Bioaccessibility of potentially harmful elements (PHEs) from environmental matrices and implications for human health

Internationally publicized impacts upon human health associated with exposure to potentially harmful elements (PHE) have been reported globally. Particular concern has surrounded the exposure to Pb indicated by the presence of highly elevated concentrations of Pb in blood and hair samples amongst internally displaced populations (IDPs) in Mitrovica, Kosovo, following the Kosovan War (Runow, 2005). The exposure risk to humans depends in part on the potential of the PHE to mobilise from its matrices in the human digestive and respiratory systems (bioaccessibility) and enter the blood stream (bioavailability). This study utilizes physiologically based in-vitro extraction methods to assess the bioaccessibility of PHEs in surface soils and metallurgical waste in Mitrovica and assesses the potential daily ingestion of soil-bound PHEs (As, Cd, Cu, Mn, Pb, and Zn) and inhalation (Pb) of particulate matter < 10 μm (PM10). A total of 63 samples (52 surface soils and 11 mine/smelter waste) were selected based on PHE loadings and their spatial distribution. For the in-vitro oral bioaccessibility 0.3 g subsamples were analysed using the UBM method (adopted by BARGE, Wragg et al., 2009). The mean bioaccessibility of Cd, Pb and Zn in the gastric phase is 51 %, 57 % and 41 %, respectively, compared to 18 %, 16% and 14%, respectively, in the gastric-intestinal phase. The trend with As and Cu data is less consistent across the sample locations, with a mean of 20 % and 22 % in the gastric phase and 22 % and 26 % bioaccessibility in the gastric-intestinal phase, respectively. To investigate the role of mineralogy in understanding the bioaccessibility data subsamples (< 250 μm) were submitted to the British Geological Survey, Nottingham, for X-ray diffraction (XRD) analyses. Samples associated with lower bioaccessibilities typically contain a number of XRD-identifiable primary and secondary mineral phases, particularly As- and Pb-bearing arseninian pyrite, beudantite, galena and cerrusite. For the inhalation bioaccessibility, PM10 subsamples were extracted from 33 samples using a locally developed laboratory based wet method. The 0.3 g PM10 subsamples were analysed using a new tracheobronchial fluid and protocol developed as part of this study. The bioaccessibility of Pb for all the 33 samples tested ranged from 0.02 to 11 % and it is consistent with a range (0.17 to 11 %) previously reported by Harris and Silberman (1988) for Pb bioaccessibility in inhalable particulates (< 22 μm) using canine serum. Quantification of the potential human exposure risk associated with the inhalation and ingestion of soil-associated PHEs indicates the likely possibility of local populations exceeding the recommended tolerable daily intake of Pb. IEUBK model (USEPA, 2007) predicted mean blood Pb concentrations for children based on bioaccessible (ingestion) data are above the CDC level of concern (10 μg/dL)

Lead concentrations and risk exposure assessment in surface soils at residential lands previously used for auto-mechanic and auto-welding activities in Port Harcourt, Nigeria

This study investigated lead concentrations in &lt; 250 μm and &lt; 75 μm of deposited dust and&lt; 2000 μm, &lt; 250 μm, and &lt; 75 μm of surface soils at undeveloped residential lands leased to auto-mechanic artisans for a minimum of ten years and estimated exposure risk for children that will reside on the polluted lands after the lease periods. Soil-Pb levels ranges obtained were between 40.0 - 411 mg/kg, 62.0 – 435 mg/kg , and 61.0 – 491 mg/kg for &lt; 2000 μm, &lt; 250 μm and &lt; 75 μm fractions, respectively. Dust-Pb levels ranges were between 138 – 1819 mg/kg, and 128 – 1584 mg/kg for &lt; 250 μm and &lt; 75 μm fractions, respectively. The estimated daily intake were in the range of 0.17 – 1.22 μg Pb Kg-1 body weight [BW]d-1 and 0.39 – 5.11 μg Pb Kg-1 BWd-1 for soil and deposited dust, respectively. This study has highlighted possible risks to occupants of lands previously used for auto-mechanic and auto-welding activities.Keywords: Lead, Exposure, Children, Auto-mechanic, Auto-welding, soi

