Background. The primary environmental risk associated with artisanal small-scale gold mining (ASGM) activities in Sekotong and Taliwang is waste discharged directly into the environment. This waste contains variable concentrations of heavy metals and a high level of mercury. When these elements are released into the environment, plants and animals can be contaminated. If mercury is methylated to methylmercury, levels can increase in concentration at each level of the food chain (biomagnify). Fish are a primary risk vector for methylmercury poisoning in humans, and represent a significant source of protein for the Sekotong and Taliwang communities. Objectives. The present study aimed to identify the concentration of mercury in fish from ASGM sites in Sekotong and Taliwang. Methods. Descriptive research was used to describe the mercury concentrations of fish in the present study. The fish species collected for the samples represented commercially available fish most commonly consumed by the community on a daily basis. Results. In Sekotong's ASGM area, the mercury concentration in Pilsbryoconcha exilis tissue was 596 ppb, 721 ppb for Sephia officinalis and 50% of the Euthynnus affinis samples had a high level of mercury, above the World Health Organization (WHO) maximum permissable limit for the sale of fish for human consumption of 0.5 ppb. Conclusions. Some fish species from the studied ASGM sites had high mercury concentrations above the maximum permissible mercury concentration in edible fish tissue. The risks associated with mercury exposure from fish consumption threaten community health. Ethics Approval. All experiments were performed in accordance with relevant local guidelines and regulations. Competing Interests. The authors declare no competing financial interests.

Background. The use of strain-specific microbial fermentation in the production of organic acids for the removal of heavy metals from sludge has been extensively studied. However, there is scarce information on the use of microflora for fermentation. Objectives. To assess the efficacy of cassava peel extracts for the removal of heavy metals from hospital sewage sludge in Nigeria. Methods. A composite sewage sludge sample was collected from the University College Hospital sewage treatment plant in Ibadan, Nigeria and analyzed for heavy metals using standard methods. Aspergillus niger fermentation and crude fermentation extract were obtained from the cassava peels strain of Aspergillus niger and indigenous microflora, respectively. The experiment was carried out by adding 10 ml of the treatment to 3 g of each sludge sample (extracts and controls) at varied temperatures (room and elevated) and pH (3–5). The mixture was centrifuged after a contact time of 1–12 days at 1000 rpm for 1 hour. The filtrate was analyzed for heavy metals concentrations and compared with the standards. Data were analyzed using descriptive statistics and adsorption models. Results. Mean heavy metal concentrations in the sludge were estimated for copper (2.22±0.2 mg/kg), zinc (52.3±0.1 mg/kg), chromium (1.46±0.1 mg/kg), nickel (5.6±0.01 mg/kg), and lead (1.9±0.1 mg/kg) and were below permissible limits. Optimum heavy metal removal for Aspergillus niger fermentation extract at room temperature was achieved on day 12 at pH 3.5 for zinc (74.5%), while optimum heavy metal removal at elevated temperature was achieved on day 9 at pH 3.0 for lead (79.3%). The optimum pH for crude fermentation extract lies between pH 3.0–4.5 for nickel (76.2%) at room temperature and chromium (76.6%) at elevated temperature. Conclusions. Crude fermentation extract of cassava peel was found to be effective in removing heavy metals from sewage sludge. Therefore, its use could be adopted and promoted for removing heavy metals from sewage sludge to achieve safe disposal. Competing Interests. The authors declare no competing financial interests.

Background. Traffic-related air pollution (TRAP) is a major source of ambient air pollution in urban areas. Shopkeepers of heavily trafficked roadside shops are persistently exposed to high levels of TRAP. Objectives. To estimate the prevalence of respiratory morbidity in shopkeepers of shops in heavily trafficked roadside areas in Bhopal city (India) and to determine any association with long term exposure to TRAP. Methods. This cross-sectional study was conducted among 251 shopkeepers working in roadside shops of three major traffic corridors in Bhopal city. The demographic profile and prevalence of respiratory morbidity were collected by administering a validated questionnaire. The total exposure period (TEP) to TRAP was calculated for each individual by multiplying their work duration (in years) and average working hours per day. Odds ratios were calculated to estimate the association of TEP with respiratory morbidity. Results. The age of the study population was 44.8±13.5 years old and 95% were male. Nearly 55% of the shopkeepers reported at least one respiratory symptom. The prevalence of bronchial asthma, chronic bronchitis, breathlessness, and cough was 3.6% (95% confidence interval (CI): 1.9–6.7), 13.9% (95% CI: 10.2–18.8), 41.8% (95% CI: 35.9–48.0), and 18.3% (95% CI: 14.0–23.6), respectively. The adjusted risk ratios of bronchial asthma 2.17 (95% CI: 0.35–13.41), chronic bronchitis 1.42 (95% CI: 0.58–3.48), breathlessness 1.71 (95% CI: 0.94–3.11), and cough 0.97 (95% CI: 0.47–2.03) for those with a TEP over 100. Conclusions. Shopkeepers working in heavily trafficked roadside shops suffer from respiratory morbidity and the risk increases with higher TEP. Total exposure period is a valuable indicator to estimate the effects of long-term TRAP exposure. Informed Consent. Obtained Ethics Approval. The study was approved by the Institutional Ethics Committee of the National Institute for Research in Environmental Health (Bhopal, India). Competing Interests. The authors declare no competing financial interests.

