A screening-level in vitro test was developed to evaluate the relative solubility of ingested lead (Pb) from different mine wastes in the gastrointestinal (GI) tract. The in vitro method, modeled after assay methods for available iron from food, used a laboratory digestion procedure designed to reproduce GI tract chemistry and function. The in vitro method was independently calibrated against a rabbit feeding study, demonstrating that only 1-6% of the total Pb in four mine-waste samples with disparate Pb mineralogy was bioaccessible. In vitro method development tests indicated that H+ concentration and Clc omplexation control dissolution of Pb-bearing minerals in the stomach and that both GI tract enzymes and organic acids are necessary to maintain Pb in the soluble form on entering the small intestine. The experimental results indicate that ingestion of Pb-bearing mine wastes results in limited Pb solubility and that the in vitro test provides a screening-level estimate of the maximum available Pb from mine wastes.

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Superfund risk assessments and the resulting soil arsenic (As) cleanup levels selected for mining sites are currently based on the toxicity of soluble As in drinking water. However, Anaconda soils and house dusts contain less soluble smelter-related As phases, consisting primarily of metal−arsenic oxides and phosphates. If accidentally ingested, As bioaccessibility is restricted by the sparingly soluble nature of As-bearing phases, the prevalence of authigenic carbonate and silicate rinds, the kinetic hindrance to dissolution, and the inaccessibility of encapsulated As. These limitations to As disolution explain the lower bioavailability factors observed for Anaconda As-bearing soils.

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A wide variety of conditions lead to delirium (i.e., metabolic encephalopathies) in human beings and animals. Despite the varied etiology the clinical consequences are relatively stereotyped which suggests that the diverse insults that cause delirium may act by common metabolic and cellular “final pathways.” Related molecular and cellular mechanisms may be involved in aging and Alzheimer's disease, conditions that predispose to the development of delirium. Animal models of delirium better reflect age-related disorders such as Alzheimer's disease than those that impair a single neurotransmitter system such as the cholinergic system; the metabolic encephalopathies produce global cognitive disturbance, which is more typical of these disorders. Thus, research related to delirium has far-reaching implications for normal and abnormal brain function.

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