Background. Acute widespread lead poisoning took place in Zamfara State, Nigeria in 2010. Over 735 children were reported dead and thousands sickened by the neurotoxin. The source was traced to artisanal gold mining and processing in the villages. An immediate medical response protocol was developed to provide oral chelation therapy to the vulnerable population. In order not to compromise the efficacy of the chelation therapy, immediate remediation of the affected villages was carried out. An over 95% reduction in soil lead levels was reported immediately after the remediation exercise. Objectives. The aim of the present study was to perform a general audit of soil lead concentrations, conducted between June and July 2013 in Dareta village (one of the most affected villages), to evaluate the soil pollution status of the village three years after the remediation exercise. Methods. Soil samples were collected from residential compounds, cultivated farmlands and other common areas. Lead contents of the samples were determined using atomic absorption spectrophotometer (Shimadzu, model AA-6800, Japan) after wet digestion. Speciation of lead in soil was done following standard analytical methods. Results. Mean soil lead concentrations for residential areas were 1029.42±98.50 mg/kg, 1523.99±201.00 mg/kg, 1404.57±141.00 mg/kg and 6724.68±84.00 mg/kg for residential compounds, market square, old grinding mills and new grinding mills, respectively. The concentrations exceeded both the Dutch target and intervention values and US Environmental Protection Agency limit for soil lead levels in residential areas. Based on the index of geo-accumulation, the ranking of intensity of lead (Pb) pollution of Dareta soils ranged from strongly polluted to extremely polluted, indicating they pose a range of moderate to very high potential ecological risk to the other components of the environment. At the current rate of accumulation, by the year 2025, soil Pb levels of Dareta common areas are expected to exceed the pre-remediation levels associated with several deaths. Conclusions. Findings of this study indicate that the problem of lead poisoning is ongoing in Dareta village. Zamfara State authorities should address the challenge through sustained periodic assessment and cleanup of affected areas. Implementation of safer mining practices should be enforced immediately. Competing Interests. The authors declare no competing financial interests

Background. Mercury in dental amalgam is a hidden source of global mercury pollution, resulting from the illegal diversion of dental mercury into the artisanal and small-scale gold mining sector, to crematoria emissions from the deceased and sewage sludge that is sold to farmers. These significant mercury sources result in air, water, and food contamination that consequently have a negative impact on human health. Objectives. The aim of the present study was to investigate and report on all of the various pathways mercury in dental amalgam can enter the environment. Methods. The present study searched the electronic data bases of PubMed and Google Scholar. Peer reviewed journals and references of studies included for full-text review were examined for potentially relevant studies. Articles published between 2000 to 2018 were searched and specifically screened for articles that referenced “Dental Amalgam,” and the following key words in various combinations: “Minamata Convention on Mercury Treaty,” “Sewage Sludge,” “Cremation,” and “Artisanal and Small-Scale Gold Mining.” Data were included on the most populous countries of China, India, the United States, Brazil, and the European Union collectively. We also included data on cremation statistics and current global trends, looking at populations where cremation is a common practice, such as Japan and India. Discussion. Dental amalgam represents a significant, but understudied area of global mercury pollution that includes cremation, sewage sludge, burial, and small-scale gold mining. Conclusions. Mercury used in products and processes, including dental amalgams, is a global pollutant. Even after the last mercury dental amalgam is placed, its toxic legacy will continue for decades, because of its pervasive bioaccumulation in the environment. Government regulatory agencies should make it mandatory to utilize available technologies, not only in developing countries, but also in developed countries, to reduce mercury contamination. Competing Interests. The authors declare no competing financial interests.

Background. High arsenic levels in potable water are a threat to public health in India. About 85% of the water in India's rural areas comes from groundwater and roughly 27 million people are at risk of arsenic (As) contamination. Objectives. The present study was performed to examine the feasibility of providing an effective and affordable means for arsenic abatement in socio-economically poor and rural areas in India. This is the first report on the effectiveness of powder Nelumbo nucifera Gaertn (lotus) root biomass for As (III) eradication from aqueous solution. Methods. Batch experiments were conducted to determine the effects of various operating parameters, including pH, initial As (III) ion concentration, adsorbent dosages, and contact time for As (III) sorption onto lotus root. Discussion. The sorption efficiency of lotus root biomass for As (III) at pH 7 was found to be quantitative (96%) from 50 mg/L aqueous solution at a dose of 5gL−1. Capacity of the biosorbent for As (III) ion adsorption and the interaction between adsorbate with biosorbents were studied using Langmuir and Freundlich isotherm models. In the present study, the equilibrium parameter values ranged between 0 and 1, indicating that the adsorption of the As (III) ion onto lotus root biomass was favorable. Conclusions. Lotus root powder biomass was found to be an effective adsorbent for As (III) and could be used as an efficient, cost-effective and environmentally safe biosorbent for the sorption of arsenic from aqueous solutions. Competing Interests. The authors declare no competing financial interests.

