A study scheduled for publication in the Dec. 15 issue of the American Chemical Society's journal, Environmental Science and Technology, shows that for the first time, toxic metals emitted from automotive catalytic converters have been detected in urban air in the United States. The research was done by Swedish scientists working in collaboration with researchers from the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution. The researchers found high concentrations of platinum, palladium, rhodium and osmium in air over the Boston metropolitan area. Although these particles -- known as platinum group elements -- are not yet considered a serious health risk, evidence suggests they potentially could pose a future danger as worldwide car sales increase from an estimated 50 million in 2000 to more than 140 million in 2050. Finding ways to "stabilize" these metal particles within the converters "should be a priority to limit their potential impact," says lead researcher Sebastien Rauch, Ph.D., of Chalmers University of Technology in Göteborg. In addition to the United States -- where catalytic converters were first introduced -- scientists have also detected elevated concentrations of these elements in Europe, Japan, Australia, Ghana, China and Greenland. Catalytic converters reduce emissions of carbon monoxide, hydrocarbons, nitrogen oxides and other pollutants.