Concentrations and Human Health Risk of Heavy Metals in Rivers in Southwest Nigeria

Investigation of groundwater quality in the Southern Coast of the Black Sea: application of computational health risk assessment in Giresun, Türkiye

Potentially toxic elements (PTEs), especially arsenic in drinking water, pose significant global health risks, including cancer. This study evaluates the groundwater quality in Giresun province on the Black Sea coast of Türkiye by analyzing twelve groundwater resources. The mean concentrations of macronutrients (mg/L) were: Ca (10.53 ± 6.63), Na (6.81 ± 3.47), Mg (3.39 ± 2.27), and K (2.05 ± 1.10). The mean levels of PTEs (µg/L) were: Al (40.02 ± 15.45), Fe (17.65 ± 14.35), Zn (5.63 ± 2.59), V (4.74 ± 5.85), Cu (1.57 ± 0.81), Mn (1.02 ± 0.76), As (0.93 ± 0.73), Cr (0.75 ± 0.57), Ni (0.41 ± 0.18), Pb (0.36 ± 0.23), and Cd (0.10 ± 0.05). All PTE levels complied with WHO drinking water safety guidelines, and overall water quality was excellent. The heavy metal evaluation index (HEI < 10) and heavy metal pollution index (HPI < 45) indicate low pollution levels across all stations. Irrigation water quality was largely adequate, as shown by the magnesium hazard (MH), sodium adsorption ratio (SAR), Na%, and Kelly's ratio (KR). The total hazard index (THI) values consistently remained below 1, indicating no non-carcinogenic health risks. However, at station 10 (city center), the cancer risk (CR) for adults due to arsenic was slightly above the threshold (1.44E-04). Using principal component analysis (PCA), positive matrix factorization (PMF), and geographic information system (GIS) mapping, the study determined that most PTEs originated from natural geological formations or a combination of natural and human sources, with minimal impact from human activities. These findings highlight the safety and reliability of the groundwater sources studied, emphasizing their potential as a long-term, safe water supply for nearby populations.

Sorption of cadmium, chromium, lead, and vanadium from artificial wetlands using Lemna aequinoctialis

The efficacy of the lesser duckweed, Lemna aequinoctialis (Welw.), to remediate varying concentrations of cadmium, chromium, lead, and vanadium from an organo-metallic contaminated media was tested in artificial surface wetland mesocosm experiment. A 100 g of fresh-weight duckweed was introduced into each of the mesocosm, except for the control setup and monitored for 120 days while the metals removal rate was quantified using an atomic absorption spectrometer. A time-dependent and partial sorption of metals was observed with the highest removal rate recorded for cadmium (71.96%), followed by lead (69.23%), vanadium (55.22%), and chromium (41.64%). The uptake and bioaccumulation of metals were reflected in the increased plant biomass (p < 0.05, F = 97.12) and relative growth rate (p < 0.05, F = 1214.35) in duckweed. A coefficient (r2) of 0.951, 0.919, 0.970, and 0.967 was recorded for cadmium, chromium, lead, and vanadium respectively, indicating that the remediation of metals followed the first-order kinetic rate model. This study highlights the efficacy of the lesser duckweed to preferentially remediate metals in an organo-metallic complex medium for potential wastewater treatment in the petrochemical industry.

Biowastes of slaughterhouses and wet markets: an overview of waste management for disease prevention

Slaughterhouse and wet market wastes are pollutants that have been always neglected by society. According to the Food and Agriculture Organization of the United Nations, more than three billion and nineteen million livestock were consumed worldwide in 2018, which reflects the vast amount and the broad spectrum of the biowastes generated. Slaughterhouse biowastes are a significant volume of biohazards that poses a high risk of contamination to the environment, an outbreak of diseases, and insecure food safety. This work comprehensively reviewed existing biowaste disposal practices and revealed the limitations of technological advancements to eradicate the threat of possible harmful infectious agents from these wastes. Policies, including strict supervision and uniform minimum hygienic regulations at all raw food processing factories, should therefore be tightened to ensure the protection of the food supply. The vast quantity of biowastes also offers a zero-waste potential for a circular economy, but the incorporation of biowaste recycling, including composting, anaerobic digestion, and thermal treatment, nevertheless remains challenging.