Background. The enrichment of lead (Pb) in a rapidly expanding urban environment is largely caused by industrial and anthropogenic activities. However, very few studies have come from sub-Sahara Africa as a whole, in spite of the increased rate of population, industrialization and urbanization in this region. The city of Onitsha is the commercial heartland of southeast Nigeria. Objectives. To determine the concentration of Pb in soils and sediments in Onitsha and the surrounding area and to identify the possible sources of Pb content in the environmental media. Methods. One hundred and sixty-two (162) samples (120 top and subsoils, and 42 stream and side drain sediments) were collected from the city of Onitsha, Nigeria to determine Pb concentrations, identify the main sources of Pb in this region, and determine its fate in soil and sediments using Pb isotopes. Thirty (30) 15 g clay fractions of soil and sediment samples, and a sample each of galena (from the Lower Benue Trough), coal and soot from vehicle exhaust and battery cells were collected from the city and analyzed for lead isotopes (Pb204, Pb206, Pb207 and Pb208) using ultra-trace inductively coupled plasma emission spectrometry. Results. The distribution and concentration of Pb in the soil of Onitsha was observed to be influenced by land use patterns with very elevated concentrations of Pb observed for mechanic and metal workshop samples (1444.3, 1067.5, 1048.1, 1730.5 and 580.5 ppm); active waste dump samples (448.4 and 311.9 ppm); and farmland and garden samples (366.2 ppm). The concentration of Pb in the sediments also showed varying elevated concentrations across locations, ranging from 45.7–540.1 ppm. A comparison with the control samples revealed that the Pb concentrations measured in the environmental media were several folds higher than that of the control. The Pb isotope analysis indicated that most of the Pb in environmental media was anthropogenic in origin and had been predominantly contributed by unsustainable environmental practices such as indiscriminate waste dumps, hydrocarbonbased products emissions, by-products from mechanical workshops that have been haphazardly constructed in the city, and industrial plants located within urban areas. Conclusions. The relatively higher concentrations of Pb in soils and sediments were found to be influenced by land use, as also observed in the Pb isotope readings, which will, over time, adversely affect environmental media and biota. Competing Interests. The authors declare no competing financial interests.

Background. Brasilia, the capital of Brazil, currently has the largest dumpsite of the Americas at Estrutural, with over 30 million tons of waste accumulated. Recyclable waste collectors are a group of workers who, in addition to having a low socioeconomic status and residing in vulnerable areas, work sorting garbage in inadequate and unsanitary areas. This profession puts individuals at risk, resulting in death, mutilation, and disease for workers. Objectives. The aim of this study was to understand the effects of waste on recyclable collectors, along with their perceptions of associated risks. Methods. A qualitative study was conducted, using interviews with 34 participants at Estrutural. Results. Collectors were exposed to several hazards, including biological, physical, and more extreme hazards (e.g. being run over by waste trucks). Personal protective equipment was not adequately used, exposing recyclable collectors to injury. Accidents included cuts, burns, skin lesions, eyes lesions, and arm, leg, head, feet, and hand injuries and amputations. Often, homecare remedies and collected medical waste (e.g. pain killers) were used on these injuries instead of seeking out proper medical care. Conclusions. Recyclable collectors were aware of occupational hazards, but lacked education on the risks and consequences associated with exposure to medical hazards. Moreover, Brazil recently formally closed all dumpsites, complicating this issue. The findings of the present study confirm the need to address these hazards to provide a safe working environment for waste pickers. Participant Consent. Obtained Ethics Approval. This study was approved by the Research and Ethics Committee of the Health School of Brasília University under Opinion n. 1.517.670/2016. Competing Interests. The authors declare no competing financial interests.

Background. Soil pollution by heavy metals in urban areas is of major concern to city planners and policy makers because of the potential threat to human health. Hence, an investigation of soil pollution is crucial to urban environmental assessment and management. Objective. To determine the spatial distribution and health risk assessment of seven heavy metals (cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn)) around Ijebu-ode, southwest Nigeria. Methods. Surface soil samples were analyzed for Cd, Cr, Cu, Mn, Ni, Pb, and Zn levels using standard procedures. Geographic information system (GIS) data, pollution indices (enrichment factor, geo-accumulation index), and the health risk assessment model, respectively, were used to analyze the spatial distribution, pollution level, and potential health risk of heavy metals. Results. Low pH was observed in the urban soils. The average concentrations of the seven heavy metals investigated were in order of Zn > Pb > Mn > Cu > Cd > Ni > Cr. There was high spatial variation in the distribution patterns of the heavy metals. The cancer risks for Cu, Mn, Pb, and Zn for children (1.50 × 10−3 – 2.71 × 10−2) and Mn, Pb, and Zn for adults (7.89 × 10−4 – 2.97 × 10−3) were higher than the acceptable range of 1 × 10−6 - 1 × 10−4. Conclusions. Anthropogenic activities from different urban land uses contribute to the pollution levels and spatial distribution of heavy metals in soils. Increasing pollution of urban soil may contribute to the occurrence of some health risk for residents in the study area. Competing Interests. The authors declare no competing financial interests.

