of catfishes Chrysichthys nigrodigitatus (marine catfish), Clarias gariepinus (African catfish), and Schilbe mystus (silver catfish) in Ikoli Creek, Bayelsa State. The potential human health risks to consumers in the study area were investigated. The heavy metal concentration in the three species of catfishes was found in the following order: Fe > Zn > Cr > Pb > Cd. The levels were below WHO/FAO guideline, except for Fe having the highest value of 88.23 ± 0.09 mg/kg in C. gariepinus, 85.54 ± 0.26 mg/kg in S. mystus, and 66.36 ± 0.10 mg/kg in C. nigrodigitatus, which were above the acceptable regulatory limits in the fishes. The Chronic Daily Intake (CDI) values of all the metals were lower than the USEPA-recommended limits except for Cd in C. nigrodigitatus, C. gariepinus, and S. mystus. The Target Hazard Quotient for C. nigrodigitatus, C. gariepinus, and S. mystus was > 1. Life Cancer Risk from the consumption of Cr in C. nigrodigitatus and S. mystus was 1.65E-03 and 8.11E-04, indicating a probable risk of one chance of cancer for the populace that consumed fishes obtained from Ikoli creek. Heavy metal contamination of fishes caught in Ikoli creek may pose a health risk to the local populace via consumption of fishes.

Rutin abrogates manganese-Induced striatal and hippocampal toxicity via inhibition of iron depletion, oxidative stress, inflammation and suppressing the NF-κB signaling pathway

Excess exposure to Manganese (Mn) promotes oxidative stress and neuro-inflammation. Rutin (RUT) has been found to exhibit both anti-oxidative stress and anti-inflammatory properties. This study aimed to investigate the effects of RUT on Mn accumulation, endogenous iron (Fe) depletion, oxidative stress, inflammation and nuclear factor kappa B (NF-κB) signaling pathways in the hippocampus and striatum of Mn - induced rats. Rats were treated with 30 mg/kg Mn body weight alone or orally co-treated by gavage with RUT at 50 and at 100 mg/kg body weight for 35 consecutive days. Thereafter, we investigated Mn and endogenous Fe levels, acetylcholinesterase activity, oxidative stress markers, pro-inflammatory cytokines and nuclear factor kappa B (NF-κB) in the hippocampus and striatum of rats. The results indicate that Mn induced Mn - accumulation, Fe depletion, oxidative stress, inflammation and the activation of acetylcholinesterase activity and NF-κB signaling pathways in the hippocampus and striatum of the rats. However, RUT attenuated Fe depletion, oxidative stress and inflammation and suppressed acetylcholinesterase activity and NF-κB pathway via downstream regulations of tumor necrosis factor alpha, interleukin I beta and interleukin 6. Taken together, our present study demonstrates that RUT abrogates Mn - induced striatal and hippocampal toxicity via inhibition of Fe depletion, oxidative stress, inflammation and suppressing the NF-κB signaling pathways. Our results indicate that RUT may be of use as a neuroprotective agent against Mn - induced neuronal toxicity.

Potential Human Health Risk Assessment of Heavy Metals via Consumption of Root Tubers from Ogoniland, Rivers State, Nigeria

This study was designed to investigate the concentration of heavy metals and their associated human health risk via consumption of root tubers cultivated in three major communities in Ogoniland, Rivers State, Nigeria. The concentration of heavy metals, especially, Cr and Pb in soil, indicates a moderate contamination (˃ 1.00 mg/kg) level. The concentrations of heavy metals in the root tubers Manihot esculenta, Colocasia esculenta, and Dioscorea alata harvested from Choba, Kpean, and Bodo City ranged from 0.20 ± 0.01-0.84 ± 0.04, 0.01 ± 0.001-0.09 ± 0.02, 0.01 ± 0.002-0.63 ± 0.04, 2.11 ± 0.03-11.8 ± 2.12, and 6.30 ± 1.18-118.6 ± 0.19 mg/kg for Cr, Pb, Ni, Mn, and Fe respectively, while Cd had the same value of 0.01 ± 0.001 mg/kg in the three samples across the three sites. The bio-accumulation factor (BAF) for Cd was ˃ 1. The estimated daily intake were below the FAO/WHO permissible limit, while the target hazard quotient (THQ) has a trend of Mn> Fe> Pb> Cd> Ni> Cr, and were ˂ 1 for all the sampling areas. The HI values for M. esculenta for children in Choba, Kpean, and Bodo City were ˃ 1, indicating that children among the local populace were susceptible to heavy metals health risks. The carcinogenic risk (CR) value of Cr indicates that there was appreciable lifetime cancer risk for Cr as the CR value in all the sampling sites were ˃ 10^-4. Furthermore, CR values of Ni and Cd were also within the predicted lifetime risks of carcinogens. Heavy metal contamination of root tubers cultivated in Ogoniland may posed a great health risk to local populace especially for children via consumption of root tubers.