Concentrations, bioaccumulation, and health risk assessments of heavy metals in fishes from Nigeria's freshwater: a general overview

Heavy metals (HMs) have attracted global attention due to their toxicity, persistence, and accumulation in aquatic fish in the polluted water environment. The consumption of these fishes exposed humans to a higher risk of non-carcinogenic and carcinogenic risks. In this study, we provided a critical overview of the potential sources and concentration of HMs in Nigeria's freshwater. Furthermore, we reported their pollution level in widely eaten fish species in the country. Our findings show that effluent from anthropogenic and industrial activities is one of the major sources HMs in the country. The mean concentration of Zn (9.02 mg/L), As (7.25 mg/L), Cu (4.35 mg/L), Fe (1.77 mg/L), and Pb (1.46 mg/L) in Nigeria's freshwaters were found to be high than Nigerian Standard for Drinking Water Quality permissible limit. This study demonstrated considerable health risks associated HMs via dietary consumption of different fishes from polluted waters. Therefore, we recommended an urgent need for effective management HMs in water bodies in order to protect the lives of people living in the country.

Cadmium and zinc accumulation and depuration in tilapia (Oreochromis niloticus) tissues following sub-lethal exposure

Oreochromis niloticus was subjected to sub-lethal Cd and Zn concentrations for 14 days in order to evaluate their accumulation in the gills, liver, and muscle. Following that, the fish were placed to uncontaminated water for 7 days to allow the metals to be removed from the tissues. The gills had the highest bio-concentration factor for Cd and Zn. The gills showed the highest Cd accumulation rate, and the muscle showed the lowest. The muscle had the highest Cd depuration rate, while the liver had the lowest. The liver exhibited the highest Zn accumulation rate, while the gills and muscle had nearly similar values. Zn depuration rates were very consistent across all tissues.

Comprehensive evaluation of the possible impact of roofing materials on the quality of harvested rainwater for human consumption

Water is a vital natural resource that influences life and contributes to domestic and industrial activities. Availability and accessibility of safe water sources are crucial for a country's economic growth. Harvesting of roof runoffs is an alternative source of water used for domestic purposes. However, the quality of harvested rainwater can be affected by roofing materials. This research seeks to assess heavy metals concentration, physicochemical and bacteriological parameters in roof runoffs and estimate the water quality index and health risk these metals pose to consumers. Rainwater samples were collected from Aluzinc, Aluminum, Galvanized, and Asbestos roofing materials within the Ejisu municipality. Rainwater collected directly from the sky was used as control. All runoffs from the four roofing materials recorded Cd, Fe, Cr, turbidity, pH, E.coli, total and fecal coliform levels above WHO limit for drinking water. There was a significant variation in pH, EC, Zn, Cd, Cr, Fe, E. coli, total and fecal coliform levels between control samples and roof runoffs (p < 0.05). The estimated water quality index for runoffs from the four roofing materials exceeded 100 indicating their unsuitability for drinking. Cadmium recorded the highest non-cancer health risk to children and adults in all the roof runoffs. Hazard quotients (HQs) above one were recorded for a child (HQ = 40.1) and an adult (HQ = 13.6) via dermal exposure to Cd in runoff from Aluminum roofing material. Hazard quotient of 9.53 and 4.08 were estimated for a child and an adult respectively via oral exposure to Cd in runoffs from Asbestos roofing material. The estimated cancer risks were above 10^-3 for a child and an adult via oral and dermal exposure to Cd in all roof runoffs, suggesting a possible cancer health effect. The study concludes that the four roofing materials impact negatively on the quality of runoffs.

Health risk assessment of heavy metal concentrations in selected fish species from İznik Lake Basin, Turkey

Various wastes, especially heavy metals, which are introduced to water sources in an uncontrolled manner, accumulate in aquatic organisms in the food web. Through the consumption of fish and invertebrates, those contaminants reach humans. In response to rapid industrialization, the accumulation of heavy metals in fish adversely impacts human health. The purpose of this study was to evaluate the accumulation of some heavy metals (Chromium, Cadmium, Mercury, Lead, Iron, Copper, Zinc, and Arsenic) among 11 fish species inhabiting in İznik Lake Basin (Turkey) that are threatened by anthropogenic pollution. Results showed significant differences among species with the accumulation of heavy metals (p < 0.001 and p < 0.05). Chromium, zinc, arsenic, and lead presented the highest contents in Capoeta tinca caught from Çakırca Stream. The contents of lead, copper, and zinc were higher than the guidelines of various authorities. The potential human health risk assessment was conducted by provisional tolerable weekly intake (PTWI). In Rutilus rutilus and Cyprinus carpio, the estimated weekly intake (EWI) for mercury was higher than the PTWI. The findings of this study are of great importance in terms of understanding the effect of fish consumption on human health in the heavy metal polluted area.

