Boron sources, speciation and its potential impact on health

The behaviour of boron (B) and its fate in the environment remains in many respects obscure. The major B sources and fluxes seem to have been identified, although there are many uncertainties about the magnitude and importance of each; published evaluations vary greatly. Little is known about B speciation of living matter-bearing formations, i.e. soils, natural waters, and sediments. Many authors suppose that B in nature occurs only as oxo-compounds, although, natural inorganic and organic B compounds and complexes have been described. Moreover, the most common approach to B biogeochemistry in terms of inorganic B compounds (as boric acid and borates) seems to oversimplify the matter. Data on the physiological functions of B are fragmentary and often contradictory. Some data exists on endemic symptoms and diseases among humans and grazing cattle that are supposedly triggered by B abundance in the natural environment. Unfortunately, the published data are scarce and vague. In this paper, we review the up-to date references on B sources, turnover, and speciation in the environment and the element potential impact on health.