Photo-catalytic Degradation of Chlorendic Acid: 1. Degradation Products

The photo-catalytic degradation of chlorendic acid in the presence of TiO2 was conducted to investigate the reaction pathways and possible degradation products as a means of assessing the environmental legacies of polyesters that are designed with both chlorendic acid and TiO2 chemicals. Comparison of liquid chromatography/mass spectrometry spectra of chlorendic acid and degradation solutions suggests HCl, H2O and chlorendic acid anhydride as the main products of the degradation process

Enhancing the interpretation of in vitro bioaccessibility data by using computer controlled scanning electron microscopy (CCSEM) at the individual particle level

The adverse health effects resulting from exposure to contaminated soil on internally displaced populations in Mitrovica, Kosovo can be determined by how the potentially harmful elements are bound in the soils. Certainly this was the case for Pb, present at concentrations ranging from 624 to 46,900 mg/kg, and at bioaccessibilities ranging <5% to nearly 90%. To assess why the soil Pb might differ so markedly in terms of its bioaccessibility, computer controlled scanning electron microscopy (CCSEM) was employed to determine how the Pb was associated with other elements at the individual particle (IP) level in soils from the area. It was found that the Pb-bearing particle types were, for the most part, different in each sample. We consider these differences as the main control on Pb bioaccessibility in these soils. Pb solubility at the IP level was evaluated by examining Pb-particles from these soils in the electron microscope before and after successive immersions in a simulated gastric fluid. This analysis (differential IP analysis) confirmed the CCSEM characterization that Pb associated with other higher atomic number elements (Fe, Zn, Cu and Ni) was less soluble than when it was present as isolated phases (e.g., as carbonate) or when it was bound with lower atomic number elements (Na, Al, Si, K, Ca). The heterogeneity in solubility and composition of the Pb-particles suggested that the Pb originated from a range of different anthropogenic activities. The nature of these different anthropogenic activities created the wide differences in Pb-bioaccessibilty by producing Pb bound in many different forms in the soil particles. This type of Pb-particle characterization highlights the role CCSEM analysis, and IP acid extraction, can play in providing supporting evidence alongside bioaccessibility data for applications in human health risk assessment and management of contaminated soil

Phytochemical Screening and Evaluation of the Antioxidant Activity of Ficus capreifolia Leaf Extract via in-vitro Models

Aims: To carry out preliminary phytochemical screening and determine the antioxidant ability of Ficus capreifolia leaf extract. Study Design: The study was designed to evaluate the phytochemical profile of Ficus capreifolia leaf and the potential antioxidant activity and comparing to reference antioxidant vitamin C. Place and Duration of Study: The research was done in the Department of Chemistry, Rivers State University from May to August 2016. Methodology: The extract was screened for the presence of some phytochemicals. Thereafter, the antioxidant potential was determined by assessing the hydrogen peroxide scavenging ability, hydroxyl radical scavenging activity and ferrous ion reducing ability and comparing them to the corresponding ability of vitamin C. Results: Phytochemicals detected include tannins, carotenoids, alkaloids, flavonoids, steroids, cardiac glycosides and polyphenols. The extract also scavenged hydrogen peroxide, hydroxyl radicals and also reduced ferrous ions significantly when compared to vitamin C. Conclusion: The leaf extract exhibited significant antioxidant activities which could be ascribed to antioxidant phytochemicals such as flavonoids, polyphenols which were detected. This corroborates the reported traditional use of the plant and can be further exploited pharmacologically

A new simple, low-cost approach for generation of the PM10 fraction from soil and related materials: Application to human health risk assessment

A new simple, robust and low-cost wet laboratory method for the generation of the <10 μm (PM10) particle size fraction is reported. A sedimentation method is directly compared with a centrifugation method for generation of the PM10 fraction. Both approaches are based on an integrated form of Stokes’ law. Subsequently the sedimentation method was adopted. The results from the sedimentation method were corroborated using particle size distribution measurements. This approach for the generation of the PM10 fraction was applied to soil and mine waste samples from Mitrovica, Kosovo as part of an investigation in to the human risk assessment from inhalation of the PM10 fraction containing potentially harmful elements (PHEs). The average daily dose for Cd from the inhalation of suspended soil particles was calculated to be 0.021 and 0.010 μg kg−1BW d−1 for a child and an adult, respectively. This corresponded to an inhalation dose of 0.50 and 0.70 μg Cd d−1 for a child (20 kg) and an adult (70 kg), respectively