Background. Exposure to cadmium (Cd) is a global public health concern. The primary Cd exposure pathways are inhalation and ingestion. Globally, Cd production and consumption has increased, along with nickel-cadmium battery production, alloys, anticorrosive coatings, pigments, polyvinyl chloride stabilizers, semiconductors for solar cells, etc. After the end use of these elements, improper management may cause Cd pollution in different spheres of the environment and living organisms that eventually lead to adverse effects on human health. Objectives. The aim of the present study is to demonstrate the sources and routes of Cd that enter different environmental spheres, their concentrations, and describe associated human health impacts in Bangladesh. Methods. The present study searched a total of 304 peer-reviewed articles in the National Center for Biotechnology Information database, Science Direct, Web of Science, Springer Link, BanglaJOL, and university libraries and ultimately selected 71 articles. Afterwards, the relevant findings on Cd exposure through inhalation and diet and age-based impacts (i.e., adults, women, children and infants) in Bangladesh were combined. Finally, the results were processed with a cross-tabulation technique. Results. The present study found that Cd concentration in the local diet and river water is within the World Health Organization and Bangladesh Standard Testing Institute guidelines. Discussion. The concentration of Cd in sediments is comparatively higher than in river water in Bangladesh. Cadmium has been found in samples of foods, including leafy and non-leafy vegetables collected from different places in Bangladesh and may ultimately enter the human body via dietary intake of these foods. Consequently, individuals may be exposed to Cd and may be suffering from long-term adverse health effects. Conclusions. The comparison of concentrations in this study with national and international standards will assist with the formulation of effective pollution mitigation measures in Bangladesh. Competing Interests. The authors declare no competing financial interests.

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.

Background. India's rapidly increasing population and growing urbanization pose a great challenge for wastewater treatment efforts, leading to increased pollution of surrounding waterbodies. Objectives. A field sampling-based study was conducted to analyze water quality, heavy metals and bioconcentration and bioaccumulation in the roots and shoots of naturally growing vegetation in an urban lake, Laxmi Taal. The lake receives domestic sewage from Jhansi city in Central India. Methods. Temperature, pH, electrical conductivity, turbidity, and water-soluble ions were measured with appropriate instruments. Plant accumulation of metals was measured with the bioconcentration factor (BCF), the ratio of metal concentration in the root to wastewater. The translocation factor (TF) was estimated as the ratio of metal concentration in the shoot to the root. Results. Water quality and heavy metal concentrations were found to be within the prescribed limit as per Indian standards IS-2296 “D”. In the present study, BCF was assessed to be >1 and the plants Typha angustifolia and Echhornia crassipus were determined to be accumulator plants. The TF study revealed that translocation of all the metals studied were significant, except for manganese (Mn), where concentration was found to be below detection limit. Conclusions. The present study validated that Typha angustifolia and Echhornia crassipus could be used for bioremediation purposes in cases of urban waterbodies receiving varying amounts of domestic wastewaters which have relatively limited concentrations of toxic metals. Competing Interests. The authors declare no competing financial interests

