![]() ![]() ![]() In Handbook of Stable Isotope Analytical Techniques, 2009 Publisher Summaryīoron has two natural stable isotopes, 10B and 11B, with an average abundance of approximately 19.9% and 80.1% respectively. While urine serves as the primary pathway for excretion of boron, bile, sweat, and exhaled breath constitute other routes of elimination. The kidneys are the primary site of homeostatic regulation of boron in the body, and at normal dietary or supplemental levels, there is no evidence for boron accumulation over time. Cessation of dietary boron results in a rapid drop in bone boron levels, with a direct relationship observed between ingestion and urinary excretion rates, which accounts for elimination of nearly 100% of the boron load. Boron metabolism in the body is not energetically feasible, with 523 kJ mol −1 energy being required to break boron–oxygen bonds. An oral dose of boron is readily and completely (approximately 95%) absorbed in humans and appears rapidly in the blood and body tissues. The decisive factor for the degree of liberation of boron from boron-containing topical products is the nature of the vehicle, with water-based vehicles resulting in higher boron levels achieved in blood and urine. ![]() While absorption through intact skin is negligible, it can occur through denuded or irritated skin. Betharia, in Encyclopedia of Toxicology (Third Edition), 2014 Toxicokineticsīoron-containing compounds can be absorbed from both the gastrointestinal and respiratory tracts, as indicated by an increase in levels of boron in the blood, tissues, or urine or by systemic toxic effects observed in the exposed individuals or laboratory animals. ![]()
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