The aetiology of numerous grievous human diseases, including Alzheimer’s and Parkinson’s Disease is not well understood. Conversely, the concentration of toxic metals and metalloids, such as As, Cd, Hg and Pb in human blood of the average population is well established, yet we know strikingly little about the role that they might play in the aetiology of disease processes. Establishing functional connections between the chronic exposure of humans to these and other inorganic pollutants and the aetiology of certain human diseases is therefore viewed by many as one of the greatest challenges in the post-genomic era. Conceptually, this task required the author to uncover hitherto unknown biomolecular mechanisms which must explain how small doses of a toxic metal/metalloid compound (low íg per day) – or mixtures thereof – may eventually result in a particular human disease. The biological complexity that is inherently associated with mammals, however, makes the discovery of these mechanisms a truly monumental task. Recent findings suggest that a better understanding of the bioinorganic chemical of inorganic pollutants in the mammalian bloodstream represents a fruitful strategy to unravel relevant biomolecular mechanisms. The adverse effect(s) that toxic metals/metalloid compounds exert on the transport of essential ultratrace elements to internal organs appear particularly pertinent. A brief overview of the effect that arsenite and Hg2+ exert on the mammalian metabolism of selenium is presented.