A comprehensive review on the use of algal-bacterial systems for wastewater treatment with emphasis on nutrient and micropollutant removal

The scarcity of water resources and environmental pollution have highlighted the need for sustainable wastewater treatment. Existing conventional treatment systems are energy-intensive and not always able to meet stringent disposal standards. Recently, algal-bacterial systems have emerged as environmentally friendly sustainable processes for wastewater treatment and resource recovery. The algal-bacterial systems work on the principle of the symbiotic relationship between algae and bacteria. This paper comprehensively discusses the most recent studies on algal-bacterial systems for wastewater treatment, factors affecting the treatment, and aspects of resource recovery from the biomass. The algal-bacterial interaction includes cell-to-cell communication, substrate exchange, and horizontal gene transfer. The quorum sensing (QS) molecules and their effects on algal-bacterial interactions are briefly discussed. The effect of the factors such as pH, temperature, C/N/P ratio, light intensity, and external aeration on the algal-bacterial systems have been discussed. An overview of the modeling aspects of algal-bacterial systems has been provided. The algal-bacterial systems have the potential for removing micropollutants because of the diverse possible interactions between algae-bacteria. The removal mechanisms of micropollutants - sorption, biodegradation, and photodegradation, have been reviewed. The harvesting methods and resource recovery aspects have been presented. The major challenges associated with algal-bacterial systems for real scale implementation and future perspectives have been discussed. Integrating wastewater treatment with the algal biorefinery concept reduces the overall waste component in a wastewater treatment system by converting the biomass into a useful product, resulting in a sustainable system that contributes to the circular bioeconomy.

Photocatalytic membrane reactors for produced water treatment and reuse: Fundamentals, affecting factors, rational design, and evaluation metrics

Treatment and reuse of produced water (PW), the largest wastewater stream generated during oil and gas production, provides a promising option to address the increasing clean water demands. High-performance treatment technologies are needed to efficiently remove the organic and inorganic contaminants in PW for fit-for-purpose applications. Photocatalytic membrane reactor (PMR) is an emerging green technology for removal of organic pollutants, photoreduction of heavy metals, photo-inactivation of bacteria, and resource recovery. This study critically reviewed the mechanisms of photocatalysis and membrane processes in PMR, factors affecting PMR performance, rational design, and evaluation metrics for PW treatment. Specifically, PW characteristics, photocatalysts properties, membranes applied, and operating conditions are of utmost importance for rational design and reliable operation of PMR. PW pretreatment to remove oil and grease, colloidal and suspended solids is necessary to reduce membrane fouling and ensure optimal PMR performance. The metrics to evaluate PMR performance were developed including light utilization, exergetic efficiency, water recovery, product water improvement, lifetime of the photocatalyst, and costs. This review also presented the research gaps and outlook for future research.

Cancer and non-cancer risks in humans exposed to trace elements in drinking water from a crater lake (Bosumtwi/Bosomtwe)

The total and dissolved lead, cadmium, mercury, nickel, chromium, cobalt, and arsenic in 30 water samples collected from Bosomtwe Lake were analyzed. Arsenic bioavailability was also determined using the ARSOlux test system. Except for chromium, their mean values in the study results exceeded the WHO permissible limit for potability. Cancer and non-cancer effects associated with exposure to dissolved and total metals by a child and an adult via oral and dermal routes were estimated. The hazard quotient (HQ) values obtained (except adult exposure to total arsenic of 1.71 × 10⁰⁰ ) were less than unity. Between child and adult, the recorded hazard index (HI) was 0.82 and 1.75, respectively. The HI results indicate that the adult population is at risk for non-cancer health effects. Arsenic was the element of concern, and it remained biologically available for uptake by target groups. For child and adult, respectively, arsenic contributed 96.39% and 97.29% to HI values. The risk values for cancer in a child and an adult with oral and dermal exposure to dissolved and total arsenic were lower than the USEPA range. Principal component and cluster analysis identified atmospheric deposition, geogenic, and unregulated application of agrochemicals as plausible sources of water pollution in Bosomtwe Lake. PRACTITIONER POINTS: The hazard quotient (HQ) values obtained for adult exposure to total arsenic was 1.71 × 10⁰⁰ . Arsenic remained biologically available for uptake by target groups. The calculated health index (HI) indicated that the adult population is at risk for non-cancer health effects. Arsenic contributed 96.39% and 97.29% to HI values for a child and an adult. Atmospheric deposition, geogenic, and unregulated application of agrochemicals were the plausible sources of water pollution in Bosomtwe Lake.

Spectrum of neurological diseases across gangetic belt: a hospital based prospective observational study

OBJECTIVE

Neurological disorders are the most common cause of morbidity and mortality in riverside cities. Earlier studies reported the presence of heavy metals in the riverside of Gangetic belt. Our study objective was to determine the prevalence of neurological diseases in Ganga riverside and further divided into sections as just across riverside within 25 kms and non-riverside as 25 kms away from the Ganga river.

METHODS

This was a prospective observational study conducted in a tertiary care hospital of selected Gangetic belt.

