Abandoned mines in Romania leach waters contaminated by heavy metals into rivers. A Hungarian chemical plant produces more than 100,000 tons of toxic substances a year. Soil in eastern Slovakia is contaminated with cancer-producing PCBs.

The flood of toxic sludge in Hungary is but one of the ecological horrors that lurk in Eastern Europe 20 years after the collapse of the Iron Curtain, serving as a reminder that the region is dotted with disasters waiting to happen.

Much of Eastern Europe is free of many of its worst environmental sins with the help of Western funds and conditions imposed on Hungary, Romania, Bulgaria, Slovakia and the Czech Republic in exchange for membership in the European Union....