The growing efficiency, and falling prices of metal detectors are becoming a problem for tourists who visit battlefields. The World War I battlefields of Europe still see several accidents a year as tourists discover, and try to recover, World War I munitions. Particularly dangerous are the thousands of chemical shells that are still out there. A new danger is looming as more tourists armed with metal detectors visit Russian World War II battlefields. The munitions here are not as old, and more likely to go off with a large bang is mishandled. Moreover, the Russian battlefields are not as well supervised as the European ones, where staff will often catch tourists before they can do something dangerous with what they've found.