Background. Health risks arising from heavy metal pollution have attracted global attention. As a result, many studies on the accumulation of heavy metals in soil-plant systems have performed human health risk assessments. Objectives.We aimed to examine the ability of Zea mays (maize) to accumulate heavy metals and assess the bioaccumulation factor (BAF) by collecting, collating, and analyzing data on heavy metal concentrations in Zea mays. Methods. This study reviewed the accumulation of five selected heavy metals, cadmium (Cd), chromium (Cr), lead (Pb), copper (Cu), and zinc (Zn) in soil and the corresponding BAF of Zea mays grown on those soils using a systematic search of peer-reviewed scientific journals. A total of 27 research works were reviewed after screening 52 articles for subject matter relevancy, including dumpsites, industrially polluted soils, inorganically fertilized soils, mining sites, smelting sites, municipal wastewater irrigated soils, and a battery waste dumpsite. Results. Among the reviewed sites, concentrations of Cd and Cr were highest at a tin mining site, where prolonged mining, mineral processing and other production activities contributed heavy metal pollution in the soil. The soil at a battery waste dumpsite exhibited the highest Pb concentration, while the soil at a Zn smelting site presented the highest concentration of Zn. The highest soil Cu concentration was found in an area where sewage irrigation had been carried out over a long period. The BAF of the five heavy metals in Zea mays increased with the metal concentrations in the soil. The BAF of Cd, Cr, Pb, Cu, and Zn in Zea mays from the study areas fall within the ranges of 0–0.95, 0–1.89, 0–1.20, 0.011–0.99, and 0.03–0.99, respectively. Cadmium and Zn had the highest bioconcentration factors values in maize plants, likely due to their higher mobility rate compared to the other heavy metals. Conclusions. The study concluded that Zea mays is capable of accumulating high amounts of heavy metals, although accumulation of these heavy metals is influenced by multiple factors including soil texture, cation exchange capacity, root exudation and especially soil pH and chemical forms of the heavy metals. Zea mays should not be planted on metal-contaminated soils because of its potential to act as a hyperaccumulator. Competing Interests. The authors declare no competing financial interests.

Background. Eucalyptus species have been used for the remediation of mine tailings dams in Zimbabwe. However, a traditional medicinal remedy (TMR) for the treatment of mild acute respiratory infections, such as common cold and flu includes the use of Eucalyptus leaves. Objectives. The aim of the present study was to determine total concentrations of selected potentially toxic trace elements (PTEs) in gold mine tailings and leaves of Eucalyptus grandis and to identify extractable fractions of PTEs in leaves via boiling for 10 minutes in water, which is the process used to create TMRs to treat common cold and flu. Methods. Mine tailings and leaves of E. grandis were randomly collected at a gold mine tailings dam between April and June 2019. They were digested for laboratory analysis using standard analytical methods. Leaves were boiled in water for 10 minutes to prepare the TMR as practiced by the local community. The concentrations of PTEs were determined spectrometrically. Significant differences between PTEs in young and mature leaves were determined by analysis of variance. Results. Mine tailings were acidic (pH 4.52±0.62) with very low content of organic matter (0.02%) and contained PTEs in increasing concentrations of cadmium (Cd) < nickel (Ni) < lead (Pb) < chromium (Cr) < copper (Cu) < zinc (Zn) (n = 27). Mature leaves of E. grandis had higher concentrations than young leaves for Cr, Pb and Zn (p <0.05) which were lower than permissible limits in medicinal plants. Overall, boiling leaves in water for 10 minutes resulted in low extraction of PTEs (< 20%). Participant Consent. Obtained Conclusions. Concentrations of PTEs in leaves and leaf extracts of E. grandis were very low. However, TMRs should not be prepared from medicinal plants growing on metalliferous environments, such as mine tailings dams, due to the presence of cumulative toxins such as Cd and Pb. Further studies are needed to investigate the effect of various boiling times and should include arsenic in the studied PTEs. Competing Interests. The authors declare no competing interests for this study.

Background. Over and improper use of chemical pesticides can have adverse effects on the environment, human health, and social capital. Objectives. The present study investigated pesticides available in the market, as well as handling and usage of pesticides by farmers in the Northern Region of Ghana. Methods. Cluster sampling was used to select 20 communities from the Tolon District. Simple random sampling was then used to select 5 households from each community and one farmer from each household, giving a sample size of 100 farmers. Results. The survey identified 39 agrochemical shops in the Tamale Metropolis. Thirty-six different pesticides were identified on the market, mainly comprised of insecticides and herbicides. The predominant active ingredients were cypermethrin and glyphosate in insecticides and herbicides, respectively. The survey revealed 18 kinds of pesticides commonly used by the farmers on their fields, with atrazine being the most commonly used herbicide (42%) and Lambda Super 2.5 EC the most commonly used insecticide (50%). The study also revealed that 64% of the respondents disposed of their empty pesticide containers indiscriminately and 44% stored used and unused pesticides in their bedrooms. Conclusions. The mode of disposal of used pesticides containers and storage of pesticides by the respondents contribute to human health and environmental hazards. Measures to educate farmers on pesticide usage and storage to help accomplish the target of environmentally friendly and sustainable agricultural production should be taken by the appropriate authorities. Participant Consent. Obtained Competing Interests. The authors declare no competing financial interests.