Recent developments in selenium research.

Some of the main biochemical features of selenium have emerged only in the last five years, although it has been known to be an essential element for nearly 40 years. The investigations into selenoproteome gene expression and a better understanding of the selenocysteine synthetic pathway have undoubtedly provided the evidence that underpins the biochemical roles of the element. To date, 25 selenium-containing proteins have been identified in humans but the functions of a number of these have yet to be elucidated. The roles of the selenium-containing enyzmes (glutathione peroxidases, thioredoxin reductases and iodothyronine deiodinases) are well established, the first two being linked with antioxidant activity, and the latter involved with thyroid hormone metabolism. Recently, the interaction between sulphur, in the same periodic group and therefore chemically similar, and selenium has been investigated in a bid to understand the role of both elements in disease. There is renewed interest in the anticancer properties of selenium-containing compounds as evidence of their effectiveness in animal models has been demonstrated. Herein, selenium metabolism, gene expression, interaction with sulphur, and role in cancer are reviewed.

Surface analysis and depth profiling of corrosion products formed in lead pipes used to supply low alkalinity drinking water.

Modern analytical techniques have been applied to investigate the nature of lead pipe corrosion products formed in pH adjusted, orthophosphate-treated, low alkalinity water, under supply conditions. Depth profiling and surface analysis have been carried out on pipe samples obtained from the water distribution system in Glasgow, Scotland, UK. X-ray diffraction spectrometry identified basic lead carbonate, lead oxide and lead phosphate as the principal components. Scanning electron microscopy/energy-dispersive x-ray spectrometry revealed the crystalline structure within the corrosion product and also showed spatial correlations existed between calcium, iron, lead, oxygen and phosphorus. Elemental profiling, conducted by means of secondary ion mass spectrometry (SIMS) and secondary neutrals mass spectrometry (SNMS) indicated that the corrosion product was not uniform with depth. However, no clear stratification was apparent. Indeed, counts obtained for carbonate, phosphate and oxide were well correlated within the depth range probed by SIMS. SNMS showed relationships existed between carbon, calcium, iron, and phosphorus within the bulk of the scale, as well as at the surface. SIMS imaging confirmed the relationship between calcium and lead and suggested there might also be an association between chloride and phosphorus.