Validation of x-ray fluorescence measurements of metals in toenail clippings against inductively coupled plasma mass spectrometry in a Nigerian population<sup/>

OBJECTIVE

Metal exposures have been linked with many adverse health outcomes affecting nearly every system in the body. Exposure to metals has been tracked primarily using blood. Blood metal concentrations have drawbacks as biomarkers stemming from the metals' short biologic half-lives, shipping and storage requirements, and invasive collection procedures. Toenails, which capture a longer exposure period, can be collected non-invasively and stored at room temperature, and can be more feasible and cost-effective for large-scale population studies.

APPROACH

Inductively coupled plasma mass spectrometry (ICP-MS) has been used for analysis of toenail metal concentrations, but x-ray fluorescence (XRF) has many advantages in versatility and cost effectiveness over these analyses. This study compared toenail concentrations of manganese (Mn) and lead (Pb) measured with XRF against ICP-MS, in samples collected from 20 adults in Nigeria. To do this we developed a novel calibration method that corrects XRF measurements for toenail weight and thickness to reduce the variability in XRF measurements of toenail clippings.

MAIN RESULTS

We found a high correlation (R  =  0.91) between toenail manganese metal measurements made with XRF and ICP-MS and a correlation of (R  =  0.32) between toenail lead XRF and ICP-MS with over half of the lead results below the detection limit of the instrumentation.

SIGNIFICANCE

XRF can be used effectively to quantify metals at the part per million level or lower depending on the XRF equipment used in the measurements.

Heavy metal contamination in the muscle of Aegean chub (Squalius fellowesii) and potential risk assessment

Especially after the industrial revolution, the amount of contaminants released in aquatic ecosystems has considerably increased. For this reason, the necessity to carry on research on the existence of contaminants, specifically heavy metals, has emerged. In this study, heavy metal concentrations in muscle tissues of Aegean chub, which was an endemic species of south western part of Turkey, gathered from Tersakan River were examined. Heavy metal concentrations of the samples were analyzed with ICP-MS. Estimated daily intakes (EDI), target hazard quotient (THQ), and carcinogenic risk (CR) of elements were calculated. The heavy metals detected in muscle tissues were Zn > Cu > Cr > Mn > Pb > Cd, consecutively. According to the results of the applied health risk assessment (EDI, THQ and CR) for heavy metal exposure from fish consumption in children and adults, it was determined that there was no any significant threat to human health.

Biomarkers of oxidative stress and health risk assessment of heavy metal contaminated aquatic and terrestrial organisms by oil extraction industry in Ogale, Nigeria

Ogale community in Rivers State, Nigeria is characterized by crude-oil contamination of its land resources. The present study aimed to evaluate the health risk and metal (Cd, Pb, Zn, Cr, and Ni) contamination level of the vegetable (Telfairia occidentalis), snail (Achatina achatina) and the catfish (Clarias gariepinus) collected from Ogale community. Samples collected from Elele Alimini community, a less polluted area was used as control. Oxidative damage was evaluated in tissues of snail and in the liver of catfish. The concentration of most of the tested metals in the food samples collected from the polluted sites were higher than those from the reference sites and in most cases exceeded the acceptable permissible limits. The accumulation of the metals by the food samples followed the order: T. occidentalis > A. achatina > C. gariepinus. The tissues of the snail from the polluted sites showed higher malondialdehyde (MDA) and lower glutathione (GSH) levels, and higher MDA and GSH levels in the fish liver compared to control values. The health risks associated with these metals in terms of dietary intake and target hazard quotients (THQs) showed higher non-carcinogenic effect and carcinogenic risks especially for Pb and Cd from the ingestion of Telfairia occidentalis and Achatina achatina from polluted sites. The health hazards due to metal pollution for the highly-exposed consumers of the food samples, especially in Ogale require attention. The oxidative stress response to accumulation status of metals provides a relevant tool for the assessment of metal pollution.

