Selected Chemical and Physical Properties of Soils and Gut Physiological Processes that Influence Lead Bioavailability (original) (raw)
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Lead bioavailability as influenced by its sources, speciation and soil properties
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Lead has been of particular concern as a neurotoxin since the 1970s due to its permanent adverse effects on human health. People can be exposed to Pb by ingestion (either through accidental oral ingestion or through food or drinking), inhalation (e.g. fine Pb particles in dust) and dermal uptake. Ingestion of Pb contaminated soils poses a significant risk to humans, especially children and babies due to their behaviors including crawling and hand-to-mouth activities, fast metabolic rates and rapidly developing neuronal systems. Thus, determining the bioavailability of Pb (Pb-BA) in soils is critical in human health risk assessment. However, it remains a serious challenge due to measurement uncertainties and the lack of information on the influences of sources of Pb contamination, Pb speciation and soil properties to Pb-BA. Consequently, this thesis focuses on the following issues: 1) validation of a reliable model to measure Pb bioaccessibility (Pb-BAc) and minimization of associate...
Environmental pollution (Barking, Essex : 1987), 2015
Lead (Pb) is a non-threshold toxin capable of inducing toxic effects at any blood level but availability of soil screening criteria for assessing potential health risks is limited. The oral bioaccessibility of Pb in 163 soil samples was attributed to sources through solubility estimation and domain identification. Samples were extracted following the Unified BARGE Method. Urban, mineralisation, peat and granite domains accounted for elevated Pb concentrations compared to rural samples. High Pb solubility explained moderate-high gastric (G) bioaccessible fractions throughout the study area. Higher maximum G concentrations were measured in urban (97.6 mg kg(-1)) and mineralisation (199.8 mg kg(-1)) domains. Higher average G concentrations occurred in mineralisation (36.4 mg kg(-1)) and granite (36.0 mg kg(-1)) domains. Findings suggest diffuse anthropogenic and widespread geogenic contamination could be capable of presenting health risks, having implications for land management decisi...
Long term in situ reduction in soil lead bioavailability measured in the mouse model
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Effects of different soil amendment treatments on the bioavailability of lead (Pb) in soil from a smelter emission contaminated site in Joplin, Missouri, were evaluated in a mouse model. Similar estimates of relative bioavailability for Pb in untreated or treated soil were obtained in mice and in the well-established juvenile swine model. In the mouse model, chemical and physical remediation strategies using phosphate (phosphoric acid or triple superphosphate) combined with iron oxide or biosolids compost significantly reduced soil Pb bioavailability. Notably, effects of these remediation procedures were persistent, given that up to 16 years had elapsed between soil treatments and sample collection. Remediation of soils was associated with changes in Pb species present in soil. Differences in Pb species in ingested soil and in feces from treated mice indicated that changes in Pb speciation occurred during transit through the gastrointestinal tract. Use of the mouse model facilitates...