RESULTS

A total of 2016 patients were recorded in this period. Mean age of the participants was 47.89 years, majority were males 59.2%. Most of the patients n = 1154 were from within 25 kms of Ganga riverside and n = 862 patients were from non-riverside (25 kms away from Ganga river). Common neurological diseases were ischemic stroke 22.7%, haemorrhagic stroke 20.7%, seizures 13.7%, septic encephalopathy 9.4%, neuropathy 8.9%, Parkinson's disease 4.3%, myopathy 4.1%, myelitis 2.8%, headache 2.4%, amyotrophic lateral sclerosis 1.9% and functional disorder 1.9%.

CONCLUSION

Present study showed that neurological diseases were more common in Ganga riverside and stroke including ischemic and hemorrhagic are most common neurological diseases noted in our study.

A review of potentially harmful chemicals in crumb rubber used in synthetic football pitches

Recycling end-of-life tires (ELTs) reduces waste and provides a low-cost source of energy and materials such as crumb rubber, used as infill in artificial turf football pitches. However, some concerns were raised and remain about its safety. The potentially toxic human exposure to chemicals such as polycyclic aromatic hydrocarbons (PAHs), metals and others (volatile organic compounds (VOCs), plasticizers, antioxidants and additives) existing in ELTs (and in the resulting crumb rubber) is being studied, with no definitive conclusions. The literature existing so far suggests the possibility of their release from synthetic turf infill into the environment as water leachates and to the air surrounding the pitches, but there is the need of further research, also to assess the contribution of other materials present in synthetic turf. The database available comprised crumb rubber infill studies from pitches in 6 countries (USA, Norway, Netherlands, Portugal, Italy, Spain) and revealed a myriad of hazardous chemicals, with benzo[a]pyrene (n.d.-4.31 ± 3.95 mg/kg) and zinc (n.d.-14150 ± 1344 mg/kg) often exceeding the established limits. A dependence on indoor/outdoor conditions and the age of the source material was evaluated, often showing significative differences. From this standpoint, this review is intended to add knowledge about the presence of contaminants in this recycled material, aiming to ensure the safety of end-users and the environment.

A glance at one decade of water pollution research in Iranian environmental health journals

Background

Due to the importance of water, the negative effects of water pollution on human health and the lack of proper knowledge of the state of research in this regard, the purpose of this study was to analyse scientific publications on water pollution in Iranian journals of environmental health.

Methods

This cross-sectional study was conducted using a scientometric method over a ten-year period (2008–2017) on articles published in five specialised environmental health journals emphasising the issue of water pollution. Data were collected through a researcher-based checklist using the International Committee of Medical Journal Editors (ICMJE) and the World Association of Medical Editors (WAME) recommendations. Data processing was done using descriptive statistics and VOSviewer software.

Results

A review of 1276 articles in specialised environmental health journals revealed that 33.7% of the articles were in the field of water. Physical and chemical factors in water were the main subjects of 21.4% of studies, and temperature and turbidity were the most important physical factors. Microbial agents in groundwater and surface water were the main subjects of 14.1% of the articles. The findings show that 55 of 430 articles related to water were written with contributions from 20 countries (including Iran), with the most contributions from researchers from Asia.

Conclusions

Good conditions do not exist to investigate the status of articles on water pollution in specialised environmental health journals in Iran over a ten-year period. Health policymakers should therefore provide mechanisms to encourage national researchers, especially environmental health professionals, by setting national research priorities on quality and water pollution to conduct studies in this regard.

Bioremediation Options for Heavy Metal Pollution

BACKGROUND

Rapid industrialization and anthropogenic activities such as the unmanaged use of agro-chemicals, fossil fuel burning and dumping of sewage sludge have caused soils and waterways to be severely contaminated with heavy metals. Heavy metals are non-biodegradable and persist in the environment. Hence, remediation is required to avoid heavy metal leaching or mobilization into environmental segments and to facilitate their extraction.

OBJECTIVES

The present work briefly outlines the environmental occurrence of heavy metals and strategies for using microorganisms for bioremediation processes as reported in the scientific literature.

METHODS

Databases were searched from different libraries, including Google Scholar, Medline and Scopus. Observations across studies were then compared with the standards for discharge of environmental pollutants.

DISCUSSION

Bioremediation employs microorganisms for removing heavy metals. Microorganisms have adopted different mechanisms for bioremediation. These mechanisms are unique in their specific requirements, advantages, and disadvantages, the success of which depends chiefly upon the kind of organisms and the contaminants involved in the process.

CONCLUSIONS

Heavy metal pollution creates environmental stress for human beings, plants, animals and other organisms. A complete understanding of the process and various alternatives for remediation at different steps is needed to ensure effective and economic processes.

COMPETING INTERESTS

The authors declare no competing financial interests.