Vortex-assisted ionic liquid-based dispersive liquid-liquid microextraction for assessment of chromium species in artificial saliva extract of different chewing tobacco products

A novel dispersive liquid-liquid microextraction (ILDLLμE) method using an extracting solvent (ionic liquid) and dispersant (Triton X-114) was developed for the separation and preconcentration of hexavalent chromium (Cr⁶⁺) in artificial saliva extract (ASE) of chewing tobacco products, gutkha, and mainpuri (n = 23). In the proposed method, the extraction of Cr⁶⁺ was accomplished by using ammonium pyrrolidinedithiocarbamate (APDC) as complexing agent and 1-butyl-3-methylimidazolium hexafluorophosphate [C₄MIM] [PF₆] as extracting solvent. The tiny droplet of metal chelate was then dispersed into TX-114 emulsion, using vortex mixer. Various parameters such as concentration of APDC, pH of the solution, volume of [C₄MIM] [PF₆], and TX-114 as well as extraction time were studied. Under the most favorable conditions, the limit of detection was found to be 0.068 μg/L with the relative standard deviation <5 %. The enrichment factor of developed method was found as 62.5, and method has been effectively applied for the analysis of Cr species in artificial saliva extract of gutkha and mainpuri products. The Cr⁶⁺ was quantitatively recovered (<97 %) under optimal conditions, while the recovery of trivalent specie (Cr³⁺), at the same experimental conditions, was observed to be <5 %. The Cr³⁺ was determined by the difference of total Cr and Cr⁶⁺ in artificial saliva extract of selected STP. Health risks associated with the intake of total Cr in gutkha and mainpuri were assessed in terms of estimated daily intake, such as carcinogenic and noncarcinogenic risks. Estimated daily intake of Cr via chewing 10 g/day of gutkha and mainpuri was found to be below the maximum tolerable daily intake, whereas the calculated risk of cancer for Cr was observed in the acceptable range of 10E^-6-10E^-4, except some brands of gutkha. Graphical Abstract ᅟ.

The effects of arsenic contaminated drinking water of livestock on its total levels in milk samples of different cattle: Risk assessment in children

This work was carried out to evaluate the arsenic (As) levels in milk samples of different milch animals, sheep, goats, cows, buffaloes and camels in Tharparkar, Pakistan. The concentration of As in the milk samples of cows, buffalos, sheep, goats and camels were observed in the range of 15.1-18.4, 2.6-7.7, 25.7-33.2, 10.5-37.3 and 6.6-13.7 μg/L, respectively. The levels of As in livestock drinking water of each farms/flocks was found in the range of 238-2000 μg L^-1. A positive correlation with Pearson correlation coefficients, ranged as, 0.926-0.974 (p = 0.001-0.011) was observed between the As concentration in milk samples of cattle and in corresponding drinking water of farms/flocks. The high bio-transfer factor of As was occurred in the milk samples of sheep. The content of As in scalp hair of children was observed to be elevated, who consumed milk of lower cattle (sheep and goat) than cow and camel. The As content in scalp hair directly proportional to the age of children. The hazardous quotient value of As due to consumption of milk was observed in decreasing order as, sheep > goats > camels > cows. The total hazardous quotient or noncarcinogenic risk values for children consuming the milk of sheep, goat, cow and camels were found >1 of reference dose for As, creates adverse effects on health in childhood stage. The children of all three age group have higher carcinogenic risk factor who are consuming milk of goat and sheep than larger cattle.