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.

Background. Occupational exposures to chromium (Cr), which can have adverse effects on immune function, have not yet been extensively investigated. Hexavalent chromium (Cr (VI)), used in mineral tanning processes, poses a threat to the health of workers in the leather tanning industry. Objectives. The aim of the present study was to evaluate the effects of long-term Cr exposure on the physical health and immunological parameters of male tannery workers in Bangladesh compared with a control group. Methods. A health examination was performed with tannery workers (N=195) and control subjects (N=125) by physicians, demographic data were recorded in questionnaires and peripheral blood samples were collected. Serum Cr levels were analyzed by an atomic absorption spectrophotometer (AAS), immunoglobulin (Ig)G, IgA, and complement components C3 and C4 were determined by nephelometry, IgE was measured by sandwich enzyme-linked immunosorbent assay and complement function was assayed by bactericidal activity. Results. The mean duration of work exposure for the tanners was 9.4±7.1 years. Their body mass index (21.8±3.0 kg/m2), was not significantly different from the controls (22.7±3.2 kg/m2). The mean serum level of Cr in 30 long-term exposed tannery workers (26.97±21.11 μg/dL) was significantly higher than that of 30 randomly selected control subjects (7.38±6.81 μg/dL). The tannery workers had rough skin, rashes, itchy and decolorized skin, allergic diseases and respiratory illness, and had significantly lower levels of serum IgG, IgA, C3 and C4, but significantly higher levels of IgE than the controls. IgG, IgA and C3 levels were all inversely associated with Cr, while IgG, IgE and bactericidal activity showed an inverse correlation with duration of exposure. Conclusions. The results of the present study suggest that chronic exposure to Cr is associated with impaired immune function in male tannery workers. Participant Consent. Obtained Ethics Approval. The present study was approved by the Ethical Review Committee of the faculty of Biological Sciences, University of Dhaka, Bangladesh. Competing Interests. The authors declare no competing financial interests.

Background. In parts of Cambodia, irrigation of rice with groundwater results in arsenic accumulation in soils and rice, leading to health concerns associated with rice consumption. In Bangladesh and China, low zinc levels in rice have been found in regions where arsenic levels in rice are high. Furthermore, there have been claims that zinc deficiency is responsible for stunting of children in Cambodia. There are limited data on zinc in Cambodian rice, but in rural Asia, rice is the major source of zinc. Objectives. To provide a preliminary evaluation of the zinc content in rice grain in Preak Russey, an area with elevated levels of arsenic. The importance of zinc in rice for infants was also assessed. Methods. Rice cultivation was evaluated in sixty farms along the Mekong River in Cambodia. Analyses for metals, total arsenic, and arsenic species in the water and rice were conducted at the University of Ottawa, Canada by inductively coupled plasma – mass spectrometry. Analysis of total zinc and arsenic in soils were analyzed in Phnom Penh using X-ray fluorescence spectrometry (XRF). Total zinc in rice was also measured by XRF analysis. Results. Rice in the Preak Russey area contained zinc with ½ to ¼ of the 1987 Codex standard for rice in Infant Formula. Moreover, our average zinc concentration in rice samples was less than a third that recommended for zinc fortification in rice by the United Nations World Food Programme. There was a significant (α=0.05) negative correlation between the arsenic and zinc content of rice with the lowest zinc levels occurring near the irrigation wells, the source of arsenic. There was a significantly higher content of zinc in rice from farms that fertilized with cow manure. Conclusions. Handheld XRF spectrometers are useful tools for detection of zinc levels in rice. The potential for zinc deficiency in farmers in areas of Cambodia with arsenic toxicity is high. Competing Interests. The authors declare no competing financial interests.

The present study was aimed to reveal the effect of cadmium (Cd)-polluted soil on the activation of antioxidant enzymes, photosynthesis, pigments, water relation, and other biochemical traits and comparative effect of synthetic and organic chelators. A pot experiment was conducted using two maize varieties grown in Cd-contaminated (15 and 30 mg kg⁻¹) soil and chelators (1 mM EDTA, and 1 mM citric acid). Cd decreased biomass and photosynthetic traits while increased malondialdehyde (MDA) contents, total proteins, and antioxidant enzyme activities. Addition of EDTA enhanced Cd uptake, antioxidative enzyme, and total proteins; however, it reduced the water, osmotic, and turgor potential as compared to Cd alone. Addition of citric acid has lessened the antioxidant enzyme activities and MDA contents and enhanced the plant biomass as compared to Cd alone. Increases in antioxidants and MDA content were found to be positively related to the Cd contents in shoot and root. The application of citric acid significantly alleviated the Cd-induced toxic effects, showing remarkable improvement in biomass. These results indicated that EDTA was more effective for mobilizing Cd from soil to the root and shoot than citric acid; however, the physiological traits and plant biomass were more strongly inhibited by EDTA than by the Cd. Our study implies that citric acid ameliorated the negative effect of Cd on physiological traits and biomass, and hence could be used effectively for Cd phytoextraction.