Photo-catalytic Degradation of Chlorendic Acid: 1. Degradation Products

The photo-catalytic degradation of chlorendic acid in the presence of TiO2 was conducted to investigate the reaction pathways and possible degradation products as a means of assessing the environmental legacies of polyesters that are designed with both chlorendic acid and TiO2 chemicals. Comparison of liquid chromatography/mass spectrometry spectra of chlorendic acid and degradation solutions suggests HCl, H2O and chlorendic acid anhydride as the main products of the degradation process

Determination and Risk Assessment of Heavy Metals Concentrations collected from Indoor houses at Lagos State of Nigeria

The aim of this study is to determine the levels of selected heavy metals (As, Pb, Zn, Cu and Cr) at 60 homes from the 20 local governments in Lagos State, Nigeria. Approval was sought from respective residential landlords and occupants of the sampledcommunities. Three dust samples were collected from each local government. A total of 60 dust samples were collected andlabelled according to the first three letters of each Local government. Indoor dust samples from households (furniture, containerbags, window slides, ceiling fan and standing fan) were collected using soft paint brushes. 0.5g of the homogenized mixture wasmeasured in triplicate labelled 1, 2 and 3 in different boiling tubes for digestion process. Each triplicate samples were digestedusing aqua regia for 1 hour at a temperature of about 100 degree celcius. Heavy metal concentrations were determined usingAgilent Technologies 4210 MP-AES Atomic Absorption Spectrometer (AAS). The concentration of heavy metals in the indoor dustwere dominated by Arsenic with an average concentration of 57.76-111.93 mg/kg followed Lead 13.81-116.60 mg/kg, Zinc 22.73-224.2 mg/kg, Copper 8.27-228.75 mg/kg and Chromium with concentration of 2.53-22.60 mg/kg respectively. The concentrationsof heavy metal in the areas investigated followed the order: Ar&gt;Pb&gt;Zn&gt;Cu&gt;Cr. The exposure dose was also estimated throughingestion, inhalation and dermal contacts, and the exposure route was highest for ingestion pathway. The health risk (carcinogenic and non-carcinogenic) of these heavy metals were assessed based on the United States Environmental ProtectionAgency health risk models. The estimated values were compared to standard guidelines and human health limits by the UnitedStates Environmental Protection Agency, USEPA and California Environmental Protection Agency, Ca/EPA. For noncarcinogenic risk, the hazard index values for all the studied metals were lower than the safe level of 1. The Total Lifetime Cancer Risk for adults and children were below the limit (1x10-6– 1x10-4) as standardized by USEPA except in children which was slightly higher than the permissible limit in two local government areas; (Shomolu L.G.A 1.03x10-4) and (Lagos Mainland 1.02x10-4). This indicates that the risk of carcinogenic effect occurring is likely in children with exposure to arseni

Effects of Anthropogenic Activities on the Surface Water Quality of Idim Esiere Ebom Stream in Calabar South Lga, Cross River State, of Nigeria

The Idim Esiere Ebom Stream is a major source of freshwater in Garden street, Calabar South LGA of Cross River State,&nbsp; Nigeria, as well as a spring of potable water to the residents. However, there is the dearth of scientific information on the water quality of the stream; Thus, the need to evaluate its water quality. To this end, the effects of the physicochemical characteristics of the water quality and some heavy metals of the surface water and sediments of the Idim Esiere Ebom stream were studied. In this study, samples of the surface water and sediments were collected from 5 different stations of the stream monthly for 6 months (March-August) representing early wet (EW) season (March to May) and Peak wet (PW) season (June to August). The mean levels of the spatial and temporal distribution of Physicochemical parameters (pH, Temperature, Dissolved Oxygen, Salinity, Total dissolved Solids, Electric conductivity, Turbidity, Biochemical Oxygen Demand) of surface water and heavy metals (Iron, Copper, Lead, Chromium, Cadmium and Nickel) of the surface water and sediments were determined. The results from the analysis were compared with national and international standards. From the results obtained, it was observed that levels of most physicochemical characteristics and heavy metals exceeded the permissible limits. In conclusion, the anthropogenic activities into the stream has an impact in some stations of the stream