VOA常速英语2008年-Traces of Drugs Found in US Drinking Water

An Associated Press survey shows much of the drinking water in major American cities contains traces of prescription¹ drugs.  The news service reports that researchers are unsure of the risk to humans from decades of persistent², random³ exposure to low levels of drugs.  But a U.S. environmental official tells the AP it is "a growing concern.:"  More from VOA's Carol Pearson.