Background. Lung function tests reflect the underlying physiological condition of the airways and the alveoli. Therefore, they help to evaluate the respiratory health of an individual. Lung functions are compromised far before appearance of the signs and symptoms of chronic respiratory diseases. Air pollution adversely affects lung function. Exposure to sources of pollution differ between men and women due to commuting and smoking habits. The present study was carried out in Delhi to assess the association of exposure to air pollution sources with lung function of young adult females, as this younger age group is expected to have a different exposure profile than older women. Methods. The present study was conducted on the campus of a central university in Delhi among 18- to 25-year old females (n=200). A pre-tested, close-ended and interviewer-administered questionnaire was used that consisted of information on sociodemographic details of the participants and self-reported exposure to air pollution sources at the residence of participants, during their commute to and from college, and at school. Both active and passive smoking status were recorded. Lung function was assessed using a digital spirometer. Results. A significant association was observed between percentage of predicted value of forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) and peak expiratory flow (PEF) with the number of years the participant had resided in Delhi (p<0.05). Forced vital capacity and FEV1 of those using closed transport methods such as car, metro, and air-conditioned (A/C) bus were significantly better than those who used open transport methods such as non-A/C bus and scooter (p<0.05). Forced vital capacity and FEV1 were significantly decreased among those who had a smoke-producing factory in the vicinity of their residence (p<0.05). A significant decrease in FVC and FEV1 was observed among active smokers and among those who were exposed to passive smoking by family members in comparison to those who were not exposed (p<0.05). Conclusions. The results of the present study suggest that air pollution exposure plays a role in determining the lung function profile of young adult females. This study provides baseline data on lung function of young adult females which could be used in future longitudinal cohort studies. Participant Consent. Obtained Ethics Approval. The study was approved by the Institutional Ethics Committee of University College of Medical Sciences. Competing Interests. The authors declare no completing financial interests.

Background. Anthropogenic activities such as artisanal mining pose a major environmental health concern due to the potential for discharge of toxic metals into the environment. Objectives. To determine the distribution and pollution patterns of arsenic (As), iron (Fe), nickel (Ni), cobalt (Co), chromium (Cr), manganese (Mn), copper (Cu) and zinc (Zn) in the topsoil of a mining community in Ghana, along with potential human health risks and in vitro bioaccessibility. Methods. Concentrations of metals were determined using X-ray fluorescence techniques and validated using inductively coupled plasma-mass spectrometry. Results. Concentrations of the metals in topsoil were in the order of magnitude of Cu (31.38 mg/kg) < Ni (45.39 mg/kg) < As (59.66 mg/kg) < Cr (92.87 mg/kg) < Zn (106.98 mg/kg) < Mn (1195.49 mg/kg) < Fe (30061.02 mg/kg). Geo-statistical and multivariate analyses based on hazard indices including contamination, ecological risks, geo-accumulation, and pollution load suggest that the topsoils are contaminated in the study area. The potential ecological risk index (PERI) showed high ecological risk effects (PERI=269.09), whereas the hazard index (1×10−7) and carcinogenic risk index (1×10−5) indicated low human health risks. Elevated levels of As, Cr, Ni, and Zn were found to emanate from anthropogenic origins, whereas Fe, Mn, and Cu levels were attributed mainly to geological and atmospheric depositions. Physicochemical parameters (pH, electrical conductivity and total organic carbon) showed weak positive correlations to the metal concentrations. Elemental bioaccessibility was variable, decreasing in the order of Mn (35± 2.9%) > Cu (29± 2.6%) > Ni (22± 1.3%) > As (9± 0.5%) > Cr (4± 0.6%) > Fe (2± 0.4%). Conclusions. Incorporation of in-vitro bioaccessibility into the risk characterization models resulted in a hazard index of less than 1, implying low human health risks. However, due to accumulation effects of the metals, regular monitoring is required. Competing Interests. The authors declare no competing financial interests.

Background. Recycling of electronic waste (e-waste) in developing nations poses a risk to the environment and human health through the release of heavy metals. Objectives. The aim of the present study was to evaluate the levels of heavy metals in Douala, Cameroun, the site of e-waste recycling activities. Methods. Soil samples were collected from Makea, Ngodi and New Bell e-waste recycling sites, as well as from a control site. Samples were digested and levels of heavy metals were determined. Results. The concentrations of the heavy metals in Makea occurred in the order of lead (Pb) (290±40) > zinc (Zn) (160±30) > chromium (Cr) (130±40) > copper (Cu) (130±20) > nickel (Ni) (56±5.7) > cadmium (Cd) (20±3.0); Pb (310±30) >Zn (150±20) >Cu (80±30) >Cr (70±40) >Ni (50±1.0) >Cd (30±5.0) in Ngodi; and Pb (280±40) >Zn (155±35) >Cu (80±50) >Cr (70±40) >Ni (53±2.0) >Cd (20±10) in New Bell. The levels of metals in all of the samples were higher compared to the control site, which was composed of vegetation and far from the e-waste sites, and in some cases, higher than permissible limits or guidelines. The ecological risk index of heavy metals for soil samples in all the e-waste sites indicated a very high risk. Conclusions. Heavy metals concentrations in soil around e-waste recycling sites present serious health risks and further investigations are needed. Competing Interests. The authors declare no competing financial interests.