Low-Dose Arsenic: In Search of a Risk Threshold

cientists long ago linked high levels of arsenic in groundwater to cancer and other environmental illnesses, particularly in Taiwan, Bangladesh, and South America, where the contamination can often reach extraordinarily high levels of 1,000 ppb or more.Now concerns are shifting to the health effects of much lower doses such as those that many Americans live with every day. Margaret Karagas, who directs the Children's Environmental Health and Disease Prevention ResearchCenter at Dartmouth College, says researchers increasingly believe that arsenic risks are more widespread than previously recognized, particularly during vulnerable periods such as pregnancy and childhood.Protecting against low-level exposure is challenging, however, given that arsenic is a natural element in the Earth's crust and ubiquitous throughout the environment.