Low doses of arsenic have broad impact on hormone activity

From Dartmouth Medical School today: investigators are learning more about how low doses of arsenic, such as the levels found in drinking water in many areas of the United States, affect human physiology. In a paper published online on Dec. 2 in the journal Chemical Research in Toxicology, the researchers report that three different steroid hormones all show similar responses to arsenic, suggesting a broader effect and a common mechanism of arsenic on how these hormones function. At very low doses (comparable to what is found in drinking water at the current and previous U.S. regulatory limits, in the range of 5-50 ppb) arsenic enhances hormone-stimulated gene expression, by two- to three-fold. At slightly higher doses (in the range of 50-200 ppb, commonly found in drinking water from contaminated wells in New Hampshire and elsewhere in the U.S.) arsenic has the exact opposite effect, strongly and almost completely inhibiting hormone-stimulated gene expression by these receptors.